[vsnet-grb-info 28426] GRB 210724A: Swift/UVOT Upper Limits

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  30529
SUBJECT: GRB 210724A: Swift/UVOT Upper Limits
DATE:    21/07/27 06:17:13 GMT
FROM:    Sam LaPorte at PSU  <sjl5346 at psu.edu>

 GRB 210724A: Swift/UVOT Upper Limits

S. J. LaPorte (PSU) and P. D'Avanzo (INAF-OAB)
report on behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 210724A
125 s after the BAT trigger (D'Avanzo et al., GCN Circ. 30497).
No optical afterglow consistent with the XRT position
(D'Avanzo et al. GCN Circ. 30497)
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           125          275          147         >20.8
u_FC               283          513          226         >20.1
white              125          275          147         >20.8
u                  283          513          227         >20.1

The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.097 in the direction of the burst
(Schlegel et al. 1998).