Sheila McBreen (UCD/MPE) and Andreas von Kienlin (MPE)
report on behalf of the Fermi GBM Team:
"At 12:43:59.99 UT on 16 December 2008, the Fermi Gamma-Ray Burst Monitor
triggered and located GRB 081216 (trigger 251124240 / 081216531).
The on-ground calculated location, using the GBM trigger
data, is RA = 123.2, DEC = +13.7 (J2000 degrees,
equivalent to 08 h 13 m, +13 d 42'), with an uncertainty
of 7 degrees (radius, 1-sigma containment,
statistical only; there is additionally a systematic
error which is currently estimated to be 2 to 3 degrees).
The angle from the Fermi LAT boresight is 95 degrees.
This burst was also independently detected by
Suzaku-WAM, INTEGRAL-SPI-ACS, and Konus-Wind (Golenetskii et al., GCN 8677)
and the GBM localisation is consistent with the IPN localisation.
This short, hard burst consists of 2 pulses
with a duration (T90) of about 0.96 s (10-1000 keV). The second and
main pulse starts at T0+0.5 s and was detected by Golenetskii et al.
The time-averaged spectrum from T0-0.13 s to T0+0.83 s is
adequately fit by a Band function with Epeak = 1235 +/- 264 keV,
alpha = -0.70 +/-0.09, and beta = -2.17+/-0.21
(chi squared 358 for 356 d.o.f.).
The event fluence (10-1000 keV) in this time interval is
(3.6 +/- 0.1)E-06 erg/cm^2. The 32 ms peak photon flux measured from
T0+0.62 s in the 10-1000 keV band is 55 +/- 3 ph/s/cm^2.
The spectral analysis results presented above are preliminary;
final results will be published in the GBM GRB Catalog."