GCN Circular 8982
Subject
GRB 090309, Swift-BAT lag analysis
Event
Date
2009-03-13T09:58:16Z (17 years ago)
From
Takanori Sakamoto at NASA/GSFC <takanori.sakamoto-1@nasa.gov>
T. Sakamoto (GSFC/UMBC), J. P. Norris, T. N. Ukwatta (GWU/GSFC),
S. D. Barthelmy (GSFC), N. Gehrels (GSFC), M. Stamatikos (GSFC/ORAU)
(for the Swift-BAT team):
For GRB 090309 (Evans et al. GCN Circ. 8964), we are unable to determine
if this is a short or long burst. The reasons are as follows: (1) the
spectral lag is 0.044 +/- 0.16 sec (between the 50-100 and 15-25 keV).
(2) The T90 duration is 3.0 +- 1.4 sec (Palmer et al. GCN Circ. 8967)
which is midway between the two T90 distributions. (3) The photon index
is 1.36 +/- 0.33 (Palmer et al. GCN Circ. 8967) is also in the middle of
the short and hard distributions (Figure 13 of Sakamoto et al., ApJS, 175, 179).