Central Bureau for Astronomical Telegrams

CBAT "Transient Object Followup Reports"

TCP J21013299+3957043

TCP J21013299+3957043   2018 02 24.7943*  21 01 32.99 +39 57 04.3  12.3 U             Cyg       6 0

2018 02 24.794

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 = 13.0, who writes nothing is visible at this location on the previous frame (limit mag = 12.8) taken 2018 Feb. 23.810 and also a frame (limit mag = 13.8) on 2017 May 28 UT. There is a 2MASS star at the position of 33s.44 and 03".7 and also a star (mag = 15.5) at 34s.03 and 03".5.

2018 02 25.24

The abovementioned '2MASS star at the position of 33s.44 and 03".7' is the M-dwarf 2MASS J21013344+3957037 = LSPM J2101+3957 with a proper motion of pmRA= -151 mas/yr, pmDE= -2 mas/yr. The IPHAS DR2 source IPHAS J210133.03+395703.8 (r=19.15, i=17.87, ha=18.20 mag) is only 0.7" away from the transient's reported position. --- Patrick Schmeer (Saarbrücken-Bischmisheim, Germany)

2018 02 24.822

Although Kojima has confirmed this star on six frames on 2018 Feb. 24.794 - 24.795, but 40 minutes later he could not find a star on Feb. 24.822 UT (limiting mag.= 13.0).

2018 02 25.55

This brief brightening was possibly a flare of the M-dwarf LSPM J2101+3957. --- Patrick Schmeer (Saarbrücken-Bischmisheim, Germany)

2018 02 25.5112

No new object visible at the given position (limiting mag 16.5V) on 2x60s CCD V images taken by Robert Fidrich (Budapest, Hungary) using the 0.1m iTelescope.net astrograph at Mayhill, New Mexico on 2018. Feb 25.5112 UT

2018 02 25.522

Mag. V= 16.26, I= 12.91, position end figures 33s.20, 03".6 observed by K. Yoshimoto, Yamaguchi-ken, Japan, using 0.43-m f/6.8 Mayhill reflector with f/4.5 focal reducer, remotely, who identified with a 2MASS object (position at 33s.44 and 03".7, J mag = 10.990, H mag = 10.403, Ks mag = 10.116).