NGC 5273 is a lenticular galaxy located 54 million light-years away in the northern constellation of Canes Venatici. This galaxy was discovered by William Herschel on May 1, 1785. It is positioned 1+1⁄4° to the southeast of the star 25 Canum Venaticorum. The morphological classification of this galaxy is SA0(s), indicating it is lenticular in form. It displays a faint, unbarred spiral structure within a generally elliptical profile. NGC 5273 is classified as a type 1.5 Seyfert galaxy, with the X-ray emission from its active galactic nucleus undergoing significant absorption. However, data collected between the year 2000 and 2022 suggest this is a changing–look Seyfert, with the type ranging from 1 to 1.8/1.9. The activity level shows strong variability, allowing reverberation mapping of the supermassive black hole at the core. This object has an estimated mass of (4.7±1.6)×106 M☉.
References
Further reading Vincentelli, F. M.; et al. (February 2020), "X-ray reverberation lags from the 1.5 Seyfert galaxy NGC 5273", Monthly Notices of the Royal Astronomical Society, 492 (1): 1135–1141, arXiv:1912.06196, Bibcode:2020MNRAS.492.1135V, doi:10.1093/mnras/stz3511. Chromey, F. R. (November 1973), "Studies of Ir II galaxies. I. NGC 4753 and NGC 5273", Astronomy and Astrophysics, 29: 77–84, Bibcode:1973A&A....29...77C.


