Transient EPW20240219aa: J-band upper limits from WINTER

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).