Abstract:
The 3.6m optical telescope, currently the largest optical telescope in India is being
built at Devasthal with an aim to develop an observational facility with spectral
and seeing limited imaging capabilities at visible and near infrared bands.
Electromagnetic radiation received on Earth are the major carriers of cosmological
information. The ability of a telescope to collect the least possible signal describes
its sensitivity. The aim of the project was to characterize the photometric and
spectroscopic sensitivity of this telescope. A measure of sensitivity is given by the
signal to noise ratio of the telescope. The signal to noise ratio for imaging as well
as spectroscopy at various zenith angles and observing conditions has been
calculated using MATLAB. In imaging, a signal-to-noise ratio of 3.9 has been
obtained for a 25mag point source in V band, measured at zenith for an exposure
time of 30 minutes, using a 4KX4K CCD camera with a pixel size of
15microns,three days from New Moon. And, in spectroscopy, a signal to noise
ratio of 7.5 has been obtained for a 20 mag point source at 0.5 μm, measured at
zenith for an exposure time of 10 minutes.
