[vsnet-grb-info 13236] Swift/UVOT observations of GRB130505A

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  14573
SUBJECT: Swift/UVOT observations of GRB130505A
DATE:    13/05/05 16:28:36 GMT
FROM:    Massimiliano de Pasquale at MSSL-UCL  <m.depasquale at ucl.ac.uk>

M. De Pasquale (MSSL/UCL) and J. K. Cannizzo (NASA/UMBC) report on behalf
of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 130505A
107 s after the BAT trigger (Cannizzo et al., GCN Circ. 14563). A bright 
but
rapidly fading source is detected in the finding chart and initial exposures
within the XRT error circle (Evans et al., GCN Circ. 14569).

The preliminary UVOT position is:
   RA(J2000)  =    09:08:14.64 = 137.0610
   DEC(J2000) =   +17:29:05.2  = +17.48478
with a 90%-confidence error radius of about 0.5 arc sec.

Preliminary detections and 3-sigma upper limits using the UVOT
photometric system (Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for
the early exposures are:

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

white (FC)         107          256        147          14.14 ± 0.05
white             3952         4151        197          17.96 ± 0.07
v                 4362         4561        197          17.50 ± 0.11
b                 3503         3946        197          17.71 ± 0.08
u                  320          542        218          14.66 ± 0.04
uvw1              4772         4971        197          19.28 ± 0.29 (~3 
sigma)
uvm2              4567         4766        197          >19.6
uvw2              4158         4357        197          >19.9

The non-detection of the optical source in um2 and uw2 filters is
consistent with the redshift z=2.27 found by Tanvir et al (GCN Circ. 14567)

The magnitudes in the table are not corrected for the Galactic
extinction due to the reddening of E(B-V) = 0.04 in the direction of
the burst (Schlegel et al. 1998).