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GBM Team DC2 Effort

GBM Team DC2 Effort . Charles Meegan Giselher Lichti Narayana Bhat Michael Briggs Valerie Connaughton Roland Diehl Gerald Fishman Jochen Greiner R. Marc Kippen Andreas von Kienlin Chryssa Kouveliotou William Paciesas Robert Preece Helmut Steinle Robert Wilson

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GBM Team DC2 Effort

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  1. GBM Team DC2 Effort Charles Meegan Giselher Lichti Narayana Bhat Michael Briggs Valerie Connaughton Roland Diehl Gerald Fishman Jochen Greiner R. Marc Kippen Andreas von Kienlin Chryssa Kouveliotou William Paciesas Robert Preece Helmut Steinle Robert Wilson Colleen Wilson-Hodge Modeling: Nicola Omedei Francesco Longo Jay Norris Felix Ryde Simulations: Nicola Omodei David Band Analysis: Nicola Omodei Johann Cohen-Tanugi

  2. GLAST Burst Monitor 12 NaI Detectors 0.5 x 5in 8 keV – 1 MeV 2 BGO Detectors 5 x 5in 150 keV – 30 MeV

  3. GBM Triggering • 2 NaI detectors > 4.5 sigma above background 50—300 keV, various timescales. • Expect >200 triggered GRB’s per year. • In DC2 we have 64 GRB’s in 55 days! We apply a fluence threshold to avoid those that would not have triggered GBM.

  4. GBM Trigger Threshold

  5. LAT GRBs per year

  6. Data Types • Continuous: CTIME (0.256 sec, 8 channels) and CSPEC ( 8.192 sec, 128 channels). In flight, temporal resolution increased on triggering. • Triggered: TTE photon lists (2 microsec, 128 channels) for 300 sec after trigger + 500k buffered pre-trigger events. • Triggered: TRIGDAT. Immediate and calculated information (location, intensity, backgrounds, Maximum detector rates). • Housekeeping + Diagnostic.

  7. Burst Localization • Use relative rates in detectors of different orientations. • On board: 15 degrees accuracy using table and comparing rates expected for zenith pointing and “average” spectrum. Enough for LAT repoint. • On ground: 3 degrees using grid search. Immediate (automated) + Refined. • Statistical (intensity-dependent) and systematic errors. • In DC2: move true location after generating data… as if we had a ground location. Incorporate both statistical and systematic error.

  8. GBM On-Board localization For bright bursts error will Be dominated by systematics: Burst spectrum, S/C elevation.

  9. GRB characteristic distributions Typical GRB spectrum characterized at BATSE energies by the Band parameterization α, β, A, Epeak or some similar function where the physical meaning of these parameters is not specified.

  10. GRB Durations In DC2: No measure of duration given, just the trigger time (Warning!).

  11. GBM Intensities In Flight and In DC2: Calculated Information will be Standard Intensity which is the source-angle adjusted sum of peak 50—300 keV Counts in brightest 2 NaI detectors expressed as Rates.

  12. DC2 GBM Data Generation • IDL programs read spectral parameters at 16 ms resolution output from GLEAM. • Calculate response to burst at this location. Proceed only with viewable detectors. • Generate counts in each detector. • Superimpose on typical background file. • Many approximations !!! • Calculate peak intensity, statistical burst location error, and move true location accordingly. • Write data files -- as close as possible to Level 1 Data Products defined in ICD (but no TRIGDAT).

  13. DC2 Data Products 1 each per viewable detector per burst: • CSPEC: GLG_CSPEC_N6_BN050718002_V01.FIT • CTIME: GLG_CTIME_N6_BN050718002_V01.FIT • TTE: GLG_TTE_N6_BN050718002_V01.FIT • Background: GLG_BCK_N6_BN050718002_V01.BAK • Response: GLG_CSPEC_N6_BN050718002_V01.RSP 1 each per viewable detector per day: • Daily CTIME: GLG_CTIME_N6_050718_V01.FIT • Daily CSPEC : GLG_CSPEC_N6_050718_V01.FIT 1 per burst: • Notice to replace TRIGDAT in DC2: GLG_NOTICE_050718002.TXT. Notice is an ascii file giving TJD, trigger time, burst location, 1 sigma statistical error in burst location, standard intensity (flux), 2 closest NaI detectors, closest BGO detector.

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