GLAST Tracker Calibration

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J.P. Norris, J.D. Scargle, J.T. Bonnell
Long Bursts Multi-? Afterglows,
Redshifts, Galaxies,
Star-Forming Regions (?)
Short Bursts Small Bump in the
Duration Distribution
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Abridged History of Short GRBs Discovery of
Sub-Class Mazets et al. 1979 Frequency ¼ of
total Norris et al. 1984 Harder
Spectra Kouveliotou et al. 1993 Selection
Effects ? More Shorts Petrosian Lee
1996 Distributions Npulse, Width, Norris et al.
1994, Intv explain 2-s minimum ? Wang 1996 Pulse
?r / ?d increases with time Gupta et al. 2000
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Max Lags ?longs 20 ? ?shorts
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Mode (Longs) 50 ms Mode
(Shorts) 0 ms
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Lag Distribution symmetric about lag 0.
Abswell determined lags lt 5 ms. Tail to
?25 ms
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Long bursts Lee, Bloom Petrosian 2000
lt Npulses (longs) gt Order of Magnitude .GT.
lt Npulses (shorts) gt
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Summary Conclusions

• Short Bursts are a different phenomenon
  (e.g., by Harwit criteria)
• Their lags are 1020 ? shorter than lags for
  Long Bursts.
• Their lag distribution appears close to
  symmetric, about zero.
• They have an order of magnitude fewer pulses
  than do Long Bursts.
• Shorts mode (250 ms) 100 ? shorter than
  Longs mode (25 s).
• Short Bursts temporal characteristics are not a
  continuation of Long Bursts The two classes
  appear to be disjoint.
• If the lag-luminosity relationship were
  extensible to Short Bursts, they
• would be as luminous and more than the
  most luminous Long Bursts.
• Short bursts, by their nature, are a difficult
  study
• They appear to be the only remaining high-energy
  astrophysical
• phenomenon with no Rosetta Stone.