[vsnet-grb-info 25144] GRB 200227A: Swift/UVOT Upper Limits

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  27244
SUBJECT: GRB 200227A: Swift/UVOT Upper Limits
DATE:    20/02/27 21:16:21 GMT
FROM:    Samantha Oates at MSSL  <samantha.oates at alumni.ucl.ac.uk>

S. R. Oates (U. Birmingham) and S. Laha (GSFC/UMBC/CRESST)
report on behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 200227A
93 s after the BAT trigger (Laha et al., GCN Circ. 27234).
No optical afterglow consistent with the XRT position
(Beardmore et al. GCN Circ. 27243)
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          93          243          147        >20.3
u_FC              305	      555          246        >19.7
white	          93	      1185         353        >20.8
v	          634	      1235         78         >18.3
b	          560	      1160         58         >19.2
u                 305	      1135         285        >19.8
w1                685	      1284         58         >18.4
m2                659         1259         78         >18.4
w2                610         1210         78         >18.6

The magnitudes in the table are not corrected for the Galactic extinction
due to the significant reddening of E(B-V) = 0.28 in the direction of the burst
(Schlegel et al. 1998).