[vsnet-grb-info 26093] AX J1846.4-0258: Swift-BAT refined analysis

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  28193
SUBJECT: AX J1846.4-0258: Swift-BAT refined analysis
DATE:    20/08/02 19:00:05 GMT
FROM:    Amy Lien at GSFC  <amy.y.lien at nasa.gov>

S. Laha (GSFC/UMBC), S. D. Barthelmy (GSFC),
J. R. Cummings (CPI), H. A. Krimm (NSF),
A. Y. Lien (GSFC/UMBC), C. B. Markwardt (GSFC),
D. M. Palmer (LANL), T. Sakamoto (AGU),
M. Stamatikos (OSU), T. N. Ukwatta (LANL)
(i.e. the Swift-BAT team):

Using the data set from T-239 to T+722 sec from the recent telemetry
downlink, we report further analysis of the SGR-like burst from
AX J1846.4-0258/PSR J1846-0258 (trigger #985320)
(Krimm et al., GCN Circ. 28187).
The BAT ground-calculated position is
RA, Dec = 281.633, -3.006 deg which is
   RA(J2000)  =  18h 46m 32.0s
   Dec(J2000) = -03d 00' 20.9"
with an uncertainty of 2.0 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 100%.

The mask-weighted light curve shows a single pulse structure that
starts at ~T0, peaks at ~T+0.007 s, and ends at ~T+0.012.
T90 (15-350 keV) is 0.012 +- 0.006 sec (estimated error including
systematics). The source went out of the BAT field of view at ~T+130 s.

The time-averaged spectrum from T+0.00 to T+0.012 sec fit by a simple
power-law model shows the power law index of 3.05 +- 0.28
(chi squared 50.60 for 57 d.o.f.). The fluence in the 15-150 keV band
is 1.2 +- 0.2 x 10^-8 erg/cm2.

A single blackbody fit to the time-averaged spectrum shows the blackbody
temperature of 6.31 +- 0.99 keV (chi squared 39.29 for 57 d.o.f.).
A thermal bremsstrahlung model fit shows the temperature of
24.18 +- 6.24 keV (chi squared 40.51 for 57 d.o.f.).
All the quoted errors are at the 90% confidence level.

The results of the batgrbproduct analysis are available at
http://gcn.gsfc.nasa.gov/notices_s/985320/BA/