{
  "bibcode": "2008GCN..8685....1L",
  "body": "W. Landsman (GSFC), P. Kuin (MSSL), F. Marshall (GSFC), M. Page (MSSL), \nP. Roming (PSU), N. Gehrels (GSFC) report on behalf of the Swift/UVOT team\n\nThe Swift/UVOT has modified its automated response to GRBs with a BAT \ntrigger rate larger than 100 cps.   For these bright GRBs, a 50s UV \ngrism exposure is now inserted following the first 150s finding chart in \nthe white filter.      Roughly half of all Swift GRBs are sufficiently \nbright to trigger the use of the grism.\n\nThe UVOT grism covers the spectral range 1700 - 5500 A, and  can provide \nuseful spectra for GRBs brighter than about V~13.     Further details \nare available in Kuin et al. (2008, astro-ph 0812/2943 ) who report \ntheir analysis of the UVOT grism spectrum of GRB081203A.\n\nThe grism zero-order spectrum in the 50s exposure can provide photometry \nfor sources brighter than B-18.    The zero-order spectrum includes \nvisible light and its brightness roughly  correlates with Johnson B \nmagnitude, with a scatter of about 0.23 mag.",
  "circularId": 8685,
  "createdOn": 1229721047000,
  "email": "wayne.b.landsman@nasa.gov",
  "subject": "Modification of Swift/UVOT response to bright GRBs",
  "submitter": "Wayne Landsman at GSFC/SSAI  <wayne.b.landsman@nasa.gov>"
}