aat Acta Astrophys. Tau. Acta Astrophysica Taurica 2712-925X Kiselev Nikolai Nikolaevich, Mosсow, settlement Moskovskii, Tat'yanin Park Str., 12, Moscow, Russia. RU 118 Research articles Forming a unified database of solar observations in the HeI 10830 Å line acquired in 1999–2025 at the CrAO STT-2 telescope Andreeva Olga Plotnikov Andrey Malaschuk Valentina Crimean Astrophysical Observatory, Nauchny 298409 Crimean Astrophysical Observatory, Nauchny 298409 Crimean Astrophysical Observatory, Nauchny 298409 25 12 2025 6 4 29 34 24 12 2025 Copyright (c) 2026 Andreeva O., Plotnikov A., Malaschuk V. 2026 Olga Andreeva, Andrey Plotnikov, Valentina Malaschuk The metadata for this submission is licensed under a Creative Commons Attribution 4.0 International License. Copyright and publishing rights for texts published in Acta Astrophysica Taurica is retained by the authors, with first publication rights granted to the journal.Texts are free to use with proper attribution and link to the licensing (Creative Commons Attribution 4.0 International).

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.

observations in the HeI 10830 Å line database of solar observations coronal holes The work was supported by the Ministry of Science and Higher Education of the Russian Federation under the state assignment No. 122022400224-7. Andreeva O.A., Plotnikov A.A., Malashchuk V.M., 2025. Database of the Sun Observations in the HeI 1083 nm Line Obtained With the STT-2 Telescope at the Crimean Astrophysical Observatory. ESDB repository, GC RAS, Moscow, doi:10.2205/ESDB-SAD-CrAO. Bukach A.B., Didkovskii L.V., Stepanyan N.N., Sunitsa G.A., Shcherbakova Z.A., 1990. Izv. Krymsk. Astrofiz. Observ., vol. 82, p. 172. (In Russ.) Semyonov D.G., Sunitsa G.A., Kutsenko A.S., 2021. Izv. Krymsk. Astrofiz. Observ., vol. 117, no. 1, p. 15. (In Russ.) Stepanyan N.N., Dolgopolova E.V., Elizarov A.I., et al., 2000. Izv. Krymsk. Astrofiz. Observ., vol. 96, p. 194. (In Russ.)