[vsnet-grb-info 27382] GRB 210211A: Swift/UVOT Detection

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  29485
SUBJECT: GRB 210211A: Swift/UVOT Detection
DATE:    21/02/11 22:59:12 GMT
FROM:    Paul Kuin at MSSL  <npkuin at gmail.com>

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

The Swift/UVOT began settled observations of the field of GRB 210211A
78 s after the BAT trigger (Troja et al., GCN Circ. 29472). A source
consistent with the XRT position (Osborne et al. GCN Circ. 29478) and
the REM detection (d'Avanzo et al., GCN Circ. 29474)is detected in
the initial UVOT exposures.

The preliminary UVOT position is:
    RA  (J2000) =  17:57:45.68 = 269.44035 (deg.)
    Dec (J2000) = -46:16:01.6  = -46.26711 (deg.)
with an estimated uncertainty of 0.47 arc sec. (radius, 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

white               78          227          147         17.89 +/- 0.06
white              596          611           15        >18.6
white             5391         5587          197        >20.3
v                 4239         4438          197        >19.8
b                  545          565           19        >18.4
u                  290          489          196        >18.6
m2                4444         4491           47        >18.3
w2                4034         4234          197        >19.4

The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.127 in the direction of the burst
(Schlegel et al. 1998).