{
  "bibcode": "2022GCN.32754....1N",
  "body": "Michela Negro, Alberto Manfreda, Nicola Omodei and \nFabio Muleri report on behalf of the IXPE Collaboration \n\nIXPE performed the first observation of X-ray polarization of a \nGRB afterglow in the 2 ��� 8 keV energy range.\nIXPE observed GRB 221009A from 2022-10-11T23:34:28UTC to \n2022-10-14T00:45:31UTC  for an effective exposure of 100 ks. \n\nFrom a quick-look analysis of the *image-, time- and energy- averaged\nlow-level instrument data (prior to pipeline processing at the IXPE\nSOC), we report:\n\nPolarization degree (PD) < 11.1% upper limits are derived with 99% C.L.\n\nThese results are preliminary. The IXPE Collaboration will report \nthe final results in a forthcoming publication.\n\nThe Imaging X-ray Polarimetry Explorer, commonly known as IXPE \nis a space observatory with three identical telescopes designed \nto measure the polarization of cosmic X-rays. X-ray polarimetry \nenabled by IXPE can be performed in energy-, time-, and \nangle-resolved fashions. The observatory, which was launched \non 9 December 2021, is an international collaboration between \nNASA and the Italian Space Agency (ASI).\n\n[Editor's note: Reformatted at the request of the submitter.]",
  "circularId": 32754,
  "createdOn": 1665752320000,
  "email": "mnegro1@umbc.edu",
  "subject": "GRB 221009A: IXPE preliminary upper limits of X-ray polarization",
  "submitter": "Michela Negro at CRESST/NASA-GSFC/UMBC  <mnegro1@umbc.edu>",
  "eventId": "GRB 221009A"
}