{
  "bibcode": "2020GCN.27356....1G",
  "body": "Adam Goldstein (USRA), Aaron Tohuvavohu (U Toronto), Jimmy DeLaunay (Penn\nState), and Jamie Kennea (Penn State) report on behalf of Fermi/GBM and\nSwift/BAT:\n\n\n\nThe Fermi/GBM Flight-Position notice, distributed at T0+7 seconds, from the\nFermi/GBM detected GRB 200307A (GCN. 27344) triggered the  Swift Mission\nOperations Center operated Gamma-ray Urgent Archiver for Novel\nOpportunities (GUANO; Tohuvavohu et al. 2020, in prep). Upon trigger by the\nFermi notice, GUANO sent a command to the Swift Burst Alert Telescope (BAT)\nto save 200 seconds of BAT event-mode data from [-50,+150] seconds around\nthe time of GRB 200307A. All the requested event mode data was delivered to\nthe ground.\n\n\n\nIn a ground analysis of the event data, we detect GRB 200307A, determine\nthe signal in BAT is of astrophysical origin, and can confidently rule out\nan origin from inside the contemporaneous BAT field-of-view. At T0, the\nEarth's position and size relative to Swift were:\n\n\n\nEarth RA: 30.0439\n\nEarth Dec: 5.2549\n\nEarth Radius: 67.139 deg\n\n\n\nThe Earth, with respect to Swift, occulted over 60% of the Fermi/GBM\nlocalization region and can be ruled out for the GRB localization.\n\n\n\nFermi GBM provides an updated map by removing the Earth-occulted regions\nand can be found at the following links:\n\n\n\nSkymap image:\nhttps://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2020/bn200307894/quicklook/glg_skymap_all_bn200307894.png\n\n\n\nHEALPix:\nhttps://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2020/bn200307894/quicklook/glg_healpix_all_bn200307894.fit\n\n\n\nThe 50% confidence region has decreased from 885 square degrees to 290\nsquare degrees and the 90% confidence region has decreased from 2784 square\ndegrees to 978 square degrees.",
  "circularId": 27356,
  "createdOn": 1583870773000,
  "email": "adam.michael.goldstein@gmail.com",
  "subject": "GRB 200307A: Updated localization from Fermi/GBM and Swift/BAT-GUANO",
  "submitter": "Adam Goldstein at Fermi-GBM, USRA  <adam.michael.goldstein@gmail.com>",
  "eventId": "GRB 200307A"
}