Astron. Astrophys. Suppl. Ser. 136, 19-25
P. Pant - C.S. Stalin - R. Sagar
Send offprint request: P. Pant, e-mail: ppant@upso.ernet.in
U. P. State Observatory, Manora Peak, Nainital 263 129, India
Received August 28; accepted October 21, 1998
In order to detect the microthermal fluctuations introduced by the atmospheric
turbulence very near to the ground at Devasthal site, a PC based
instrumentation 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 between 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
can be achieved, if the telescope is located at a height
of 
m above the ground.
Key words: site atmospheric effects -- site testing
Copyright The European Southern Observatory (ESO)