GCN Circular 41391
Subject
GRB 250814A: GRAWITA TNG NIR observations
Event
Date
2025-08-15T12:07:02Z (5 days ago)
From
Paolo D'Avanzo at INAF - OAB <paolo.davanzo@inaf.it>
Via
email
P. D'Avanzo, (INAF-OAB), M.T. Botticella, L. Izzo (INAF - OACn), A. Rossi (INAF-OAS), V. D’Elia (ASI-SSDC), G. Greco (INFN), M.G. Bernardini (INAF-OAB), B. Patricelli (Univ. Pisa), E. Cappellaro (INAF-OAPd), E. Brocato (INAF-OAR), V. Lorenzi, G Mainella (INAF-TNG), on behalf of GRAWITA report:
We observed the field of GRB 250814A detected by Swift/BAT and Fermi/GBM (Caputo et al. GCN Circ. 41358; Fermi team, GCN Circ. 41357) and possibly associated with the sub-threshold GW trigger S250814bg (LVK, GCN Circ. 41364) with the Italian 3.6m TNG telescope, located in Canary Islands (Spain), equipped with the near-infrared camera NICS in imaging mode.
A series of images were obtained with the H filter starting on 2025-08-14T20:33:39 UT (i.e. 13.0 hours post T0) and with the K filter starting on 2025-08-14T22:06:25 UT (i.e. 14.5 hours post T0), centered at the position of the X-ray afterglow detected by Swift/XRT (Caputo et al. GCN Circ. 41358; Salvaggio et al., GCN Circ. 41379).
Within the Swift/XRT error circle (Salvaggio et al., GCN Circ. 41379) we detect two sources. Below we report the source positions and AB magnitudes derived from preliminary photometry (calibrated against the 2MASS catalogue).
Source 1
RA (J2000) = 20:25:13.86
Dec (J2000) = +48:23:56.3
+/- 0.3"
H = 21.3 +/- 0.2 mag
K = 21.4 +/- 0.3 mag
Source 2
RA (J2000) = 20:25:14.06
Dec (J2000) = +48:23:54.8
+/- 0.3"
H = 21.8 +/- 0.2 mag
K = 21.2 +/- 0.2 mag
We note that Source 1 is the same reported by several authors in both the NIR and optical bands (Karambelkar et al. GCN Circ. 41337; Castro-Tirado et al. GCN Circ. 41381; Ahumada et al. GCN Circ. 41382). Compared with the results reported so far, our preliminary photometry suggests that this source has not varied, in agreement with the findings of Ahumada et al. (GCN Circ. 41382).
Further NIR observations are encouraged to check for any brightness evolution of Source 2.