GRB 120229A

V. Mangano (INAF-IASFPA), S. D. Barthelmy (GSFC),
A. P. Beardmore (U Leicester), D. N. Burrows (PSU),
S. Campana (INAF-OAB), J. R. Cummings (NASA/UMBC), V. D'Elia (ASDC),
P. A. Evans (U Leicester), N. Gehrels (NASA/GSFC), B. Gendre (ASDC),
C. Guidorzi (U Ferrara), S. T. Holland (STScI), J. A. Kennea (PSU),
A. Y. Lien (NASA/GSFC/ORAU), O. M. Littlejohns (U Leicester),
F. E. Marshall (NASA/GSFC), A. Maselli (INAF-IASFPA),
A. Melandri (INAF-OAB), P. T. O\'Brien (U Leicester),
K. L. Page (U Leicester), D. M. Palmer (LANL),
P. Romano (INAF-IASFPA), B. Sbarufatti (INAF-OAB/PSU),
C. A. Swenson (PSU), G. Tagliaferri (INAF-OAB) and B.-B. Zhang (PSU)
report on behalf of the Swift Team:

At 14:35:11 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 120229A (trigger=516571).  Swift could not slew to the burst
due to a sun constraint. 
The BAT on-board calculated location is 
RA, Dec 20.035, -35.807 which is 
   RA(J2000) = 01h 20m 08s
   Dec(J2000) = -35d 48' 26"
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty).  The BAT light curve showed a single short peak
structure with a duration of about 0.5 sec.  The peak count rate
was ~3000 counts/sec (15-350 keV), at ~0 sec after the trigger. 

Due to a Sun observing constraint, Swift cannot slew to the BAT
position until 19:46 UT on 2012 April 17. There will thus be no XRT or
UVOT data for this trigger before this time. 

We note that this location is 5 arc minutes from the relatively
nearby (z=0.03) galaxy 6dFGSgJ012000.6-355307 . 

Burst Advocate for this burst is V. Mangano (vanessa AT ifc.inaf.it). 
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.)

C. B. Markwardt (GSFC), S. D. Barthelmy (GSFC), W. H. Baumgartner (GSFC/UMBC),
J. R. Cummings (GSFC/UMBC), E. E. Fenimore (LANL), N. Gehrels (GSFC),
H. A. Krimm (GSFC/USRA), V. Mangano (INAF-IASFPA), D. M. Palmer (LANL),
T. Sakamoto (GSFC/UMBC), G. Sato (ISAS), M. Stamatikos (OSU), J. Tueller (GSFC),
T. N. Ukwatta (MSU)
(i.e. the Swift-BAT team):

Using the data set from T-60 to T+243 sec from the recent telemetry downlink,
we report further analysis of BAT GRB 120229A (trigger #516571)
(Mangano, et al., GCN Circ. 12997
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 ).  The BAT ground-calculated position is
RA, Dec = 20.033, -35.796 deg which is
    RA(J2000)  =  01h 20m 07.9s
    Dec(J2000) = -35d 47' 44.0"
with an uncertainty of 1.9 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 85%.

The mask-weighted light curve shows two peaks, the first about 0.08 seconds
long peaking at T+0.03 and the second about 0.14 seconds long peaking at
T+0.21 seconds.  T90 (15-350 keV) is 0.22 +- 0.03 sec (estimated error
including systematics).

The time-averaged spectrum from T+0.01 to T+0.27 sec is best fit by a simple
power-law model.  The power law index of the time-averaged spectrum is
1.29 +- 0.24.  The fluence in the 15-150 keV band is 4.1 +- 0.7 x 10^-08 erg/cm2.
The 1-sec peak photon flux measured from T-0.36 sec in the 15-150 keV band
is 0.5 +- 0.1 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/516571/BA/

J. Norris (BSU), S.D. Barthelmy (GSFC) for the BAT Team:

We report the spectral lag analysis for GRB 120229A (GCN Circ. 12997
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 )
based on the BAT data.  Using 4-ms binned light curves, the spectral lag
for the 15-25 keV to 50-100 keV bands is 0.8 +-8 msec, and 3.6 +5/-7 msec
for the 25-50 keV to 100-350 keV bands for both peaks combined.
These lag values place this burst in the short burst category.

W. Fong, E. Berger, N. Sanders (Harvard), K. Cooksey, A. Zangari (MIT) and
N. Morrell (LCO) report:

"We observed the location of the short-duration GRB 120229A (GCN 12997
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 )
with the Low Dispersion Survey Spectrograph 3 (LDSS3) mounted on the
Magellan/Clay 6.5-meter telescope. We obtained 3x180-sec
r-band observations on 2012 March 01.01 UT (9.6 hours post-burst) at
high airmass in mediocre seeing conditions (1.3"). To check for the
presence of a fading optical source, we re-observed the field (6x180-sec)
on 2012 March 02.01 UT (33.6 hours post-burst and 24.0 hours after
the first observations) at similar airmass. Digital image subtraction
of the two epochs using the ISIS software package reveals no
residuals within the BAT-refined position (GCN 12998
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 ). Therefore,
calculating the zeropoint from a standard star field at similar
airmass based on several stars, we place a 3-sigma limit of r>22.4 mag on
the optical afterglow of GRB 120229A at 9.6 hours after the burst."