GCN Circular 9990
Subject
GRB 091003: Swift/UVOT Detection of an Optical Afterglow
Date
2009-10-04T23:42:48Z (15 years ago)
From
Tyler Pritchard at PSU <tapritchard@astro.psu.edu>
T. A. Pritchard (PSU) , E.A. Hoversten (PSU), and
R.L.C. Starling (U. Leicester) report on behalf of the
Swift/UVOT team:
The Swift/UVOT began settled observations of the field of
GRB 091003 approximately 15.5 hours after the FERMI/GBM Trigger (Rau,
GCN Circ. 9983) A faint source is detected with 3.9-sigma confidence
in the summed UVOT observations at the Swift UVOT-enhanced XRT
position (R.L.C. Starling, et al. GCN Circ. 9988).
The observed magnitudes and upper limits using the UVOT photometric
system (Poole etal. 2008, MNRAS, 383, 627) for the initial exposures
are:
Filter T_start(s) T_stop(s) Exp(s) Mag
=======================================================================
w2 56820 64169 1150 21.08 � 0.28 (3.9 sigma)
w1 103712 104474 750 20.70 � 0.32 (3.4 sigma)
b 92252 92954 685 20.80 � 0.26 (4.1 sigma)
m2 98013 98715 691 > 21.63
v 86432 87195 741 > 20.27
The values quoted above are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.02 in the direction of the burst
(Schlegel et al. 1998).