Volume 5, Issue 3 of Acta Astrophysica Taurica contains materials presented at two All-Russian astronomical conferences with international participation: 'Magnetism and activity of the Sun and stars - 2021', held from August 31st to September 3d, 2021 in Nauchny and  'Modern Instruments and Methods in Astronomy', held at SAO RAS from 04 to 09 September 2023. The collection is intended for specialists in astronomy and astrophysics.