Brinkman A.C., Dam J., Mels W.A. et al. Non-thermal and very high temperature phenomena in x-ray astronomy. // Roma: Univers. "La Sapienzia", Istittuto Astronomico, 1985, edited by Perola, G.C.; Salvati, M. P.263.

Van Beek et al. A MWPC read-out system with novel photon identification capabilities // 1984, IEEE Trans. Nucl. Sc. NS-31, p. 45

BREUS, TAMARA. X-ray astronomy instruments to operate on Mir station. // In its USSR Report: Space p 50-51 (SEE N88-10050 01-12) Transl. into ENGLISH from APN: Advances of Science and Technology (Moscow, USSR), no. 21, 5 Nov. 1986 p 1-3

The Soviet Salyut orbital stations were the first to carry X-ray telescopes into space. The Mir station offers still greater opportunities for astronomical observations by ensuring high guidance accuracy in the automatic regime. Even more important, it extends the period of observations without impairing other research programs. The X-ray telescopes will operate within a wide band of energies, making it possible to solve in principle astrophysical tasks unattainable for the available space-based telescopes. Equipment and instruments for the Mir X-ray observatory were developed and manufactured through the collective efforts of the Soviet Union, the Netherlands, West Germany, and the European Space Agency. The design and advantages of the telescope are discussed.

Syunyaev, R. A.; Kaniovskii, A.; Efremov, V.; Gilfanov, M.; Dhurazov, E.; Grebenev, S. A.; Kuznetsov, A. V.; Melioranskii, A. S.; Yamburenko, N. S.; Yunin, S.; Stepanov, D.; Chulkov, I.; Pappe, N.; Boyarskii, M. N.; Gavrilova, E. A.; Loznikov, V. M.; Prudkoglyad, A.; Rodin, V. G.; Reppin, C.; Pietsch, W.; Engelhauser, J.; Trumper, J.; Voges, W.; Kendziorra, E.; Bezler, M.; Staubert, R.; Brinkman, A. C.; Heise, J.; Mels, W. A.; Jager, R.; Skinner, G. K.; Al-Emam, O.; Patterson, T. G.; Willmore, A. P. Detection of Hard X-Rays from Supernova 1987A - Preliminary Mir-Kvant Results // 1987, Sov. Astron. Lett. 13, 431

SUNYAEV, R.; KANIOVSKIY, A.; EFREMOV, V.; GILFANOV, M.; CHURAZOV, E.; GREBENEV, S.; KUZNETSOV, A.; MELIORANSKIJ, A.; YAMBURENKO, N.; YUNIN, S.; STEPANOV, D.; CHULKOV, I.; PAPPE, N.; BOYARSKIY, M.; GAVRILOVA, E.; LOZNIKOV, V.; PRUDKOGLYAD, A.; DKOGLYAD, A.; RODIN, V.; REPPIN, C.; PIETSCH, W.; EUGELHAUSER, J.; TRUMPER, J.; VOGES, W.; KENDZIORRA, E.; BEZLER, M.; STAUBERT, R.; BRINKMAN, A. C.; HEISE, J.; MELS, W. A.; JAGER, R.; SKINNER, G. K.; AL-EMAM, O.; PATTERSON, T. G.; WILLMORE, A. The detection of hard X-ray emission from SN 1987A - Preliminary results from the Kvant module. // Pis'ma v Astronomicheskii Zhurnal (ISSN 0320-0108), vol. 13, Dec. 1987, p. 1027-1041. In Russian.

On August 10, 1987, instruments in the Kvant module of the Mir space station detected hard X-ray emission from SN 1987A in the LMC. Upper limits to the radiation flux in the 3-20 and 300-1000 keV regions were obtained. Upper limits were also established for the emission measure of gas heated by a shock wave, the density of the gas in front of the shock-wave front, and the mass loss rate of the presupernova several years before the star explosion. Models in which the decay of radioactive cobalt or of a young pulsar is the photon source are in the best agreement with observational data.

'HEXE' - X-ray observatory in space // Astronautik (ISSN 0004-6221), vol. 24, Apr.-June 1987, p. 41, 42. In German.

An overview is given of the design concept and scientific goals of the High-Energy X-ray Experiment (HEXE), developed in the FRG (by the Max Planck Institute for Extraterrestrial Physics and the Astronomical Institute of Tuebingen University) for operation on the Soviet space station Mir. HEXE was launched to LEO using a Kvant vehicle on March 31, 1987; after initial docking problems, it was joined to Mir by two cosmonauts in a 3-hour EVA on April 12. HEXE has dimensions 45 x 45 x 75 cm and weight 180 kg; it employs an 800-sq-cm Tl-doped NaI/CsI phoswich detector for 15-250-keV X-rays, complementing the other Mir instruments: the ESTEC high-pressure gas-scintillation proportional counter (3-100 keV), the Soviet high-energy detector (20-800 keV), and the Dutch-British X-ray camera (2-30 keV). The Mir observations are intended to explore the energy spectra and time evolution of compact galactic and extragalactic objects.

SKINNER, G. K.; PONMAN, T. J.Coded mask telescopes for X-ray astronomy.// British Interplanetary Society, Journal (Space Science) (ISSN 0007-084X), vol. 40, April 1987, p. 169-172.

The principle of the coded mask techniques are discussed together with the methods of image reconstruction. The coded mask telescopes built at the University of Birmingham, including the SL 1501 coded mask X-ray telescope flown on the Skylark rocket and the Coded Mask Imaging Spectrometer (COMIS) projected for the Soviet space station Mir, are described. A diagram of a coded mask telescope and some designs for coded masks are included.

SUNIAEV, R.; KANIOVSKII, A.; EFREMOV, V.; GILFANOV, M.; CHURAZOV, E. Discovery of hard X-ray emission from supernova 1987A //Nature (ISSN 0028-0836), vol. 330, Nov. 19, 1987, p. 227-229.

The discovery of hard X-rays from the region of the SN1987A in the LMC is reported. The observations were made from the Mir-Kvant observatory Roentgen. Hard X-rays were first observed on August 10, 1987; a total of 115 pointings on 21 days were made up to September 15, 1987. The flux showed little variation during the observation period. The measured spectrum extends from 20 keV to 300 keV and is extremely hard, having a photon power-law index of about 1.4. At low energies, the spectrum becomes even flatter, and there is indication of a cutoff between 10 and 25 keV. The luminosity over the energy range 20-300 keV is about 2 x 120 to the 38th erg/s, assuming a distance of 55 kpc. The error box for the hard source has a 2-sigma radius of 10 arcmin and contains SN1987A.

BEATTY, J. KELLY. The high-flying Kvant module. // Sky and Telescope (ISSN 0037-6604), vol. 74, Dec. 1987, p. 599-601.

The detection of X-rays from Supernova 1987A by instruments aboard the Soviet Kvant spacecraft is discussed. The Kvant module is 19 feet long and 13.6 feet across at its widest. On board are four telescopes for X-ray detection (TTM, gas-scintillation proportional counter, high-energy X-ray experiment, and Pulsar X-1) collectively weighing about 1,800 lbs. It is noted that observations are usually limited to the 20-min periods when Mir is over the equatorial region.

IAU Circ. N 4606. 1988. ASM 2000+25

R. Sunyaev and the Kvant Team, Space Research Institute, U.S.S.R. Academy of Sciences, report: "The MIR-Kvant Rontgen Observatory detected this x-ray nova on May 15 and 17 in the spectral band 4-250 keV. The Pulsar X1 Phoswich device discovered a hard power-law x-ray tail in the spectral band 20-250 keV with flux 0.5 E**-1.7 photons cm**-2 s**-1 keV**-1, where E is the photon energy measured in keV. The Hexe device discovered the same tail in the band 15-150 KeV. On May 17 the GSPC device detected the soft component of the spectrum in the band 4-15 keV. For a thermal bremsstrahlung model the best fit gives a plasma temperature of 1.86 +/- 0.05 keV. The soft component, which was reported earlier by the Ginga Team, corresponds to a luminosity of 3 x 10**36 erg/s for a distance of 1 kpc; the luminosity of the hard component is three times smaller. These values refer only to to the spectral bands mentioned above."

IAU Circ. N 4691. 1988. Supernova 1987A in the Large Magellanic Cloud

R. Sunyaev and the Kvant Team (Space Research Institute of the U.S.S.R. Academy of Sciences, Max-Planck-Institut fur Extraterrestrische Physik and Astronomisches Institut of the University of Tubingen) report: "The hard x-ray experiment HEXE on board the Kvant module of the MIR space station detected a continuous decrease of the x-ray flux from SN 1987A in the energy range 20-120 MeV from April to November. The flux in September and October was three times weaker than that observed in January, when it was at maximum. In November and December HEXE detected a further decrease of the hard x-ray flux, which is now approximately six times weaker than in January."

Syunyaev, R. A.; Gilfanov, M. R.; Churazov, E. M.; Yamburenko, N. S.; Brinkman, A. C.; Heise, J.; Intzand, J. J. M.; Jager, R.; Skinner, G. K.; Al-Emam, O.; Patterson, T. G.; Willmore, A. P. Upper Limits of the X-Ray Emission from Supernova 1987A in 2-32-KEV Energy Band in 1987 JUN/AUG // 1988, Sov. Astron. Lett. 14, 252.

Syunyaev, R. A.; Efremov, V. V.; Kaniovskii, A. S.; Stepanov, D. K.; Yunin, S. N.; Kuznetsov, A. V.; Loznikov, V. M.; Melioranskii, A. S.; Rodin, V. G.; Prudkoglyad, A. V.; Grebenev, S. A.; Reppin, C.; Pietsch, W.; Engelhauser, J.; Trumper, J.; Voges, W.; Kendziorra, E.; Bezler, M.; Staubert, R. HARD X-RAY BRIGHTENING OF SUPERNOVA 1987A - THE MIR-KVANT DATA // SOVIET ASTR. LETT.(TR:PISMA) V.14, NO. 4, P. 247, 1988

SUNYAEV, R. A.; EFREMOV, V. V.; KANIOVSKY, A. S.; STEPANOV, D. K.; YUNIN, S. N.; KUZNETSOV, A. V.; LOZNIKOV, V. M.; MELIORANSKY, A. S.; RODIN, V. G.; PRUDKOGLYAD, A. V.; GREBENEV, S. A.; REPPIN, C.; PIETCH, W.; ENGELHAUSER, J.; TRUMPER, J.; VOGES, W.; KENDZIORRA, E.; BEZLER, M.; STAUBERT, R.. The increase in the hard X-ray flux from SN 1987A detected with the Hexe and Pulsar X-1 telescopes aboard the Kvant module's Roentgen observatory // Pis'ma v Astronomicheskii Zhurnal (ISSN 0320-0108), vol. 14, July 1988, p. 579-590. In Russian.

Observations of SN 1987A carried out during August 1987-February 1988 using the Hexe and Pulsar X-1 telescopes aboard the Mir station's Kvant module revealed a significant increase in the hard X-ray flux from the supernova in the 20-400 keV range. The radiation spectrum and its rate of increase can only be explained by models associated with gamma-line Comptonization, which arises during radioactive Co-57 decay. The early appearance of Co-57 line emission and the relatively slow increase in intensity suggests either substantial Co mixing over a significant part of the ejected envelope, or significant nonspherical geometry of the supernova envelope.

Syunyaev, R. A.; Gilfanov, M. R.; Churazov, E. M.; Yamburenko, N. S.; Brinkman, A. C.; Heise, J.; Intzand, J. J. M.; Jager, R.; Skinner, G. K.; Al-Emam, O.; Patterson, T. G.; Willmore, A. P.  Stabilization of Mir-Kvant - the TTM X-Ray Data // SOVIET ASTR. LETT.(TR:PISMA) V.14, P. 296.

SIUNIAEV, R. A.; GIL'FANOV, M. R.; CHURAZOV, E. M.; IAMBURENKO, N. S.; BRINKMAN, A. C. Stabilization of the Mir-Kvant complex using data of the TTM X-ray telescope// Pis'ma v Astronomicheskii Zhurnal (ISSN, 0320- 0108), vol. 14, Aug. 1988, p. 695-705. In, Russian.

The international X-ray observatory on the Kvant module of the Mir space station has been operating since June 1987. The observation of bright X-ray sources by the TTM instrument on the Kvant module indicates that the direction to sources is held with an accuracy of about 2 arcmin in the course of about 20 min.

Sunyaev, R. A.; Gilfanov, M. R.; Churazov, E. M.; Loznikov, V. M.; Efremov, V. V.; Kaniovskii, A. S.; Kuznetsov, A. V.; Melioranskii, A. S.; Voges, W.; Pietsch, W.; Dobereiner, S.; Engelhauser, J.; Reppin, C.; Trumper, J.; Ogelman, H.; Kendizorra, E.; Mony, B.; Maisack, M.; Staubert, R.; Smith, A.; Parmar, A. N. HERCULES-X-1 Spin-Up - the KVANT Data 1987-1988 // SOVIET ASTR.LETT.(TR:PISMA) V.14, NO.6/NOV/DEC, P. 416, 1988.

SUNYAEV, R.; GILFANOV, M.; CHURAZOV, E.; LOZNIKOV, V.; EFREMOV, V.; KANIOVSKIV, A.; KUZNETSOV, A.; MELIORANSKIY, A.; VOGES, W.; PIETSCH, W.; DOEBEREINER, S.; ENGLHAUSER, J.; REPPIN, C.; TRUEMPER, J.; OEGELMAN, H.; KENDZIORRA, E.; MONY, B.; MAISACK, M.; STAUBERT, R.; SMITH, A.; PARMAR, A. N. The acceleration of the rotation of the X-ray pulsar Hercules X-1 - Results of Kvant module observations in August 1987-July 1988 // Pis'ma v Astronomicheskii Zhurnal (ISSN 0320-0108), vol. 14, Nov. 1988, p. 979 - 991. In Russian.

Using observations of the Hercules X-1 pulsation period made with the Roentgen X-ray observatory on the Kvant module between August 1987 and July 1988, the average period derivative is estimated at (-4.9 + or - 1.5) X 10 to the -6th/year. The comparison of Kvant data with previous observations shows that, between 1984 and 1988, Hercules X-1 underwent quasi-stationary acceleration similar to that observed in 1972-1978.

Syunyaev, R. A.; Lapshov, I. Y.; Grebenev, S. A.; Efremov, V. V.; Kaniovskii, A. S.; Stepanov, D. K.; Yunin, S. N.; Gavrilova, E. A.; Loznikov, V. M.; Prudkoglyad, A. V.; Rodin, V. G.; Babushkina, O. P.; Kiselev, S. V.; Kuznetsov, A. V.; Melioranskii, A. S.; Smith, A.; Parmar, A. N.; Pietsch, W.; Dobereiner, S.; Engelhauser, J.; Reppin, C.; Trumper, J.; Voges, W.; Kendziorra, E.; Maisack, M.; Mony, B.; Staubert, R. Detection of a Hard Component in the Spectrum of the Vulpecula X-Ray Nova - Preliminary KVANT Results // SOVIET ASTR.LETT.(TR:PISMA) V.14,  P. 327, 1988.

SUNYAEV, R. A.; LAPSHOV, I. YU.; GREBENEV, S. A.; EFREMOV, V. V.; KANIOVSKY, A. S.; STEPANOV, D. K.; YUNIN, S. N.; GAVRILOVA, E. A.; LOZNIKOV, V. M.; PRUDKOGLYAD, A. V.; RODIN, V. G.; BABUSHKINA, O. P.; KISELEV, S. V.; KUZNETSOV, A. V.; MELIORANSKY, A. S.; MELIORANSKY, A. S.; SMITH, A.; PARMAR, A.; PIETCH, W.; DOEBEREINER, S.; ENGLHAUSER, J.; REPPIN, C.; TRUEMPER, J.; VOGES, W.; KENDZIORRA, E.; MAISACK, M.; MONY, B.; STAUBERT, R. The detection of the hard component in the radiation spectrum of the X-ray nova in Vulpecula - Preliminary results from the Kvant module // Pis'ma v Astronomicheskii Zhurnal (ISSN 0320-0108), vol. 14, Sept. 1988, p. 771-786. In Russian.

Two components were detected in the spectrum of the X-ray nova in Vulpecula. A soft component is found to be dominant in the 4-15 keV band. A hard power law component accounts for 10 percent of the source luminosity and dominates the spectrum in the 15-200 keV band. An energy drop is observed above 200 keV.

Mels et al. A large-area position sensitive X-ray detector for astrophysical observations // 1988, Nucl. Instrum. Meth. A273, 689

MONY, BRUNO. Examination of the background by High Energy X ray Experiment (HEXE) on the space station MIR // Thesis Tuebingen Univ. (Germany). Astronomisches Inst. Publication Date: 08/1988

The last results of the HEXE mission showed considerable declinations between the known x ray source positions and the view direction of the HEXE, which reduces the photon flux from the source, significantly in some cases. For this experiment many programs were written and tested for the reduction of data. Quick-look programs are presented that allow the data acquisition. A program was developed that can give the measurement results of the housekeeping counter by way of the catalog system and gathering in plot files. An orbit program is proposed to carry out the center correction for the arrival time of the photons and to study the influences of the geomagnetic field on the background observed by HEXE.

SKINNER, G. K.; AL-EMAM, O.; BRINKMAN, A. C.; CHURAZOV, E.; GILFANOV, M. Coded mask X-ray observations of SN 1987A from Mir // Supernova 1987A in the Large Magellanic Cloud; Proceedings of the Fourth George Mason Astrophysics Workshop, Fairfax, VA, Oct. 12-14, 1987 (A89-28851 11-90). Cambridge and New York, Cambridge University Press, 1988, p. 361-365.

Observations made of the supernova SN 1987A with the TTM coded mask imaging X-ray telescope on the Mir-Kvant observatory 'Rontgen' are reported. Upper limits for the flux below 20 keV from SN 1987A are below the extrapolation of the higher energy emission observed from the region by other instruments, implying a cutoff or change of slope. Useful limits can be placed on the density of the region into which the supernova is expanding.

TRUEMPER, J.; REPPIN, C.; PIETSCH, W.; ENGLHAUSER, J.; VOGES, W. The hard X-ray spectrum of SN 1987A // Supernova 1987A in the Large Magellanic Cloud; Proceedings of the Fourth George Mason Astrophysics Workshop, Fairfax, VA, Oct. 12-14, 1987 (A89-28851 11-90). Cambridge and New York, Cambridge University Press, 1988, p. 355-360.

The discovery of hard X-rays in the energy range from 20 to 350 keV by the Hexe and Pulsar X-1 instruments on the Mir-Kvant Rontgen observatory is reported. The hard X-rays were first observed on August 10, 1987, and thereafter SN 1987A became the main target of the observatory. The measured spectrum is extremely hard. At high energies the photon spectrum has a power law index of about 1.4. At lower energies the spectrum becomes flatter and there is indication of a cut-off below 25 keV. The luminosity in the above energy band is about 2 x 10 to the 38th erg/s. The flux shows little variation between August 10 and begining of October.

IAU Circ. N 4769. 1989. A0535+26

R. Sunyaev and the Kvant Team (Space Research Institute, U.S.S.R. Academy of Sciences; Birmingham University; Netherlands Space Research Organization, Utrecht; Max-Planck-Institut fur Extraterrestrische Physik; and Astronomisches Institut, University of Tubingen) communicate: "On Apr. 8 and 9, the transient source A0535+26 was observed by the Mir-Kvant-Rontgen Observatory. The Coded Mask Imaging Spectrometer TTM has the Crab nebula in the same field- of-view. Direct comparison gives the following intensities of the transient in various bands: 2-6 keV, 0.6 Crab; 6-10 keV, 1.5 Crab; 10-16 keV, 2.5 +/- 0.2 Crab; 16-26 keV, 4.3 +/- 1 Crab. The observed energy spectrum is approximately flat in the 2- to 26-keV band. The pulsation period was 103.267 +/- 0.003 s. The average flux in six sessions over 10 hr on Apr. 9 (700 s each) did not reveal long-term flux variations > 10 in the 2- to 26-keV energy band. The hard x-ray detectors HEXE and Pulsar X-1 detected significant x-ray flux up to 100 keV. The source was 3.9 times brighter than the Crab in the 30- to 40-keV band. Figures for the range 70-100 keV were obtained using a Bremsstrahlung approximation for the observed spectrum in the band 2-100 keV."

IAU Circ. N 4800. 1989. V404 Cygni

R. Sunyaev and the Kvant Team (Space Research Institute, U.S.S.R. Academy of Sciences; Birmingham University; Netherlands Space Research Organization, Utrecht; Max-Planck-Institut fur Extraterrestrische Physik; and Astronomisches Institut, University of Tubingen) telex: "V404 Cyg = GS 2023+338 was observed several times during June 9-10 by the instruments of the Kvant module of the Mir space station. The source was localized at R.A. = 20h22m06s, Decl. = +33 42.2 (equinox 1950.0) with approximately 0'.4 error using the positions of Cygnus X-1 and Cygnus X-3 in the field-of-view of the Coded Mask Imaging Spectrometer (TTM). The star V404 Cyg is inside this error box. The source is significantly detected up to 300 keV by the HEXE and Pulsar X-1 instruments. It has a flat spectrum with a strong absorption and high energy exponential cut-off at energies > 100 keV. The source is strongly variable. Maximal detected fluxes are 0.1 Crab at 5 keV, 1.5 Crab at 20 keV, and 3.5 Crab at 100 keV."

IAU Circ. N 4839. 1989. Transient X-Ray Burster KS 1731-260.

R. Sunyaev and the Kvant Team report: "During observations of the GX 1+4 field on Aug. 16 the TTM instrument of the Mir-Kvant X-ray Observatory discovered a new transient x-ray burster at R.A. = 17h31m.1, Decl. = -26d03' (equinox 1950.0; uncertainty 1'). The persistent flux from this source in the 2-27-keV band varies from 50 to 90 mCrab, and a bremsstrahlung fit to the spectrum corresponds to temperature kT = 5 keV. During subsequent observations on Aug. 20-21 the source was also bright. Several outbursts of duration less than 15 s and averaged peak flux up to 0.6 Crab were detected during Aug. 16-21. Further analysis has revealed this source in a lower state during observations of the galactic center region on 1988 Oct. 21, the 2-27-keV flux then being 25 mCrab."

IAU Circ. N 4850. 1989. KS 1947+300.

G. K. Skinner, University of Birmingham, on behalf of the TTM/Kvant Team (Space Research Institute, USSR Academy of Sciences; University of Birmingham; Space Research Laboratory, Utrecht), writes: "A transient x-ray source, KS 1947+300, has been observed in data obtained with the TTM Coded Mask Imaging Spectrometer on Mir during the period June 8-15. The source position is R.A. = 19h47m35s.2, Decl. = +30 04'47" (equinox 1950.0), with an error circle radius of 30". A thermal bremsstrahlung fit to the spectrum gives a temperature of 9 keV with strong, low-energy absorption, consistent with obscuration by dust clouds apparent on survey plates in this direction. The mean 2- to 10-keV flux over the period of the observations was 50 mJy."

IAU Circ. N 4879. 1989. GX 1+4

G. K. Skinner, University of Birmingham, on behalf of the TTM/Kvant team (IKI, U.S.S.R. Academy of Sciences; University of Birmingham; Space Research Laboratory, Utrecht) writes: "In view of the report of radio emission from near GX 1+4 (IAUC 4871), we have obtained a new independent position for the x-ray source using data obtained with the TTM Coded Mask Imaging Spectrometer on Mir during 1989 August. The centroid of the 30"-radius error circle is R.A. = 17h28m58s.3, Decl. = -24 42'28" (equinox 1950.0). This is consistent with the Copernicus and SAS-3 positions and with the optical candidate. It lies between the two radio source positions and excludes both, so that neither can be the direct counterpart of the x-ray source. We place upper limits of 5 mJy on the 2- to 10-keV x-ray flux from the positions on IAUC 4871."

GILFANOV, M.; SUNYAEV, R.; CHURAZOV, E.; LOZNIKOV, V.; EFREMOV, V.; KANIOVSKJII, A.; KUZNETSOV, A.; YAMBURENKO, N.; MELIORANSKII, A.; SKINNER, G. K.; AL-EMAM, O.; PATTERSON, T. G.; WILLMORE, A. P.; BRINKMAN, A. C.; HEISE, J.; INTZAND, J. J. M.; JAGER, R.; VOGES, W.; PIETSCH, W.; DOEBEREINER, S.; ENGLHAUSER, J.; TRUEMPER, J.; REPPIN, C.; OEGELMAN, H.; KENDIZORRA, E.; MONY, B.; MAISACK, M.; STAUBERT, R.; PARMAR, A. N.; SMITH, A. OBSERVATIONS OF X-RAY PULSARS WITH THE RONTGEN OBSERVATORY ON THE KVAN MODULE // SOVIET ASTR.LETT.(TR:PISMA) V.15, NO. 4/JUL, P. 291, 1989.

Gilfanov, M.; Sunyaev, R.; Churazov, E.; Loznikov, V.; Efremov, V.; Kaniovskjii, A.; Kuznetsov, A.; Yamburenko, N.; Melioranskii, A.; Skinner, G. K.; Al-Emam, O.; Patterson, T. G.; Willmore, A. P.; Brinkman, A. C.; Heise, J.; Intzand, J. J. M.; Jager, R.; Voges, W.; Pietsch, W.; Doebereiner, S.; Englhauser, J.; Truemper, J.; Reppin, C.; Oegelman, H.; Kendizorra, E.; Mony, B.; Maisack, M.; Staubert, R.; Parmar, A. N.; Smith, A. OBSERVATIONS OF THE X-RAY PULSARS FROM THE KVANT MODULE // PISMA V. ASTRONOMICHESKII ZHURNAL V. 15:8, P. 675, 1989

Syunyaev, R. A.; Kaniovskii, A. S.; Efremov, V. V.; Grebenev, S. A.; Kuznetsov, A. V.; Loznikov, V. M.; Melioranskii, A. S.; Engelhauser, J.; Dobereiner, S.; Pietsch, W.; Reppin, C.; Trumper, J.; Kendziorra, E.; Maisack, M.; Mony, B.; Staubert, R. HARD X-RAY DECLINE OF SUPERNOVA 1987A IN 1988 - THE MIR / KVANT DATA // SOVIET ASTR.LETT.(TR:PISMA) V.15, NO.2/MAR,APR, P. 125, 1989.

SUNYAEV, R. A.; KANIOVSKY, A. S.; EFREMOV, V. V.; GREBENEV, S. A.; KUZNETSOV, A. V.; LOZNIKOV, V. M.; WELIORANSKY, A. S.; ENGLHAUSER, J.; DOEBEREINER, S.; PIETSCH, W.; REPPIN, C.; TRUEMPER, J.; KENDZIORRA, E.; MAISACK, M.; MONY, B.; STAUBERT, R. Decrease of the hard X-ray flux of SN 1987A - Kvant module data // Pis'ma v Astronomicheskii Zhurnal (ISSN 0320-0108), vol. 15, April 1989, p. 291-300. In Russian.

The HEXE telescope on the Kvant module detected a 6-fold decrease of the hard X-ray flux of SN 1987A in the 15-200 keV energy range during observations from April to December 1988. A slight hardening of the spectrum was also detected. The X-ray light curve can be explained by a model that assumes a homogeneous mixing of radioactive Co-56 over the envelope.

BALEBANOV, V. M. Instrumentation and methods for space exploration.// Moscow, Izdatel'stvo Nauka, 1989, 240 p. In Russian. For individual items see A91-23963 to A91-23989.

Instrumentation for investigations in the areas of space plasma physics, high-energy astrophysics, and the physics of planets and planetary atmospheres is described. Particular attention is given to the development and ground testing of such systems as the Phobos probe, the Rentgen astrophysical module on the Mir station, and the Granat astrophysical observatory.

IUNIN, S. N.; STEPANOV, D. K.; CHULKOV, I. V. Physical calibration of the Pulsar X-1/Spektr-3/IRA X-ray spectrometer of the international orbital observatory Rentgen on the Kvant module. // Instrumentation and methods for space exploration (A91-23962 08-19). Moscow, Izdatel'stvo Nauka, 1989, p. 200-212. In Russian.

MELIORANSKII, A. S.; SIUNIAEV, R. A.; SINAIKO, E. I.; GOLUBEV, S. I.; EFENDIEV, K. E. Detectors of the X-ray spectrometer Pulsar X-1 which is part of the Rentgen complex of the Kvant module. // Instrumentation and methods for space exploration (A91-23962 08-19). Moscow, Izdatel'stvo Nauka, 1989, p. 192-200. In Russian.

AREFEV, V.; BOROZDIN, K.; CHURAZOV, E.; EFREMOV, V.; GILFANOV, M.; KANIOVSKIY, A.; KUZNETSOV, A.; MELIORANSKIY, A.; SUNYAEV, R.; YAMBURENKO, N.; PIETSCH, W.; DOEBEREINER, S.; ENGLHAUSER, J.; REPPIN, C.; TRUMPER, J.; VOGES, W.; KENDZIORRA, E.; MAISACK, M.; MONY, B.; STAUBERT, R.; SKINNER, G. K.; AL-EMAM, O.; PATTERSON, T. G.; WILLMORE, A. P.; BRINKMAN, A. C.; HEISE, J.; INT-ZAND, J. J. M.; JAGER, R.X-RAY OBSERVATIONS OF GS:2023+338 BY THE KVANT MODULE // Proceedings of the 23rd. ESLAB Symposium on Two Topics in X-Ray Astronomy, held in Bologna, Italy, September 13-20, 1989. Vol. 1: X-Ray Binaries. Vol. 2: AGN and the X-Ray Background. Editors, J. Hunt, B. Battrick; Publisher, European Space Agency, ESA Publications Division, ESTEC, Noordwijk, The Netherlands, 1989. ISBN # 92-9092-026-2. LC # QB472.A1 E84 1989 v.1 and v.2. P.255, 1989

Following the discovery of GS2023+338 by Ginga, the source was detected in the 2 to 300 keV energy band by the experiments onboard the Kvant module. The source position was localized using data from the coded mask imaging spectrometer. Between Jun. 8 to Aug. 1989 a continuous decrease of X-ray luminosity and strong short time variability were detected. Timing analysis showed strong low frequency noise in the power spectrum of the source.

BORISOV, N. V.; BOCHKAREV, N. G.; GLADYSHEV, S. A.; GREBENEV, S. A.; DOLGUSHIN, A. I.; ZHEKOV, S. A.; KARITSKAYA, E. A.; KUROCHKIN, N. E.; NEIZVESTNY, S. I.; PAVLENKO, E. P. X ray nova GS 2000+25 = Nova Vul 1988: X ray and optical light curves, spectra, and model // The 23rd ESLAB Symposium on Two Topics in X Ray Astronomy. Volume 1: X Ray Binaries p 305-309 (SEE N90-25711 19-89).

The results of optical and X-ray observations of X-ray Nova Vul 1988 are presented. The observations, performed on the module Kvant, revealed a soft and a hard component of the X-ray spectrum. The discussion is carried out in the framework of the model of nonstationary disc accretion. The assumption on the disk accretion taking place onto a black hole of stellar mass is made.

EFREMOV, V. V.; GREBENEV, S. A.; KANIOVSKY, A. S.; KUZNETSOV, A. V.; LAPSHOV, I. Y.; SUNYAEV, R. A.; SMITH, A.; PARMAR, A.; DOEBEREINER, S.; ENGLHAUSER, J.; REPPIN, C.; PIETCH, W.; TRUEMPER, J.; VOGES, W.; KENDZIORRA, E.; MAISACK, M.; MONY, B.; STAUBERT, R. THE X-RAY SPECTRUM OF NOVA VULPECULAE 1988 - MIR-KVANT DATA // Proceedings of the 23rd. ESLAB Symposium on Two Topics in X-Ray Astronomy, held in Bologna, Italy, September 13-20, 1989. Vol. 1: X-Ray Binaries. Vol. 2: AGN and the X-Ray Background. Editors, J. Hunt, B. Battrick; Publisher, European Space Agency, ESA Publications Division, ESTEC, Noordwijk, The Netherlands, 1989. ISBN # 92-9092-026-2. LC # QB472.A1 E84 1989 v.1 and v.2. P. 15, 1989.

The X-ray spectrum of the two components, detected in Vulpeca GS 2000+25, are presented. Two components of X-ray spectrum were detected: a soft component with a temperature of 20 million Kelvin and a hard component up to the energy 200 to 300 keV. Soft component dominates in the 4 to 15 keV band and contains 90 percent of the source luminosity.

GILFANOV, M.; SUNYAEV, R.; CHURAZOV, E.; LOZNIKOV, V.; EFREMOV, V.; KANIOVSKIY, A.; KUZNETSOV, A.; YAMBURENKO, N.; MELIORANSKIY, A.; SKINNER, G. K.; AL-EMAM, O.; PATTERSON, T. G.; WILLMORE, A. P.; BRINKMAN, A. C.; HEISE, J.; INT-ZAND, J. J. M.; JAGER, R.; PIETSCH, W.; DOEBEREINER, S.; ENGLHAUSER, J.; REPPIN, C.; TRUEMPER, J.; VOGES, W.; KENDZIORRA, E.; MAISACK, M.; MONY, B.; STAUBERT, R.; PARMAR, A. N.; SMITH, A. OBSERVATIONS OF THE X-RAY PULSARS FROM THE KVANT MODULE // Proceedings of the 23rd. ESLAB Symposium on Two Topics in X-Ray Astronomy, held in Bologna, Italy, September 13-20, 1989. Vol. 1: X-Ray Binaries. Vol. 2: AGN and the X-Ray Background. Editors, J. Hunt, B. Battrick; Publisher, European Space Agency, ESA Publications Division, ESTEC, Noordwijk, The Netherlands, 1989. ISBN # 92-9092-026-2. LC # QB472.A1 E84 1989 v.1 and v.2. P. 71, 1989

The results of observations of the following X-ray pulsars are discussed: Cen X-3, SMCX-1, Her X-1, Vela X-1, A0535+26, 4U 1626-67 and GX 1+4. The observations were performed by the instruments onboard Kvant module from 1987 to 1989. The pulsation period measurements are presented and the values of the periods are reduced to the solar system baricenter and (except in the case of A0535+26 and 4U 1626-67) to the binary system baricenter.

SUNYAEV, R.; CHURAZOV, E.; GILFANOV, M. R.; YAMBURENKO, V. LOZNIKOV N.; SKINNER, G. K.; PATTERSON, T. G.; WILLMORE, A. P.; EMAM, O.; BRINKMAN, A. C.; HEISE, J.; INT-ZAND, J. J. M.; JAGER, R. X-RAY OBSERVATIONS OF THE LARGE MAGELLANIC CLOUD FIELD BY THE TTM INSTRUMENT ON BOARD THE KVANT MODULE - 1988NOV - 1989JUN // Proceedings of the 23rd. ESLAB Symposium on Two Topics in X-Ray Astronomy, held in Bologna, Italy, September 13-20, 1989. Vol. 1: X-Ray Binaries. Vol. 2: AGN and the X-Ray Background. Editors, J. Hunt, B. Battrick; Publisher, European Space Agency, ESA Publications Division, ESTEC, Noordwijk, The Netherlands, 1989. ISBN # 92-9092-026-2. LC # QB472.A1 E84 1989 v.1 and v.2. P.633, 1989

The results of the Large Magellanic Cloud (LMC) observations in the 2 to 30 keV band by the coded mask imaging spectrometer instrument of the Mir-Kvant X ray observatory are presented. The observations were performed during the period Nov. 1988 to Jun. 1989. An upper limit on the flux from supernova SN1987A is found to be 0.6 mCrab in this band. The results of monitoring and spectral observations of LMC X-1, LMC X-2, LMC X-3, LMC X-4 and PSR0540-693 are given.

SUNYAEV, R.; EFREMOV, V.; KANIOVSKY, A.; GREBENEV, S.; REPPIN, C.; PIETSCH, W.; ENGLHAUSER, J.; TRUMPER, J.; VOGES, W.; KENDZIORRA, E.; STAUBERT, R. UPPER LIMITS ON 57/CO ABUNDANCE IN SUPERNOVA 1987A ACCORDING TO KVANT DATA // Proceedings of the 23rd. ESLAB Symposium on Two Topics in X-Ray Astronomy, held in Bologna, Italy, September 13-20, 1989. Vol. 1: X-Ray Binaries. Vol. 2: AGN and the X-Ray Background. Editors, J. Hunt, B. Battrick; Publisher, European Space Agency, ESA Publications Division, ESTEC, Noordwijk, The Netherlands, 1989. ISBN # 92-9092-026-2. LC # QB472.A1 E84 1989 v.1 and v.2. P.171, 1989

Seven hard X-ray spectra of SN1987A obtained at different times by instruments onboard Kvant module are presented. During June observations the flux from the supernova was not detected. Only three sigma limits are presented. The 50-millisecond pulsar PSR 0540-693 and LMC X-1 were also in the field of view of HEXE instrument during the June observations.

SUNYAEV, RASHID A.; CHURAZOV, E.; GILFANOV, M. R.; LOZNIKOV, V.; YAMBURENKO, N.; SKINNER, G. K.; PATTERSON, T. G.; WILLMORE, A. P.; EMAM, O.; BRINKMAN, A. C. A new transient X ray burst source near GX 1+4 // The 23rd ESLAB Symposium on Two Topics in X Ray Astronomy. Volume 1: X Ray Binaries p 641-646 (SEE N90-25711 19-89).

The observations of the GX1+4 field on Aug. 16 1989 are reported. During these observations, the cooled mask imaging spectrometer instrument of the Mir-Kvant observatory discovered a new transient X ray burster. The persistent flux in the 2 to 27 keV band from this source varied from 50 to 100 millicrabs. Several bursts with durations of 10 to 20 s and peak flux up to 0.6 Crab were detected in the period from 16 to 31 Aug.

CARLI, RAFFAELLO. High energy x ray observations on the Crab nebula and the double star source GX 1+4 // Ph.D. Thesis Tuebingen Univ. (Germany, F.R.). Fakultaet fuer Physik.

With help of the data from the HIBAU 86 experiment and the High Energy X-ray Experiment onboard the Soviet space station MIR, an experiment of the period development of the galactic double star source GX 1+4 was carried out. This source is characterized by its spin-up time scale of 50 years instead of the usual 1,000 years for an x ray pulsar. Because of the long period, it was considered as a sample example for a slow rotator, that was a long way from a theoretically predicted equilibrium state (between accelerating and braking-torques). These new measurements and those that were made with the Japanese x ray satellite GINGA, give the assumption that GX 1+4 is much nearer to an equilibrium state than it was previously believed. By taking the Ghoshand Lamb theory into account, it can be established that the magnetic field of the neutron stars is 100 Teragauss strong.

DOEBEREINER, S.; ENGLHAUSER, J.; PIETSCH, W.; REPPIN, C.; TRUEMPER, J.; KENDZIORRA, E.; MAISACK, M.; MONY, B.; STAUBERT, R.; EFREMOV, V. V. Observations of black hole candidates with the Mir-Kvant HEXE // Contributions of the X Ray Astronomy Group of the Max-Planck-Institut fuer Extraterrestrische Physik p 5-10 (SEE N90-24196 17-89)

The spectra and light curves, obtained with improved data processing techniques, of black hole candidates are presented. The three black hole candidates Cygnus X-1.GX339-4, and the x ray transient source GS2000+25 were observed with the High Energy X ray Experiment (HEXE) aboard the Soviet space station MIR. The spectra of Cygnus X-1 and GS2000+25 in the energy range from 30 to 180 keV deviate significantly from simple power laws and are compatible with either thermal bremsstrahlung from a hot and optically thin plasma or low energy photons comptonized to high x ray energies in a hot plasma cloud.

DOBEREINER, S.; ENGLHAUSER, J.; PIETSCH, W.; REPPIN, C.; TRUMPER, J.; KENDZIORRA, E.; MAISACK, M.; MONY, B.; STAUBERT, R.; EFREMOV, V. V.; KANIOVSKY, A. S.; KUZNETSOV, A. V.; SUNYAEV, R. A. OBSERVATIONS OF BLACK-HOLE CANDIDATES WITH THE MIR-KVANT HEXE // Proceedings of the 23rd. ESLAB Symposium on Two Topics in X-Ray Astronomy, held in Bologna, Italy, September 13-20, 1989. Vol. 1: X-Ray Binaries. Vol. 2: AGN and the X-Ray Background. Editors, J. Hunt, B. Battrick; Publisher, European Space Agency, ESA Publications Division, ESTEC, Noordwijk, The Netherlands, 1989. ISBN # 92-9092-026-2. LC # QB472.A1 E84 1989 v.1 and v.2. P.387, 1989.

The three black hole candidates Cygnus X-1, GX339-4, and the X-ray transient source GS2000+25 were observed with the High Energy X-ray Experiment (HEXE) aboard the Soviet Space Station Mir. The spectra and light curves obtained with improved data processing techniques are presented. The spectra of Cygnus X-1 and GS2000+25 in the energy range from 30 to 180 keV deviate from simple power laws and are compatible with either thermal bremsstrahlung from a hot and optically thin plasma or low energy photons comptonized to high X-ray energies in a hot plasma cloud.

ENGLHAUSER, J.; DOEBEREINER, S.; PIETSCH, W.; REPPIN, C.; TRUEMPER, J.; KENDZIORRA, E.; MAISACK, M.; MONY, B.; STAUBERT, R.; EFREMOV, V. V. Mir-Kvant-Hexe hard x ray light curve of SN 1987A // Contributions of the X Ray Astronomy Group of the Max-Planck-Institut fuer Extraterrestrische Physik p 1-4 (SEE N90-24196 17-89).

The observations of supernova 1987A, performed by High Energy X ray Experiment (HEXE) on board of the Mir-Kvant module, are reported. A total observation time of 530,000 s was spent on that target, and data are available from day 144 to 843 after the outburst. Comparison with published results, data from four detectors, and improved background subtraction method are considered. A final energy calibration is established. Hard x ray flux from SN 1987A are discovered. X ray light curves are presented in three energy bands, extending the time coverage to June 1989. The new results confirm the results published.

ENGLHAUSER, J.; DOBEREINER, S.; PIETSCH, W.; REPPIN, C.; TRUMPER, J.; KENDZIORRA, E.; MAISACK, M.; MONY, B.; STAUBERT, R.; EFREMOV, V.; KANIOVSKY, A.; KUZNETSOV, A.; SUNYAEV, R.MIR-KVANT HEXE HARD X-RAY LIGHTCURVE OF SUPERNOVA 1987A // Proceedings of the 23rd. ESLAB Symposium on Two Topics in X-Ray Astronomy, held in Bologna, Italy, September 13-20, 1989. Vol. 1: X-Ray Binaries. Vol. 2: AGN and the X-Ray Background. Editors, J. Hunt, B. Battrick; Publisher, European Space Agency, ESA Publications Division, ESTEC, Noordwijk, The Netherlands, 1989. ISBN # 92-9092-026-2. LC # QB472.A1 E84 1989 v.1 and v.2. P.397, 1989.

The observations of the supernova 1987A by the High Energy X-ray Experiment (HEXE) on board the Mir-Kvant module are discussed. A total observation time of 530000s was spent on that target, and data are available from day 144 to 843 after the outburst. Four detectors and an improved background subtraction method were used and a final energy calibration was established. A hard X-ray flux from SN 1987A already on day 144 was discovered. X-ray light curves are presented in three energy bands, extending the time coverage to June 1989. The new results confirm the results published earlier.

INT-ZAND, J. J. M.; PATTERSON, T. G.; BRINKMAN, A. C.; HEISE, J.; JAGER, R.; SKINNER, G. K.; WILLMORE, A. P.; AL-EMAM, O.; SUNYAEV, R.; CHURAZOV, E.; GILFANOV, M. R.; YAMBURENKO, N. TTM / KVANT OBSERVATIONS OF THE GALACTIC PLANE // Proceedings of the 23rd. ESLAB Symposium on Two Topics in X-Ray Astronomy, held in Bologna, Italy, September 13-20, 1989. Vol. 1: X-Ray Binaries. Vol. 2: AGN and the X-Ray Background. Editors, J. Hunt, B. Battrick; Publisher, European Space Agency, ESA Publications Division, ESTEC, Noordwijk, The Netherlands, 1989. ISBN # 92-9092-026-2. LC # QB472.A1 E84 1989 v.1 and v.2. P.693, 1989

A preliminary analysis of observations obtained on the galactic plane with the TTM X ray widefield camera (coded mask imaging spectrometer) in Kvant relealed in addition to 29 known sources the probable existence of four unknown sources, KS1731-261, KS1724-356, KS1632-477 and KS1739-304. The accuracy of the position of two known X ray sources could be improved: 4U1708-40 and GS1826-24.

KENDZIORRA, E.; MONY, B.; MAISACK, M.; STAUBERT, R.; DOEBEREINER, S.; ENGLHAUSER, J.; PIETSCH, W.; REPPIN, C.; TRUEMPER, J.; EFREMOV, V. V. Hard X ray pulses from Vela X-1 // The 23rd ESLAB Symposium on Two Topics in X Ray Astronomy. Volume 1: X Ray Binaries p 467-471 (SEE N90-25711 19-89).

The high mass X-ray binary Vela X-1 (4U 0900-40) was observed with the high energy X-ray experiment on board the Kvant module in Nov. 1988 and Feb. 1989 for a total of 8 hours. Individual pulses during an active state were observed up to 70 KeV. The time averaged spectra for four binary phases were fitted with a power law plus exponential cutoff. During the flare state at binary phase 0.16 the spectrum is slightly softer. In all but the flare observation a significant excess flux between 70 and 96 KeV is observed. The spectral feature can be fitted with an emission line around 85 KeV, possibly a cyclotron line. The observed width is consistent with the energy resolution of the detector.

MAISACK, M.; KENDZIORRA, E.; MONY, B.; STAUBERT, R.; DOEBEREINER, S.; ENGLHAUSER, J.; PIETSCH, W.; REPPIN, C.; TRUEMPER, J.; EFREMOV, V. V. Hard X ray observations of AGN // The 23rd ESLAB Symposium on Two Topics in X Ray Astronomy. Volume 2: AGN and the X Ray Background p 975-979 (SEE N90-25841 19-89).

Preliminary spectral results of hard X-ray observations (20 to 200 keV) of Active Galactic Nuclei (AGN) are presented. The observations were performed with the High Energy X-ray Experiment (HEXE) instrument of the Kvant module docked to the Soviet Space Station Mir. Three AGNs were observed: 3C 273, Cen A and NGC4151. Power law fits to the data gave the following results: for 3C 273, the photon index was 1.49 + or - 0.11, the intensity was (6.93 + or - 0.29) x 0.00001 photons/sq cm sec keV. For Cen A, the best fit photon index was about 1.6 for two observations about a year apart. The intensity increased by a factor of at least 1.7 between the two observations. For NGC4151, no change in spectral shape was found between November 1987 and January 1989. A common fit gave the photon index of 1.54 + or - 0.11. The intensity can only be determined for the November 87 data. The 50 keV intensity was found to be (5.72 + or - 0.29) x 0.00001 photons/sq cm sec keV.

MONY, B.; KENDZIORRA, E.; MAISACK, M.; STAUBERT, R.; DOBEREINER, S.; ENGLHAUSER, J.; PIETSCH, W.; REPPIN, C.; TRUMPER, J.; KANIOVSKY, V. EFREMOV S.; KUZNETSOV, A.; SUNYAEV, R.HIGH ENERGY X-RAY OBSERVATIONS OF GX:1+4 WITH HEXE // Proceedings of the 23rd. ESLAB Symposium on Two Topics in X-Ray Astronomy, held in Bologna, Italy, September 13-20, 1989. Vol. 1: X-Ray Binaries. Vol. 2: AGN and the X-Ray Background. Editors, J. Hunt, B. Battrick; Publisher, European Space Agency, ESA Publications Division, ESTEC, Noordwijk, The Netherlands, 1989. ISBN # 92-9092-026-2. LC # QB472.A1 E84 1989 v.1 and v.2. P.541, 1989

Two observations with the High Energy X ray Experiment (HEXE) on board the Soviet Kvant module and performed on the X ray pulsar GX 1+4(4U1728-24) are reported. During the first observation on Oct. 31, 1987 the luminosity in the energy range 20 to 60 keV was 2 x 10 (exp 37) erg/sec. For the second observation, lasting from 23 to 27 Sep. 1988 there is no reliable aspect information available. The phase averaged spectra of both observations are well fitted by a thermal bremsstrahlung. A comparison to spectra, gained during the high state of GX 1+4, shows that the spectrum is now significantly harder. The timing analysis using an epoch folding method allowed obtaining of pulsational periods. The pulse periods fit well together with periods determined by Ginga, defining a long term spin down of GX 1+4.

PATTERSON, T. G.; SKINNER, G. K.; WILLMORE, A. P.; EMAM, O.; BRINKMAN, A. C.; HEISE, J.; INTZAND, J. J. M.; JAGER, R.; SUNYAEV, RASHID A.; CHURAZOV, E. Identification of galactic bulge X ray bursts with persistent X ray counterparts // The 23rd ESLAB Symposium on Two Topics in X Ray Astronomy. Volume 1: X Ray Binaries p 567-572 (SEE N90-25711 19-89).

Details of five X ray bursts seen during a survey of the galactic bulge are presented. They were made with the coded-mask imaging X ray spectrometer between Oct. 1988 and Apr. 1989. The bursts are shown to originate from the previously known burst sources 1702-429, 1728-337 and from close to SLX1744-299. The results which showed that there are in fact two adjacent sources, SLX1744-299 and SLX1744-300, and that it is the latter which is a burst source, are confirmed.

IAU Circ. N 5104. 1990. GX 1+4, KS 1731-260, GRS 1741.9-2853, A1524-62

R. Sunyaev, on the behalf of the Granat team (Space Research Institute, Moscow; Centre d'Etude Spatiale des Rayonnements, Toulouse; Service d'Astrophysique, Centre d'Etudes Nucleaires de Saclay, Gif sur Yvette), reports: "The field of the well-known pulsar GX 1+4 was observed with the Granat observatory on Aug. 23. The pulsations with period 114.60 +/- 0.05 s (at solar barycenter) were detected both by ART-P (2-60 keV) and SIGMA (> 35 keV) instruments. Comparison with the Mir-Kvant measurements in 1988 yields the following value of the average spindown rate during the elapsed period: P-dot/P = 1.0 x 10E-2 yrE-1. This value is remarkably lower than that observed with Ginga and Kvant in 1987- 1988 (P-dot/P = 1.3 x 10E-2 yrE-1). The source luminosity (3-20 keV) was found to be (2.3 +/- 0.2) x 10E36 erg/s (for distance 8.5 kpc).

In the same field, ART-P detected the transient x-ray burster KS 1731-260 (IAUC 4839), with the 3- to 20-keV luminosity being 1.2 x 10E37 erg/s (for distance 8.5 kpc). During these observations, the source was two times weaker than during Apr. 4 Granat observations (the 3- to 20-keV luminosity being 2.1 x 10E37 erg/s) and similar to that observed in 1989 Aug.-Sept. by Mir-Kvant (the 3- to 20-keV luminosity being 1.5 x 10E37 erg/s).

Further analysis of 1990 Mar. 24 and Apr. 8 observations of the Galactic Center by ART-P (IAUC 5032) improves the error box of x-ray source to within 10' of Sgr A. Previously this source was tentatively identified with 1E 1741.7-2850. Now the 99-percent- confidence error circle (1'.6 radius) does not overlap with error boxes of 1E 1741.7-2850 and GS 1741.2-2859/GS 1741.6-289. The coordinates of the new transient x-ray source GRS 1741.9-2853 (GRanat Source) are: R.A. = 17h41m52s, Decl. = -28 52'55" (equinox 1950.0). The 4- to 20-keV averaged luminosity of this source was 1.3 x 10E36 erg/s (for distance 8.5 kpc). A bremsstrahlung fit to the spectrum gives a temperature of 8 keV.

BORORDIN, K.; GILFANOV, M.; SUNYAEV, R.; CHURAZOV, E.; LOZNIKOV, V.; YAMBURENKO, N.; SKINNER, G. K.; PATTERSON, T. G.; WILLMORE, A. P.; EMAM, O.; BRINKMAN, A. C.; HEISE, J.; IN'TZAND, J. J. M.; JAGER, R. A new transient X-ray source KS 1947 + 300 in the Cygnus constellation // Sov. Astron. Lett.  (ISSN 0320-0108), vol. 16, Sept. 1990, p. 345.

It is reported that a new transient X-ray source, KS 1947 + 300, was discovered through observations of the GS 2023 + 338 field. The observations took place on June 8, 1989. The average flux in the 2 - 27 keV band was equal to 70 + or - 10 mCrab at that time. Thereafter the flux from the source decreased and, by August 19, the upper limit (3 sigma) of the flux measured 10 mCrab.

SUNYAEV, R.; GILFANOV, M.; CHURAZOV, E.; LOZNIKOV, V.; YAMBURENKO, N.; SKINNER, G. K.; PATTERSON, T. G.; WILLMORE, A. P.; EMAM, O.; BRINKMAN, A. C.; HEISE, J.; IN'T ZAND, J. J. M.; JAGER, R. A new transient X-ray burster KS 1731-260. // Sov. Astron. Lett.  (ISSN 0320-0108), 1990, vol. 16, p. 59.

A new transient X-ray burster, KS (Kvant Source) 1731-260, was discovered by the TTM instrument on the Kvant X-ray observatory during observations of the GX 1 + 4 field on August 16, 1989. The persistent flux in the 2-27 keV band from this source varied from 50 to 100 mCrab. Several bursts with durations of 10-20 sec and a peak flux up to 0.6 Crab were detected in the period from August 16 to 31.

Р.Сюняев, М.Гильфанов, Е.Чуразов и др. Новый рентгеновский транзиентный барстер KS 1731-260.  // Письма в астрон. журнал, 1990, Т. 16, 2, С. 136.

Во время наблюдений площадки неба, содержащей известный рентгеновский пульсар GX 1+4, 16 августа 1989 г. телескопом ТТМ на модуле "Квант" космической станции "Мир" был открыт новый рентгеновский транзиентный барстер Kvant Source (KS) 1731-260. Поток от источника в спокойном состоянии в диапазоне 2-27 кэВ изменялся от 50 до 100 мКраб. Во время наблюдений с 16 по 31 августа 1989 г. было зарегистрировано несколько всплесков рентгеновского излучения от этого источника продолжительностью 10 - 20 с и потоком в пике до 0.6 Краб.

SUNYAEV, R.; GILFANOV, M.; CHURAZOV, E.; LOZNIKOV, V.; YAMBURENKO, N.; SKINNER, G. K.; PATTERSON, T. G.; WILLMORE, A. P.; EMAM, O.; BRINKMAN, A. C.; HEISE, J.; IN'T ZAND, J. J. M.; JAGER, R. X-ray observations of the Large Magellanic Cloud by the TTM telescope on the Quant module during November 1988 - June 1989 // Sov. Astron. Lett.  (ISSN 0320-0108), vol. 16, Feb. 1990, p. 55.

Results of LMC observations in the 2-27 keV band on the Kvant X-ray observatory are presented. The flux from SN 1987A is found to be 0.6 mCrab in this band. Spectral observations of LMC X-1, LMC X-2, LMC X-3, and PSR 0540-693 are reported.

Syunyaev, R. A.; Kaniovskii, A. S.; Efremov, V. V.; Grevenev, S. A.; Kuznetsov, A. V.; Engelhauser, J.; Doebereiner, S.; Pietsch, W.; Reppin, C.; Truemper, J.; Kendziorra, E.; Maisack, M.; Mony, B.; Staubert, R. Hard X-Radiation from Supernova 1987A - Roentgen Observatory Observations from 1987 TO 1989 // Sov. Astron. Lett.  (ISSN 0320-0108), 1990, vol. 16, p. 171.

Observations performed with the Hexe instrument onboard the Kvant module indicate that, by May-June 1989, the hard X-ray flux from SN1987 had declined by more than a factor of 8 compared with the maximum of the X-ray light curve. The upper limits to the Co-57/Co-56 abundance ratio at the level of three standard deviations was obtained. The value of this ratio exceeds that of the Fe-57/Fe-56 ratio on earth by a factor of 1.5.

Р.А.Сюняев, А.С. Каниовский, В.В. Ефремов и др. Жесткое рентгеновское излучение от сверхновой 1987А. Результаты наблюдений обсерватории "Рентген" на модуле "Квант" в 1987-1989 гг.  // Письма в астрон. журнал, 1990, Т. 16, 5, С. 403.

Подводятся итоги двухлетних наблюдений жесткого рентгеновского излучения сверхновой 1987А прибором ГЕКСЕ обсерватории "Рентген" на модуле "Квант". К маю - июню 1989 г. поток жесткого излучения упал более чем в 8 раз по сравнению с потоком в максимуме кривой рентгеновского блеска. Найден верхний предел соотношения обилий Со-57/Со-56 на уровне трех стандартных отклонений. Он в 1.5 раза превышает отношение обилий Fe-57/Fe-56 на Земле.

SIUNIAEV, R. A.; CHURAZOV, E.; EFREMOV, V.; GIL'FANOV, M.; GREBENEV, S. Highlights from the Kvant mission // (COSPAR, International Academy of Astronautics, and IAU, Plenary Meeting, 27th, Symposium on X-ray and Gamma-ray Astronomy, 14th, Espoo, Finland, July 18-29, 1988) Advances in Space Research (ISSN 0273-1177), vol. 10, no. 2, 1990, p. 41-46.

The Roentgen international X-ray observatory aboard the Kvant module was launched by the Proton rocket and docked to the Mir space station in order to perform X-ray observations. The instruments involved in the Roentgen are listed and a cyclogram of the observations is given. Findings that have been made concerning the LMC field, the discovery of a hard component in the X-ray spectrum of the ASM 2000+25 transient, the Crab Nebula, extragalactic sources, pulse-timing observations of Her X-1, and gamma bursts are reviewed.

SIUNIAEV, R. A.; EFREMOV, V.; KANIOVSKII, A.; STEPANOV, D.; UNIN, S. Hard X-rays from supernova 1987A // (COSPAR, International Academy of Astronautics, and IAU, Plenary Meeting, 27th, Symposium on X-ray and Gamma-ray Astronomy, 14th, Espoo, Finland, July 18-29, 1988) Advances in Space Research (ISSN 0273-1177), vol. 10, no. 2, 1990, p. 47-53.

On August 10, 1987 the HEXE instrument on the Mir-Kvant observatory Roentgen detected hard X-ray emission from the region of SN 1987A in the 20-100-keV spectral band at a 10-standard-deviation level. From then on SN 1987A became the main observation target. During the August observations, the Pulsar X-1 instrument detected a significant X-ray flux from the region of the SN in the 50-300-keV energy band. The HEXE data allowed an accurate localization of the hard X-ray source, and the calculated position coincides well with that of SN 1987A.

MONY, B. ET AL. Hard X-ray observations of Vela X-1 with HEXE. // Astron. Gesellschaft Abstract Ser., 4, 51 (1990)

MONY, B.; KENDZIORRA, E.; MAISAK, M. ET AL. High energy X-ray observations of GX 1+4 HEXE.// Astron. Gesellschaft Abstract Ser., 4, 50 (1990)

Syunyaev, R.; Gilfanov, M.; Churazov, E.; Pavlinskii, M.; Babalyan, G.; Dekhanov, I.; Kuznetsov, A.; Grebenev, S.; Yunin, S.; Yamburenko, N.; Cordier, B.; Lebrun, F.; Laurent, P.; Ballet, J.; Mandrou, P.; Roques, J. P.; Vedrenne, J.; Boucher, L. Two hard X-ray sources near the galactic center: the known source 1E1740.7-2942 and the newly discovered source GRS 1758-258 // 1991, Sov. Astron. Lett. 17, 50

Syunyaev, R. A.; Arefev, V. A.; Borozdin, K. N.; Gilfanov, M. R.; Efremov, V. V.; Kaniovskii, A. S.; Churazov, E. M.; Kendziorra, E.; Mony, B.; Kretschmar, P.; Maisack, M.; Staubert, R.; Dobereiner, S.; Englhauser, J.; Pietsch, W.; Reppin, C.; Trumper, J.; Skinner, G. K.; Nottingham, M. R.; Pan, H.; Willmore, A. P. Broadband X-Ray Spectra of Black-Hole Candidates X-Ray Pulsars and Low-Mass Binary X-Ray Systems - KVANT Module Results // SOVIET ASTR.LETT.(TR:PISMA) V.17, NO. 6/NOV, P. 409, 1991.

SUNYAEV, R.; AREFEV, V.; BOROZDIN, K.; GILFANOV, M.; EFREMOV, V.; KANIOVSKY, A.; CHURAZOV, E.; KENDZIORRA, E. ET AL. Broadband X-ray spectra of black hole candidates, X-ray pulsars, and low-mass X-ray binaries - Results from the Kvant module // Pis'ma v Astronomicheskii Zhurnal  (ISSN 0320-0108), vol. 17, Nov. 1991, p. 127. In Russian.

The broadband spectra of the brightest X-ray sources observed by the TTM, Hexe, and Pulsar X-1 devices of the Kvant module are discussed. They demonstrate the differences in the hardness of the spectra of neutron stars with a weak magnetic field, namely, Sco X-1, X-ray pulsars A0535 + 26, Vela X - 1, LMC X - 4, and the black hole candidates Cyg X - 1, GS2023 + 338, GS2000 + 25, and 3C273.

Syunyaev, R.; Borozdin, K.; Gilfanov, M.; Efremov, V.; Kaniovskii, A.; Churazov, E.; Skinner, G. K.; Al-Emam, O.; Patterson, T. G.; Willmore, A. P.; Brinkman, A. C.; Heise, J.; Int-Zand, J. J. M.; Jager, R.; Voges, W.; Pietsch, W.; Doebereiner, S.; Engelhauser, J.; Trumper, J.; Reppin, C.; Kendziorra, E.; Mony, B.; Maisack, M.; Staubert, R. Anomalously Hard Spectrum from the Source 1E:1740.7-294 - Data from the Rontgen Observatory on the KVANT Module // SOVIET ASTR.LETT.(TR:PISMA) V.17, P. 54, 1991.

SUNYAEV, R.; BOROZDIN, K.; GILFANOV, M. ET AL. Anomalously hard spectrum of 1E1740.7-294 according to data from the Rentgen observatory on the Kvant module//Pis'ma v Astronomicheskii Zhurnal  (ISSN 0320-0108), vol. 17, Feb. 1991, p. 126-134. In Russian.

Observations with the Granat X-ray observatory have demonstrated that hard X-ray emission from the Galactic Center region is dominated by 1E1740.7-294. Results of observations of this source with the TTM and HEXE instruments on the Kvant module in 1989 are presented here.

Syunyaev, R. A.; Kaniovskii, A. S.; Efremov, V. V.; Arefev, V. A.; Borozdin, K. N.; Gilfanov, M. R.; Churazov, E. M.; Kuznetsov, A. V.; Melioranskii, A. S.; Yamburenko, N. S.; Pietsch, W.; Dobereiner, S.; Englhauser, Y.; Reppin, C.; Trumper, J.; Voges, W.; Kendziorra, E.; Maisack, M.; Mony, B.; Staubert, R.; Skinner, G. K.; Nottingham, M. R.; Pan, H.; Willmore, A. P.; Brinkman, A. C.; Heise, J.; Int-Zand, J. M.; Jager, R. ROENTGEN OBSERVATIONS OF THE X-RAY NOVA GS:2023+338 // SOVIET ASTR.LETT.(TR:PISMA) V.17, NO. 2/MAR, P. 123, 1991.

SUNYAEV, R.; KANIOVSKIJ, A.; EFREMOV, V.; AREFEV, V.; BOROZDIN, K.; GILFANOV M. Observations of the X-ray nova GS2023 + 338 by the Roentgen observatory on board the Kvant module // Pis'ma v Astronomicheskii Zhurnal (ISSN 0320-0108), vol. 17, April 1991, p. 291-309. In Russian.

During observations made by the Roentgen observatory on board the Kvant module from June to August 1989, an X-ray spectrum of the X-ray nova GS2023 + 338 was detected in the energy band 2-300 keV. The source position was localized with an accuracy of 25 arcsec. The continuous decrease of X-ray luminosity, common to all X-ray novae, and strong chaotic variability were detected during the observations. The hard X-ray spectrum and low frequency noise detected permit this source to be classified as a black hole candidate. The spectra measured are the hardest X-ray spectra ever in the history of X-ray astronomy. The source luminosity in the 2-300 keV energy band was found, on June 10, to be 8 x 10 to the 36th (D/kpc)-squared erg/s where D is the distance to the source in kpc.

SKINNER, G. K.; PAN, H. C.; MAISACK, M.; STAUBERT, R.; BOROZDIN, K. N.; BRINKMAN, A. C.; ENGLHAUSER, J.; GILFANOV, M. R.; KANIOVSKY, A. C.; PIETSCH, W.; SUNYAEV, R. A.; IN'T ZAND, J. J. M. The spectrum and position of the hard Galactic centre source 1E1740.7 - 2942 // Astronomy and Astrophysics (ISSN 0004-6361), vol. 252, no. 1, Dec. 1991, p. 172-178.

Observations of the remarkable hard Galactic center X-ray and gamma-ray source 1E1740.7 - 2942 made with the TTM and HEXE experiments of the Roentgen observatory on the Kvant module are presented. The spectrum can be well described by a hard power-law with a high-energy cutoff and absorption at low energies. Similarities to the spectra of Cyg X-1 and other black hole candidates suggest that 21E1740.7 - 2942 may also be a black hole binary. The position of this source has been determined with an uncertainty of 12 arcsec, a significant improvement on the precision of earlier measurements.

GILFANOV, M.; SUNYAEV, RASHID A.; CHURAZOV, E.; LOZNIKOV, V.; EFREMOV, V. V.; KANIOVSKIY, A.; KUZNETSOV, A. V.; YAMBURENKO, N.; MELIORANSKIY, A.; SKINNER, G. K. Observations of x ray pulsars from the Kvant module // In NAS-NRC, High-Energy Astrophysics. American and Soviet Perspectives p 134-143 (SEE N92-12933 03-90).

The Roentgen international x ray observatory on the Kvant module of the Mir space station has been successfully operating since the beginning of June 1987. Many x ray sources were observed and among them were several x ray pulsars. Four telescopes mounted on board the Kvant module cover a wide energy range with good timing resolution. Timing analysis of the Kvant module data suffers from the presence of only short continuous intervals of source observations, separated by 90 min gaps (90 min is the orbital period of the Mir space station around the Earth). The presence of 90 min gaps leads to the appearance of beat frequencies v=v sub 0 + or - n/90 min (n = 1, 2, 3). Special analysis was applied to avoid this difficulty. Results are presented of the pulsation period measurements of the x ray pulsars Her X-1, Cen X-3, SMC X-1, Vela X-1, A0535 + 26 by the instruments on board the Kvant module in 1987 to 1989. The values of the periods are reduced to the solar system barycenter and to the binary system barycenter (excluding A0535 + 26).

GRUBER, D.; KUNZ, M.; KENDZIORRA, E.; KRETSCHMAR, P.; MAISACK, M.; BONY, B.; STAUBERT, R.; DOEBEREINER, S.; ENGLHAUSER, J. ET AL. Observations of the X-ray pulsar SMC X-1 with MIR/HEXE. // Bull. American Astron. Soc., 23, 1348 (1991)

IN'T ZAND, J. J. M.; HEISE, J.; BRINKMAN, A. C.; JAGER, R.; SKINNER, G. K.; PATTERSON, T. G.; PAN, H. -C.; NOTTINGHAM, M. R.; WILLMORE, A. P.; AL-EMAM, O. Two new X-ray transients near the Galactic center // (Recent results and perspective instrumental developments in X- and gamma-ray astronomy; Proceedings of the Topical Meeting of the Interdisciplinary Scientific Commission E /Meetings E4 and E8/ of the COSPAR 28th Plenary Meeting, The Hague, Netherlands, June 25-July 6, 1990. A91-53451 23-89) Advances in Space Research (ISSN 0273-1177), vol. 11, no. 8, 1991, p. 187-190.

The discovery of two transient X-ray sources near the Galactic center, KS1732-273 and KS1741-293, is reported, and some of their characteristics are discussed. The observations were carried out with the X-ray widefield camera TTM of the Kvant module of the Soviet manned space station Mir. KS1732-273 was detected on two days, March 20 and September 4, 1989, with the flux on both dates comparable at 22 mCrabs (3-10 keV). KS1741-293 was detected on three consecutive days, August 20-22, 1989, at a comparable flux level of about 26 mCrabs, and exhibited two bursts during the 3-day period (on August 20th and 22nd).

LEISING, MARK D. Supernova 1987A from 1 keV to 10MeV - The status as of 1990 // (Recent results and perspective instrumental developments in X- and gamma-ray astronomy; Proceedings of the Topical Meeting of the Interdisciplinary Scientific Commission E /Meetings E4 and E8/ of the COSPAR 28th Plenary Meeting, The Hague, Netherlands, June 25-July 6, 1990. A91-53451 23-89) Advances in Space Research (ISSN 0273-1177), vol. 11, no. 8, 1991, p. 207-216.

Observations of the emission from the supernova 1987A are reviewed within a framework that is set forth for interpreting the results. Observational data are presented from the Ginga X-ray satellite, the Kvant Roentgen Observatory, NASA's Solar Maximum Mission, the CsI scintillation detector on the satellite Cosmos, the Grip X-ray/gamma-ray system, and the Grad Ge spectrometer. The physics of hard photon emission are then reviewed, and radioactive and nonradioactive sources are considered for both X- and gamma-ray emission detected from the supernova 1987A. The detection of freshly synthesized radioactive Co-56 represents an important discovery with respect to the development of supernova and nucleosynthesis theories. The Sigma, Rosat, and Gro observations are expected to provide confirmation of a compact object or interaction between ejecta and circumstellar material at supernova 1987A.

KRETSCHMAR, PETER. Calibration of high energy x ray detectors at the spectrum of the Crab nebula, and x ray pulsar A0535+26 examinations // Thesis Tuebingen Univ. (Germany). Inst. fuer Astronomie.

A series of observations for the transient pulsar A0535+26 were analyzed with regard to the x ray spectrum and the pulse behavior of the source. The first spectral Crab examinations gave an extremely hard Crab spectrum, far from other published results, and great deviations between the theoretical law and measuring data, in particular at the lower edge of the High Energy X-ray Experiment (HEXE) energy field. The proper calibration parameters were tentatively determined, using existing data and Crab nebula measurement. The pulse period of the source was determined as P equal to 103.244 +/- 0.008 seconds.

KUNZ, MATHIAS. Analysis of Mir-HEXE observations: Pulsation and energy spectra of the x ray double star SMC X-1 in 20 to 80 keV energy field // Thesis Tuebingen Univ. (Germany). Inst. fuer Astronomie.

Hardware and software of the x-ray astronomy experiment, and the observations of the x-ray pulsar SMC X1 with HEXE (High Energy X Ray Experiment) are presented. The results of HEXE observations of SMC X1 are discussed with regard to already published observations and theoretical models of the physics of x-ray double stars. Statistical methods for detecting periodical signals, in particular Epoch Folding (EF) and Rayleigh Test (RT) are considered for the pulse period determination of SMC X1. Both methods give the same results. The pulse period of the x-ray signal is determined for three observation groups. It is found that hydrogen absorption by the material compassing the neutron stars is low.

MAISACK, M.; YAQOOB, T. A search for reflection features in the X-ray spectrum of NGC4151// Astronomy and Astrophysics (ISSN 0004-6361), vol. 249, no. 1, Sept. 1991, p. 25-30.

Observations of the AGN NGC4151 are discussed as taken from the Ginga and the HEXE instrument at 4-120 keV with high sensitivity and energy resolution. The observational data demonstrate that the source is in a low state of emission in the X-ray range, and a single power law is developed to describe the spectrum. A second model is also considered to describe the spectrum in which a layer of reflecting cold matter is introduced, but the reflection is considered to be marginal due to the edge-on geometry of the observations. The present data are examined in terms of constraints on the parameters of possible pair models where the X-ray emission is produced by inverse Compton scattering. Pairs are thought to play a minor role in the X-ray/gamma-ray emission of NGC 4151. The source is concluded to be moderately compact and potentially starved of photons, and it is recommended that a broadband observation of the high state of NGC4151 be undertaken.

MAISACK, MICHAEL. Search of signatures for pair production and reflection in high energy x ray spectra of active galaxies // Ph.D. Thesis Tuebingen Univ. (Germany, F.R.). Fakultaet fuer Physik.

The observations of active galaxies, using the X-ray detector HEXE were evaluated, and the measured spectra were compared with the predictions of astrophysical plasma models. Particular attention was given to the effects of electron positron pair production by photon collision and reflection of a primary continuum on a colder matter, in particular an accretion disk. The objects considered were the quasar 3C 273, the Seifert galaxy NGC4151 and the radiogalaxy CEN A. A joint evaluation, using data of the Japanese X-ray satellite GINGA showed that the share of a reflective component in the spectra of 3C 273 and NGC4151 was very low. It was shown that only NGC4151 could be described, using a pair cascade model.

MONY, BRUNO. Analysis of high energy x ray observations of long periodic pulsars // Ph.D. Thesis Tuebingen Univ. (Germany). Fakultaet fuer Physik.

The high energy x-ray observations of the three long periodic x-ray pulsars, GX 1+4, Vela X-1, and A0535 +26, carried out on the Space Station Mir with the High Energy X-ray Experiment (HEXE) were analyzed. Phenomena, which were unknown up to now, were identified for each pulsar. From the measured spectra, GX 1+4 is deduced to have a relatively strong magnetic field. A common characteristic of Vela X-1 and A0535 +26 is the variability of the spectral hardness over the pulse phase. Using theories describing the spin up and spin down behavior of pulsars, a value was deducted for the magnetic field hardness.

SKINNER, G. K. The position of GRS1758 - 258 // Gamma-ray line astrophysics; Proceedings of the International Symposium, Paris, France, Dec. 10-13, 1990 (A92-43619 18-90). New York, American Institute of Physics, 1991, p. 358-360.

Data on the hard source GRS1758 - 258 from the Spacelab-2 coded mask telescope and from TTM, a similar but smaller telescope on the Mir Kvant module, are briefly examined. GRS1758 - 258 appears to be a weak, persistent and somewhat variable source with a well-defined position.

SIUNIAEV, R.; GREBENEV, S.; KANIOVSKII, A.; EFREMOV, V.; KUZNETSOV, A.; PAVLINSKII, M.; IAMBURENKO, N.; ENGLHAUSER, J.; DOEBEREINER, S.; PIETSCH, W. Hard X-rays from supernova 1987A - Results of Mir-Kvant and Granat in 1987-1990 and expectations // Gamma-ray line astrophysics; Proceedings of the International Symposium, Paris, France, Dec. 10-13, 1990 (A92-43619 18-90). New York, American Institute of Physics, 1991, p. 211-217.

Results of the supernova 1987A hard X-ray observations in 1987-1990 with Mir-Kvant and Granat are presented. They make it possible to estimate the degree of Co-56 mixing over the envelope and set hard restrictions on abundances of radioactive Co-57, Ti-44, and Na-22 produced during the outburst. The upper limit at three standard deviation level on the Co-57/Co-56 ratio inside the envelope is equal to 1.5 of the earth's Fe-57/Fe-56 ratio. Future evolution of the SN1987A hard X-ray luminosity connected mainly with central source is discussed.

SIUNIAEV, R. A.; AREF'EV, V.; BOROZDIN, K.; CHURAZOV, E. M.; EFREMOV, V.; GIL'FANOV, M. R.; GREBENEV, S.; KANIOVSKII, A.; KUZNETSOV, A. V.; LAPSHOV, I. The results of the Mir-Kvant in 1987-1989 // (Recent results and perspective instrumental developments in X- and gamma-ray astronomy; Proceedings of the Topical Meeting of the Interdisciplinary Scientific Commission E /Meetings E4 and E8/ of the COSPAR 28th Plenary Meeting, The Hague, Netherlands, June 25-July 6, 1990. A91-53451 23-89) Advances in Space Research (ISSN 0273-1177), vol. 11, no. 8, 1991, p. 5-16.

The results of the Mir-Kvant X-ray observatory obtained in 1987-1989 are presented. These include the discovery and study of hard X-ray radiation from SN 1989A, long-term observations of the LMC field by TTM telescope, observations of X-ray pulsars (including Her X-1, 4U 1626 - 67, and GX 1 + 4), observations of bright X-ray transients GS 2000 + 25 and GS 2023 + 338, and observations of the Galactic plane. New X-ray transients were discovered and described, which included KS1731 - 260, KS1741 - 293, and KS1947 + 300. In 1989, two additional modules were attached, and the Mir station is now in the 'T' shape instead of the simple 'I' shape. The first observations of the Crab nebulae carried out on October 23 and November 4, 1990 did not reveal any degradation in the performance of the main instruments and proved excellent stabilization of the spacecraft, with accuracy better than 1 arcmin.

SIUNIAEV, R. A.; CHURAZOV, E. M.; GIL'FANOV, M. R.; PAVLINSKII, M.; GREBENEV, S.; DEKHANOV, I.; KUZNETSOV, A. V.; IYAMBURENKO, N. S.; SKINNER, G. K.; PATTERSON, T. G. Imaging of the Galactic center field by Kvant and Granat // (Recent results and perspective instrumental developments in X- and gamma-ray astronomy; Proceedings of the Topical Meeting of the Interdisciplinary Scientific Commission E /Meetings E4 and E8/ of the COSPAR 28th Plenary Meeting, The Hague, Netherlands, June 25-July 6, 1990. A91-53451 23-89) Advances in Space Research (ISSN 0273-1177), vol. 11, no. 8, 1991, p. 177-185.

Two currently operating international X-ray observatories Mir-Kvant and Granat are carrying a number of coded mask telescopes with imaging capabilities in wide energy range from 2 up to 1300 keV. The Galactic center region is the highest priority target for these instruments. Their results in 1988-1990 demonstrate the efficiency of coded mask telescopes observations in hard X-rays.

SUNYAEV, RASHID A.; KANIOVSKY, A. S.; EFREMOV, V. V.; GREBENEV, S. A.; KUZNETSOV, A. V.; CHURASOV, E.; GILFANOV, M.; YAMBURENKO, N.; ENGLHAUSER, J.; DOEBEREINER, S. X ray radiation from Supernova 1987A. The results of the Kvant module in 1987-1989 // n NAS-NRC, High-Energy Astrophysics. American and Soviet Perspectives p 368-384 (SEE N92-12933 03-90).

The results of two years of SN1987A hard X-ray observations by the HEXE instrument aboard the Kvant module are summarized. By May to June 1989, the hard x-ray flux had declined more than 8.5 times in comparison with the maximum of the x-ray light curve. The upper limit of the ratio of Co-57/Co-56 abundances at the level of ratio of Fe-57/Fe-56 abundances at the Earth is a factor of 1.5.

SIUNIAEV, R. A.; AREF'EV, V. A.; BOROZDIN, K. N.; CHURAZOV, E. M.; EFREMOV, V. V.; GIL'FANOV, M. R.; KANIOVSKII, A. S.; KUZNETSOV, A. V.; MELIORANSKII, A. S.; IAMBURENKO, N. S.Galactic X-ray sources with extremely hard spectra - 'Kvant' module observations // Gamma-ray line astrophysics; Proceedings of the International Symposium, Paris, France, Dec. 10-13, 1990 (A92-43619 18-90). New York, American Institute of Physics, 1991, p. 373-379.

Extremely hard spectra of a number of Galactic X-ray sources observed by Kvant X-ray detectors, including Crab nebula, Cyg X-1, and X-ray transients GS2000+25 and BS2023+338 detected by the Ginga satellite, are shown. The X-ray characteristics and optical measurements show that the novae are accreting objects with low-mass companions and are obvious black hole candidates of the type of A0620-00.

In 't Zand et al. The spectral variability in 2-28 keV of GS2023+338 during its 1989 outburst // 1992, A&A 266, 283

KENDZIORRA, E.; MONY, B.; KRETSCHMAR, P.; MAISACK, M.; STAUBERT, R.; DOEBEREINER, S.; ENGLHAUSER, J.; PIETSCH, W.; REPPIN, C.; TRUEMPER, J. Hard x ray observations of Vela X-1 and A0535+26 with HEXE: Discovery of cyclotron lines.// Goddard Space Flight Center, The Compton Observatory Science Workshop p 217 (SEE N92-21874 12-90).

The X ray pulsars Vela X-1 (4U 0900-40) and A0535+26) were observed with the High Energy X ray Experiment (HEXE) onboard the Mir space station at energies above 20 keV. The pulse profiles of Vela X-1 (P = 283.22 s for JD 244 7486) and A0535+26 (P = 103.27 s for JD 244 7626) were measured up to at least 100 keV. The time averaged pulse profiles of the two sources both show a clear double peak structure with an asymmetric main pulse and a more symmetric secondary pulse. The spectrum of the main pulse is significantly harder than that of the secondary. Pulse phase resolved spectra show absorption features at 54 keV and possibly 27 keV for Vela X-1 and around 100 keV for A0535+26. If these features are interpreted as second and first harmonic (fundamental) cyclotron absorption lines, lower limits are derived of 2.6 x 10(exp 12) and 4.3 x 10(exp 12) Gauss for the magnetic fields of the neutron stars in Vela X-1 and A0535+26, respectively.

MAISACK, M.; KENDZIORRA, E.; MONY, B.; STAUBERT, R.; DOEBEREINER, S.; ENGLHAUSER, J.; PIETSCH, W.; REPPIN, C.; TRUMPER, J.; EFREMOV, V.; KANIOVSKY, S.; KUSNETZOV, A.; SUNYAEV, R.HEXE observations of active galactic nuclei - Constraints on pairs and Compton reflection // Astronomy and Astrophysics (ISSN 0004-6361), vol. 262, no. 2, p. 433-440.

We present results of X-ray observations of the three brightest Active Galaxies in hard X-rays, the quasar 3C 273 (1226+02), the Seyfert galaxy NGC4151, and the radio galaxy Cen A (NGC5128). The observations were made with the HEXE instrument (20-200 keV) on board the Mir space station. We discuss the spectra of the sources in the context of models including pair production, reflection and spatially separated emission regions. We find that pairs play a minor role in 3C 273 and Cen A. The relative contribution of a reflected component cannot be constrained from our data, but the 'canonical' model with simple pair cascades and Compton reflection can be ruled out for 3C 273 and Cen A. For NGC4151, the importance of reflection can be constrained by the combined analysis of data from HEXE and Ginga taken simultaneously.

MAISACK, M.; YAQOOB, T.; STAUBERT, R.; KENDZIORRA, E. Constraints on pairs and reflection in active galaxies. // Testing the AGN paradigm; Proceedings of the 2nd Annual Topical Astrophysics Conference, Univ. of Maryland, College Park, Oct. 14-16, 1991 (A93-29801 11-90), p. 362-365.

Models including photon-photon pair production and reprocessing by cold material by Compton scattering and absorption have recently received wide attention, especially since Ginga spectra of many Seyfert galaxies have shown a hard X-ray tail, expected from the latter process. We discuss hard X-ray observations of three AGN (NGC4151, 3C 273 and Cen A) by the HEXE instrument in the light of these models.

STAUBERT, R. Recent results on 3C 273. // In MPI fuer Extraterrestrische Physik, X Ray Emission from Active Galactic Nuclei and the Cosmic X Ray Background p 42-49 (SEE N93-17094 05-90).

Recent results on 3C 273, one of the nearest and brightest quasars at high photon energies from observations with Rosat, Ginga, (Japanese X-ray satellite), High Energy X-ray Experiment (HEXE), Gamma Ray Observatory (GRO) and ground based instruments are discussed. Two Rosat observations clearly establish a time variable 'soft excess' spectral component, the second observation being simultaneous with Ginga allows construction of a combined spectrum from 0.1 keV to 20 keV; a combined HEXE/Ginga spectrum (1.5 to 150 keV) constrains 'pairs and reflection'; multifrequency observations in Jun./Jul. 1991, including data from GRO, will provide a 'snapshot' spectrum from radio frequencies to high energy gamma rays.

IAU Circ. N 5878. 1993. X-RAY NOVAE

A. Kaniovsky, K. Borozdin, and R. Sunyaev, on behalf of the Mir-Kvant team, report: "The soft x-ray transient GRS 1009-45, discovered by Granat/WATCH and more precisely localized by BATSE (IAUC 5864), was observed by the TTM and HEXE instruments of Mir-Kvant on Sept. 30. Preliminary analysis shows that the source spectrum in the band 2-200 keV is similar to the spectra of the x-ray novae QZ Vul = GS 2000+25 and GU Mus (= Nova Mus 1991) = GRS 1124-684. A bright, soft component can be approximated by a black-body spectrum with a temperature of 0.52 +/- 0.03 keV. The source spectrum at the higher energies 10-100 keV is well approximated by a power law with spectral index -2.53 +/- 0.05. The flux from the source at 3 and 20 keV was equal to 1 and 0.1 Crab unit, respectively." K. Borozdin, V. Arefiev, and R. Sunyaev, on behalf of the Mir- Kvant-TTM team, report: "Mir-Kvant observed the hard x-ray transient GRS 1716-249 = GRO J1719-24 and found that the source spectrum in the band 2-27 keV is approximated by a single power law with spectral index -1.57 +/- 0.13. No trails of the soft component were detected in the spectrum; it is reminiscent of the spectra of V1357 Cyg = Cygnus X-1, 1E 1740.7-2942, and the x-ray novae V404 Cyg = GS 2023+338 and GRO J0422+32. The flux was continuously growing, from 200 mCrab on Sept. 26 and 550 mCrab on Sept. 27 up to 750 mCrab on Oct. 3 in the band 12-17 keV."

IAU Circ. 5886. 1993.  X-RAY NOVA IN VELA

K. Borozdin, R. Sunyaev and N. Alexandrovich, on behalf of the Mir-Kvant-TTM team, report: "The x-ray nova GRS 1009-45 (IAUC 5864, 5878) continues to be bright. The flux on Oct. 27 within the 2-6 keV spectral band was 530 mCrab (a 25 percent decrease in four weeks). The spectrum is soft and might be approximated by a power law with photon spectral index -5.0 or black body spectrum with kT = 0.56 keV. Owing to the presence of Vela X-1 in the same field TTM was able to localize the source to within a narrow strip 1.2 arcmin wide and 1.3 degree long with corners at R.A. = 10h10m.8, Decl. = -45d43'.2; 10h10m.8, -45d42'.7; 10h12m.4, -44d26'.0 and 10h12m.5, -44d26'.1 (equinox 1950.0). By combining the Granat/WATCH and BATSE data it is possible to reduce the strip's length by up to 0.5 deg."

Blom et al. New Measurements of the X-Ray Hardness / Intensity Correlation of GX:5-1 // 1993, A&A 277, 77

KUNZ, M.; GRUBER, D. E.; KENDZIORRA, E.; KRETSCHMAR, P.; MAISACK, M.; MONY, B.; STAUBERT, R.; DOBEREINER, S.; ENGLHAUSER, J.; PIETSCH, W.; REPPIN, C.; TRUMPER, J.; EFREMOV, V.; KANIOVSKY, S.; KUSNETZOV, A.; SUNYAEV, R. Spectral and temporal properties of the X-ray pulsar SMC X-1 at hard X-rays. // Astronomy and Astrophysics (ISSN 0004-6361), vol. 268, no. 1, p. 116-122.

The binary X-ray pulsar SMC X- 1 has been observed at hard X-rays with the High Energy X-Ray Experiment (HEXE) on nine occasions between Nov. 1987 and March 1989. A thin thermal bremsstrahlung fit to the phase averaged spectrum yields a plasma temperature (14.4 +/- 1.3) keV and a luminosity above (1.1 +/- 0.1) x 10 exp 38 erg/s in the 20-80 keV band. Pulse period values have been established for three observations, confirming the remarkably stable spin-up trend of SMC X-1. In one of the three observations the pulse profile was seen to deviate from a dominant double pulsation, while at the same time the pulsed fraction was unusually large. For one observation we determined for the first time the pulsed fraction in narrow energy bands. It increases with photon energy from about 20 percent up to over 60 percent in the energy range from 20 to 80 keV.

NOTTINGHAM, M. R.; SKINNER, G. K.; WILLMORE, A. P.; BOROZDIN, K. N.; CHURAZOV, E.; SIUNIAEV, R. A.Observations of the Galactic centre with the TTM instrument. // Astronomy and Astrophysics Supplement Series (ISSN 0365-0138), vol. 97, no. 1, p. 165-167.

A new technique has been developed for the analysis of data from the TTM instrument coded mask telescope. Preliminary spectral results are presented for diffuse emission and point sources in the Galactic center.

PAN, H. C.; IN'T ZAND, J. J. M.; SKINNER, G. K.; BOROZDIN, K. N.; GIL'FANOV, M. R.; SIUNIAEV, R. A.Observations of X-ray transient source GS2023+338 with the TTM coded mask telescope. // Astronomy and Astrophysics Supplement Series (ISSN 0365-0138), vol. 97, no. 1, p. 273-275.

TTM observations in which the bright X-ray transient source GS2023+338 (=V404 Cyg) in the period June-August 1989 are reported. The observed spectral structure can be modeled using a model of a power-law source with a photon index of about 1.5, surrounded by partially ionized material. The observed X-rays consist of a component from the power-law source and those reflected (down-scattered) by the partially ionized material. Varying the clumpy structure or changing the ionization state of the circumstellar matter will cause the low-energy absorption to fluctuate.

SUNYAEV, R. A.; KANIOVSKY, A. S.; BOROZDIN, K. N.; EFREMOV, V. V.; AREF'EV, V. A.; MELIORANSKY, A. S.; SKINNER, G. K.; PAN, H. C.; KENDZIORRA, E.; MAISACK, M.; DOEBEREINER, S.; PIETSCH, W. Broad-band X-ray observations of the GRO J0422+32 X-ray nova by the 'Mir-Kvant' observatory // Astronomy and Astrophysics (ISSN 0004-6361), vol. 280, no. 1, p. L1-L4.

Observations of GRO J0422+32 X-Ray Nova with the instruments of the 'Mir-Kvant' observatory show that the X-ray spectrum is similar to that of the well-known black-hole candidate Cyg X-1 in its 'low' state. In the standard 2-20 keV X-ray range both have power law spectra with no strong soft component while at energies higher than 100 keV an exponential cutoff is clearly seen in the spectrum in both cases. Such cutoffs are typical of thermal comptonization of low-frequency photons in the high-temperature plasma of accretion disks.

IAU Circ. 6080. 1994. GRS 1915+105

N. Alexandrovich, K. Borozdin, and R. Sunyaev, on behalf of the MIR-KVANT-TTM team, report: "Strong x-ray flux from GRS 1915+105 was registered by the TTM coded-mask instrument onboard the MIR space station during observations on Sept. 8 (500 mCrab at 5 keV), 10 (460 mCrab), and 11 (840 mCrab). The spectrum of the source is very soft (black-body fit gives the radiation temperature as 1.25 +/- 0.05 keV with absorption column NH = 2 x 10E22 cmE-2). The observation of Sept. 11 showed the appearance of the hard tail with flux 140 +/- 30 mCrab in the spectral band 17-25 keV, in addition to the soft component."

 IAU Circ. 6083. 1994. KS 1730-312

K. Borozdin, N. Alexandrovich, V. Arefiev and R. Sunyaev, Space Research Institute, Moscow, on behalf of the MIR-KVANT-TTM team, communicate: "During observations of the Galactic Center field by the TTM coded-mask instrument onboard the MIR space station on Sept. 23, a flux of 70 +/- 10 mCrab within the energy band 2-30 keV was detected from R.A. = 17h30m.3, Decl. = -31d11' (equinox 1950.0, uncertainty +/- 2'). The source spectrum can be approximated by a power law with spectral index -1.9 +/- 0.4."

X-RAY NOVA 1993 IN OPHIUCHUS

Borozdin and Alexandrovichreport: "The TTM coded-mask instrument onboard MIR registered x-ray emission from the direction of the 1993 x-ray nova with flux 55 +/- 15 mCrab (at 2-30 keV), averaged over observations on 1994 Aug. 31, Sept. 1 and 23. The photon index of the power-law approximation is 2.0 +/- 0.7."

N. Alexandrovich, K. Borozdin, V. Efremov and R. Sunyaev, Space Research Institute, Moscow, on behalf of the MIR-KVANT team, report: "According to data from the TTM telescope onboard the MIR space station this x-ray nova is in a high (soft) spectral state typical of black-hole candidates and similar to that observed recently in the superluminous radio source GRS 1915-105 (IAUC 6080). The flux detected at 5 keV was 500 mCrab on Sept. 24 and 600 mCrab on Sept. 25. The source spectrum within the 2-15-keV band can be approximated by a blackbody fit with kT = 1.06 +/- 0.02 keV. According to MIR-KVANT-HEXE data, the 3-sigma upper limit to the tail of the hard flux is 5 and 15 mCrab in the 15-45-keV and the 45-105-keV data, respectively. In hard x-rays the source is much weaker than 4U 1700-37 (50 mCrab in 15-45-keV band), which is separated from the Sco x-ray nova by less than three degrees."

IAU Circ. 6088. 1994. KS 1730-312

K. Borozdin, N. Alexandrovich and R. Sunyaev, Space Research Institute, Moscow, on behalf of the MIR-KVANT team,report: "This x-ray transient (cf. IAUC 6083) continues to increase in luminosity in the standard x-ray spectral band. According to data obtained on Sept. 26 with the MIR-KVANT-TTM coded-mask instrument, the spectrum can be approximated by a power law with photon index 2.7 +/- 0.2 and column density NH = 4 x 10**22 cm-2. The flux at 4 keV was about 600 mCrab. An even higher flux (850 mCrab at 4 keV) and softer spectrum were detected on Sept. 28, when the power-law index was 4.2 +/- 0.2 and NH = 8 x 10**22 cm-2. Possibly this is another x-ray nova."

IAU Circ. 6091. 1994. KS 1730-312

M. Gilfanov, E. Churazov, J. Ballet and E. Jourdain, on behalf of Granat team, report: "In the course of observations of the Galactic Center region on Sept. 26-27 Granat/SIGMA marginally detected KS 1730-312 (cf. IAUC 6083) with a 40-150-keV flux of 40 +/- 15 mCrab.  During subsequent observations on Sept. 28-30 the hard x-ray emission from the source was below SIGMA sensitivity (2 sigma limit 30 mCrab).  The fast increase of the flux in the standard x-ray band observed by TTM (cf. IAUC 6088) was thus accompanied by a decrease of the hard x-ray flux, this behavior being consistent with dramatic steepening of the broad-band source spectrum observed by both TTM and SIGMA."
 

ALEKSANDROVICH, N. L.; AREFEV, V. A.; BOROZDIN, K. N.; KANIOVSKII, A. S.; SYUNYAEV, R. A. OBSERVATIONS OF THE X-RAY PULSAR GX:301-2 WITH THE TTM TELESCOPE OF THE KVANT MODULUS ON BOARD THE MIR ORBITAL STATION // 1994, Astron. Lett. 20, 565

Н.Л. Александрович, В.А. Арефьев, К.Н. Бороздин и др. Наблюдения рентгеновского пульсара GX301-2 телескопом ТТМ модуля "Квант" орбитальной станции "Мир".  // Письма в астрон. журнал, 1994, Т. 20, 9, С. 660-663.

Представлены результаты наблюдений рентгеновского пульсара GX301-2 вблизи апоцентра орбиты этой двойной системы (в минимуме блеска) рентгеновским телескопом ТТМ орбитальной обсерватории "Квант" комплекса космической станции "Мир" по сериям наведений с 3 по 10 января 1993 г. и с 4 по 9 января 1994 г. Найдены периоды пульсаций источника, хорошо согласующиеся с полученными ранее данными других приборов. Определены фазированные энергетические спектры источника для энергий от 2 до 27 кэВ и построены профили импульса пульсара для различных энергетических диапазонов.

Kaniovskii, A. S.; Arefev, V. A.; Borozdin, K. N.; Efremov, V. V.; Syunyaev, R. A.; Maisack, M.; Pietsch, W.; Reppin, C. Observations of the Transient X-Ray Pulsar GRS:0834-43 in its Low State with the Instruments of the Roentgen Observatory on Board the Mir-Kvant Module in 1992NOV // 1994, Astron. Lett. 22, 207.

KANIOVSKII, A. S.; AREFEV, V. A.; BOROZDIN, K. N.; EFREMOV, V. V.; SUNYAEV, R. A.; MAISACK, M.; PIETSCH, W.; REPPIN, C. OBSERVATIONS OF THE TRANSIENT X-RAY PULSAR GRS:0834-43 IN ITS LOW STATE WITH THE INSTRUMENTS OF THE ROENTGEN OBSERVATORY ONBOARD THE MIR / KVANT MODULE IN 1992NOV. // PISMA V. ASTRON. ZHURNAL V. 20, NO. 4, P. 253, 1994

Syunyaev, R. A.; Borozdin, K. N.; Aleksandrovich, N. L.; Arefev, V. A.; Kaniovskii, A. S.; Efremov, V. V.; Maisack, M.; Reppin, C.; Skinner, J. K. Observations of X-ray novae in Vela (1993), Ophiuchus (1993), and Perseus (1992) using the instruments of the Mir-Kvant module // 1994, Astron. Lett. 20, 777.

Р.А. Сюняев, К.Н. Бороздин, Н.Л. Александрович и др. Наблюдения рентгеновских Новых в созвездиях Парусов (1993), Змееносца (1993) и Персея (1992) приборами модуля "Мир-Квант". // Письма в астрон. журнал, 1994, T. 20, 12 , C. 890-900.

Приборы ТТМ и ГЕКСЕ орбитальной рентгеновской обсерватории "Мир-Квант" провели в сентябре - ноябре 1993 г. серию наблюдений двух рентгеновских новых: в Змееносце GRS 1716-249 = GRO J1719-24 и в Парусах GRS 1009-45. Ранее, в августе - сентябре 1992 г., наблюдения модуля "Мир-Квант" позволили построить широкополосный спектр рентгеновской новой Персее GRO J0422+32. Спектры GRO J0422+32 и GRS 1716-249 подобны спектру известного кандидата в черные дыры Лебедь Х-1 в низком состоянии, так как они не имеют интенсивной мягкой компоненты и являются степенными в диапазоне до 100 кэВ. На энергиях свыше 100 кэВ у этих источников наблюдается экспоненциальный завал в спектре, характерный для процесса комптонизации низкочастотных фотонов в высокотемпературной плазме. В то же время спектр источника GRS 1009-45 имеет ярко выраженную мягкую компоненту и жесткую переменную во времени компоненту, также наблюдавшуюся вплоть до энергий порядка сотни кэВ. В статье приводится сравнение спектров пяти рентгеновских новых, наблюдавшихся обсерваторией "Мир-Квант" в 1987 - 1993 гг.

DOEBEREINER, S.; MAISACK, M.; ENGLHAUSER, J.; PIETSCH, W.; REPPIN, C.; TRUEMPER, J.; KENDZIORRA, E.; KRETSCHMAR, P.; KUNZ, M.; STAUBERT, R.; EFREMOV, V.; KANIOVSKY, A.; KUSNETZOV, A.; SUNYAEV, R. HEXE observations of black hole X-ray transients. // Astronomy and Astrophysics (ISSN 0004-6361), vol. 287, no. 1, p. 105-112.

We present results of Mir-Kvant-HEXE observations in the energy range 20-200 KeV of the three X-ray transients and black hole candidates GS 200+25, GRO J0422+32, and GS 2023+338, observed between 1988 and 1992. The spectra of GS 2023+338 GRO J0422+32 can be interpreted as due to thermal Compton-upscattering low-energy photons to hard X-ray energies in a hot plasma with electron temperatures of typically 35 to 40 keV, or as due to Compton reflection of hard photons off cool matter with covering factors f(sub c) ranging from 0.4 to 0.8. A combination of Compton-upscattering and Compton reflection is also possible. The spectrum of GX 200-25 is softer and can be described by a power law with a photon index alpha approximately = 2.0 (E greater than 20 keV).

KENDZIORRA, E.; KRETSCHMAR, P.; PAN, H. C.; KUNZ, M.; MAISACK, M.; STAUBERT, R.; PIETSCH, W.; TRUEMPER, J.; EFREMOV, V.; SUNYAEV, R. Evidence for cyclotron line features in high energy spectra of A 0535+26 during the March/April 1989 outburst. // Astronomy and Astrophysics (ISSN 0004-6361), vol. 291, no. 2, p. L31-L34.

The X-ray pulsar A 0535+26 has been observed during its March/April 1989 outburst with the Coded Mask Telescope TTM and the High Energy X-ray Experiment HEXE on board the Mir space station at energies between 4 and 156 keV. Pulsed emission (P = 103.26 s for JD 244 7626) has been detected up to at least 100 keV. Above 20 deV the time averaged pulse profiles show a clear double peak structure with an asymmetric main pulse and a more symmetric secondary pulse. The spectrum of the main pulse is significantly harder than that of the secondary pulse. The phase resolved spectra can only be fitted by a power law with exponetial cutoff modified by two absorption lines around 50 and 100 keV. We interpret these features as the fundamental and first harmonic cyclotron resonances. The corresponding strength of the magnetic field of the neutron star is 4.3 x 10(exp 12) Gauss.

MAISACK, MICHAEL; KENDZIORRA, ECKHARD; PAN, HONGCHAO; SKINNER, GERRY; ENGLHAUSER, JAKOB; REPPIN, CLAUS; EFREMOV, VALERI; SUNYAEV, RASHID. Compton reflection in Scorpius X-1 and Cygnus X-3? // The Astrophysical Journal Supplement Series, vol. 92, no. 2, p. 473-475.

The Compton reflection of X-ray photons by an accretion disk has been proposed to play a role in active galactic nuclei and galactic black hole candidates as well as in binary systems that contain a neutron star as a compact accreting object. We present HEXE (20-200 keV) and TTM (2-30 keV) data of the low-mass X-ray binary (LMXB) system Sco X-1 and of Cyg X-3 and discuss the results of Compton reflection fits. We find that a reflected component from an incident bremsstrahlung spectrum can describe the spectra of Sco X-1, while a Compton-reflected component (assuming an incident power-law spectrum) is not required for Cyg X-3.

PAN, H. C.; KRETSCHMAR, P.; SKINNER, G. K.; KENDZIORRA, E.; SUNYAEV, R. A.; BOROZDIN, K. N. Variable soft X-ray absorption and excess of Vela X-1. // The Astrophysical Journal Supplement Series, vol. 92, no. 2, p. 448-450

We present preliminary results from a study of the stellar wind modulation of the X-ray spectrum of Vela X-1 using the broad-band (2-200 keV) data obtained in period 1988-1991 with the TTM and HEXE instruments on-board the MIR space station. We find that the hydrogen column density of the absorbing material varies from a negligible value up to 7 x 10(exp 23) atoms cm(exp -2). A soft X-ray flux excess, when compared with the extrapolation of the spectrum measured at higher energies with absorption due to cold matter, is detectable at all binary phases. It is variable and exhibits two different patterns of behavior. The soft excess is strong in the phase range when the column density is low and is then approximately correlated with the source flux. When the column density is high no such correlation is seen.

PAN, H. C.; SKINNER, G. K.; SUNYAEV, R. A.; BOROZDIN, K. N. TTM observations of X 1755-338. // Proc. IAU Colloq. 151 1994Dec 05-09, ed. Greiner J., Duerbeck H.W. & Gershberg R.E., Springer, "Flares and Flashes", 334-335 (1994).

IAU Circ. 6141. 1995. X-RAY NOVA 1993 IN OPHIUCHUS

K. Borozdin, N. Alexandrovich, and R. Sunyaev, Space Research Institute, Moscow, on behalf of the MIR-Kvant team, report: "This object (GRS 1716-249 = GRO J1719-24) continues to be bright according to observations made on Feb. 16 with the TTM instrument onboard MIR-Kvant. The flux from the source in the energy band 2-27 keV was equal to 275 +/- 20 mCrab, which is the highest value detected by the TTM from this source since the main outburst in Sept. 1993 (IAUC 5878). The spectrum can be approximated by a power law with index 2.1 +/- 0.3."

IAU Circ. 6143. 1995. X-RAY NOVA 1994 IN SCORPIUS

N. Alexandrovich, K. Borozdin, and R. Sunyaev, on behalf of the MIR-Kvant team, report: "The superluminal radio source GRO J1655-40 (cf. IAUC 6046, 6051, 6056, 6078, 6087, etc.) was found to be very bright during a TTM observation on Feb. 22. The flux in the energy band 3-5 keV was close to 1.7 Crab. The source spectrum was soft and could be approximated by a blackbody fit, with temperature kT = 1.04 +/- 0.02 keV in the energy band 2-12 keV."

IAU Circ. 6216. 1995. GRO J1735-27

S. Grebenev, K. Borozdin, and R. Sunyaev, Space Research Institute, Moscow, on behalf of the Mir-Kvant/TTM and Granat/ART-P teams, communicate: "The ROSAT position of a new x-ray pulsar GRO J1735-27 (= RX J1735.9-2726; cf. IAUC 6207, 6212) is within the 1' error circle for KS 1732-273, the source discovered by Mir-Kvant/ TTM on 1989 Mar. 20 and Sept. 4 (in't Zand et al. 1991, Adv. Space Res. 11, (8)187); the mean flux from the source was about 22 mCrab in the band 3-10 keV during both 1989 observations. The source was marginally detected with Granat/ART-P on 1990 Apr. 4, when its flux at 3-10 keV was 13.4 +/- 2.2 mCrab, but it was not found (at the flux level of 26 mCrab, 3-sigma upper limit) on 1990 Oct. 11. Thus, the 1989 and 1990 observations noted above, together with those on 1990 Sept. 5-7 by ROSAT and on 1995 Aug. 14 by GRO, are likely due to episodic accretion during the periastron passage (by an accreting neutron star in the binary system) and provide us with an estimate of the binary period (5-6 months)."

Aleksandrovich, N. L.; Aref'ev, V. A.; Borozdin, K. N.; Syunyaev, R. A.; Skinner, G. K.  Detection of the x-ray sources KS J1748-248 and KS J1716-389 near the galactic center // 1995, Astron. Lett. 21, 431.

Н.Л. Александрович, В.А. Арефьев, К.Н. Бороздин и др. Открытие рентгеновских источников KS J1748-248 и KS J1716-389 в области Центра Галактики. //Письма в астрон. журнал, 1995 Т. 21, 7, С. 486-490.

При обработке данных рентгеновского телескопа ТТМ, полученных во время наблюдений области Центра Галактики в 1994 г., были обнаружены три новых рентгеновских источника. В данной статье описываются источники KS J1748-248 и KS J1716-389.

Borkus, V. V.; Kaniovsky, A. S.; Efremov, V. V.; Borozdin, K. N.; Sunyaev, R. A.; Aleksandrovich, N. L.; Arefev, V. A.; Kretschmar, P.; Kunz, M.; Maisack, M.; Staubert, R.; Englhauser, J.; Pietsch, W.; Reppin, C.; Truemper, J.; Skinner, G. K. Observations of the X-ray source Cygnus X-1 from the Roentgen Observatory aboard the orbiting Mir-Kvant module // 1995, Astron. Lett. 21, 794.

В.В. Боркус, А.С. Каниовский, В.В. Ефремов, К.Н. Бороздин, Р.А. Сюняев, Н.Л. Александрович, В.А. Арефьев и др. Наблюдения рентгеновского источника Лебедь Х-1 обсерваторией РЕНТГЕН на орбитальном модуле МИР-КВАНТ. // Письма в астрон. журнал, 1995, Т. 21, 12, С. 883-893.

В 1988 - 1994 гг. приборами обсерватории "Рентген" были проведены исследования временного и спектрального поведения рентгеновского источника - кандидата в черный дыры Лебедь Х-1 в диапазоне энергий 2-200 кэВ. Большую часть времени источних находился в жестком спектральном состоянии с характерным для комптонизации спектром. Средний на один день наблюдений поток излучения от источника в диапазоне энергий 45 - 140 кэВ изменялся примерно вдвое - от ~0.07 до ~0.15 фотон/с/кв. см. Наблюдались также сильные хаотические колебания потока в течение суток, с амплитудой отклонения от среднего до 15%. При этом какой-либо систематической зависимости жесткости спектра источника от его светимости обнаружено не было. В феврале 1994 г. жесткость во всем рентгеновском диапазоне значительно снизилась, а в спектре появилась мягкая компонента с температурой чернотельного излучения ~ 0.5 кэВ. Прибором ГЕКСЕ был обнаружен низкочастотный шум в спектре мощности источника. В диапазоне частот 0.01- 10 Гц спектр мощности шума хорошо описывается приближением в форме плато в низкочастотной области и степенного спада в высокочастотной. В ходе наблюдений частота, соответствующая излому в спектре, и амплитута плоского участка значимо изменялись. В одном из спектров мощности была обнаружена широкая (FWHM порядка центральной частоты) особенность, которая может быть интерпретирована как пик квазипериодических осцилляций. Проведенные в различных энергетических диапазонах измерения величины rms источника указывают на то, что спектр в целом и спектр переменной компоненты идентичны. Была обнаружена также значимая (3.5 сигма) корреляция между светимостью источника и его rms.

Borozdin, K. N.; Aleksandrovich, N. L.; Aref'ev, V. A.; Syunyaev, R. A.; Skinner, G. K. The Bright X-Ray Transient KS1730-312 in Scorpius. // 1995, Astron. Lett. 21, 212.

К.Н. Бороздин, Н.Л. Александрович, В.А. Арефьев, Р.А. Сюняев и др. Яркий транзиентный рентгеновский источник KS 1730-312 в созвездии Скорпиона . //Письма в астрон. журнал, 1995, Т. 21, 4, С. 243-247.

K. Borozdin, N. Alexandrovich, V. Arefiev, M. Gilfanov et. all. KVANT-TTM observations of the Galactic center region in 1988-1994.   // 30th COSPAR Scientific Assembly Hamburg, Germany, 11-21 July 1994. II.Abstracts. 1994, 2, 242. Elsevier Science Ltd, Oxford, England.

K. Borozdin, N.Alexandrovich, R. Sunyaev, J. Skinner. Два новых рентгеновских источника, открытых телескопом ТТМ вблизи Центра Галактики.  //  17th TEXAS Symposium on Relativistic Astrophysics, Munchen, Germany, 12-17 December 1994

DOEBEREINER, S.; ENGLHAUSER, J.; PIETSCH, W.; REPPIN, C.; TRUEMPER, J.; KENDZIORRA, E.; KRETSCHMAR, P.; KUNZ, M.; MAISACK, M.; STAUBERT, R.; EFREMOV, V.; SUNYAEV, R. HEXE observations of Cygnus X-1. // Astronomy and Astrophysics, v.302, p.115.

The High Energy X-ray Experiment (HEXE) observed the black hole candidate Cyg X-1 on several occasions during the years 1987 to 1991. Together, these observations comprise the most sensitive measurements in the hard X-ray range of 20-200keV of this source to date. We present results of the spectroscopy and the timing analysis. During all observation periods in 1987 to 1991 Cyg X-1 was in the low, hard state. The variability of the hard X-ray intensity on long time scales was less than 20%. The flux was comparable to the {gamma}_2_ level as observed by HEAO 3. There were no significant spectral changes during all this time. Comptonisation models do not give a good description for the time-averaged spectrum. A much better fit can be obtained using a Compton reflection model, assuming a primary hard power law spectrum with photon index {alpha}=1.64+/-0.01, which is partially reflected by cool matter with a covering factor of 0.59+/-0.04. The timing analysis shows the pattern of a low-frequency plateau followed by a 1/f decrease in the power spectrum, which is well known from observations at lower energies. No QPO peaks were detected.

MAISACK, M.; STAUBERT, R.; BALUCINSKA-CHURCH, M.; SKINNER, G.; DOEBEREINER, S.; ENGLHAUSER, J.; AREF'EV, V. A.; EFREMOV, V. V.; SUNYAEV, R. A. Broad-band X-ray observations of Cir X-1. // Advances in Space Research (ISSN 0273-1177), vol. 16, no. 3, p. 91-94.

We present broad-band (2-88 keV) X-ray observations of the X-ray binary Cir X-1 with the TTM and HEXE instruments on board of the Mir space station. The observations were made in January/February 1989. The spectrum is best described by a model with 3 components: a blackbody at low energies, an iron line and a Comptonized hard continuum. The spectrum is variable during our observations; when the Comptonized component becomes harder, the spectrum becomes softer below 15 keV. The high-energy spectrum resembles that of X-ray binary pulsars.

PAN, H. C.; SKINNER, G. K.; SUNYAEV, R. A.; BOROZDIN, K. N. X-ray spectrum of the black hole candidate X1755-338. // Monthly Notices of the Royal Astronomical Society, Volume 274, Issue 1, pp. L15-L18.

We report the first detection of a hard power-law tail in the X-ray spectrum of the black hole candidate (BHC) binary X1755-338, which was observed in 1989 March-September during the TTM Galactic Centre Survey. In addition, an ultrasoft thermal component with a temperature of ~1.1-1.4 keV was also detected. We demonstrate that the soft and hard X-ray components of X1755-338 vary independently, as in the spectra of the well-known BHCs LMC X-1, LMC X-3 and GX339-4 in their high (intensity) state. If the hard tail observed from X1755-338 is generated near the black hole by energetic electrons upscattering low-energy photons, the uncorrelated variations imply that the soft X-rays from the accretion disc may not be the main photon seeds needed for inverse Comptonization. The TTM observations strongly suggest that X1755-338 does indeed belong to the family of BHCs.

R. Sunyaev, V. Arefiev, K. Borozdin, N.Alexandrovich et. all. Observation of X-ray novae for 1992-1993 by TTM telescope. //  30th COSPAR Scientific Assembly Hamburg, Germany, 11-21 July 1994. II.Abstracts. 1994, 2, 236. Elsevier Science Ltd, Oxford, England

IAU Circ. 6350. 1996. GRS 1739-278 AND GRO J1744-28

K. Borozdin, N. Alexandrovich, and R. Sunyaev, Space Research Institute, Moscow, report on behalf of MIR-KVANT-TTM team: "The TTM experiment onboard the Mir-Kvant Space Station has detected GRS 1739-278 (IAUC 6348) as a very bright and soft x-ray source. The 2- to 27-keV flux was equal to 200 +/- 50 mCrab on Feb. 28, rising to 500 +/- 50 mCrab on Mar. 1. The TTM position (R.A. = 17h42m40s, Decl. = -27o45'.8, equinox 2000.0; uncertainty +/- 1'), is inside the SIGMA/Granat error box. The source was weaker than 100 mCrab during previous TTM sessions of GC observation (Feb. 6-7). The spectrum in the band 2-27 keV can be roughly fitted by a power law with spectral index 2.7 +/- 0.1 and hydrogen absorption column density (4.1 +/- 0.7) x 10E22 cmE-2. However, the two-component (soft component plus hard power law) model with smaller absorption provides better agreement with data obtained on Mar. 1. Such x-ray spectra are typical for accreting blackhole candidates. GRO J1744-28 was observed simultaneously during galactic field observations. The 2- to 27-keV flux was 1650 +/- 70 mCrab on Feb. 7, 515 +/- 30 mCrab on Feb. 28, and 1220 +/- 50 mCrab on Mar. 1. The TTM localized the source at R.A. = 17h44m34s, Decl. = -28o45'.2 (uncertainty +/- 1'); this source has a much harder spectrum in the band 2-27 KeV than does GRS 1739-278."

BALUCINSKA-CHURCH, M.; CHURCH, M. J.; MAISACK, M.; BELLONI, T.; SKINNER, G. K.; STAUBERT, R.; DOEBEREINER, S.; ENGLHAUSER, J. Spectral behaviour of Cygnus X-1 in a broad band 0.1 - 200 keV based on ROSAT, TTM and HEXE observations.// Mem. Soc. Astron. Ital., 67, 389-394 (1996).

KRETSCHMAR, P.; PAN, H. C.; KENDZIORRA, E.; KUNZ, M.; MAISACK, M.; STAUBERT, R.; PIETSCH, W.; TRUEMPER, J.; EFREMOV, V.; SUNYAEV, R. Absorption features in the hard X-ray spectra of PSR A 0535+26 and Vela X-1. // Astronomy and Astrophysics Supplement, v.120, p.175-178.

We present the results of broad band (2-200keV), pulse-phase-resolved spectral analysis of A0535+26 and Vela X-1, observed by the instruments HEXE and TTM on Mir-KVANT. Both sources show a double peaked pulse profile at energies >10keV with pulses distinctly different in shape. Convincing evidence for cyclotron absorption features has been found for A0535+26, similar features - though less significant - are also found in the Vela X-1 spectra. For both sources these features are pulse phase dependent and occur especially strong in the pulse getting more prominent with increasing energy.

А.Н. Александрович, А.В. Арефьев, К.Н. Бороздин, А.В. Прудкогляд. Методы определения параметров наведения приборов модуля "Квант". Планирование наблюдений. // Препринт ИКИ РАН. Пр - 1959. 1996.

Данная работа состоит из двух основных частей. В первой части описываются способы определения параметров наведения (углов alf, del и fi) приборов модуля "Квант". Точное определение параметров наведения по данным телескопа ТТМ возможно только при наличии в его поле зрения не менее двух источников с известными экваториальными координатами. Другой способ нахождения параметров наведения использует данные телеметрии оптических звездных датчиков системы ориентации станции. Показано, что этот метод не позволяет вычислить alf, del и fi с необходимой для астрофизических приборов точностью. Отмечено улучшение стабилизации станции по сравнению с 1987-1989 г.г. Во второй части изложены начальные данные и последовательность вычислений для планирования наблюдений. Оценки возможности разворота станции в заданную ориентацию основаны на переходе к инерциальной системе координат, определяемой плоскостью орбиты станции и направлением на Солнце.

Borkus, V. V.; Kaniovsky, A. S.; Sunyaev, R. A.; Efremov, V. V.; Kretschmar, P.; Staubert, R.; Englhauser, J.; Pietsch, W. HEXE/Mir-Kvant observations of the bursting X-ray pulsar GRO J1744-28 // 1997, Astron. Lett. 23, 421.

BORKUS, V. V.; KANIOVSKY, A. S.; SUNYAEV, R. A.; EFREMOV, V. V.; KRETSCHMAR, P.; STAUBERT, R.; ENGLHAUSER, J.; PIETSCH, W. HEXE/Mir-Kvant observations of the bursting X-ray pulsar GRO J1744-28. // Pis'ma Astron. Zh., 23, 483-495 (1997).

We present the results of a timing and spectral analysis of the bursting X-ray pulsar GRO J1744√28 performed by the HEXE instrument of the Mir√Kvant Observatory. In early 1996, we carried out two series of observations separated by a month and detected no significant prolonged luminosity variations. The mean lumi nosity in the energy range 20√100 keV was ~ 2 1036d2 erg s1 and ~ 1.5 1036d2 erg s1 during the first and second series of observations, respectively (assuming that a point source is located at distance d kpc). The period of the pulsar, ~0.46706 s, and the rate of its evolution match the BATSE values. The constructed pulse profile is nearly sinusoidal in shape, and the pulse fraction changes from ~20% (rms 13.8 0.6% at energies up to 30 keV to ~25% (rms 17.5 1.2%) in harder energy channels. During the observations, four strong bursts of duration 8√10 s were detected. The burst luminosity at maximum was a factor of 5√10 higher than the mean value for the source. After each of the bursts, the flux from the source rapidly decreased to ~80% of the normal level and then began to slowly rise. However, the temporal properties of these processes differ for dif ferent bursts. Within the limits of the available statistics, the 20√80-keV burst spectra are similar to the spectrum of the primary component. The averaged spectrum of the source turned out to be harder than the spectrum pre dicted by the ⌠canonical■ model and exhibits a considerable excess of photons in the band 60√120-keV, which can be offset either by introducing an additional power-law component or (in part) by introducing an absorption gyroline at energy E1 ~ 45 keV. However, because of the high density of sources in the region of the Galactic center, the additional component cannot be uniquely attributed to GRO J1744√28.

S.V.Lavrov, K.N.Borozdin, N.L.Aleksandrovich, V.A.Aref'ev, R.A.Sunyaev, and G.K.Skinner. Two Spectral States of the Black Hole Candidate GX339-4. //Astronomy Letters, V. 23, 7, 433 (1997).

We performed two series of observations of the X-ray source GX 339√4, a black-hole candidate, between 1989 and 1994 using the TTM instrument of the Roentgen Observatory. In March 1989, the source was in a soft state with a spectrum described by a multicolor accretion disk model (Shakura and Sunyaev 1973). In March 1994, a hard state with a power-law spectrum and a transition from the hard to the soft state was observed. The spectral states of the source show similarities to the spectra of other black-hole candidates. The presence of two states is considered as evidence that GX 339√4 belongs to this class of objects.

С.В. Лавров, К.Н. Бороздин, Н.Л. Александрович, В.А. Арефьев и др. Спектральные состояния кандидата в черные дыры GX 339-4. // Письма в астрон. журнал, 1997, Т. 23, 7, С. 496 - 502.

BOROZDIN, KONSTANTIN N.; ALEXANDROVICH, N. L.; AREFEIV, V. A.; GILFANOV, M. R.; REVNIVTSEV, M.; SUNYAEV, R. A.; TRUDOLYUBOV, S. P. Observations of bright X-ray transients by MIR-KVANT module in 1988-1996. // "All-Sky X-Ray Observations in the Next Decade", 1997, RIKEN, Japan, eds. M. Matsuoka and N. Kawai, p. 49.

MIR-KVANT module being on the orbit during ten years since 1987 was able to observe a set of bright X-ray transients from Vul X-Nova in 1988 to GRS1739-278 in 1996. Broad-band X-ray spectra and temporal variability of them are discussed.

The most of studied transients belong to X-ray Novae - group of X-ray transients with common observational features. The transients appear at X-ray sky with a frequency about 1-1.5 per year and are available for observations by experiments with ~ 10 mCrab sensitivity during few monthes after the outburst. Measured mass function several of those objects exceeds 3 solar masses and considered to be a solid prove of black-hole presense in the system. Other exotic objects observed were Galactic 'microquasars' GRS1915+105 and GRO J1655-40, also pulsar-burster GRO J1744-28.

Almost all of the objects discussed were discovered by X-ray all-sky monitors ``Ginga'', WATCH/GRANAT, BATSE/GRO, so they are sources of primary interest for future all-sky monitors. From the other hand most of these objects are located in densely populated Galactic Center region which requires quite good angular resolution for fine studies.

KANIOVSKY, A. S.; AREFIEV, V. A.; ALEKSANDROVICH, N. L.; BORKOUS, V. V.; BOROZDIN, K. N.; EFREMOV, V. V.; SUNYAEV, R. A.; KENDZIORRA, E.; Three hard X-ray transients: GRO J0422+32, GRS 1716-24, GRS 1009-45. Broad band observations by Roentgen-MIR-KVANT observatory. // Advances in Space Research, v. 19, Issue 1, p. 29-34.

KRETSCHMAR, P.; PAN, H. C.; KENDZIORRA, E.; MAISACK, M.; STAUBERT, R.; SKINNER, G. K.; PIETSCH, W.; TRUEMPER, J.; EFREMOV, V.; SUNYAEV, R. Phase resolved X-ray spectra of Vela X-1. // Astronomy and Astrophysics, v.325, p.623-630.

Combining simultaneous observations of Vela X-1 by the instruments HEXE and TTM on Mir-Kvant, we have analyzed pulse profiles and pulse phase resolved spectra over a broad energy band (2-120keV). The pulse profiles show the well known transition from a complex shape at low energies to a double peak structure at energies >20keV. The high-energy lightcurves exhibit strong pulse-to-pulse variations. We find indications for spectral features at ~23 and ~45keV in the phase averaged spectra, which can be interpreted as the fundamental and first harmonic cyclotron resonances, but we caution that the first feature coincides with the spectral cutoff of the continuum spectra used. Pulse phase resolved spectroscopy shows that the shape of the continuum spectrum varies significantly with pulse phase and that the cyclotron features are mainly visible in one of the two pulses seen at high energies.

N.L.Aleksandrovich, K.N.Borozdin, V.A.Aref'ev, R.A.Sunyaev, and G.K.Skinner. TTM/MIR-KVANT Observations of the X-ray Transient Bursting Pulsar GRO J1744-28. // Astronomy Letters, V. 24, 1, 7 (1998).

The bursting pulsar GRO J1744√28, which flared up in December 1995, has become one of the most interesting objects for X-ray astrophysics. The observations of this source with the TTM instrument on the Kvant module of the Russian Mir Space Station are discussed. The light curves obtained during the five recorded bursts from the source are presented. The TTM localization of the X-ray source with an accuracy of 1arc. min. is given. The burst source is shown to coincide in position with GRO J1744√28. The 2√27-keV spectra of the object during and between bursts are constructed.

Н.А. Александрович, К.Н. Бороздин, В.А. Арефьев, Р.А. Сюняев, Дж.К. Скиннер.Наблюдения рентгеновского транзиентного пульсара - барстера GRO J1744-28 телескопом ТТМ орбитальной обсерватории "Мир-Квант". // Письма в астрон. журнал, 1998, Т. 24, 1, С. 10 - 18.

Пульсар-барстер GRO J1744-28, вспыхнувший в декабре 1995 г., стал одним из интереснейших объектов для рентгеновской астрофизики. В статье обсуждаются результаты наблюдений этого источника прибором ТТМ модуля "Квант" российской космической станции "Мир". Представлены кривые блеска во время пяти зарегистрированных вспышек источника. Приводится локализация источника рентгеновского излучения телескопом ТТМ с точностью до 1 угл.мин. Показано, что положение источника всплесков совпадает с положением GRO J1744-28. Построены спектры объекта в диапазоне 2-27 кэВ во время вспышек и в промежутке между ними.

N.L.Aleksandrovich, K.N.Borozdin, A.N.Emel'yanov, R.A.Sunyaev, and G.K.Skinner. Upper Limits on the Fluxes from X-ray Transients of the Galactic Center Region in the Off State // Astronomy Letters, volume 24, page 742 (1999).

Н.Л. Александрович, К.Н.Бороздин, А.Н.Емельянов, Р.А.Сюняев и Дж. Скиннер. Верхние пределы на потоки от рентгеновских транзиентов области Центра Галактики в "выключенном" состоянии // Письма в астрон. журнал, 1998, Т. 24, 11, С. 855.

В последние годы в области Галактического Центра было обнаружено несколько рентгеновских транзиентов. Эти источники характеризуются изменением излучаемого потока на порядки величины. В данной статье мы приводим верхние пределы на поток в диапазоне 2-27 кэВ по данным телескопа ТТМ обсерватории "Мир-Квант" от следующих источников: KS 1730-312, GRS 1758-258, GRS 1716-249, GRO J1735-27, GRO J1750-27, GRO J1744-28, GRS 1739-278, GRS 1716-299, GRS 1737-31, SAX J1750.8-2900, XTE J1755-324, SAX J1808.4-3658, XTE J1739-302 и XTE J1709-267 в их "выключенном" состоянии. Поток от перечисленных источников вне вспышек почти все время находился ниже порога чувствительности телескопа ТТМ. Некоторые из них в отдельных сериях сеансов были обнаружены на пределе чувствительности прибора.

BORKUS, V. V.; KANIOVSKY, A. S.; SUNYAEV, R. A.; EFREMOV, V. V.; KRETSCHMAR, P.; STAUBERT, R.; ENGLHAUSER, J.; PIETSCH, W. Properties of the Pulsar GX 301-2 in the Hard X-ray Range. // Astronomy Letters, volume 24, page 60 (1998).

In 1993-1994, we performed a series of observations of the X-ray pulsar GX 301-2 with the HEXE instrument of the Mir-Kvant Observatory. We measured the period of the source (it varied between 675 and 678 s) and constructed the pulse profiles in various bands of the energy range 20-75 keV. The measured 20-100-keV luminosity varied between 8 x 10^34 and 7 x 10^35 d^2 erg s-1 (for a point source at distance d kpc). The observed spectrum can be described quite satisfactorily by the `canonical' model for X-ray pulsars with gamma = 1.3, E_c ~ 23keV, and E_f ~ 9 keV. The spectrum changed little from measurement to measurement, but at maximum light, it was slightly softer than that in all the other states. We detected significant variations of the hardness with pulse phase, but the accumulated data were not enough to study the related variations in the spectral parameters. The spectrum exhibited no statistically significant traces of cyclotron lines. The interpretation of the pulse profiles in terms of the model of a rotating neutron star with two emitting polar caps that includes gravitational effects indicates that the most probable inclination of the pulsar's magnetic axis with respect to its spin axis is 40 deg - 70 deg, and that the angle between the observer's direction and the spin axis is ~75 deg - 85 deg.

V.V.Borkus, A.S.Kaniovsky, R.A.Sunyaev, V.V.Efremov, P.Kretschmar, R.Staubert, J.Englhauser, and W.Pietsch. Hard X-ray Observations of the X-ray Pulsar A0535+26 // Astronomy Letters, volume 24, page 350 (1998).

We present the observations of three `giant' outbursts from the X-ray pulsar A0535+26 in April 1989, November 1993, and February 1994 by the HEXE instrument on board the Mir-Kvant Observatory. We measured the pulsation periods, constructed the pulse profiles in various energy bands, and studied their variability with time. The power spectrum of the fractional rms in the range 2 x 10^-3 to 1 Hz is given; its shape is typical of flicker noise, which is commonly observed in black-hole candidates and in some pulsars. The fractional rms slightly increases with increasing energy from ~20% at 20 keV to ~30% at 80 keV. We constructed the photon spectra in the range 15 to 200 keV and studied their variability with pulse phase. The shape of each of these spectra can be approximately described by a `canonical' continuum model for X-ray pulsars with a photon index nu ~ 1.1, a break at E_c ~ 23 keV, and E_f ~ 19 keV; the fitting parameters depend only slightly on the luminosity. The greatest deviation from the above continuum is observed for the main pulse at energy ~100 keV. A cyclotron absorption line is assumed to be responsible for this deviation. The HEXE data are compared with the CGRO data. The properties of the pulsar A0535+26 at luminosity ~10^38 erg s^-1 are shown to differ qualitatively from its properties at luminosity ~ 5 x 10^36 erg s^-1. At the same time, the data are consistent with the assumption that the structure of the polar cap at L ~ 10^38 erg s^-1 changes qualitatively, and that accretion columns extended along the magnetic-field lines are formed at the poles.

K.N.Borozdin, M.G.Revnivtsev, S.P.Trudolyubov, N.L.Aleksandrovich, R.A.Sunyaev, and G.K.Skinner. The X-ray Nova GRS 1739-278 Near the Galactic Center // Astronomy Letters, volume 24, page 435 (1998).

The soft X-ray nova GRS 1739-278 flared up in 1996 near the Galactic center. We present the observations of this interesting source, a black-hole candidate, with the instruments on board the Mir-Kvant module and the RXTE satellite. The TTM data allow the spectrum of the X-ray nova to be studied during the rise in its brightness. The source's spectrum in this period is satisfactorily described by a power law with a gradually increasing index. The RXTE spectra after the source passed its maximum brightness have the appearance that is typical of the high and very high states of black-hole candidates; they are described by a two-component model. The broad-band spectra of the source are discussed in terms of the processes that proceed near an accreting black hole in a binary system.

Revnivtsev et al."Hard X-ray observations of X-ray Nova Ophiuchi 1993 (GRS 1716-249) with GRANAT/SIGMA"// 1998, A&A 331, 557.

S. Trudolyubov, E. Churazov, M. Gilfanov, M. Revnivtsev, R. Sunyaev, N. Khavenson, A. Dyachkov, I. Tserenin, M. Vargas, P. Goldoni, P. Laurent, J. Paul, E. Jourdain, J.-P. Roques, P. Mandrou, G. Vedrenne. Spring, 1997 it GRANAT/SIGMA observations of the Galactic Center: discovery of the X-ray nova GRS 1737-31 // 1999A&A...342..496T.

The results of GRANAT/SIGMA hard X-ray observations of the Galactic center in March, 1997 are reported. One new source - GRS 1737-31 and two previously known sources - 1E 1740.7-2942 and GRO J1744-28 were detected. The spectral and temporal behavior of GRS 1737-31 suggests that this source may be a distant X-ray Nova and a black hole candidate.
The comparison of the hard X-ray transient detection rates by GRANAT/SIGMA and currently operating all-sky monitors (CGRO/BATSE, GRANAT/WATCH) leads to following conclusions regarding the spatial and luminosity distributions of the hard X-ray transients:

(i) the spatial distribution of X-ray Novae exhibits a concentration towards the Galactic Center similar to the distribution of the visible matter in the Galaxy. In particular, it is more concentrated than Galactic disk population.

(ii) if hard X-ray transients follow distribution of visible mass in the Galaxy then their peak luminosity in the 35-150 keV band is close to 10(37) erg s(-1) with a relatively small scatter.

A.N.Emelyanov, N.L.Aleksandrovich, and R.A.Sunyaev. A Catalog of X-ray Sources as Observed by the TTM/COMIS Telescope of the MIR-KVANT Observatory in 1988-1998 // Astronomy Letters, volume 26, page 297 (2000).

A catalog of X-ray sources as observed by the TTM/COMIS telescope onboard the Mir√Kvant observatory is presented. Brief information about the 67 sources detected at a confidence level higher than 4 between 1988 and 1998 is provided. X-ray properties and characteristic spectra of different types of sources are briefly described.

А.Н.Емельянов, Н.Л.Александрович, Р.А.Сюняев. Каталог рентгеновских источников по данным наблюдений телескопом ТТМ/COMIS обсерватории "Мир-Квант" в 1988-1998 гг. // Письма в астрон. журнал, 2000, Т. 26, 5, С. 355.

Представлен каталог рентгеновских источников по данным наблюдений телескопом ТТМ/COMIS обсерватории "Мир-Квант". Приведена краткая информация о 67 источниках, зарегистрированных со значимостью более 4s, в период с1988 по 1998 гг. Дано краткое описание рентгеновских свойств и характерные спектры разных типов источников.

Н.Л. Александрович, В.А.Арефьев. Итоги работы орбитальной обсерватории "Рентген" // Земля и Вселенная, 6, 2000, С. 14-27 (статья написана по материалам раздела Важнейшие результаты, полученные приборами обсерватории "Рентген").

В конце 60-х гг. произошла революция в астрофизике и физической космологии. Были открыты реликтовое излучение, квазары, радиопульсары, компактные рентгеновские источники - аккрецирующие нейтронные звезды и черные дыры. Теория подготовила колоссальный рывок наблюдательной астрофизики и космологии. Обсерватория "Рентген", размещенная на модуле "Квант" пилотируемого орбитального комплекса "Мир", внесла немалый вклад в исследование рентгеновских источников, обнаружив несколько новых нейтронных звезд и черных дыр. Авторы рассказывают о результатах исследований 1987-1999 гг., выполненных с помощью комплекса рентгеновских приборов обсерватории.

 Emelyanov, A. N.; Aref'ev, V. A.; Churazov, E. M.; Gilfanov, M. R.; Sunyaev, R. A. A Deficit of Type I X-ray Bursts from Low-Accretion-Rate Binaries: Data from the TTM/COMIS Telescope Onboard the Mir-Kvant Observatory// Astronomy Letters, volume 27, page781-789 (2001).

А.Н.Емельянов, В.А.Арефьев, Е.М.Чуразов, М.Р.Гильфанов, Р.А.Сюняев. Дефицит рентгеновских всплесков I типа от двойных систем с низким темпом аккреции: данные телескопа TTM/COMIS обсерватории МИР-КВАНТ // Письма в астрон. журнал, 2001, Т. 27, 12, С. 908

Emelyanov, A. N.; Revnivtsev, M. G.; Aref'ev, V. A.; Sunyaev, R. A. A Ten-Year-Long Peak of the X-ray Flux from the Burster 4U 1724-307 in the Globular Cluster Terzan 2: Evolution of the Donor Star or the Influence of a Third Star? // Astronomy Letters, volume 28, page 12-18  (2002).

А.Н. Емельянов, М.Г. Ревнивцев, В.А. Арефьев, Р.А.Сюняев. Десятилетний пик рентгеновского потока барстера 4U~1724-307 в шаровом скоплении Терзан 2: эволюция звезды-донора или влияние третьей звезды? //  Письма в Астрономический журнал, 2002, T.28, 1, C. 14-21.

Aleksandrovich, N. L.; Revnivtsev, M. G.; Aref'ev, V. A.; Sunyaev, R. A.; Skinner, G. K.Long-Term Mir-Kvant Observations of the Transient X-ray Burster KS 1731-260 // Astronomy Letters, volume 28, page 279-286  (2002).

Н.Л. Александрович, М.Г.Ревнивцев, В.А.Арефьев, Р.А.Сюняев и Дж. Скиннер.  Долговременные Наблюдения Рентгеновского Транзиентного Барстера KS1731-260 Орбитальной  Обсерваторией "Мир-Квант" // Письма в Астрономический журнал, 2002, T. 28, 5, C. 323-330.

Aleksandrovich, N. L.; Aref'ev, V. A. The Soft X-ray Novae, Black-Hole Candidates XTE J2012+381 and XTE J1550-564 // Astronomy Letters, volume 28, page 660-668 (2002).

Н.Л. Александрович, В.А.Арефьев.Мягкие рентгеновские новые, кандидаты в черные дыры XTE J2012+381 XTE J1550-564 // Письма в Астрономический журнал, 2002, T. 28, 10, C. 732-740.

В.А.Арефьев, Н.Л. Александрович. Рентгеновские всплески первого рода из "пустых мест" - индикаторы "слабоаккрецирующих" барстеров? // Письма в Астрономический журнал, 2004, T. 30, 2, C. 105-114.