[vsnet-grb-info 308] GRB020801: Imaging of Suggested OT Counterpart at the Magellan

[GCN Circulars <gcncirc@lheawww.gsfc.nasa.gov>]

TITLE:   GCN GRB OBSERVATION REPORT
NUMBER:  1465
SUBJECT: GRB020801: Imaging of Suggested OT Counterpart at the Magellan
DATE:    02/08/04 00:09:52 GMT
FROM:    George Ricker at MIT  <grr@space.mit.edu>

GRB020801: Imaging of Suggested OT Counterpart at the Magellan Observatory

M. Garcia and D. Rusin (CFA); N. Butler, A. Dullighan, G. Ricker, and 
R. Vanderspek (MIT)

write:

We have imaged the suggested optical counterpart of GRB020801 
(Kilmartin and Gilmore; GCN 1462), which was localized in the X-ray 
band by HETE, with the LDSS-2 instrument on Magellan 1 (Walter A. 
Baade Telescope), obtaining two broadband CCD images.  By comparing 
the Kilmartin-Gilmore object with the USNO A-2 stars in the field, we 
derive approximate magnitudes of 19.31 (03 Aug 2002, 02:01 UT) and 
19.61 (03 Aug 2002, 02:20 UT) for the object.  We estimate our 
magnitude conversion to R has a zero point rms error of 0.4 
magnitudes, and that our internal photometric errors have rms errors 
of 0.03 magnitudes.  The brightness of the Kilmartin-Gilmore object 
which we measure agrees well with that cited in GCN 1462, but also 
indicates that the object is variable.  The lack of fading rules out 
this object as the GRB afterglow counterpart (as suggested by Fox and 
Price; GCN 1464); the fluctuations may indicate that it is a variable 
(dMe?) star.

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