TITLE:   GCN GRB OBSERVATION REPORT
NUMBER:  2893
SUBJECT: GRB 041219: Keck IR Observations and Astrometric Refinement of the
DATE:    04/12/21 08:32:22 GMT
FROM:    Josh Bloom at Harvard/CFA  <jbloom@cfa.harvard.edu>

GRB 041219: Keck IR Observations and Astrometric Refinement of the IR Flash

J. S. Bloom (CfA/UCB), J. X. Prochaska (UCSC), C. McCabe (UCLA),
A. Ghez (UCLA), K. Stapelfeldt (JPL), G. Duchene (Grenoble),
Q. Konopacky (UCLA), K. Hurley (UCB/SSL), C. Blake (CfA), D. Starr
(Gemini) report:

Comparing the IR flash discovery images (GCN #2870) of GRB 041219 (GCN
#2866; #2874) to 25 stars in the 2MASS catalogue, we find a refined
absolute astrometric position of the IR flash to be (J2000):

   RA = 00:24:27.68 (+/- 0.124"), Dec = +62:50:33.501 (+/- 0.228")

This is 4.310" East and 8.415" North from a nearby brighter point source.

In J-band imaging (though clouds) with NIRC on the Keck I 10-m
telescope on Mauna Kea, HI, the IR transient (IRT) was detected on
20.25 December 2004 UT, significantly faded from the first night of
PAIRITEL imaging. In 0.7" seeing, the IRT appears point-like; that is,
there is no indication yet for the presence of an underlying host
galaxy. We note that the IRT is located 2.5 arcsec south-south-west of
a faint compact source."

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