[vsnet-grb-info 12282] GRB 120815A: Swift/UVOT Detection of the Optical Afterglow
GCN Circulars
gcncirc at capella2.gsfc.nasa.gov
Fri Aug 17 21:25:25 JST 2012
TITLE: GCN CIRCULAR
NUMBER: 13666
SUBJECT: GRB 120815A: Swift/UVOT Detection of the Optical Afterglow
DATE: 12/08/17 12:25:18 GMT
FROM: Stephen Holland at STScI <sholland at stsci.edu>
S. T. Holland (STScI) and
C. Pagani (U Leicester)
report on behalf of the Swift/UVOT team:
The Swift/UVOT observed the field of GRB 120815A starting 2672 s
after the BAT trigger (Pagani et al., 2012, GCNC 13645). Settled
observations started at 2690 s. We detect an uncatalogued source
inside the UVOT-enhanced XRT error circle (Goad et al., 2012, GCNC
13650) with preliminary coordinates
RA (J2000.0) 18:15:49.88 = 273.95783 (deg)
Dec (J2000.0) -52:07:52.1 = -52.13114 (deg)
and an estimated uncertainty of 0.6 arcsec (radius, 90% confidence,
statistical + systematic). The UVOT detection is consistent with the
optical afterglow reported by Sudilovsky et al. (2012, GCNC 13648)
Source magnitudes and 3-sigma upper limits at this location are given
below. The afterglow is 4.27 arcsec northeast of the USNO-B1.0 source
0378-0977505, so the following photometry should be considered
preliminary.
Filter TSTART TSTOP Exp Time Mag Err Sigma
------------------------------------------------------------
v 2847 3046 100 19.34 0.29 3.9
b 3667 4120 226 20.11 0.24 4.7
u 3462 3661 100 >20.5
uvw1 3257 3457 100 >20.2
uvm2 3052 3252 100 >19.9
uvw2 4330 4530 100 >20.3
white 2690 2840 75 19.94 0.19 5.8
------------------------------------------------------------
The quoted magnitudes and upper limits have not been corrected for
the Galactic extinction along the line of sight to this burst of
E_{B-V} = 0.10 mag (Schlafly et al. 2011, ApJS, 737, 103).
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