Central Bureau for Astronomical Telegrams

CBAT "Transient Object Followup Reports"

TCP J10240289+4808512

TCP J10240289+4808512   2019 05 25.4972*  10 24 02.89 +48 08 51.2  11.8 U             UMa       9 0

2019 05 25.497

Discovered by T. Kojima, Gunma-ken, Japan, who found this on three frames (limiting mag.= 13.8) taken by Canon EOS 6D + 200-mm f/3.2 lens. Nothing is visible at this location on two frames taken on 2019 May 7.476 UT with 135-mm lens under the limiting mag.= 13.

2019 05 24.166

Recent observations by the ASAS-SN Sky Patrol (Shappee et al. 2014ApJ...788...48S and Kochanek et al. 2017PASP..129j4502K) confirm this transient: 2019 May 23.247 UT, gmag. fainter than 16.74; 24.166, 11.65; no previous outbursts were recorded since 2012 Jan. 11; complete light curve at https://asas-sn.osu.edu/light_curves/09c6e373-f4d6-4b51-a5ae-6d33af960ec7 --- Patrick Schmeer (Saarbrücken-Bischmisheim, Germany)

2019 05 25.62

The likely (blue) progenitor is USNO-A2.0 1350-07764996 (Bmag. 18.8, Rmag. 19.0) with Gaia DR2 position end figures 02.697s, 51.01" (equinox J2000.0, epoch 2015.5; Gmag. 19.44; parallax 2.9864 ± 0.3584 mas, distance 0.34 ± 0.05 kpc). Other designations are CSS_J102402.7+480850, USNO-B1.0 1381-0249998, GSC2.3 N99I009022 (Fmag. 19.39, Bjmag. 19.95, Vmag. 19.03), PSO J102402.689+480851.170 (gmag. 19.55, rmag. 19.61), GALEX J102402.6+480851, etc. The transient is probably a dwarf nova outburst with an amplitude of about 8 magnitudes (WZ Sge type?). Spectroscopy as well as multiband and time-resolved photometry are strongly recommended. --- Patrick Schmeer (Saarbrücken-Bischmisheim, Germany)

2019 05 26.5788

Photometery results were B=12.03, V=12.18, Rc=12.33 and Ic=12.30 with 25cm Schmidt-Cassegrain telescope + QSI 683 ccd at TAO Kamagaya. http://meineko.sakura.ne.jp/ccd/TCPJ10240289+4808512.jpg Seiichiro Kiyota (Kamagaya,Japan)