[vsnet-grb-info 17813] GRB 160401: Swift/UVOT Upper Limits

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  19256
SUBJECT: GRB 160401: Swift/UVOT Upper Limits
DATE:    16/04/02 20:08:19 GMT
FROM:    Paul Kuin at MSSL  <npkuin at gmail.com>

Paul Kuin (MSSL/UCL) and L.M. McCauley (PSU) report on behalf of the
Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 160401
43ks s after the INTEGRAL trigger (Mereghetti et al., GCN Circ.19251).
No optical afterglow consistent with the INTEGRAL position is detected
in the initial UVOT exposures. The burst location was also observed by
MASTER-IAC (Rebolo et al., GCN Circ. no. 19252); LT (Guidorzi et al.
GCN Circ. no. 19254), and the Zadko observatory (Klotz et al. GCN
Circ. 19255); none of whom observed an afterglow.
Preliminary 3-sigma upper limits using the UVOT photometric system
(Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for the initial exposures
are:

Filter         T_start(s)   T_stop(s)      Exp(s)         Mag

white            43678        44209          522         >20.8
v                44509        45370          843         >19.5
u                42847        43671          811         >19.9

The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 1.13 in the direction of the burst
(Schlegel et al. 1998).