[vsnet-grb-info 26382] GRB 200922A: Swift/UVOT Detection

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  28482
SUBJECT: GRB 200922A: Swift/UVOT Detection
DATE:    20/09/23 13:04:40 GMT
FROM:    Mike Siegel at PSU/Swift MOC  <mhs18 at psu.edu>

M. H. Siegel (PSU) and M. J. Moss (GWU)
report on behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 200922A
86 s after the BAT trigger (Moss et al., GCN Circ. 28471).
We identify a fading source near the XRT position
(Osborne et al. GCN Circ. 28473) and also at the location of a weak source
in the DSS.  The source position is:

  RA(J2000)  =	19:47:48.76 = 296.95317
  DEC(J2000) = -55:12:16.5  = -55.20457

Which is 3.0 arc-second from the enhanced XRT position. 

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               86          236          147      14.37+/-0.02
white             4770         4970          196      17.51+/-0.04
white            28889        28909           19      18.62+/-0.20
v                 3745         3945          196      17.35+/-0.10
v                 9268        23149         1460      17.79+/-0.05
b                 4566         4765          196      17.95+/-0.07
b                27982        28889          881      18.49+/-0.05
u                 4360         4560          196      17.18+/-0.06
u                15921        16791          848      18.20+/-0.06
uvw1              4156         4355          196      17.23+/-0.10
uvw1             11089        15915          887      18.26+/-0.09
uvw1             50455        56029          225      18.97+/-0.27
uvm2              3950         4150          196      17.12+/-0.12
uvm2             10182        11081          885      18.19+/-0.10
uvm2             50396        55850          223      19.26+/-0.36
uvw2              3541         5089          307      17.14+/-0.09
uvw2             21653        22553          885      18.77+/-0.12
uvw2             50338        55672          223            >19.44

The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.05 in the direction of the burst
(Schlegel et al. 1998).