{
  "body": "B. Grefenstette (Caltech) reports 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 GRB 250516B in both the NuSTAR CsI anti-coincidence shields and in the CdZnTe detectors. This GRB was identified through a blind search using the CsI shield rates. Details of the search algorithm will be described in a future paper.\n\nThe NuSTAR SINGS algorithm triggered at 2025-05-16 06:31:39 with a resolution ~5-seconds. This is consistent with the GECAM-B reported time of 2025-05-16T06:31:34.7 (Wang et al., GCN circ. 40469). \n\nThe GRB is a broad burst with multiples peaks. The brightest has a peak count rates in the anti-coincidence shields near 4,000 cps over a baseline of ~1,000 cps. The burst is also clearly seen in the CdZnTe detectors.\n\nDiscovery report and a preliminary lightcurves for this GRB can be found here:\n\nhttps://nustarsoc.caltech.edu/NuSTAR_Public/grbs/reports/2025/250516B/\n\nInformation on NuSTAR SINGS can be found here: \n\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",
  "submittedHow": "web",
  "createdOn": 1747508894846,
  "circularId": 40484,
  "eventId": "GRB 250516B",
  "format": "text/plain",
  "subject": "GRB 250516B: NuSTAR Detection of the Prompt Emission",
  "bibcode": "2025GCN.40484....1G",
  "submitter": "Brian Grefenstette at Caltech/NuSTAR <bwgref@srl.caltech.edu>"
}