{
  "bibcode": "2025GCN.41585....1S",
  "circularId": 41585,
  "format": "text/plain",
  "subject": "EP250827a: Swift/UVOT Detection",
  "submitter": "Mike Siegel at PSU/Swift MOC <mhs18@psu.edu>",
  "submittedHow": "web",
  "createdOn": 1756441101049,
  "eventId": "EP250827a",
  "body": "M. H. Siegel (PSU) reports on behalf of the Swift/UVOT team:\n\nThe Swift/UVOT began settled observations of the field of EP250827a 3.2 ks after the EP trigger (Hua et al., GCN Circ. 41553). An uncatalogued source consistent with the XRT position (Evans et al., GCN Circ. 41563) and the optical transient (Levan et al., GCN Circ. 41554; Li et al., GCN Circ. 41555; Lipunov et al., GCN Circ. 41558; Gritsevich et al., GCN Circ. 41559; An et al., GCN Circ. 41560; Ghosh et al., GCN Circ. 41564; O'Neill et al., GCN Circ. 41567) is detected in the UVOT exposures.\n\nThe preliminary UVOT position is:\n    RA  (J2000) =  00:13:52.24 =   3.46767 (deg.)\n    Dec (J2000) = -56:29:52.2  = -56.49784 (deg.) \nwith an estimated uncertainty of 0.42 arc sec. (radius, 90% confidence).\n\nPreliminary detections and 3-sigma upper limits using the UVOT photometric system\n(Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for the early exposures are: \n\nFilter         T_start(s)   T_stop(s)      Exp(s)           Mag\n\nu                 3192         9257         1566      18.29+/-0.04\nu                54232        60071          939      19.69+/-0.19\nu               121367       127685          754            >20.36\nuvw1             53286        59775         1903      19.86+/-0.13\nuvw1            120301       127006         2040            >21.21\n\nThe magnitudes in the table are not corrected for the Galactic extinction\ndue to the reddening of E(B-V) = 0.011 in the direction of the burst\n(Schlegel et al. 1998)"
}