GCN Circular 462
Subject
R-band Observations of GRB991208 at TNG
Date
1999-12-16T15:46:06Z (25 years ago)
From
Nicola Masetti at ITeSRE,CNR,Bologna <masetti@tesre.bo.cnr.it>
N. Masetti, E. Palazzi, E. Pian, F. Frontera (ITESRE, CNR, Bologna),
S. Benetti, A. Magazzu' (TNG), A.J. Castro-Tirado (LAEFF-INTA and
IAA-CSIC) and B.L. Jensen (Univ. of Copenhagen), on behalf of a
larger collaboration, report:
"R images of the optical afterglow of GRB991208 (GCN #452 and #453) were
obtained between Dec. 12.29 and Dec. 15.29 UT at Roque de Los Muchachos
(Canary Islands, Spain) with the 3.58-meter Telescopio Nazionale Galileo
(TNG) + OIG CCD camera. We clearly detected the optical transient in all
R images. The following table shows the results of these observations:
Date (UT) Exptime Magnitude Seeing
1999 Dec 12.29 500 sec 20.25 +- 0.15 1".8
1999 Dec 13.29 360 sec 20.3 +- 0.2 1".6
1999 Dec 14.29 600 sec 21.25 +- 0.15 1".5
1999 Dec 15.29 900 sec 21.6 +- 0.3 1".5 (clouds)
Photometric calibration was tied to the USNO A2.0 star 1350-08916561
(R = 15.85 +- 0.1 was assumed).
Preliminary analysis of R data shows that these are consistent with a
power-law decay with index alpha = -2.15 (GCN #454 and #456) with the
exception of the observation of Dec. 13.29, which may however be affected
by uncertainties associated with the observing conditions and with the
shorter exposure time."
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