TITLE:   GCN GRB OBSERVATION REPORT
NUMBER:  492
SUBJECT: IR observations of GRB991216
DATE:    99/12/18 19:07:47 GMT
FROM:    Paul Vreeswijk at U of Amsterdam  <pmv@astro.uva.nl>

P.M. Vreeswijk, E. Rol (U. of Amsterdam), C. Kouveliotou (USRA,
NASA/MSFC), E. Pian (ITESRE, Bologna), A. Castro-Tirado (LAEFF-INTA,
Madrid), H. Pedersen (KUO, Copenhagen) and J. Greiner (AIP, Potsdam)
report on behalf of a larger European collaboration:

Around Dec. 18.13 UT, we imaged the optical transient to GRB991216
(Uglesich et al., GCN #472) in the infrared J, H and Ks bands with the
New Technology Telescope (NTT) at the European Southern Observatory
(ESO, Chile).  The counterpart is clearly detected in each filter. We
calibrated the field by observations of the NICMOS standard 9115, and
we estimate the error in this calibration to be 0.1 mag. We obtain the
following magnitudes (and measurement error) for the IR counterpart:

	 J=17.56 (0.02), H=16.74 (0.02), Ks=16.76 (0.02).



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