TITLE: GCN CIRCULAR NUMBER: 41641 SUBJECT: EP250827b: Swift observations of AT 2025wkm DATE: 25/09/01 20:57:31 GMT FROM: xjh@andrew.cmu.edu Xander J. Hall (Carnegie Mellon U.), Tomas Ahumada (Caltech), and Robert Stein (UMD) on behalf of the ZTF collaboration: We requested Swift ToO observations of the X-ray flare EP250827b and optical transient AT 2025wkm reported by Schroeder et al. (GCN 41635). The observation was taken with a midpoint time of 2025-08-31 at 21:13:29 UT, approximately 4.62 days after the flare, with a duration of 4ks. The source was not detected with XRT with an upper limit of 2.5 * 10^-3 cts/s at 0.3 - 10 keV. Given the redshift reported by Sevilla & Ho (GCN 41639) of z = 0.1200 this gives a rough luminosity upper limit of 4.5 * 10^42 erg/s. We clearly detect a source at the position of AT 2025wkm in UVOT observations. We use a synthetic galaxy model to produce subtracted magnitudes and correct for galactic extinction. We report in the UVW1 filter, a magnitude of m= 21.7 +/- 0.4 AB and in the UVM2 filter, a magnitude of m = 22.2 +/- 0.3. We thank the Swift team, Observatory Duty Scientists and the PI for promptly scheduling and making these observations possible. View this GCN Circular online at https://gcn.nasa.gov/circulars/41641. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0LW...