Technique for processing the RATAN-600 sky survey at the declination of the Crab Nebula

Abstract

In this paper we present the results of developing a method for processing the sky survey obtained with the fixed antenna of the RATAN-600 Western Sector ($Az =270^\circ$) at the declination of the pulsar in the Crab Nebula. The sky survey was conducted in 2018-2019 using a complex of three four-channel radiometers at a central frequency of 4.7 GHz. We consider the peculiarities of the passage of sources at a parallactic angle through the antenna beam pattern, with input horns of radiometers located along the focal line of the secondary mirror. A sample of 205 sources with $S/N > 50$ ($S_{4.7}  > 15$ mJy) was processed. For the detected and identified sources, we calculated ephemerides for the observational epoch, depending on their offset relative to the telescope beam pattern centers in each receiving horn of the radiometers. During data accumulation, the measured positions of the sources were corrected, and a change in the gain of the radiometers due to ambient temperature was taken into account. The proposed method allows one to determine both the position of the detected sources with an accuracy of 1-2 seconds and flux densities with an accuracy of 5-10%.