[vsnet-grb-info 20491] GRB 180402A: Swift/UVOT Upper Limits

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  22587
SUBJECT: GRB 180402A: Swift/UVOT Upper Limits
DATE:    18/04/03 15:38:17 GMT
FROM:    Sam Emery at MSSL-UCL  <samuel.emery.15 at ucl.ac.uk>

S.W.K. Emery (UCL-MSSL) and A. Y. Lien (GSFC/UMBC)
report on behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 180402A
140 s after the BAT trigger (Lien et al., GCN Circ. 22580).
No optical afterglow consistent with the XRT position
(D'Elia et al., GCN Circ. 22586)
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          4328         4478          147         >20.8
u_FC               140          390          246         >19.7
white             4328         6805          407         >20.6
v                  423         5916          286         >19.2
b                 5101         6736          393         >20.2
u                  140         6531          845         >20.3
w1                4691         6326          393         >20.4
w2                5512         5712          197         >19.6

The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.77 in the direction of the burst
(Schlegel et al. 1998).