[vsnet-grb-info 27533] GRB 210306A: Swift/UVOT Detection

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  29636
SUBJECT: GRB 210306A: Swift/UVOT Detection
DATE:    21/03/09 14:05:28 GMT
FROM:    Kira Simpson at PSU  <kira.simpson1984 at gmail.com>

GRB 210306A: Swift/UVOT Detection

K. K. Simpson (PSU) and V. D'Elia (SSDC)
report on behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 210306A
85 s after the BAT trigger (D'Elia et al., GCN Circ. 29597).
A source consistent with the XRT position
(D'Elia et al. GCN Circ. 29597)
is detected in the initial UVOT exposures.

The preliminary UVOT position is:
    RA  (J2000) =  08:39:49.98 = 129.95824 (deg.)
    Dec (J2000) = +60:12:19.2  =  60.20533 (deg.)
with an estimated uncertainty of 0.42 arc sec. (radius, 90% confidence).

Preliminary detections 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               85          235          147         16.23 +/- 0.03
v                  628          648           20         17.42 +/- 0.24
b                  553          573           20         17.32 +/- 0.13
u                  297          547          246         16.86 +/- 0.04

The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.052 in the direction of the burst
(Schlegel et al. 1998).