GCN Circular 41377
Subject
GRB 250814A: Possible afterglow candidate from P200/WIRC
Event
Date
2025-08-14T19:35:32Z (10 days ago)
From
Viraj Karambelkar at Indian Inst of Tech,Bombay <karambelkarvraj21197@gmail.com>
Via
email
Viraj Karambelkar (Caltech), Mansi Kasliwal (Caltech), Steven Giacalone
(Caltech), Emily Gilbert (IPAC), Matt Lastovka (UMD), Vishwajeet Swain
(IITB), Gaurav Waratkar (IITB), Tomas Ahumada (Caltech) report:
We observed the field of the Fermi and Swift GRB 250814A (Fermi team, GCN
Circ. 41357, Caputo et al. GCN Circ. 41358) coincident with the
sub-threshold GW trigger S250814bg (GCN Circ. 41364) in the near-infrared J
and Ks bands with the Wide-field infrared Camera (WIRC, Wilson et al. 2003)
on the Palomar 200-inch telescope. Observations started on 2025-08-14 at
11:31:29 UT and lasted for 1665 seconds in the J-band, and started at
12:09:12 UT and lasted for 810 seconds in the Ks-band.
We marginally detect a faint source in the Ks-band image at RA=20:25:13.9,
Dec=48:23:55.9 (J2000), ~0.6 arcsec from the enhanced position of the X-ray
counterpart reported by Caputo et al (GCN 41358). We also detect a marginal
source at this location in the more sensitive J-band image, however, it is
blended with several faint sources and is near the detection limit of the
image. We performed aperture photometry at the location of this source and
measured the following magnitudes
Ks ~ 21.2 +/- 0.35 mag (AB),
J ~ 21.6 mag +/- 0.4 mag (AB)
We encourage deep NIR observations to trace the brightness evolution and
confirm the nature of this source.