Abstract:
In order to detect the microthermal fluctuations introduced by the atmospheric turbulence very near
to the ground at Devasthal site, a PC based instrumenta
tion has been developed. The optical image degradation
due to such turbulence has been quantified. The results
of the optical seeing due to the surface layer at Devasthal
site are presented and compared with the seeing results
obtained from the Differential Image Motion Monitor.
Microthermal measurements were taken on 20 nights be-
tween March and June 1998, using sensors placed at three
equally spaced levels on a 18 m high mast. We found a significant decrease in the optical turbulence over the height
of the mast with a mean value of 0.32 for the 12 to 18 m
slab and 1.28 for the 6 to 12 m slab. For Devasthal site, a
seeing of ∼ 0.6 can be achieved, if the telescope is located
at a height of ∼ 13 m above the ground.
