[AAVSO-HEN] GRB 070612A: spectral lag

[grb at aavso.org]

The following is a GCN Circular circulated via the AAVSO network.
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TITLE:   GCN CIRCULAR
NUMBER:  6529
SUBJECT: GRB 070612A:  spectral lag
DATE:    07/06/13 19:28:21 GMT
FROM:    Jay Norris at Stanford U  <jpnorris at stanford.edu>

J.P. Norris (U.Denver), S.D. Barthelmy (GSFC), N. Gehrels (GSFC):

Spectral lag analysis of the two main emission episodes in GRB 070612A,
described in GCN Circ. 6522 (Barthelmy et al.) indicate that this burst
has relatively long lags, comparable to and longer than that of GRB 980425
(~ 2-3 s), the first burst associated with a supernova.

For the first, brighter FRED-like pulse structure, the lag measurement
between BAT energy bands 15-25 keV and 50-100 keV (25-50 and 100-350 keV)
is 2.5 s +2.1-1.8 s (2.5 +0.7-0.5 s).

For the second, dimmer pulse structure, the 15-25 keV to 50-100 keV
lag is 5.8 s +2.6-1.9 s.  The flux in the 100-350 keV band for this
second episode was too low to make a useful measurement.

Spectral lags of several seconds indicate a relatively low luminosity
burst, consistent with the nearby host (z ~ 0.1) described in GCN Circ.
6525 (Cenko et al.).