Forming a unified database of solar observations in the HeI 10830 Å line acquired in 1999–2025 at the CrAO STT-2 telescope

Abstract

Experimental data on solar activity are currently widely used in fundamental and applied scientific research, namely in studying phenomena occurring on the Sun and their impact on Earth. The most valuable data are those obtained over many years of observations. The unique observational material for more than two solar cycles has been accumulated by using the STT-2 telescope. Since 1999, more than 4500 maps of the full solar disk in the HeI 10830 Å line have been acquired, which allow us to explore the evolution and characteristics of coronal holes, filaments, and active regions. Due to the fact that during this period the observational process was continuously upgraded and some changes were made in the processing programs, we have several series of solar maps of different types. In this paper we aim to process all observational material according to a unified methodology and to form a unified database of observations in the HeI 10830 Å line. The algorithm for processing observations is briefly described; a few fragments of the database and its updated structure are presented.