{
  "format": "text/plain",
  "submittedHow": "web",
  "subject": "GRB 260721A: NuSTAR detection of prompt emission",
  "submitter": "Brian Grefenstette at Caltech/NuSTAR <bwgref@srl.caltech.edu>",
  "eventId": "GRB 260721A",
  "createdOn": 1784651791392,
  "body": "B. Grefenstette (Caltech) and G. Waratkar (Caltech) report on behalf of the NuSTAR Search for INteresting Gamma-ray Signals (SINGS) working group:\n\nThe NuSTAR SINGS working group reports the detection of prompt emission from the long-duration GRB 260721A in both the NuSTAR CsI anti-coincidence shields. Details of the search algorithm will be described in a future paper.\n\nThe NuSTAR SINGS algorithm, triggered at 2026-07-21 01:17:08 UTC, shows a detection of GRB 260721A, also detected by Konus-Wind (Svinkin, priv. Comm & GCN notices). \n\nThe NuSTAR CsI shield data are recorded at 1 Hz. We detect a burst lasting for about 10-s. Offline analysis indicates that the burst first appeared in the NuSTAR data 6 to 7-s prior to the trigger time (with a non-barycenter corrected, offline T0 of roughly 2026-07-21T01:17:02). The peak count rate is ~2000-cps with a baseline rate of ~1000-cps during this time period. We do not see any evidence in the signal above 100 keV in the CZT detectors.\n\nLightcurves and analysis for this GRB can be found here:\nhttps://nustarsoc.caltech.edu/NuSTAR_Public/grbs/reports/2026/260721A/\n\nInformation on NuSTAR SINGS can be found here: \nhttps://nustarsoc.caltech.edu/NuSTAR_Public/grbs/     \n\nNuSTAR is a NASA Small Explorer mission led by Caltech and managed by JPL for NASA's Science Mission Directorate in Washington.\n",
  "circularId": 45192
}