[vsnet-grb-info 11630] GRB 120308A: Swift/UVOT Detection
GCN Circulars
gcncirc at capella2.gsfc.nasa.gov
Fri Mar 9 04:32:31 JST 2012
TITLE: GCN CIRCULAR
NUMBER: 13025
SUBJECT: GRB 120308A: Swift/UVOT Detection
DATE: 12/03/08 19:32:24 GMT
FROM: Paul Kuin at MSSL <npkuin at gmail.com>
N. P. M. Kuin (MSSL-UCL) and W. H. Baumgartner (GSFC/UMBC)
report on behalf of the Swift/UVOT team:
The Swift/UVOT began settled observations of the field of GRB 120308A
158 s after the BAT trigger (Baumgartner et al., GCN Circ. 13017).
A source consistent with the optical position reported by Virgili et al.
(GCN Circ. 13018) is detected in the initial UVOT exposures, but only
in the v and b band. In u there is no evidence for a source, which
suggests that the source is at a redshift of z < 4, and in case there
is no contamination of dust, z ~ 3.2.
The best UVOT position is
RA(J2000) = 14h 36m 20.05s
Dec(J2000) = 79d 41' 12.2"
with an uncertainty of 0.55" (90% confidence).
Preliminary detections and 3-sigma upper limits using the UVOT
photometric system
(Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for the early exposures are:
Filter T_start(s) T_stop(s) Exp(s) Mag
v 463 483 20 17.02 +/- 0.17
b 413 432 19 17.65 +/- 0.13
u 158 7690 1020 >20.9
w1 512 13962 1165 >21.3
m2 636 13409 1415 >21.3
w2 438 8103 646 >21.5
b 711 730 19 18.40 +/- 0.25
v 761 1082 39 18.14 +/- 0.29
The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.03 in the direction of the burst
(Schlegel et al. 1998).
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