[vsnet-alert 15634] Bright CV in Cygnus MASTER OT J210736.73+340227.1

[Denis Denisenko]

MASTER-Amur has detected a new optical transient in Cygnus MASTER OT
J210736.73+340227.1 with unfiltered magnitude 15.5m on 2013-04-18.768
UT. It was found by Vsevolod Yecheistov and published in Astronomer's
Telegram ATel #4995, http://www.astronomerstelegram.org/?read=4995

The object is about 18.2m at minimum. There are several previous
detections by MASTER-Amur and MASTER-Tunka up to 15.1m on
2011-08-08.615 UT.

Object IDs:
USNO-B1.0 1240-0472261 (21 07 36.725 +34 02 28.07 B1=19.13 R1=17.61
B2=18.43 R2=18.04 I=17.40)
USNO-A2.0 1200-17148414 (21 07 36.74 +34 02 28.0 R=17.9 B=18.5)
2MASS 21073673+3402280 (J=15.74+/-0.07 H=15.43+/-0.11 K=15.93+/-0.27)

The object was detected in a high state on many archival MASTER
images. It is possible that MASTER OT J210736.73+340227.1 is a
cataclysmic variable of VY Scl or AM Her type (anti-nova or polar).
Less likely it is a very frequent outburster.

Color-combined (BRIR) finder chart:
http://master.sai.msu.ru/static/OT/J210736+340227-BRIR5x5.jpg

Photometric time series are encouraged.

Denis Denisenko
Member of MASTER team at SAI MSU