GRB 971214
ATel #5; S. R. Kulkarni, A. N. Ramaprakash, J. Bloom, S. Djorgovski, Caltech; R. Goodrich, Keck Observatory/CARA and D. Frail, VLA/NRAO report on behalf of the Caltech GRB effort
on 12 Jan 1998; 21:31 UT
Credential Certification: rutledge@rosat.mpe-garching.mpg.de
Subjects: Optical, Gamma-Ray Burst
The optical transient (IAUC # 6788 ) of GRB 971214 (IAUC # 6787 ; IAUC
# 6792 ) was observed by J. Aycock using the LRIS instrument on Keck II.
The observations were conducted between 1400--1600 UT of January 10,
1998 and images were obtained in the R band. The seeing was
consistently 0.86 arcsec and 12 frames each of five minute duration
were obtained. A source is clearly detected at the position of the
OT. This source is fainter by 5.5 +/- 0.17 mag compared to object 2
of Henden et al. (GCN note [#016] of Dec 24, 1997). We measured pixel
offsets between this source and object 2 and compared to similar
offsets in the LRIS I-band image of Dec 15.47 1997 UT (see GCN note of
Dec 17, 1997). The offsets match to better than 0.15 arcsec in each
axis.
A power law fit to the I-band data of Halpern et al. (IAUC # 6788 )
and our LRIS I-band data of Dec 16.52 and Dec 17.45 UT predict an
I-band magnitude between 26.2 and 27.0 on January 10, 1998. The
uncertainty represents maximum errors in the extrapolation. Diercks
et al. (IAUC # 6791 ) note that the OT had R-I=1.0+/-0.4 on Dec 15.5
1997 UT. The subsequent two R band measurements (IAUC # 6791 ) appear
to track the I-band points (to within errors). Thus, if there is no
color evolution in the OT then the predicted R band magnitude on 10
January 1998 UT is between 27.2 and 28.0 mag with an offset
uncertainty of 0.4 mag. We conclude that either the OT has stopped
its power law decay or more likely the host of the OT has an R
magnitude of 25.6 mag.
