GCN Circular 22166
Subject
GRB 171123A: OSN Upper Limit
Event
Date
2017-11-24T18:52:37Z (8 years ago)
From
Luca Izzo at IAA-CSIC <Luca.Izzo@ICRA.it>
L. Izzo, D. A. Kann, A. de Ugarte Postigo (all HETH/IAA-CSIC), and V. Casanova (IAA-CSIC) report:
We observed the field of GRB 171123A (Evans et al.; GCN Circ. 22148) with the 1.5-m OSN telescope in Granada, Spain.
We began observing at 03:32:53 UT (13.3 hours after the GRB trigger), and obtained 18x300s images in the Ic band. Observations were obtained in inclement conditions (clouds, bad seeing of ~2") and the last four images could not be used.
In our stacked image, we find no source at the position reported by Schmidl et al. (GCN Circ. 22162) down to a a 3-sigma limit of Ic (Vega) > 21. The calibration was performed using nearby stars in the USNO B1 catalog.