A naked-eye optical transient in Bootes
ATel #5287; Yue Zhao, P. B.Hall, P. Delaney, J. Sandal (York University)
on 15 Aug 2013; 22:30 UT
Credential Certification: Patrick Hall (yorkphall@gmail.com)
Subjects: Optical, Transient
A previously unknown transient was discovered in Bootes last year (2012 September 26 UTC)
from two digital photographs taken from Toronto on that day. The transient flared to brighter
than 5th magnitude, making it visible to the naked eye under dark conditions. The object, which
we refer to as Tr Boo, has been localized as follows:
Object Name RA (J2000) DEC(J2000) Date of Discovery(UTC)
Tr Boo 14:36:31.6+-0:02.7 +15:52:46.2+-0:39.1 2012-09-26 00:17:54
There are two images showing the existence of the transient, taken at different times with a
separation of about half an hour, with the transient located 20 to 30 degrees above the horizon.
Image Time(UTC) Exposure time Magnitude of the transient
DSC1861 2012-09-26 00:17:54 0.125 sec 4.7 +- 0.2
DSC1875 2012-09-26 00:45:50 2 sec 5.6 +- 0.3
The magnitudes above are BV magnitudes, as the camera is sensitive to both B and V band flux.
Photometry was performed relative to the nearby stars omicron Boo and pi Boo. Note that the
transient faded by about a magnitude in half an hour.
Data from The Liverpool Telescope Project all-sky camera on La Palma taken 4 hours before the
transient were discovered do not show the transient, constraining it to be fainter than 5th
magnitude at that time.
There are several stars in the vicinity of Tr Boo that might be responsible for the transient.
Candidate Magnitude Distance(") RA DEC
SDSS J1436+1553 13.99 98.38 14:36:27.19 +15:53:26.83
LP 440-48 15.96 187.83 14:36:41.59 +15:50:20.20
BD+16 2617 11.49 191.18 14:36:21.97 +15:51:09.47
TYC 1477-341-1 12.03 288.65 14:36:29.56 +15:57:29.50
None of these objects show any robust sign of variability in the ASAS or the CRTS.
Tr Boo represents a flare with an amplitude of approximately 7 to 11 magnitudes if any of the
candidates above are responsible for the transient, and of even greater amplitude if its quiescent
counterpart is a fainter object. Flares of such large amplitudes are very rare, but not
unprecedented (see AT #5276 and references therein).
For more details on our study of the transient to date, including a finding chart, click on the
link provided.
We would welcome being contacted with information regarding observations that might constrain the
peak magnitude or decay rate of this transient. Please contact us at yue.zhao32012@gmail.com and
yorkphall@gmail.com.
Paper in preparation
