{
  "eventId": "EP260321a",
  "submitter": "Brendan O'Connor at Carnegie Mellon University <boconno2@andrew.cmu.edu>",
  "body": "Brendan O'Connor (CMU) and Eleonora Troja (U Rome) on behalf of a larger collaboration:\n\nWe observed the position of EP260321a (Huang et al., GCN 44068) with the Chandra X-ray Observatory (CXO) under GO program 27400339 (PI: O'Connor). Observations were carried out with ACIS-S starting on 2026-04-05 at 22:00 UT, corresponding to ~15.4 d after the EP trigger, for a total of 19.81 ks. We do not detect any coincident X-ray source at this time. With the exception of GW170817, this observation is capable of excluding all known GRB X-ray afterglows from the Swift era, including GRB 060218 which is also located at ~150 Mpc. \n\nFurther observations are planned.\n\nWe thank the staff of the Chandra X-ray Observatory, including Pat Slane, Dan Schwartz, Jack Steiner, and Vinay Kashyap, for rapidly scheduling these observations. ",
  "createdOn": 1775772666550,
  "bibcode": "2026GCN.44250....1O",
  "submittedHow": "web",
  "circularId": 44250,
  "subject": "EP260321a: Chandra X-ray Non-detection",
  "format": "text/markdown"
}