TITLE:   GCN CIRCULAR
NUMBER:  36262
SUBJECT: LIGO/Virgo/KAGRA S240422ed: WINTER J-band upper limits on the Swift/XRT source S240422ed_X61
DATE:    24/04/23 19:01:55 GMT
FROM:    Viraj Karambelkar at Indian Inst of Tech,Bombay <karambelkarvraj21197@gmail.com>

Viraj Karambelkar (Caltech), Geoffrey Mo (MIT), Robert Stein (Caltech),
Nathan Lourie (MIT), Danielle Frostig (MIT), Tomas Ahumada (Caltech),
Robert Simcoe (MIT), and Mansi Kasliwal (Caltech)

During WINTER follow-up observations (GCN 36248) of the LVK event S240422ed
(GCN 36236, GCN 36240), we observed the location of the Swift/XRT source 61
(labeled as S240422ed_X61) at coordinates RA, Dec = 120.3245, -28.1765 (
https://gcn.gsfc.nasa.gov/other/S240422ed.counterpart) in the near-infrared
J-band. Our observations of this field began at UTC 2024-04-23T03:13:34 and
lasted for 480 seconds.

There are no archival J-band images of this field, so we compare the WINTER
image to a y-band image from the PS1 survey (https://ps1images.stsci.edu/).
We do not detect any new source within 20 arcsec of the Swift X-ray source,
to a 5-sigma depth of 16.6 mag (AB). This estimate is not corrected for
Galactic line-of-sight extinction (integrated E(B-V) = 0.7 mag
corresponding to total A_J = 0.5 mag) along this direction.

WINTER (Wide-field INfrared Transient ExploreR) is a partnership between
MIT and Caltech, housed at Palomar Observatory, and funded by NSF MRI, NSF
AAG, the David and Lucille Packard Foundation, and the MIT Kavli Institute
for Astrophysics and Space Research.