Discovery details:
R.A. 18h32m57.90s, Decl. -16°42'21.1" (J2000.0)
2019 Apr. 2.7544 UT, 12.5 mag (CCD, unfiltered)
Discoverer: Tadashi Kojima (Gunma-ken, Japan)
2019 04 02.754 UT
Discovered by T. Kojima, Gunma-ken, Japan, on three frames with five second exposure using Canon EOS 6D digital camera + 200-mm f/3.2 lens under the limiting mag = 14.2, who writes nothing is visible at this location on two frames taken on 2019 March 16 and April 1 UT with limit mag.= 13s.
2019 04 02.85 UT
There is a red star 1.6" south of the transient's reported position with Gaia DR2 position end figures 57.892s, 22.67" (equinox J2000.0, epoch 2015.5; Gmag. 15.17). Other designations are USNO-A2.0 0675-26976582 (Bmag. 17.6, Rmag. 15.6), USNO-B1.0 0732-0651565, GSC2.3 SA79039038 (Vmag. 15.75, Fmag. 15.07, Bjmag. 17.80), UCAC4 367-131021, CMC15 J183257.8-164222, 2MASS J18325789-1642225, UGPS J183257.89-164222.6. According to recent ASAS-SN Sky Patrol (Shappee et al. 2014ApJ...788...48S and Kochanek et al. 2017PASP..129j4502K) observations the current brightening began around 2019 March 29; complete light curve at https://asas-sn.osu.edu/light_curves/2207db5c-b277-44d0-af82-948b0feee8…
--- Patrick Schmeer (Saarbrücken-Bischmisheim, Germany)
Type unknown. Symbiotic variable star? Microlensing event??
*** Spectroscopy, precise astrometry, and multiband photometry are urgently required. ***
Clear skies,
Patrick