[vsnet-grb-info 11858] GRB 120422A: A Swift/UVOT Detection

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  13248
SUBJECT: GRB 120422A: A Swift/UVOT Detection
DATE:    12/04/22 18:23:37 GMT
FROM:    Paul Kuin at MSSL  <npkuin at gmail.com>

N. P. M. Kuin (MSSL-UCL) and E. Troja (NASA/GSFC/ORAU) report on
behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 120422A
104 s after the BAT trigger (Troja et al., GCN Circ. 13243). A source
consistent with the XRT position (Beardmore et al., GCN Circ.  13247)
is detected in the summed UVOT exposures at position:

RA  (J2000) = 136.91012  deg. =  09:07:38.4
Dec (J2000) = +14.018782 deg. = +14:01:07.6

with an estimated uncertainty of 1".

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

white_FC           104          254          147         20.39 +/- 0.27
white              857         1007          147         20.51 +/- 0.29
white             5251         6888          393         20.25 +/- 0.15
v                 5662         5862         1082        >19.4
b                 5047         6683          393        >20.7
u                  262          512          246         19.89 +/- 0.32
u                 4842         6478          393         20.00 +/- 0.31
w1                4637        12807         1039         19.84 +/- 0.18
m2                5867         6067          197         19.21 +/- 0.28
m2               11245        12145          886         19.36 +/- 0.14
w2                5457         7032          332         18.98 +/- 0.16

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).