[vsnet-grb-info 27875] GRB 210509A: Swift/UVOT Upper Limits

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  29978
SUBJECT: GRB 210509A: Swift/UVOT Upper Limits
DATE:    21/05/10 10:10:56 GMT
FROM:    Paul Kuin at MSSL  <npkuin at gmail.com>

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

The Swift/UVOT began settled observations of the field of GRB 210509A
3202 s after the BAT trigger (Page et al., GCN Circ. 29970).
No optical afterglow consistent with the XRT position (Evans et al.
GCN Circ. 29971) 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          3202         3352          147         >20.8
white             3202         4585          344         >21.0
v                 3358         4934          332         >19.0
b                 4180         4380          197         >19.5
u                 3974         4174          197         >19.6
w1                3769         3969          197         >19.5
m2                3563         3763          197         >20.3
w2                4592         4792          197         >19.6

The magnitudes in the table are not corrected for the Galactic
extinction due to the reddening of E(B-V) = 0.074 in the direction of
the burst (Schlegel et al. 1998).