TITLE:   GCN CIRCULAR
NUMBER:  18760
SUBJECT: GRB 151229A Swift-BAT Spectral lag analysis
DATE:    15/12/29 23:11:56 GMT
FROM:    Scott Barthelmy at NASA/GSFC  <scott@lheamail.gsfc.nasa.gov>

J. Norris (BSU), S. D. Barthelmy (GSFC), A. Y. Lien (GSFC/UMBC) for the Swift-BAT Team:

We report the spectral lag analysis for GRB 151229A (Kocevski, et al.,
GCN Circ. 18745, & Lien 18751) based on the BAT data.  Using 8-ms binned light curve,
the spectral lag for the 25-50 keV to 100-300 keV bands is -47.6 +/-31 ms and
+12 +/-24 for the 15-25 to 50-100 bands.  Although the errors are large,
the values are marginally consistent with zero, therefore we believe
this burst belongs to a short burst category, although we can not rule out
the long burst possibility.  There is no evidence for extended emission.