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GCN Circular 36172

EP240416a: J-band observations with WINTER
2024-04-19T05:07:16Z (a month ago)
Geoffrey Mo at MIT <>
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Geoffrey Mo (MIT), Viraj Karambelkar (Caltech), Danielle Frostig (MIT), Robert Stein (Caltech), Nathan Lourie (MIT), Tomas Ahumada (Caltech), Robert Simcoe (MIT), and Mansi Kasliwal (Caltech) report:

We observed the field of the EP-WXT X-ray transient EP240416a (Cheng et al., GCN 36138) in the near-infrared J-band with the Palomar 1-m telescope, equipped with the 1 square degree WINTER camera (Lourie et al. 2020). 

Observations began at 2024-04-17T14:01:04.438 UTC (~1.5 days after the X-ray transient) and consisted of 15 x 120 s exposures. The images were processed using the WINTER data reduction pipeline ( 

We do not detect the optical counterpart discovered by Kinder and confirmed by Xinglong and NOT (Chen et al., GCN 36139, An et al., GCN 36144, Antipov et al., GCN 36142, Xiong et al., GCN 36155, Pankov et al., GCN 36157, Belkin et al., GCN 36158), setting the following upper limit: J ~ 19.4 mag (AB).

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.
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