GRB 120305A

G. Stratta (ASDC), S. D. Barthelmy (GSFC),
W. H. Baumgartner (GSFC/UMBC), D. N. Burrows (PSU),
J. R. Cummings (NASA/UMBC), N. Gehrels (NASA/GSFC), B. Gendre (ASDC),
C. Guidorzi (U Ferrara), S. T. Holland (STScI), J. A. Kennea (PSU),
H. A. Krimm (CRESST/GSFC/USRA), A. Y. Lien (NASA/GSFC/ORAU),
V. Mangano (INAF-IASFPA), C. B. Markwardt (NASA/GSFC),
F. E. Marshall (NASA/GSFC), A. Melandri (INAF-OAB),
T. Sakamoto (NASA/UMBC), C. J. Saxton (UCL-MSSL),
B. Sbarufatti (INAF-OAB/PSU), C. A. Swenson (PSU),
G. Tagliaferri (INAF-OAB), E. Troja (NASA/GSFC/ORAU) and
B.-B. Zhang (PSU) report on behalf of the Swift Team:

At 19:37:30 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 120305A (trigger=516997).  Swift slewed immediately to the burst. 
The BAT on-board calculated location is 
RA, Dec 47.546, +28.493 which is 
   RA(J2000)  =  03h 10m 11s
   Dec(J2000) = +28d 29' 36"
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty).  The BAT light curve shows a single spike
with a duration of about 200 msec.  The peak count rate
was ~32000 counts/sec (15-350 keV), at ~0 sec after the trigger. 

Using promptly downlinked data we find a bright, fading, uncatalogued
X-ray source with an enhanced position: RA, Dec 47.5368, 28.4915 which
is equivalent to:
   RA(J2000)  = 03h 10m 08.84s
   Dec(J2000) = +28d 29' 29.3"
with an uncertainty of 2.6 arcseconds (radius, 90% containment). This
location is 29 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 (1.13 x
10^21 cm^-2, Kalberla et al. 2005), with an excess column of 4
(+3.38/-2.63) x 10^21 cm^-2 (90% confidence). 

The initial flux in the 2.5 s image was 1.03e-09 erg cm^-2 s^-1 (0.2-10
keV). 

UVOT took a finding chart exposure of 150 seconds with the White filter
starting 71 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
0.43. 

We note quasi-periodic variability in the BAT lightcurve before and after the
burst.  We believe it is unrelated to the GRB and could be coming from a
different source, but will further examine the data to determine the origin. 

Burst Advocate for this burst is G. Stratta (giulia.stratta AT asdc.asi.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.)

E. Gorbovskoy, V. Lipunov, V.Kornilov, D.Kuvshinov, A.Belinski, N.Tyurina, N.Shatskiy, P.Balanutsa, D.Zimnukhov, A.Kuznetsov, V.V.Chazov, A.Kuznetsov, A.Sankovich
Sternberg Astronomical Institute, Moscow State University

A. Tlatov, A.V. Parhomenko, D. Dormidontov, V.Sennik
Kislovodsk Solar Station of the Pulkovo Observatory

V.Yurkov, Yu.Sergienko, D.Varda, E.Sinyakov
Blagoveschensk Educational State University, Blagoveschensk

K.Ivanov, S.Yazev, N.M.Budnev, O.Gres, O.Chuvalaev, V.A.Poleshchuk
Irkutsk State University

V.Krushinski, I.Zalozhnich,  A. Popov
Ural Federal University

Hugo Levato and Carlos Saffe
Instituto de Ciencias Astronomicas, de la Tierra y del Espacio (ICATE)

Claudio Mallamaci, Carlos Lopez and Federico Podest
Observatorio Astronomico Felix Aguilar (OAFA)


MASTER II  robotic telescope (MASTER-Net: http://observ.pereplet.ru) 
located in Kislovodsk was pointed to the short  GRB120305A 32 sec   after 
notice time and 57 sec after GRB time at 2012-03-05 19:38:26.385 UT  in 
two polarizations. 
On  our first (10s exposure) set we haven`t found optical transient 
within  SWIFT error-box (ra=03 10 11 dec=+28 29 21 r=0.050000).
The 5-sigma upper limit has been about 16.0 mag.
The message may be cited.

F. J. Virgili (Liverpool, JMU), C. Guidorzi (U. Ferrara), A. Melandri 
(INAF-OAB), C.G. Mundell (Liverpool, JMU) report:

"The 2-m Liverpool Telescope robotically followed up GRB 120305A
(SWIFT trigger 516997; Stratta et al., GCN Circ 13004
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 ) 14.00 min after 
the GRB trigger time.

No optical counterpart is detected within the XRT error circle to the
following conservative limits:

r' > 21.3 mag (vs USNOB1)
i' > 21.0 mag (vs USNOB1).

D. M. Palmer (LANL), S. D. Barthelmy (GSFC), W. H. Baumgartner (GSFC/UMBC),
J. R. Cummings (GSFC/UMBC), N. Gehrels (GSFC), H. A. Krimm (GSFC/USRA),
C. B. Markwardt (GSFC), T. Sakamoto (GSFC/UMBC), M. Stamatikos (OSU),
G. Stratta (ASDC), 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 recent telemetry downlinks,
we report further analysis of BAT GRB 120305A (trigger #516997)
(Stratta, et al., GCN Circ. 13004
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 ).  The BAT ground-calculated position is
RA, Dec = 47.549, 28.495 deg which is 
   RA(J2000)  =  03h 10m 11.8s 
   Dec(J2000) = +28d 29' 41.2" 
with an uncertainty of 1.0 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 92%.
 
The mask-weighted light curve shows a single FRED-like spike starting
at ~T+0.00 sec, peaking at ~T+0.02 sec, and returning to baseline
at ~T+0.20 sec.  At the ~2-sigma level, there is possible emission out to ~T+20 sec.
T90 (15-350 keV) is 0.10 +- 0.02 sec (estimated error including systematics).
 
The time-averaged spectrum from T+0.00 to T+0.136 sec is best fit by a simple
power-law model.  The power law index of the time-averaged spectrum is
1.00 +- 0.09.  The fluence in the 15-150 keV band is 2.0 +- 0.1 x 10^-7 erg/cm2.
The 1-sec peak photon flux measured from T-0.43 sec in the 15-150 keV band
is 2.2 +- 0.2 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/516997/BA/

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

Using 448 s of XRT Photon Counting mode data and 1 UVOT
images for GRB 120305A, 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 = 47.53639, +28.49191 which is equivalent
to:

RA (J2000): 03h 10m 8.73s
Dec (J2000): +28d 29' 30.9"

with an uncertainty of 2.0 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.

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

We have analysed 8.2 ks of XRT data for GRB 120305A (Stratta  et al.
GCN Circ. 13004
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 ), from 69 s to 24.9 ks after the  BAT trigger. The data
comprise 85 s in Windowed Timing (WT) mode with the remainder in Photon
Counting (PC) mode. The enhanced XRT position for this burst was given
by Beardmore et al. (GCN. Circ 13008).

The light curve can be modelled with  a power-law decay with a decay
index of alpha=2.66 (+0.22, -0.19).

A spectrum formed from the WT mode data can be fitted with an absorbed
power-law with a photon spectral index	of 1.94 (+0.21, -0.20). The
best-fitting absorption column is  4.7 (+1.1, -0.9) x 10^21 cm^-2, in
excess of the Galactic value of 1.1 x 10^21 cm^-2 (Kalberla et al.
2005). The counts to observed (unabsorbed) 0.3-10 keV flux conversion
factor deduced from this spectrum  is 4.5 x 10^-11 (7.5 x 10^-11) erg
cm^-2 count^-1. 

A summary of the WT-mode spectrum is thus:
Total column:	     4.7 (+1.1, -0.9) x 10^21 cm^-2
Galactic foreground: 1.1 x 10^21 cm^-2
Excess significance: 6.4 sigma
Photon index:	     1.94 (+0.21, -0.20)

The results of the XRT-team automatic analysis are available at
http://www.swift.ac.uk/xrt_products/00516997.

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

B. A. Zauderer, W. Fong and E. Berger (Harvard) report:

"We observed the location of the short-duration GRB 120305A (GCN 13004
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 )
with the EVLA starting on 2012 March 05.98 UT (3.9 hours post-burst). We
obtained two hours of observations at a mean frequency of 5.8 GHz. We do
not detect any radio source within the latest enhanced XRT position
(improved from GCN 13008
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  with RA = 03:10:08.76, Dec = +28:29:30.2 (J2000),
1.9" uncertainty; http://www.swift.ac.uk/xrt_positions/00516997/) to a
3-sigma limit of ~18 microJy."

F. E. Marshall (NASA/GSFC) and G. Stratta (ASDC)
report on behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 120305A
72 s after the BAT trigger (Stratta et al., GCN Circ. 13004
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 ).
No optical afterglow consistent with the enhanced XRT position
(Beardmore et al., GCN Circular 13008
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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 initial
finding chart (FC) exposures and subsequent exposures are:

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

white (FC)          72          221          147         >20.1
u (FC)             284          534          246         >20.4
white               72         6382          363         >21.1
v                 5158        11729         1082         >19.7
b                  540        18740          428         >20.4
u                  284        24898         1918         >21.2
w1                5567        24288         1968         >20.7
m2               11734        23381         1740         >21.0
w2                6388         6584          193         >20.4

The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.43 in the direction of the burst
(Schlegel et al. 1998).

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

We report the spectral lag analysis for GRB 120305A (GCN Circ. 13004
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 )
based on the BAT data.  Using 1-ms binned light curves, the spectral lag
for the 15-25 keV to 50-100 keV bands is 2.0 +0.6/-0.9 msec, and
-2.6 +0.6/-0.4 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.

Jan Strobl (1), Martin Jelinek (2), Cyril Polasek (1), Martin Nekola (1),
Martin Blazek (1), Petr Kubanek (3) and Rene Hudec (1)
(1. ASU AVCR Ondrejov, 2. IAA-CSIC Granada, 3. FZU AVCR)

We observed the field of Swift GRB 120305A (Stratta et al., GCNC 13004) 
with the 0.5m telescope D50 in Ondrejov (Czech Republic), starting at 
19:39:12.6UT i.e. 102.6s after the trigger. A sequence of 20s unfiltered 
images was obtained. We do not detect any new source in individual (limit 
Rc~17.5) nor coadded images (limit Rc~19.2).

This message can be cited.