GCN Circular 41382
Subject
GRB 250814A: P200/WIRC observations of the afterglow candidate
Event
Date
2025-08-15T06:11:05Z (4 days ago)
From
Tomas Ahumada Mena at Caltech <tahumada@caltech.edu>
Via
Web form
Tomás Ahumada (Caltech), Viraj Karambelkar (Caltech), Mansi Kasliwal (Caltech), Iver Warburton (Yale), Alessandro Peca (Yale), and Vishwajeet Swain (IITB) report:
We observed the field of the Fermi and Swift GRB 250814A (Fermi team, GCN Circ. 41357; Caputo et al., GCN Circ. 41358, Salvaggio et al. GCN Circ. 41379), which is spatially coincident with the sub-threshold GW trigger S250814bg (GCN Circ. 41364), in the near-infrared J and Ks bands using the Wide-field Infrared Camera (WIRC; Wilson et al. 2003) on the Palomar 200-inch telescope. Observations began on 2025-08-15 at 03:20 UT and consisted of 1350 s in the Ks band, followed by J-band imaging starting at 04:00 UT with a total exposure time of 1200 s.
We clearly detect the source announced in Karambelkar et al. (GCN Circ. 41337) and observed in i-band by Castro-Tirado et al. (GCN Circ. 41381) at RA = 20:25:13.9, Dec = +48:23:55.9 (J2000), in both bands. This position is consistent with the enhanced X-ray position reported by Salvaggio et al. (GCN Circ. 41379). Aperture photometry yields:
Ks = 21.3 ± 0.2 mag (AB)
J = 21.72 ± 0.15 mag (AB)
These values are consistent, within the uncertainties, with those reported in Karambelkar et al. (GCN Circ. 41337) in both bands. We therefore conclude that this source shows no significant variability and is likely unrelated to the GRB.