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GCN Circular 10335

GRB 100115A: Gemini-N photometry
2010-01-17T16:53:52Z (14 years ago)
Antonino Cucchiara at PSU <>
A. Cucchiara, D. B. Fox (PennState), E. Berger (Harvard U.)
report on behalf of a larger collaboration:

"On January 16.20 UT we observed the field of GRB100115A
(Cummings et al. 10325, Margutti et al. GCN 10326) with the
Gemini-North GMOS camera in r and g bands.
We collected a sequence of 5x180s images in each filter.
In the coadded images the afterglow candidate is visible in
both filters (GCN 10328,10331,10332).

On January 17.20 UT we collected a second epoch with the same set-up.
The following magnitude have been calibrated using the USNO-B1.0
star at RA: 00:13:30.44 Dec: -00:49:16.93 ( = 19.76 mag):

Jan. 16.20 UT:
r = 21.37 +- 0.08 mag

Jan 17.20 UT:
r = 21.86 +- 0.08 mag

A similar fading of ~0.5 mag is present in our g-band observations.
Therefore we conclude that Object "A", which shows two structures,
contains a fading transient. Further observation are planned.

We thank the Gemini staff, in particular Sandy Leggtt, for performing these
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