GRB 120328A

C. Pagani (U Leicester), W. H. Baumgartner (GSFC/UMBC),
N. Gehrels (NASA/GSFC), E. A. Hoversten (PSU),
A. Y. Lien (NASA/GSFC/ORAU), O. M. Littlejohns (U Leicester),
F. E. Marshall (NASA/GSFC), C. J. Mountford (U Leicester),
K. L. Page (U Leicester), D. M. Palmer (LANL),
B. Sbarufatti (INAF-OAB/PSU), M. Stamatikos (OSU/NASA/GSFC),
C. A. Swenson (PSU), T. N. Ukwatta (MSU) and B.-B. Zhang (PSU) report
on behalf of the Swift Team:

At 03:06:19 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 120328A (trigger=518792).  Swift slewed immediately to the burst. 
The BAT on-board calculated location is 
RA, Dec 241.550, -39.340 which is 
   RA(J2000) = 16h 06m 12s
   Dec(J2000) = -39d 20' 24"
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty).  The BAT light curve showed a complex
structure with broad peak preceding a shorter spike for a 
total duration of about 20 sec.  The peak count rate
was ~1500 counts/sec (15-350 keV), at ~1 sec after the trigger. 

The XRT began observing the field at 03:07:27.2 UT, 68.2 seconds after
the BAT trigger. Using promptly downlinked data we find a bright,
fading, uncatalogued X-ray source located at RA, Dec 241.61294,
-39.33664 which is equivalent to:
   RA(J2000)  = 16h 06m 27.11s
   Dec(J2000) = -39d 20' 11.9"
with an uncertainty of 3.9 arcseconds (radius, 90% containment). This
location is 175 arcseconds from the BAT onboard position, within the
BAT error circle. This position may be improved as more data are
received; the latest position is available at
http://www.swift.ac.uk/sper. 

A power-law fit to a spectrum formed from promptly downlinked event
data gives a column density in excess of the Galactic value (1.61 x
10^21 cm^-2, Kalberla et al. 2005), with an excess column of 1.5
(+0.62/-0.52) x 10^22 cm^-2 (90% confidence). 

The initial flux in the 2.5 s image was 1.53e-09 erg cm^-2 s^-1 (0.2-10
keV). 

UVOT took a finding chart exposure of 150 seconds with the White filter
starting 78 seconds after the BAT trigger. No credible afterglow candidate has
been found in the initial data products. The 2.7'x2.7' sub-image covers 100% of
the XRT error circle. The typical 3-sigma upper limit has been about 19.6 mag. 
The 8'x8' region for the list of sources generated on-board covers 100% of the
XRT error circle. The list of sources is typically complete to about 18 mag. No
correction has been made for the expected extinction corresponding to E(B-V) of
0.73. 

Burst Advocate for this burst is C. Pagani (cp232 AT star.le.ac.uk). 
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.)

J. Haislip, A. LaCluyze, K. Ivarsen, D. Reichart, J. Moore, H. T. 
Cromartie, R. Egger, A. Foster, N. Frank, M. Nysewander, A. Oza, E. 
Speckhard, A.Trotter, and J. A. Crain report:

Skynet observed the field of GRB120328A (Pagani et al., GCN 13147
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 , Swift 
trigger #518792) with the PROMPT telescopes located at CTIO in Chile 
beginning 4.1 minutes after the burst. We do not detect any uncatalogued 
sources in our earliest images (mean time 4.43 minutes after the burst) 
down to 3-sigma limiting magnitudes of V=17.92, R=18.73, I=18.15. 
Stacking all data taken up to 17.2 minutes after the burst yields 3-sigma 
limiting magnitudes of B=19.19, V=19.75, R=20.26, I=19.38. Limits were 
calibrated to nearby USNO-B1.0 stars for B,R,I, and nearby NOMAD stars for 
V.

Klotz A. (IRAP-CNRS-OMP), Gendre B. (ASDC/INAF-OAR),
Boer M. (UNS-CNRS-OCA), Atteia J.L. (IRAP-CNRS-OMP) report:

We imaged the field of GRB 120328A detected by SWIFT
(trigger 518792) with the TAROT robotic telescope (D=25cm)
located at the European Southern Observatory,
La Silla observatory, Chile.

The observations started 345.7s after the GRB trigger.
The elevation of the field increased from
26 degrees above horizon and weather conditions
were good.

Images are unfiltered. We do not detect any OT with
a limiting magnitude of:

t0+345.7s to t0+405.7s : R > 18.5

Magnitudes were estimated with the nearby NOMAD1 stars
and are not corrected for galactic dust extinction.

N.B. Galactic coordinates are lon=339.0212 lat= +9.5155
and the galactic extinction in R band is ~2 magnitudes
estimated from D. Schlegel et al. 1998ApJ...500..525S.

A.P. Beardmore, P.A. Evans, M.R. Goad and J.P. Osborne (U. Leicester) 
report on behalf of the Swift-XRT team.

Using 763 s of XRT Photon Counting mode data and 1 UVOT
images for GRB 120328A, we find an astrometrically corrected X-ray
position (using the XRT-UVOT alignment and matching UVOT field sources
to the USNO-B1 catalogue): RA, Dec = 241.61376, -39.33565 which is equivalent
to:

RA (J2000): 16h 06m 27.30s
Dec (J2000): -39d 20' 08.3"

with an uncertainty of 1.9 arcsec (radius, 90% confidence).

This position may be improved as more data are received. The latest
position can be viewed at http://www.swift.ac.uk/xrt_positions. Position
enhancement is described by Goad et al. (2007, A&A, 476, 1401) and Evans
et al. (2009, MNRAS, 397, 1177).

This circular was automatically generated, and is an official product of the
Swift-XRT team.

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), C. Pagani (U Leicester), 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-239 to T+963 sec from recent telemetry downlinks,
we report further analysis of BAT GRB 120328A (trigger #518792)
(Pagani, et al., GCN Circ. 13147
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 ).  The BAT ground-calculated position is
RA, Dec = 241.607, -39.322 deg, which is 
   RA(J2000)  =  16h 06m 25.8s 
   Dec(J2000) = -39d 19' 20.8" 
with an uncertainty of 1.8 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 100%.
 
The mask-weighted light curve shows two overlapping peaks.  The first starts
at ~T-20 sec, peaks at ~T+0; the second peaks at ~T+8 sec and ends at ~T+20 sec.
T90 (15-350 keV) is 24.2 +- 6.7 sec (estimated error including systematics).
 
The time-averaged spectrum from T-17.27 to T+20.61 sec is best fit by a simple
power-law model.  The power law index of the time-averaged spectrum is
1.87 +- 0.20.  The fluence in the 15-150 keV band is 4.7 +- 0.6 x 10^-7 erg/cm2.
The 1-sec peak photon flux measured from T+0.11 sec in the 15-150 keV band
is 0.7 +- 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/518792/BA/

D.N. Burrows (PSU), A.P. Beardmore (U. Leicester), P.A. Evans (U.
Leicester), V. D'Elia (ASDC), A. Maselli  (INAF-IASFPA), V. Mangano
(INAF-IASFPA), J.A. Kennea (PSU), M.C. Stroh (PSU) and C. Pagani report
on behalf of the Swift-XRT team:

We have analysed 9.0 ks of XRT data for GRB 120328A (Pagani  et al. GCN
Circ. 13147
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 ), from 62 s to 34.2 ks after the  BAT trigger. The data
comprise 139 s in Windowed Timing (WT) mode (the first 5 s were taken
while Swift was slewing) with the remainder in Photon Counting (PC)
mode. The enhanced XRT position for this burst was given by Beardmore
et al. (GCN. Circ 13153).

The late-time light curve (from T0+4.1 ks) can be modelled with  a
power-law decay with a decay index of alpha=0.98 (+0.22, -0.20).

A spectrum formed from the WT mode data can be fitted with an absorbed
power-law with a photon spectral index	of 2.5 (+0.4, -0.3). The
best-fitting absorption column is  1.5 (+0.4, -0.3) x 10^22 cm^-2, in
excess of the Galactic value of 1.6 x 10^21 cm^-2 (Kalberla et al.
2005). The PC mode spectrum has a photon index of 3.0 (+0.5, -0.4) and
a best-fitting absorption column of 1.9 (+0.5, -0.4) x 10^22 cm^-2. The
counts to observed (unabsorbed) 0.3-10 keV flux conversion factor
deduced from this spectrum  is 4.7 x 10^-11 (3.9 x 10^-10) erg cm^-2
count^-1. 

A summary of the PC-mode spectrum is thus:
Total column:	     1.9 (+0.5, -0.4) x 10^22 cm^-2
Galactic foreground: 1.6 x 10^21 cm^-2
Excess significance: 6.9 sigma
Photon index:	     3.0 (+0.5, -0.4)

The results of the XRT-team automatic analysis are available at
http://www.swift.ac.uk/xrt_products/00518792.

This circular is an official product of the Swift-XRT team.

E. A. Hoversten (PSU) and C. Pagani (U. Leicester)
report on behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 120328A
78 s after the BAT trigger (Pagani et al., GCN Circ. 13147
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 ).  No optical
afterglow consistent with the enhanced XRT position (Beardmore el al.,
GCN Circ. 13153
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 ) is detected in the initial UVOT exposures.  Preliminary
3-sigma upper limits using the UVOT photometric system (Breeveld et al.
2011, AIP Conf. Proc. 1358, 373) for the first finding chart (FC)  
exposure
and subsequent exposures are:

Filter         T_start(s)   T_stop(s)      Exp(s)         Mag

white_FC            78          228          147         >20.6
u_FC               290          540          246         >19.6
white               78          764          186         >20.5
v                  621          813           39         >18.2
b                  547          739           39         >19.1
u                  290          715          265         >19.8
w1                 670          862           39         >18.9
w2                 769          789           20         >18.6

The magnitudes in the table are not corrected for the Galactic  
extinction
due to the reddening of E(B-V) = 0.73 in the direction of the burst
(Schlegel et al. 1998).

D. Kuroda (OAO, NAOJ),  H. Hanayama, T. Miyaji, J. Watanabe (IAO, NAOJ),
K. Yanagisawa (OAO, NAOJ), S.Nagayama (NAOJ), M. Yoshida (Hiroshima),
K. Ohta (Kyoto) and N. Kawai(Tokyo Tech)
report on behalf of the MITSuME collaboration:

We observed the field of GRB 120328A (Pagani et al., GCNC 13147)
with the optical three color (g', Rc and Ic) CCD camera attached
to the Murikabushi 1m telescope of Ishigakijima Astronomical
Observatory.

The observation started on 2012-03-28 18:34:18 UT (~15.5 h after the
burst). We did not find any new point source within the enhanced XRT error
circle (Beardmore et al., GCNC 13153) in all the three bands.

Three sigma upper limits of the OT are listed below. We used GSC2.3
catalog for flux calibration.

#T0+[day]  MID-UT    T-EXP[sec]   g'     Rc    Ic
----------------------------------------------------------------------
0.68772    19:36:38   4800.0    >20.1  >20.4  >19.3
----------------------------------------------------------------------
T0+ : Elapsed time after the burst [day]
T-EXP: Total Exposure time [sec]