[vsnet-grb-info 7418] GRB 090309, Swift-BAT lag analysis
GCN Circulars
gcncirc at capella.gsfc.nasa.gov
Fri Mar 13 18:58:24 JST 2009
TITLE: GCN CIRCULAR
NUMBER: 8982
SUBJECT: GRB 090309, Swift-BAT lag analysis
DATE: 09/03/13 09:58:16 GMT
FROM: Takanori Sakamoto at NASA/GSFC <takanori.sakamoto-1 at 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).
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