All sky scanning cloud monitor for NLOT site survey

Abstract

Monitoring local sky for the cloud is one of important task before setting-up a new observatory. Here we present the design, implementation and initial results of a scanning type cloud monitor developed in Indian Institute of Astrophysics, Bangalore, India. The new cloud monitor is expected to be used in search for a potential site for India's National Large Optical Telescope project. The instrument works on the principle of detection of the Infrared radiations from the clouds. A number of thermopile sensors are arranged in the form of a circular array and are rotated in azimuth to cover the whole sky. An analog circuit was designed and fabricated to amplify the weak output of the thermopile. A customized data acquisition devise is developed for recording the output of the sensors on SD card. LabVIEW based data analysis software is developed to process raw data as well as to generate the cloud map of the sky.