TITLE:   GCN CIRCULAR
NUMBER:  32521
SUBJECT: GRB 220831A: Swift-UVOT Upper Limits
DATE:    22/09/05 22:06:27 GMT
FROM:    Noel Klingler at NASA-GSFC / UMBC  <njk5441@psu.edu>

N. J. Klingler (NASA-GSFC/UMBC/CRESST II) reports on behalf of the
Swift-UVOT team:

Swift-UVOT has performed follow-up observations of the Swift-BAT-detected
burst GRB 220831A (Tohuvavohu et al. GCN 32506), collecting 4.7 ks of
observations with the White filter between T0+51.2 ks and T0+78.8 ks.  No
source was detected in the UVOT data at the position of the X-ray source
reported by Dichiara et al. (GCN 32510), which is also positionally
coincident with the candidate near-infrared and optical counterparts
reported by D'Avanzo et al. (GCN 32513) and Freeburn et al. (GCN 32516),
respectively.

3-sigma upper limits using the UVOT photometric system (Breeveld et al.
2011, AIP Conf. Proc. 1358, 373) are:

Filter         T_start(s)   T_stop(s)      Exp(s)           Mag
white           51227          78844        4712         >23.39

The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.0161684 in the direction of the burst
(Schlegel et al. 1998).