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GCN Circular 503

Lowell/Perkins observation of GRB 991216
1999-12-20T13:34:44Z (24 years ago)
John Mattox at Boston U <>
As suggested by Garnavich et al. (GCN 495), the Lowell/Perkins 
magnitude reported by Mattox in GCN 487 was indeed to faint by 
0.8 magnitudes (due to the use of a preliminary flat with a large 
photometry radius).

A series of 400s integrations were done in R band centered at
20.30 Dec. UT (under marginal conditions, 2.6" FWHM seeing, 
and with the nearly full moon 25 deg away). GRB 991216 is apparent in 
the sum of 14 images. A preliminary R magnitude is 22.3 +/- 0.2, 
which is fainter than the extrapolation of the power law of Jensen et al. 
(GCN 498). This discrepancy could result from an error in our preliminary
reduction of these Lowell/Perkins data, or it could indicate a break
in the decay slope due to evolution of a jet.

This message should not be cited in publication - it is provided
here to encourage observations which could confirm a break from the
power law decay - a final reduction of these data will be linked to
when available.
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