On Possibility of Detection of Variable Sources Using the Data of "Cold" Surveys Carried Out on RATAN-600

TL;DR

This study evaluates the potential to detect variable radio sources using historical data from RATAN-600 surveys, identifying candidate variables through statistical analysis of flux measurements over 14 years.

Contribution

It introduces a method for assessing long-term variability in radio sources using calibration curves and statistical parameters from archival survey data.

Findings

14 out of 80 calibration sources show signs of variability

Three sources have high confidence of being variable (p > 0.95)

Some candidate variables are also variable in optical range

Abstract

In this study we attempt to assess the possibility of detection of variable sources using the data of the 7.6-cm wavelength surveys carried out on the RATAN-600 radio telescope in the period from 1980 through 1994. Objects selected according to certain criteria from the RCR catalog are used to construct the calibration curves and to estimate the accuracy of the resulting calibration curves and determine the r.m.s. errors for the measured source flux densities. To check the calibration sources for the presence of variable objects, quantitative estimates are performed for a number of parameters that characterize variability, in particular, for the long-term variability index V and the chi-square probability p. The long-term variability index was found to be positive for 14 out of approximately 80 calibration sources, possibly indicating that these sources are variable. The most likely candidate variables are the three sources with the chi-square probability p > 0.95. Five sources have chi-square probabilities in the 0.85 < p < 0.95 interval, and the remaining six in the 0.6 < p < 0.8 interval. Nine out of 14 objects are possibly variable in the optical range. The light curves and spectra are determined for possible variable sources and a number of "non-variable" objects. We plan to use the results of this study in our future searches for variable radio sources using the data of the "Cold" surveys.