PHOTOMETRIC ANALYSIS OF PI OF THE SKY DATA

Abstract

Pi of the Sky is a system of two wide field of view robotic telescopes, which search for short timescale astrophysical phenomena, especially for prompt optical GRB emissions. The system was designed for autonomous operation, monitoring a large fraction of the sky with 12m–13m range and time resolution of the order of 1–10 seconds. Two fully automatic Pi of the Sky detectors located in Spain (INTA — INTA El Arenosillo Test Centre in Mazagón, near Huelva.) and Chile (SPDA — San Pedro de Atacama Observatory.) have been observing the sky almost every night in search of rare optical phenomena. They also collect a lot of useful observations which include e.g. many kinds of variable stars. To be able to draw proper conclusions from the data received, adequate quality of the data is very important. Pi of the Sky data is subject to systematic errors caused by various factors, such as cloud cover, seen as significant fluctuations in the number of stars observed by the detector, problems with conducting mounting, a strong background of the moon or the passing of a bright object, e.g., a planet, near the observed star. Some of these adverse effects have already been detected during the cataloging of individual measurements, but the quality of our data was still not satisfactory for us. In order to improve the quality of our data, we have developed two new procedures based on two different approaches. In this article we will report on these procedures, give some examples, and we will show how these procedures improve the quality of our data.