Detection of Faint Sources by the UltraViolet Imaging Telescope Onboard AstroSat Using Poisson Distribution of Background

Abstract

We present an improved approach for constructing the UV source catalogs using observations from the UltraViolet Imaging Telescope (UVIT) onboard AstroSat, by considering the Poisson distribution of the UV background. The method is tested extensively using fields that are not crowded, the Small Magellanic Cloud (SMC) and M31 (Field 13). The results are compared with previous studies that used UVIT observations. This approach is successful in detecting fainter sources and produces a large number of new sources ($\sim 15$ to $92\%$ more). Most of the newly discovered UV sources fall in the faint end of the source distribution (m $\gtrsim 22$). The counterparts at other wavelengths are identified for most sources. This approach is more efficient for source detection and provides an opportunity to explore new classes of UV sources.