The text of the GCN note #41, submitted on 3 April 1998 PST:
GRB 980329 optical observations:
S. G. Djorgovski, S. R. Kulkarni, J. Sievers (Caltech), D. Frail and G. Taylor (NRAO), on behalf of the Caltech-NRAO GRB collaboration, report:
We have detected a galaxy coincident to within the astrometric errors (about 0.5 arcsec) with the variable radio source detected at the VLA by Taylor et al. ( GCN note #40) on deep R-band images taken with the Keck-II 10-m telescope on 02 April 1998 UT. The galaxy has a magnitude R = 25.7 +- 0.3 (preliminary reductions). The image of the field is shown at: http://astro.caltech.edu/~george/grb/grb980329.html.
We propose that this is the host galaxy of the radio transient detected at the VLA, which may be the afterglow of GRB 980329.
Further observations of this field are in progress.
This note can be cited.
The text of the GCN note #38, submitted on 2 April 1998 PST:
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 (IAUC 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.
One of the
CCD images in the R band obtained at the Keck-II telescope on UT 1998 April 02.
The field shown is approximately 168 arcsec square. This is a preliminary
reduction.
A zoom-in from a
CCD image in the R band obtained at the Keck-II telescope on UT 1998 April 02,
with the possible GRB host galaxy marked. The field shown is about 42 arcsec
square. This is a preliminary reduction of the data.
CCD images obtained at the University of Hawaii 88-inch telescope on 30 March (n1) and 31 March (n2) 1998 UT, by J. Tonry, A. Barger, and E. Fulton. Images are approximately 198 arcsec = 3.3 arcmin square, tilted with PA = -21.4 deg. Clockwise from upper left: B(n2), V(n2), R(n2), R(n1)
This image is available in
Postscript ,
and
GIF formats.
This is the zoom-in on the same DPOSS F image, field size 256 arcsec:
This image is available in
Postscript ,
and
GIF formats.
DPOSS J plate (green) image, field size 512 arcsec, Postscript
DPOSS J plate (green) image, field size 512 arcsec, GIF
DPOSS J plate (green) image, field size 256 arcsec, Postscript
DPOSS J plate (green) image, field size 256 arcsec, GIF
This is the POSS-I DSS image from SkyView, field size = 9 arcmin, available in Postscript , and GIF formats.
The same image, smoothed and stretched, without the coordinates grid,
Postscript file.
The
list of HST GSC stars marked on the chart.
