RTT150, main page
RTT150
Russian-Turkish 1.5-m Telescope

 
High energy Astrophysics department of IKI, Moscow
International astrophysical observatory Spectrum-X-Gamma
International astrophysical space observatory INTEGRAL

(C) Copyright 
HEAD IKI

Telescope's optical systems

Telescope has two main foci (Cassegrain and Coude) and allows to use six optical systems based on Ritchey-Chretien system with a common main mirror. At present scientific observations are being performed at the Cassegrain focus in main optical scheme with focal ratio of 1:7.7. Other optical schemes may be used with developing new focal instruments. All optical schemes of telescope are designed to work in the spectral range of wavelengths 325 nm < l < 1000 nm.
Summary of RTT150 optical schemes
Scheme
Equivalent
focal
length
Angular
field of
view
Linear
field of
view
Image
scale
Central
screening
in area
Shape of
focal
surface
1:3 with Meinel camera
4519 mm
1o
79 mm
45".6/mm
25.8%
flat
1:7.7 with corrector
11639 mm
1o28'
300 mm
17".6/mm
25.8%
flat
1:7.7 without corrector
11611 mm
26'40"
90 mm
17".8/mm
25.8%
sphere
1:17.3 with corrector
26007 mm
13'
100 mm
7".8/mm
17%
flat
1:16 without corrector
24029 mm
4'18"
30 mm
8".6/mm
11.6%
sphere
1:48, Coude
72257 mm
3'50"
80 mm
2".9/mm
17 %
sphere

The needed optical scheme is achieved by installing appropriate secondary hyperbolic mirror, blends and correcting lenses (if they are used in a given scheme). To use the Coude focus the removable flat diagonal mirror is also needed in the crossing point of declination axis and main optical axis of telescope. This mirror reflects the converging beam of light to the system of 3 mirrors placed inside the base yoke and after reflecting from the latter of them light is going downwards along the polar axis.

Replacment of secondary hyperbolic mirrors is performed at the tube of telescope in horizontal position using the dome crane. To protect the gear of declination axis from hits and shakes during the change of secondary mirrors or during removal/installation of main mirror cell, the yoke base with declination axis drive has fixing element which allows to hold the telescope tube in horizontal and vertical positions.

All drives, both on hour and declinations axis, are placed in the base. To protect the telescope from the possible seismic affects the couplings are provisioned which fix the telescope mount.