GRB 980329 optical observations:
S. G. Djorgovski, S. R. Kulkarni (Caltech), J. Tonry, A. Barger, E. Fulton
(U. Hawaii), R. Gal, J. Sievers, and K. Adelberger (Caltech), on behalf of
the Caltech GRB collaboration, report:
We obtained CCD images of the field of the proposed x-ray counterpart
of GRB 980329 (IUC 6854), using the University of Hawaii 88-inch telescope
at Mauna Kea, on UT 1998 March 30 and 31 (about 1 and 2 days after the
burst). R band images taken on UT March 30 have a limiting magnitude
of R ~ 22.3, and images taken on March 31 have a limiting magnitude of
R ~ 23.0. Additional B and V band images were also obtained on March 31.
No significantly variable objects have been found in these data. Moreover,
there were no objects in these CCD images which are not also present in the
digital version of POSS-II (DPOSS), which reach about 1 to 1.5 magnitudes
deeper than the publicly available DSS (POSS-I) images, above the limit of
the photographic survey.
The (stellar) object mentioned by Ilovaisky and Chevalier (IAUC 6856) is
detected in DPOSS red images, and CCD images, and it does not vary. It
is most likely a foreground Galactic star.
There is a very blue stellar object outside the SAX error circle, and thus
probably unrelated to the GRB, at RA = 07:02:42.66 DEC= +38:49:15.8 (J2000).
Additional, much deeper R and I band images of the field, with a limiting
magnitude of R ~ 27, were obtained at the WMKO Keck-II 10-m telescope on
UT April 02. Again, there are no significantly variable objects present
within the limits of the earlier (March 30 and 31) CCD data. Further
observations of the field with the Keck telescope are in progress.
These images are shown at http://astro.caltech.edu/~george/grb/grb980329.html
This note can be cited.