[vsnet-grb-info 19953] GRB 171020A: Swift/UVOT Upper Limits

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  22040
SUBJECT: GRB 171020A: Swift/UVOT Upper Limits
DATE:    17/10/22 06:43:09 GMT
FROM:    Sam LaPorte at PSU  <sjl5346 at psu.edu>

GRB 171020A: Swift/UVOT Upper Limits

S. J. LaPorte (PSU) and K. L. Page (U. Leicester)
report on behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 171020A
147 s after the BAT trigger (Page et al., GCN Circ. 22028).
No optical afterglow consistent with the XRT position
(Page et al. GCN Circ. 22028)
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           147          297          147         >20.6
u_FC               306          556          246         >20.2
white              147         7652          811         >21.4
v                  636         6640          338         >19.4
b                  562         7460          529         >20.8
u                  306         7254          756         >20.2
w1                 686         7050          491         >20.7
m2                6645         6845          197         >20.3
w2                1016         6435          216         >20.3

The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.19 in the direction of the burst
(Schlegel et al. 1998).