GCN Circular 9995
Subject
GRB 091003: WHT ACAM observations
Date
2009-10-05T17:11:44Z (15 years ago)
From
Klaas Wiersema at U of Leicester <kw113@star.le.ac.uk>
K. Wiersema, N. Tanvir (Leicester), A. Levan (Warwick) and C. Benn (ING)
report on behalf of a larger collaboration:
We observed the afterglow of Fermi GRB 091003 (Rau GCN 9983; McEnery et al
GCN 9985; Starling & Beardmore GCN 9986) with the William Herschel
Telescope, using the ACAM instrument. We took a 60 and a 250 second
exposure in imaging mode, starting at 21:11 UT, October 4 (1.69 days after
burst).
The afterglow is clearly detected, with r = 21.33 +/- 0.11 (calibrated to
SDSS field stars), at position:
RA (J2000) = 16:46:04.687
Dec (J2000) = +36:37:30.76
with uncertainty 0.3 arcseconds.
We obtained spectroscopy with ACAM immediately after, at high airmass. Two
900 second exposures were obtained using the 400V grism and a 1 arcsecond
slit. Faint continuum emission is detected over the 4000-9300 A range. No
strong absorption or emission lines are detected. The detection of
continuum at 4000A gives a upper limit to the redshift of 2.3.