[vsnet-grb-info 17041] GRB 150915A: Swift UVOT upper limits

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  18322
SUBJECT: GRB 150915A: Swift UVOT upper limits
DATE:    15/09/16 17:53:39 GMT
FROM:    Scott Barthelmy at NASA/GSFC  <scott at lheamail.gsfc.nasa.gov>

A. A. Breeveld (UCL-MSSL) and V. D'Elia (ASDC) report on behalf of the
Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 150915A
295s after the BAT trigger (D'Elia et al., GCN Circ. 18315).
No optical afterglow consistent with the XRT position (D’Elia et al.,
GGN Circ. 18315) or the GROND position (Yates et al., GCN Circ. 18317)
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

u_FC               295          545          246         >20.0
white              576          769           39         >19.9
v                  625          818           39         >18.2
b                  550          745           39         >19.2
u                  295         4267          434         >20.0

The magnitudes in the table are not corrected for the Galactic
extinction due to the reddening of E(B-V) = 0.10 in the direction of the
burst (Schlegel et al. 1998).