GCN Circular 12916
Subject
LS I +61 303: Swift-BAT refined analysis
Date
2012-02-05T20:17:30Z (13 years ago)
From
Scott Barthelmy at NASA/GSFC <scott@lheamail.gsfc.nasa.gov>
S. D. Barthelmy (GSFC), T. Sakamoto (GSFC/UMBC), D. M. Palmer (LANL),
W. H. Baumgartner (GSFC/UMBC), J. R. Cummings (GSFC/UMBC), E. E. Fenimore (LANL),
N. Gehrels (GSFC), H. A. Krimm (GSFC/USRA), C. B. Markwardt (GSFC),
G. Sato (ISAS), M. Stamatikos (OSU), J. Tueller (GSFC), T. N. Ukwatta (MSU)
(i.e. the Swift-BAT team):
Using the BAT data set from T-239 to T+963 sec from recent telemetry downlinks,
we report further analysis of the outburst from LS I +61 303 (trigger #513505)
(Burrows, et al., GCN Circ. 12914). The BAT ground-calculated position is
RA, Dec = 40.059, 61.235 deg, which is
RA(J2000) = 02h 40m 14.3s
Dec(J2000) = +61d 14' 05.9"
with an uncertainty of 2.8 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 76%.
The mask-weighted light curve shows a single, roughly symmetric pulse
starting at ~T+0.00 sec and ending at ~T+0.070 sec.
T90 (15-350 keV) is 0.040 +- 0.011 sec (estimated error including systematics).
The time-averaged spectrum from T+0.020 to T+0.064 sec is best fit by a blackbody
model. The blackbody temperature is 5.69 +- 1.22 keV. Chisq is 41.2 with 59 DoF.
The fluence in the 15-150 keV band is 8.0 +- 3.2 x 10^-9 erg/cm2. The 1-sec peak
photon flux measured from T-0.46 sec in the 15-150 keV band is 0.30 +- 0.19 ph/cm2/sec.
A simple power law fit yeilds an index of 3.92 +- 0.24 with a Chisq of 49.4 with
57 DoF. 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/513505/BA/