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GCN Circular 970

GRB010222: R-band fading behavior
2001-02-22T21:54:46Z (23 years ago)
Krzysztof Z. Stanek at CfA <>
K. Z. Stanek, S. Jha, J. McDowell, R. Kilgard, J. Roll
(Harvard-Smithsonian CfA), P. M. Garnavich (Notre Dame) and J. Kaluzny
(Copernicus Astronomical Center) report:

R-band observations of the optical afterglow of the GRB010222 carried
out with the F. L. Whipple Observatory 1.2m telescope, starting at UT
11:10 (3.8 hours after the burst), indicate a fading behavior of the
source at 14:52:12.55 +43:01:06.2 (J2000):

HJD-2450000         UT           R_c       exp
1962.9610     010222 11:10  18.18+-0.02  600 sec
1962.9695     010222 11:23  18.21+-0.02  600 sec
1963.0106     010222 12:22  18.36+-0.02  600 sec

Errors in the magnitudes are statistical only.  The R-band magnitudes
are relative to star "A" as marked in the finding chart at, assuming its
magnitude R=17.0 (see GCN 963). Our comparison star is different from
the star "A" of Henden & Vrba (GCN 967), which is saturated in our
images. These data should not be combined with that of Henden & Vrba
unless using common comparison stars.

We have also obtained UBVI observations of the afterglow, reductions
of which are under way.

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