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GCN Circular 30857

Subject
GRB 210919A: Swift/UVOT Upper Limits
Date
2021-09-21T02:35:14Z (3 years ago)
From
Mike Siegel at PSU/Swift MOC <mhs18@psu.edu>
M. H. Siegel (PSU) and A. Tohuvavohu (U. Toronto)
report on behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 210919A
100 s after the BAT trigger (Tohuvavohu et al., GCN Circ. 30846).
No optical afterglow consistent with the XRT position
(Goad et al. GCN Circ. 30850) 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           100          249          147         >20.8
u_FC               312          561          246         >19.9
white              100         1193          343         >21.4
v                  643         1244           70         >18.7
b                  568         1342           63         >19.3
u                  312         1318          304         >19.8
w1                 693         1293           58         >19.7
m2                1248         1268           19         >19.0
w2                 618         1044           39         >19.4

The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.141 in the direction of the burst
(Schlegel et al. 1998).
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