TITLE:   GCN CIRCULAR
NUMBER:  35807
SUBJECT: Transient EPW20240219aa: J-band upper limits from WINTER
DATE:    24/02/26 21:05:09 GMT
FROM:    Viraj Karambelkar at Indian Inst of Tech,Bombay <karambelkarvraj21197@gmail.com>

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

We observed the location of the X-ray flare EPW20240219aa (Zhang et al.,
ATel #16463; Zhang et al., GCN #35773) in the near-infrared J-band with the
Palomar 1-m telescope, equipped with the 1 square degree WINTER camera
(Lourie et al. 2020).

Our observations started at UTC 2024-02-25T03:24:23, and covered the 3
arcmin localization region of the X-ray flare.  The images were processed
through the WINTER data reduction pipeline implemented using mirar (
https://github.com/winter-telescope/mirar), with image subtraction
performed relative to reference images built from the UKIRT Galactic Plane
Survey (Lucas et al. 2008).


No new sources are detected to a depth of J = 18.5 mag (AB). Of the 7 radio
sources detected by the VLA in this region (Ho et al. GCN #35788), source 6
is detected in both the WINTER and archival UKIRT images, but does not show
significant variability between the two epochs (consistent with that
reported in Ferro et al. GCN #35803).