GRB 191019A
GCN Circular 26098
Subject
GRB 191019A: Zadko Telescope optical observations
Date
2019-10-30T05:46:27Z (7 years ago)
From
Bruce Gendre at UVI <bruce.gendre@gmail.com>
B. Gendre (OzGrav-UWA), H. Crisp (OzGrav-UWA), D. Coward (OzGrav-UWA),
J. Zadko (Claire Energy), J. A. Moore (OzGrav-UWA), A. Burrell
(OzGrav-UWA), A. Klotz (IRAP-OMP-UPS), P. Thierry (Auragne Observatory),
E.J. Howell (OzGrav-UWA), A. Verveer (ASA), J. Kennewell (UWA, ASA)
report:
We observed GRB 191019A (Simpson et al., GCN 26031) with the Zadko
Telescope (Coward et al. 2017), starting at 2019 October the 19th at
15:20:23 UT (7 minutes 50 seconds after the trigger) under fair conditions.
The object reported by Reva et al. (GCN 26036) is clearly visible in our
images. However, we measure an R magnitude of 18.92 at the time reported
by the GCN. Observations stopped one hour twenty three minutes after the
burst, and during that time we do not see any variation on the light
curve, similar to other teams (Perley et al., GCN 26039; Fynbo et al.,
GCN 26041; and Zhu et al., GCN 26059). At that position, the USNO
catalog reports a source of magnitude R = 19.0, consistent with our
findings. We conclude that this object is not the afterglow of GRB
191019A, but the host galaxy, as reported by Perley et al. (GCN 26062).
The Zadko Telescope has been under refurbishment during the last year,
and is still in recommissioning mode. This message can be cited.
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GCN Circular 26062
Subject
GRB 191019A: NOT optical afterglow and host association confirmation
Date
2019-10-23T21:55:37Z (7 years ago)
From
Daniel Perley at Liverpool JMU <d.a.perley@ljmu.ac.uk>
D. A. Perley (LJMU), D. B. Malesani (DTU Space), A. J. Levan (Radboud
Univ.), J. P. U. Fynbo (DAWN/NBI), and A. A. Djupvik (NOT) report on
behalf of a larger collaboration:
We obtained additional observations of the optical counterpart (Reva et
al., GCN 26036; LaPorte & Simpson, GCN 26053; Zhu et al., GCN 26059) of
GRB 191019A (Simpson et al., GCN 26031), using the Nordic Optical
Telescope (NOT) equipped with the ALFOSC camera. A total of 25 minutes
exposure was secured with mid time Oct 22.875 UT (77.8 hr after the GRB).
The archival object consistent with the XRT error circle is well
detected, with a magnitude of i = 18.71 +/- 0.02 AB, consistent with the
Pan-STARRS tabulated value of i = 18.71 +/- 0.01 and slightly fainter
than our earlier observation (Perley et al., GCN 26039), for which the
mid time was 4.60 hr after the GRB.
Digital image subtraction was carried out with ISIS (Alard 2000, A&AS,
144, 363) between the two epochs. A clear point-like residual is
detected, for which we measure a magnitude i = 21.78 +/- 0.05 AB
(assuming no residual flux in our second epoch). Its position calibrated
against the Gaia catalog is:
RA(J2000) = 22:40:05.89
Dec(J2000) = -17:19:42.6
(+/- 0.3")
An image showing the subtraction result is available here:
http://outer.space.dtu.dk/~dmales/GRB/191019A/subtraction.jpg
The transient location is 0.07" east of the galaxy nucleus,
strengthening the case for a physical association between the two
objects. The offset is within the margin of error, although the NOT
spectroscopy (Fynbo et al., GCN 26041