[vsnet-outburst 11188] Bright optical transient in Pegasus

[Hiroyuki Maehara]

 According to CBET 2273, Dae-Am Yi (Yeongwol-kun, Gangwon-do, Korea)
discovered a bright (mag 8.4 on May 7.76) optical transient in Pegasus.
The object was discovered at magnitude 10.8 on two images taken on 
May 6.77 with a Canon 5D digital camera + 93-mm lens and confirmed
on images taken with a 400-mm lens on May 7.78. The object is 
positionally coincident with GSC 2197:886 (R.A. = 21h38m06s.571,
Decl. = +26d19'57".33).  
Yamaoka-san notes that the DSS image of GSC 2197:886 is elongated 
toward the north-south indicating that it is a double/multiple star. 
Yamaoka-san also notes that there is a bright ROSAT X-ray source 
(1RXS J213807.1+261958) near the object.

I preformed multi-color photometry and astrometry of the object.
B-V and V-Ic colors of the object are coincident with those of dwarf nova
in outburst.

OT_J213806.6+261957 20100508.68292 8.67B    Mhh.VSOLJ
OT_J213806.6+261957 20100508.68472 8.74V    Mhh.VSOLJ
OT_J213806.6+261957 20100508.68580 8.87Ic   Mhh.VSOLJ

Unfiltered CCD images taken around May 8.68 using a 25-cm telescope
yield the following position for the object: R.A.= 21h38m06s.65,
Decl.=+26d19'57".1 (+/- 0.3", equinox 2000.0).

Follow-up time-resolved photometry and spectroscopy are encouraged.