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GRB 120218A

GCN Circular 12962

Subject

GRB 120218A: Swift detection of a burst

Date

2012-02-18T00:59:33Z (13 years ago)

From

Scott Barthelmy at NASA/GSFC <scott@milkyway.gsfc.nasa.gov>

C. A. Wolf (PSU), S. D. Barthelmy (GSFC),
W. H. Baumgartner (GSFC/UMBC), N. Gehrels (NASA/GSFC),
J. A. Kennea (PSU), C. B. Markwardt (NASA/GSFC), D. M. Palmer (LANL),
C. J. Saxton (UCL-MSSL), B. Sbarufatti (INAF-OAB/PSU),
C. A. Swenson (PSU), T. N. Ukwatta (MSU) and B.-B. Zhang (PSU) report
on behalf of the Swift Team:

At 00:49:22 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 120218A (trigger=515277).  Swift did not slew due to a 
Sun constraint. The BAT on-board calculated location is 
RA, Dec 319.758, -25.450, which is 
   RA(J2000) = 21h 19m 02s
   Dec(J2000) = -25d 27' 00"
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty).  The BAT light curve showed a multi-peaked
structure with a duration of about 30 sec.  The peak count rate
was ~3500 counts/sec (15-350 keV), at ~2 sec after the trigger. 

Due to a Sun observing constraint, Swift cannot slew to the BAT
position until 19:14 UT on 2012 March 20. There will thus be no XRT or
UVOT data for this trigger before this time. 

Burst Advocate for this burst is C. A. Wolf (cwolf AT swift.psu.edu). 
Please contact the BA by email if you require additional information
regarding Swift followup of this burst. In extremely urgent cases, after
trying the Burst Advocate, you can contact the Swift PI by phone (see
Swift TOO web site for information: http://www.swift.psu.edu/too.html.)

GCN Circular 12963

Subject

GRB 120218A: Swift-BAT refined analysis

Date

2012-02-18T14:51:35Z (13 years ago)

From

Scott Barthelmy at NASA/GSFC <scott@lheamail.gsfc.nasa.gov>

S. D. Barthelmy (GSFC), T. Sakamoto (GSFC/UMBC), 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), D. M. Palmer (LANL),
G. Sato (ISAS), M. Stamatikos (OSU), J. Tueller (GSFC),
T. N. Ukwatta (MSU), C. A. Wolf (PSU)
(i.e. the Swift-BAT team):
 
Using the data set from T-239 to T+303 sec from recent telemetry downlinks,
we report further analysis of BAT GRB 120218A (trigger #515277)
(Wolf, et al., GCN Circ. 12962Loading...
 
 ).  The BAT ground-calculated position is
RA, Dec = 319.7641, -25.4626 deg which is
   RA(J2000)  =  21h 19m 03.4s
   Dec(J2000) = -25d 27' 45.4"
with an uncertainty of 1.9 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 4%.

The mask-weighted light curve shows 3 or 4 overlapping peaks starting
at ~T-28 sec, with the highest peak is at ~T+3 sec, and ending at ~T+15 sec.
T90 (15-350 keV) is 27.5 +- 1.0 sec (estimated error including systematics).
 
The time-averaged spectrum from T-20.6 to T+8.9 sec is best fit by a simple
power-law model.  The power law index of the time-averaged spectrum is
1.75 +- 0.11.  The fluence in the 15-150 keV band is 5.3 +- 0.4 x 10^-6 erg/cm2.
The 1-sec peak photon flux measured from T+2.33 sec in the 15-150 keV band
is 9.1 +- 1.2 ph/cm2/sec.  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/515277/BA/