GCN Circular 26039
Subject
GRB 191019A: NOT optical observations
Date
2019-10-19T21:30:22Z (5 years ago)
From
Daniel Perley at Liverpool JMU <d.a.perley@ljmu.ac.uk>
D. A. Perley (LJMU), D. B. Malesani (DTU Space), A. de Ugarte Postigo
(HETH, IAA/CSIC; DARK/NBI), D. Xu (NAO/CAS), J. P. U. Fynbo (DAWN/NBI),
K. E. Heintz (Univ. Iceland), and N. E. Jannsen (NOT) report on behalf
of a larger collaboration:
We observed the field of GRB 191019A (Simpson et al., GCN 26031) with
the Nordic Optical Telescope (NOT) equipped with the ALFOSC imaging
camera. Observations started on 2019 Oct 19.822 UT (4.52 hr after the
trigger).
In a single 120 s image taken in the SDSS i band, we detect the object
mentioned by Reva et al. (GCN 26036), which is also visible in the
Pan-STARRS archival images and is consistent with the X-ray position
(Evans et al., GCN 26034). The target is clearly extended (FWHM 1.4"
with a seeing of 1.1").
The object centroid has coordinates (J2000, calibrated against the Gaia
catalog):
RA = 22:40:05.89
Dec = -17:19:42.7
Measuring its magnitude over an aperture of 1.7" radius, we obtain i =
18.66 +/- 0.01 AB (statistical error), compared to i = 18.71 +/- 0.01
from the Pan-STARRS catalog (Chambers et al. 2015, arXiv:1612.05560),
confirmed by our own measurement on the i-band Pan-STARRS image. The
small flux difference may be due to calibration, color effects, or
variable aperture correction, so we do not claim any afterglow
detection. A conservative limit on the afterglow magnitude at the time
of our observation would be i > 21.
We note the elevated column density measured in a preliminary analysis
of the X-ray spectra (Evans et al., GCN 26034). This may suggest a
dust-obscured event.
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