Skip to main content
Testing. You are viewing the public testing version of GCN. For the production version, go to
Introducing Einstein Probe, Astro Flavored Markdown, and Notices Schema v4.0.0. See news and announcements

GCN Circular 22056

GROND observations of GRB 171027A
2017-10-27T11:17:03Z (7 years ago)
Patricia Schady at MPE/Swift <>
P. Schady (MPE) reports:

Observations of the field of GRB 171027A (Swift trigger 783479; D'Avanzo
et al., GCN #22053) were carried out simultaneously in g'r'i'z' with GROND
(Greiner et al. 2008, PASP 120, 405) mounted at the 2.2 m MPG telescope at
ESO La Silla Observatory (Chile).

Observations started at 08:51 UT on 27-10-2017, 28.4 mins after the GRB
trigger. They were performed during astronomical twilight, at an average
seeing of 1.4" and at an average airmass of 1.4.

Using a total exposure of 4.4 min, no source is detected within the 2.1"
enhanced Swift/XRT error circle (Evans et al., GCN 22054) down to the
following 3 sigma upper limits (all in AB):

g' > 23.1
r' > 23.1
i' > 22.3
z' > 22.2

Given magnitudes are calibration against PanSTARRS and are not corrected
for the expected Galactic foreground extinction corresponding to a
reddening of E_(B-V)=0.12 mag in the direction of the burst (Schlafly &
Finkbeiner 2011).

I acknowledge the excellent support provided by Angela Hempel in obtaining
these data.
Looking for U.S. government information and services? Visit