GCN Circular 32710
Subject
Afterglow limits of GRB 221006A from OHP
Event
Date
2022-10-12T22:49:00Z (3 years ago)
From
C. C. Thoene at HETH/IAA-CSIC <christina.thoene@gmail.com>
R. O���Rourke Brogan (AIP), P. A. C. Cunha (Univ. do Porto/CAUP), G. Ma
(DAWN/NBI) and C. C. Thoene (ASU-CAS) report:
We observed the field of the MAXI GRB 221006A (GCN 32626, Mikhara et al;
GCN 32628, Sbarufatti et al.) using the 1.2m telescope at the Observatoire
de l���Haute Provence. Observations started on Oct. 06, 2022 at 20:49 UT,
~20h after the GRB under nearly full Moon conditions.
In a combined exposure of 2600s in R-band we do not detect a counterpart at
any of the positions of the three possible candidates (Source 1: RA
22:29:24.52, DEC +15:38:02.8; Source 2: RA 22:28:58.99, DEC +15:42:49.6;
Source 3: RA 22:29:23.07, DEC +15:41:38.6) down to a limiting magnitude of
R = 22 mag (3 sigma).
At the position of source 2, confirmed to be fading with a significance of
4.6 sigma (https://www.swift.ac.uk/xrt_products/TILED_GRB00108/), there are
two underlying galaxies also present in the SDSS, which we call G1 and G2.
Our image shows a combined magnitude of R=21.2 +/- 0.4 for the two
galaxies. The objects show no evidence of excess emission, which is
consistent with our upper limit. G1 has a distance of 0.5 arcsec and G2 of
3.5 arcsec from the X-ray candidate afterglow, making G1 the likely host of
GRB 221006A.
We thank the NEON observing school and the support of the 1.2m telescope
operator Stephane Favard for obtaining these data.