| Terskol Peak
is a spur of Elbrus mountain. It has altitude 3100 m
and coordinates 43°13'N, 2h50mE.
The ATsU-26 telescope was established there in 1989. The telescope
is equipped with 5-camera spectrograph, thus it allows s imultaneous
observations in five spectral regions. Diameter of the main
spherical mirror is 650 mm, focal length - 17750 mm;
diameter of the collimator and cameras - 300 mm, focal
length - 8000 mm; grating - (250*200) mm, 600 lines/mm;
dispersion in fourth order - 21.9 mm/nm at 395.0 nm,
33.0 mm/nm at 650.0 nm. The telescope scheme is
shown on the right figure. | 
(in
past the shifts exceed 12 mA). Similar results concerning
stability were obtained with Ne emission lamp. So, these results
are confident. The scattered light was measured with observing
saturated oxygen lines near 763 nm, it equals 3%. Such a high
level of scattered light is mainly because of baffles absence.
That will be corrected soon. Below, several figures with results
of the spectrograph tests are placed.
