CoLiTecVS software for the automated reduction of photometric observations in CCD-frames

Abstract

In this article, we present the new product and its description developed by the CoLiTec (Collection Light Technology) project (Khlamov & Savanevych 2020), called CoLiTecVS (CoLiTec Variable Stars) software as a set of tools for the automated light curve creation of variable stars using the sensor data received from the different sensors.CoLiTecVS allows performing the photometry and light curve creation with minimal user interaction in two different modes. The first one is an observation mode when the data are received online from the sensors directly and immediately processed by the OnLine Data Analysis System (OLDAS). This mode is called “OLDAS-Night” mode. The second one is processing the existing observations when sensor data are already received and saved. This mode is called ”CoLiTec-Day” mode.Nowadays, the modern sensors (robotic ground-based telescopes equipped with different cameras with charge-coupled device (CCD)) still have a lack of capabilities, like non-uniform sensitivity of the matrix pixels, non-linearity of the pixel response to the number of photons that have fallen, oversaturation of bright objects leads to charge transfer to neighboring pixels and the presence of cold or hot pixels. All these shortcomings of modern sensors complicate the process of obtaining the accurate photometric measurements. Such lack of capabilities of modern sensors also makes the plotting of light curves a difficult and routine task. The latter shifts astronomer’s main attention from research to the very time-consuming tasks of processing sensor data and light curve creation. To solve this problem, we developed a new tool for the automated reduction of photometric observations, which includes the computational method for the brightness assessment of the investigated and comparison stars; brightness equalization of astronomical images using an inverse median filter; and light curve plotting and its processing using different tools.This new CoLiTecVS software provides a tool for high accurate stellar brightness measuring and automated light curve creation with aperture photometry uncertainties less than 0.04 magnitude, the value of which generally depends on various imaging characteristics of telescopes, detectors, and sensors.CoLiTecVS has been tested on many different time series of 20-600 CCD-frames with variable stars and has produced high-quality photometric light curves in a fraction of the usual processing time.