Abstract:
We have developed a simple and portable device that makes precise and automated measurements of night sky extinction. Our instrument uses a commercially available telephoto lens for
light collection, which is retrofitted to a custom-built telescope mount, a thermoelectrically
cooled CCD for imaging, and a compact enclosure with electronic control to facilitate remote
observations. The instrument is also capable of measuring the sky brightness and detecting
the presence of thin clouds that otherwise would remain unnoticed. The measurements of
sky brightness made by our simple device are more accurate than those made using a large
telescope. Another capability of the device is that it can provide an instantaneous measurement
of atmospheric extinction, which is extremely useful for exploring the nature of short-term
extinction variation. The instrument was designed and developed primarily in order to characterize and investigate thoroughly the Indian Astronomical Observatory (IAO), Hanle for the
establishment of India’s future large-telescope project. The device was installed at the IAO,
Hanle in 2014 May. In this paper, we present he instrument details and discuss the results of
extinction data collected for about 250 nights.
