{
  "submittedHow": "email",
  "submitter": "Viraj Karambelkar at Indian Inst of Tech,Bombay <karambelkarvraj21197@gmail.com>",
  "subject": "LIGO/Virgo/KAGRA S250206dm: Observations from WINTER",
  "circularId": 39256,
  "body": "Robert Stein (JSI), Viraj Karambelkar (Caltech), Danielle Frostig (CfA),\nMansi Kasliwal (Caltech), Nathan Lourie (MIT), Geoffrey Mo (MIT) and Robert\nSimcoe (MIT) report:\n\nWe observed the localization region of the S250206dm (GCN 39175, 39231)\nwith the 1.2 sq. degree near-IR WINTER camera on the Palomar 1-m telescope\n(Lourie et al. 2021, Frostig et al. 2024) in J-band on two nights UTC\n2025-02-08 and 2025-02-09. Our observations began at 2025-02-08 04:05 UTC,\napproximately 30.7 hours after the merger. Our observations covered a total\nof 23.8 sq. deg. of sky for which reference images were available,\ncorresponding to 37% of the total probability. Of this, 14% was covered at\nleast twice, while 23% was covered once and will be repeated tonight. Our\nobservations reached a median depth of 18 mag AB.\n\nThe images were processed using the WINTER data reduction pipeline (\nhttps://github.com/winter-telescope/mirar,\nhttps://doi.org/10.5281/zenodo.13352565) using images from the UKIRT\nHemisphere survey (Dye et al. 2018) as references for image subtraction. We\nsearch for WINTER sources with multiple detections, and for any WINTER\nsource with a cross-match in the alert stream of the Zwicky Transient\nFacility (Bellm et al. 2019). We further remove stellar sources by\ncross-matching to Gaia, and we are left with no remaining transient\ncandidates.\n\nWe also cross-match WINTER detections to the position of all 35 sources\nreported to TNS in the localisation of S250206dm since merger. We find no\nWINTER detections for any of these transients.\n\nFurther observations of the GW event are planned over the coming days. With\nmore data, additional analysis can be performed to identify transients in\nsky regions without archival UKIRT coverage. This includes the area\ncontaining the candidate neutrino counterpart reported by IceCube (GCN\n39176), for which initial WINTER data has been taken.\n\nWINTER (Wide-field INfrared Transient ExploreR) is a partnership between\nMIT and Caltech, housed at Palomar Observatory, and funded by NSF MRI, NSF\nAAG, the David and Lucile Packard Foundation, and the MIT Kavli Institute\nfor Astrophysics and Space Research.\n",
  "bibcode": "2025GCN.39256....1S",
  "eventId": "LIGO/Virgo/KAGRA S250206dm",
  "createdOn": 1739131466705
}