On the impact of «red leak» of filters on brightness estimates of late stars using the example of observations of rapid variability of symbiotic stars

Abstract

The results of modeling the dependence of the «red leak» of photometric filters on various factors (color index 𝑉 −𝑅, luminosity class, interstellar reddening, air mass and PWV) during observations of stars are presented. The error arising from not taking into account the «red leak» in the case of filters used on the 0.6-m telescope of the CMO SAI can amount to 0.6 𝑚 − 0.8 𝑚 for late stars. Algorithms for reducing observational data are presented for filters 𝑈 and 𝐵. The results of observations of the rapid variability of two symbiotic stars CH Cyg and SU Lyn with cold components of very late spectral types are presented. For CH Cyg, rapid variability was detected on both observation dates. Taking into account the «red leak» effect, the amplitude in the 𝐵 band was 0.10𝑚 on November 6, 2019 and 0.19𝑚 on December 15, 2022, with a characteristic variability time of about 20 minutes. For SU Lyn, no rapid brightness variability was detected in the 𝐵 band on February 2, 2023 (with an accuracy of 0.003𝑚)