[vsnet-grb-info 11305] GRB 111222A: Swift/UVOT Observations

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  12717
SUBJECT: GRB 111222A: Swift/UVOT Observations
DATE:    11/12/24 06:29:06 GMT
FROM:    Mike Siegel at PSU/Swift MOC  <siegel at swift.psu.edu>

M. H. Siegel and D. Grupe (PSU) report on behalf of the Swift/UVOT team:

We have analyzed 2.3 ks of UVOT data for the IPN-detected burst: GRB
111222A (Hurley et al. et al. GCN Circ. 12714), from 92.9 ks to 95.2 ks
after the  IPN trigger. The data are entirely in the white filter.  We detect a faint
optical source consistent with the XRT source reported in Grupe (GCN Circ.
12716) at a position of RA, Dec = 179.22008, Dec = 69.07096 , which
is equivalent to:

RA (J2000): 11h 56m 52.82s
Dec(J2000): +69d 04' 15.4"

with an uncertainty of 0.51 arcsec (radius, 90% confidence). Preliminary
photometry using the UVOT photometric system (Breeveld et al. 2011, AIP
Conf. Proc. 1358, 373) shows a white magnitude of 19.34+-0.03.  The magnitude
is not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.01 in
the direction of the burst (Schlegel et al. 1998).

We note, however, that a source is present at this position in the DSS.  Follow-up
observations will be needed to determine if the X-ray/optical source is indeed the
GRB afterglow.