Luminous Blue Variables (LBVs) are extremely massive stars , often exceeding 30 solar masses.
They are characterized by unpredictable, high-amplitude variations in brightness and temperature. Often called S Doradus variables. They can display violent mass-losses and probably are in a transitional phase.
https://en.wikipedia.org/wiki/Luminous_blue_variable

Time: 01:29UT 2026-03-31 Exp.611 x 10sec
Tel. 0.254m f/5.8 ST-10XME CCD @ -25°C 1.9"/pix
Odd Trondal Obs.code 238 (Uranium). Oslo Norway.

AT2016blu (= Gaia16ada) (= ZTF17aaapufz) (= ATLAS18mmq) (= PS22eva) (= XM13MZ) (= AT2022lia) (= MSOSSP_10) (= PSN J12355230+2755559) (= TCP J12355227+2755555), CBET 2976 discovered 2012/01/11.250 by Lick Observatory Supernova Search Found in NGC 4559 at R.A. = 12h35m52s.30, Decl. = +27°55'55".9 Located 74" west and 100" south of the center of NGC 4559 Mag 16.1:3/25/2026 (15.9:4/21/2021), Type LBV (z=0.003) (References: ATEL 3865, 6303, 14460, 14638, 15808, 16115, VSnet observations, TNS, ZTF observations, Gaia observations, TNS 2022lia; SN 1941A)