TCP J05515391+6504346 (UG:)
R.A. 05h51m53.91s, Decl. +65°04'34.6" (J2000.0)
2019 Apr. 1.4504 UT, 13.2 mag (CCD, unfiltered)
Discoverer: Hideo Nishimura (Shizuoka-ken, Japan)
2019 04 01.450 UT
Discovered by H. Nishimura, Shizuoka-ken, Japan, on three frames with 15 second exposure using Canon EOS 6D digital camera + 200-mm f/3.2 lens under the limiting mag = 14.7, who writes there is no previous image since this is not his survey area and also because of a faint star, he has confirmed the appearance of this star on April 1.593 UT.
2019 04 01.65 UT
A (blue) progenitor candidate is 2.3" away at Gaia DR2 position end figures 53.825s, 36.80" (equinox J2000.0, epoch 2015.5; Gmag. 20.62). Other designations are USNO-B1.0 1550-0122180 (Bmag. 20.9, Rmag. 20.2), GSC2.3 NAQ5009716 (Fmag. 20.08, Bjmag. 21.52), PSO J055153.857+650436.965 (gmag. 20.59, rmag. 20.63), and CSS_J055153.8+650436. No outbursts were recorded by the ASAS-SN Sky Patrol (Shappee et al. 2014ApJ...788...48S and Kochanek et al. 2017PASP..129j4502K) between 2012 Jan. 11 and 2019 Mar. 30; complete light curve at https://asas-sn.osu.edu/light_curves/acb806ec-ce61-4bcf-8e9e-6e1a54a2e7…. The transient is probably a dwarf nova outburst with an amplitude of about 7 magnitudes (WZ Sge type?).
*** Spectroscopy as well as multiband and time-resolved photometry are strongly recommended. ***
--- Patrick Schmeer (Saarbrücken-Bischmisheim, Germany)
I had a look at this last night. The brightness of the target was 16.465V in an image comprising ten co-added 20s exposures midpoint 2019-04-20 21:08:50 UT. 200mm Hyperstar / Baader V filter / ASI178MM.