[vsnet-grb-info 27487] GRB 210226A: Swift/UVOT Upper Limits

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  29590
SUBJECT: GRB 210226A: Swift/UVOT Upper Limits
DATE:    21/02/28 23:29:56 GMT
FROM:    Paul Kuin at MSSL  <npkuin at gmail.com>

N. P. M. Kuin (UCL-MSSL) and A. P. Beardmore (U. Leicester)
report on behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 210226A
102 s after the BAT trigger (Beardmore et al., GCN Circ. 29568).
No optical afterglow consistent with the XRT position
(Beardmore et al. GCN Circ. 29568)
is detected in the initial UVOT exposures.
Preliminary 3-sigma upper limits using the UVOT photometric system
(Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for the first
finding chart (FC) exposure and subsequent exposures are:

Filter         T_start(s)   T_stop(s)      Exp(s)         Mag

white_FC           102          251          147         >20.9
u_FC               314          563          246         >20.4
white              102         1192          353         >21.4
v                  643         1236           72         >19.1
b                  569         1167           58         >19.9
u                  314         5121          463         >20.5
w1                 692         4935          236         >20.4
m2                4530         4730          197         >20.0

The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.049 in the direction of the burst
(Schlegel et al. 1998).