[vsnet-grb-info 246] GRB020531: Upper Limit for Detection of Two TAROT Sources

[GCN Circulars <gcncirc@lheawww.gsfc.nasa.gov>]

TITLE:   GCN GRB OBSERVATION REPORT
NUMBER:  1411
SUBJECT: GRB020531: Upper Limit for Detection of Two TAROT Sources
DATE:    02/06/05 20:47:35 GMT
FROM:    George Ricker at MIT  <grr@space.mit.edu>

GRB020531: Upper Limit for Detection of Two TAROT Sources

A. Dullighan, G. Monnelly, N. Butler, R. Vanderspek, P. Ford, and G. 
Ricker (MIT)

write:

We obtained early epoch observations of the HETE error region of the 
short gamma-ray burst GRB020531 (H2042; Ricker et al., GCN #1399) 
with the Baade 6.5m telescope at the Magellan Observatory on 2002 
June 1.17 UT using the LDSS-2 instrument. The observations took place 
1.19 days after the burst. A mosaic of seven 300s R-band exposures 
covered the entire IPN error region (Hurley et al., GCN #1402).

We detect neither source A nor source B that were reported by Boer et 
al. (GCN #1408) from TAROT observations taken 1.5 hours after the 
burst. For each of these two source locations, our 3 sigma upper 
limit is R=23.3. If source B were the afterglow of GRB020531, our 
result implies that the decay power law index was steeper than 1.93 
between the epoch of the earlier TAROT observations and that of our 
later Magellan observations.

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