GCN Circular 967
Subject
GRB010222, optical observations
Event
Date
2001-02-22T21:04:26Z (25 years ago)
From
Arne A. Henden at USNO/USRA <aah@nofs.navy.mil>
A. Henden (USRA/USNO) and F. Vrba (USNO), on behalf of the
USNO GRB team and a larger European GRB collaboration, report:
We observed the BeppoSAX error box for GRB010222 (GCN 959, 960, 966)
with the USNOFS 1.0-m telescope under cloudy conditions.
The discovery of the optical transient for this burst
was given in Henden (GCN 961, 962). The final astrometry for
the OT, relative to USNO-A2.0, is
223.05229 43.01840
14:52:12.55 +43:01:06.2 (J2000)
with internal errors of 0.2arcsec. This is in agreement
with the values given in McDowell et al. (GCN 963).
A finding chart (R-band, 4.5x4.5arcmin, NE=upperleft) is given at
ftp://ftp.nofs.navy.mil/pub/outgoing/aah/grb/grb010222r.jpg
BVRcIc frames were taken shortly after the localization
posting. However, only the preliminary R-band measures
are reported here. The quality of the photometry suffered
due to the thick clouds, but is good enough to show definite
fading of the transient:
UT exp Rc err
010222.486 1x300 18.36 0.059
010222.510 2x300 18.52 0.054
010222.518 2x600 18.68 0.059
010222.533 2x600 18.67 0.057
Where the R-band magnitudes are relative to the bright USNO-A2.0
star (identified as "A" on the finding chart) at J2000 coordinates
14:52:14.80 +43:01:40.9 and that has an assumed magnitude R=14.70.
More careful all-sky calibration of this field will be performed
on the next few nights. The intent is to only calibrate in
BVRcIc; please contact Henden if you need U-band calibration as well.