GRB 971024

We observed the entire 90% confidence RXTE_ASM localization  
of GRB971024 (Trigger No. 6448, GCN notice of 24 Oct 97 22:41:47 UT) 
with the USNO, Flagstaff Station 1.0-m telescope in the R band between 
14-14.5 hours after the GRB event. The frames were approximately as 
deep as the DSS in this region. Our frames were blinked against the
DSS and no objects substantially brighter on our frames than on the 
DSS were found.

This message is citable in publications.

F.J. Vrba, J.A. Munn, U.S. Naval Observatory, Flagstaff Station



GCN Administrative PS:
This notice is being distributed with a significate time delay (~20 hrs)
because of a network problem here at GSFC which prevented me from receiving
this notice earlier.  This is a very rare occurance.
Also, work is progressing on the automated form of these follow-up notices.

Buell Jannuzi and James Rhoads of KPNO report:  

We obtained images this evening [evening of 25-26 Oct] of the
reported position of GRB971024.  We used the KPNO 4m and
the prime focus Mosaic imager, providing a 35' field of view.
We obtained five 10 minute exposures in the R-band under
apparently photometric conditions (still need to reduce
our data and standards) in poor seeing (1.5" FWHM; the
jet stream is on top of us at the moment).  We plan to
make the reduce image available sometime tomorrow eveing via
the NOAO Web page (the mosaic data, 8kx8k, unfortunately take
awhile to reduce), and will try to obtain a second epoch tomorrow.

GRB971024                                                              #004

We reobserved the entire 90% confidence RXTE_ASM localization
of GRB971024 (Trigger No. 6448, GCN notice of 24 Oct 97 22:41:47 UT)
with the USNO, Flagstaff Station 1.0-m telescope in the R band, 48 hours
after our first set of observations (which were obtained 14-14.5 hours
after the GRB event).  The two sets of frames (both approximately as deep as
the DSS in this region) were blinked against each other.  No significantly
variable objects (approx.  1 mag) were detected to approximately R = 19
(in our previous notice, the first set of frames were blinked against DSS,
and no significantly brighter objects in our frames were found).

This message is citable in publications.

J.A. Munn, F.J. Vrba, A.A. Henden, U.S. Naval Observatory, Flagstaff Station

GRB971024                                                              #005

The KPNO reduced 4m Mosaic (8k x 8k imager) data are now available on our
web page ( http://www.noao.edu/noao/grb/971024.html ).  As briefly stated
there, these data have been block averaged (binned) 2x2 to reduce the
image size to 4k x 4k.  The images are about 77 Mb each.  The seeing was
poor, about 1.5" on the first night and about 2" on the second night, so
with the ~0.25" Mosaic pixels the images are still well sampled after
binning.

The images were taken in the R-band and total 50 minutes exposure each.
Zero points are not yet available.

Buell Jannuzi, Arjun Dey and collaborators observed, processed, and
combined these images.  James Rhoads and Ted von Hippel have performed
preliminary photometry on these images and find a large number of objects
which deviate between the two epochs when comparing aperture photometry.
Most of the objects which deviate from one epoch to the other seem to be
due to crowding causing aperture photometry differences due to the
different seeing, and some are due to image defects.  Careful psf-fitting
photometry should improve the analysis.  We are still studying these
images but do not want to delay the efforts of others, so we are now
making the reduced images available.

This message is citable in publications.