TITLE:   GCN CIRCULAR
NUMBER:  26919
SUBJECT: GRB 200127A: Swift/UVOT Upper Limits
DATE:    20/01/28 19:11:13 GMT
FROM:    Mike Siegel at PSU/Swift MOC  <mhs18@psu.edu>

A. Belles (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 200127A
150 s after the BAT trigger (Moss et al., GCN Circ. 26895).
No optical afterglow consistent with the XRT position (Evans et al.,
GCN Circ. 26902) 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           150          300          147         >20.4
u_FC               310          560          246         >19.4
white              150        11742         1368         >22.3
v                  640        16568         1317         >20.2
b                  566        10830         1121         >21.3
u                  310         6701          638         >20.2
w1                 690        18173         1095         >21.1
m2                 838        17473         1298         >20.6
w2                 615        12437         1110         >20.5

The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.16 in the direction of the burst
(Schlegel et al. 1998).