[vsnet-grb-info 4465] UVOT observations of GRB070330
GCN Circulars
gcncirc at capella.gsfc.nasa.gov
Sun Apr 1 06:18:20 JST 2007
TITLE: GCN CIRCULAR
NUMBER: 6238
SUBJECT: UVOT observations of GRB070330
DATE: 07/03/31 21:18:15 GMT
FROM: Patricia Schady at MSSL/Swift <ps at mssl.ucl.ac.uk>
N.P.M. Kuin (MSSL-UCL), D. Grupe (PSU), P. Brown (PSU) report
on behalf of the Swift/UVOT team:
The Swift/UVOT began taking data in the field of GRB070330 54s after the BAT
trigger (Grupe et al., GCN 6232). The afterglow is only detected in the first
UVOT V exposure, with a magnitude of V=18.69+/-0.24, after which the afterglow
had decayed below the UVOT detection threshold, suggesting a decay rate of
alpha_V > 0.8. The refined UVOT afterglow position is
RA (J2000) = 17:58:09.98 (269.5426)
Dec (J2000) = -63:47:34.80 (-63.7930)
We note that the refined position is 0.5" away from the preliminary UVOT
position reported in GCN 6232. The photometry results are given below for the 5
UVOT filters in which observations were made. Due to the presence of a bright
star no observations could be obtained in the UVW2 and white filters.
Filter Mid_T(s) Exp(s) Mag
V 462 393 18.69+/-0.24
V 33978 1632 > 21.45 (3-sigma upper limit)
M2 25521 2814 > 18.35 (3-sigma upper limit) `
W1 20282 1998 > 18.36 (3-sigma upper limit)
U 25521 2814 > 21.60 (3-sigma upper limit)
B 30318 3305 > 18.15 (3-sigma upper limit)
Mid_T is the weighted mid time of the exposure since the BAT trigger. These
magnitudes are not corrected for the expected reddening of E(B-V)=0.063.
For the time being it is not possible to provide a redshift given the low
signal-to-noise ratio of the data. Further analysis is ongoing. A high (~4)
redshift is possible and we encourage further ground follow-up.
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