GCN Circular 10323
Subject
GRB 100111A: Swift UVOT Refined Analysis
Event
Date
2010-01-11T21:17:29Z (16 years ago)
From
Erik Hoversten at Swift/Penn State <hoversten@astro.psu.edu>
E. A. Hoversten (PSU) and L. Vetere (PSU) report on behalf of the
Swift/UVOT team:
The Swift/UVOT began settled observations of the field of GRB 100111A
67 s after the BAT trigger (Vetere, et al., GCN Circ. 10317). A source
is detected at 17.62 magnitudes in the initial white finding chart at
the position RA, Dec (J2000) = 247.04833, 15.55064 which is equivalent
to:
RA(J2000) = 16:28:11.60 = 247.04833
DEC(J2000) = +15:33:02.3 = 15.55064
with a 90%-confidence error radius of about 0.51 arc sec. This
position is 0.8 arcsec from the UVOT-enhanced XRT position (Beardmore,
et al. GCN Circ. 10321) and the two positions agree within the error
bars. The source faded by more than a magnitude in the white filter
over the first orbit of observations. Additionally the source is
detected in the b, u, and uvw1 filters, with a marginal 2.4-sigma
detection in v and a 2.1-sigma detection in uvm2. Given the detection
in the uvw1 filter the redshift of this burst is less than 1.9.
The observed magnitudes and 3-sigma upper limits using the UVOT
photometric system (Poole et al. 2008, MNRAS, 383, 627) for the
initial exposures are:
Filter T_start(s) T_stop(s) Exp(s) Mag
=============================================================
white 67 217 147 17.62 +/- 0.05
white 858 1007 147 18.73 +/- 0.10
v 609 1057 58 > 18.41
b 535 727 39 18.76 +/- 0.27
u 279 529 245 17.37 +/- 0.07
uvw1 658 851 38 18.57 +/- 0.36
uvm2 633 827 38 > 18.99
uvw2 584 1033 58 > 19.04
The values quoted above are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.05 in the direction of the burst
(Schlegel et al. 1998).