TITLE:   GCN GRB OBSERVATION REPORT
NUMBER:  1701
SUBJECT: GRB 021112:  Afterglow or Variable Star?
DATE:    02/11/20 19:05:03 GMT
FROM:    Melissa Nysewander at UNC,Chapel Hill  <mnysewan@astro.unc.edu>

M. Nysewander, D. Reichart (U. North Carolina), A. Henden (USRA/USNO), G.
G. Williams (MMTO/SAO), and M. Schwartz (Tenagra Observatories) report on
behalf of a larger collaboration:

We observed fields containing the candidate afterglow of GRB 021112 (GCN
1696) 4 days after the burst in BVRcIc, 6 days after the burst in Rc, and 7
days after the burst in H.  Using the field calibration of Henden (GCN
1697) and 2MASS, we report preliminary photometry:

Date      Time      Filter  Magnitude         Telescope

Nov 16.2  4.0 days  V       21.48 +- 0.08     90-inch Bok
Nov 16.3  4.1 days  B       > 22.6 (3 sigma)  90-inch Bok
Nov 16.3  4.1 days  Ic      19.39 +- 0.09     32-inch Tenagra II
Nov 16.3  4.1 days  Rc      20.87 +- 0.07     32-inch Tenagra II
Nov 18.3  6.1 days  Rc      20.84 +- 0.06     1.0-meter USNO
Nov 19.2  7.0 days  H       * 17.44 +- 0.17   1.55-meter USNO

* 2MASS field not available.  Calibration based on 2MASS Quicklook image
and consequently caution is warranted.  However, candidate is strongly
detected:  Internal errors are ~0.01 mag.

Using the images of Strolger et al. (GCNs 1684, 1696), kindly provided by
J. E. Rhoads, we have placed their photometry on the same photometric
system:

Date      Time       Filter   Magnitude      Telescope

Nov 12.3  3.2 hours  Rc       20.86 +- 0.05  4-meter Mayall
Nov 13.2  1.0 days   Rc       20.31 +- 0.06  4-meter Mayall

Although we do not find evidence for variability in the R-band light curve
outside of the discovery epoch, which could be explained by an afterglow in
a R = 20.86 +- 0.03 galaxy, 1.0 arcsec seeing on Oct. 19th shows the
candidate to have a star-like profile (this image is available upon
request).

This, in addition to the candidate's location outside of HETE's 90% error
box and an otherwise rarely seen brightening a day after the burst, suggest
that the candidate is probably a variable star of some type instead of an
afterglow in a bright, compact galaxy.

[GCN OPS NOTE (27Nov02): All the "Oct dd.dd" were changed to "Nov dd.d".]