GRB 120312A

V.V.Golovnya (Main Astro Obs, Kyiv)
report: 
We have undertaken the review of the sky area in vicinity of 
GRB 120312A (V. Mangano et al. GCN Circ.13053
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 ) on 
astronegatives, collected in Ukrainian NAS Main astronomical 
observatory plate archive (1976-1996). All the plates with 
the possible object appearance are digitized using Microtek 
ScanMaker 9800XL TMA and Epson Expression 10000XL flatbed 
scanners and have been placed into Golosiiv Plate Archive 
database DBGPA with open access to them.
 	The list of plates is given in the table:
YYYYMMDD/TimeUT	--Plates--	Exp.	LimMag	Star USNOA2 
19810626/221142	GUA040C001973B	34.0	15.00	1125-07810808
19810626/221142	GUA040D001974	34.0	15.00	1125-07810808
19870424/003510	GUA040C001043A	18.0	16.10	1125-07808472
19870424/010141	GUA040C001044	16.0	15.00	1125-07810808
19890601/214206	GUA040C001474	18.0	16.65	1125-07808939
19900621/205220	GUA040C001663A	16.5	15.00	1125-07810808
19910615/211004	GUA040C001806A	22.5	16.10	1125-07808472
Plates: �the plates archive identifier of DWA (D/F=400/2000, 
GUA040C, M=103"/mm) of the Ukrainian NAS Main Astro obs.
GUA040D (Marsden's number - 83) the plate number [1].
Exp.   - Duration of the maximum exposure (minutes). 
LimM   - Limited V mag, derived in the 24 minutes area around 
       the location given in V. Mangano et al. GCN Circ.13053
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 : 
       RA(J2000)= 16h 47m 09.16s, Dec(J2000)= +23d 51' 29.4"
Star USNOA2 - Comparison star.
  The preview images of 7 areas together with  
the 24x24 min.of arc area from SkyMap can be found in  
http://gua.db.ukr-vo.org/img/grb/120312A/index.html
The images with full resolution are available via e-mail on 
demand.
References: 
1.L.Pakuliak DATABASE of GOLOSIIV PLATE ARCHIVE (DBGPA V2.0),
http://gua.db.ukr-vo.org

V. Rumyantsev, N. Pit' (CrAO), A. Pozanenko (IKI) report on behalf of larger 
GRB follow-up collaboration:

We observed the field of GRB 120312A (Stamatikos  et al., GCN 13049
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 ) with 
AZT-11  telescope of CrAO observatory starting on March 12  (UT) 23:21:13 
under moderate weather conditions and  seeing  of about 2.4 arsces.  Within 
enhanced Swift-XRT position (Mangano et al., GCN 13053
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 ) we do not detected 
any optical source, in particular afterglow candidate (Tanvir et al., GCN 
13055
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 ). A photometry is based on the  USNO-B1.0 star 1138-0244157 
(16:47:09.53 +23:51:17.4)  assuming R=17.3:

T_start UT  T0+        Filter, Exposure, OT,  uplim (3 sigma)
                  (mid, d)            (s)

23:21:13  0.3291       R     26x180    n/d     20.75

N. R. Tanvir (U. Leicester), D. Perley (Caltech), K. Wiersema (U. Leicester),
A. Cucchiara (UCSC/UCO Lick), K. Roth (Gemini) and J. Ehle (JACH)
report on behalf of a larger collaboration:

We observed the location of GRB 120312A with Gemini-N/GMOS
in the z-band and UKIRT/WFCAM in the J- and K-bands.�� All observations
were obtained approximately 23 hours post-burst.

With GMOS we detect the source reported by Tanvir et al. (GCN 13055
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 ).
Calibrating against SDSS field stars we find a magnitude z=24.35 +- 0.12,
indicating a fading compared to the WHT epoch, and confirming this
source as the afterglow of the GRB.

From a provisional reduction of the UKIRT data, the afterglow is undetected
to 3-sigma limits of J=21.1 and K=19.5 (calibrated against 2MASS), showing
that it is not extremely red, as might have been expected if its faintness
were due to a very dusty line of sight.

S. R. Oates (MSSL-UCL) and M. Stamatikos (OSU/NASA/GSFC)
report on behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 120312A
105 s after the BAT trigger (Stamatikos et al., GCN Circ. 13049
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 ).
No optical afterglow consistent with the XRT position 
(Mangano et al., GCN Circ 13053
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 ) or the WHT optical candidate 
position (Tanvir et al., GCN Circ 13055
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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           105          255          147         >21.3
u_FC               318          567          246         >20.6
white              105         7764          861         >21.9
v                  647        18848         1378         >20.5
b                  573         7559          568         >20.9
u                  318        13854         1583         >21.3
w1                 696        13039         1434         >21.0
m2                 844        19630         1998         >21.4
w2                 795        17934         1434         >21.4

The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.071 in the direction of the burst
(Schlegel et al. 1998).

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

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

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

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

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 Tunka was pointed to the  GRB120312A 403 s after notice 
time and  512 s after GRB time at 2012-03-12 16:15:01 UT in two 
polarizations. On our  first (180s exposure) set we haven`t found optical 
transient  within SWIFT  error-box.
The 5-sigma upper limit has been about 17.6 mag
The object  has been observed in high zenit distance (~80 deg).
The big time delay (in pointing) is caused by a non-standard format of the 
socket messages.
The message may be cited.

N. R. Tanvir (U. Leicester), O. Hartoog (U. Amsterdam), and
T. Schrabback (U. Bonn) report on behalf of a larger collaboration:

We imaged the field of GRB120312A (Stamatikos et al. GCN13049
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 ) using the
WHT/ACAM beginning 05:15 UT on March 13th (approximately 13 hours post-burst).
A 24 minute integration was obtained in the z-band.
��
Within the refined XRT error circle (Mangano et al. GCN13053
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 ) we find a source
at position:

RA(2000) = 16 47 09.23
dec(2000)= +23 51 28.9

The source may be slightly extended, although the S/N is too poor to
determine this with confidence.�� Its provisional magnitude is
z~23.8 +/- 0.2 calibrated against nearby SDSS DR8 stars.

Paul Vreeswijk (U. Iceland), Dong Xu (WIS), John Telting, Gintaras
Barisevicius (NOT), Daniele Malesani (DARK/NBI), Páll Jakobsson
(U. Iceland) report on behalf of a larger collaboration:

Using ALFOSC on the Nordic Optical Telescope (NOT) we have obtained
r'- (3 x 300 s) and z'-band (6 x 300 s) imaging of the field of the Swift
GRB 120312A (Stamatikos et al., GCN 13049
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 ; Barthelmy et al., GCN
12052
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 ), starting on 2012 March 13.085 UT (9.93 hr after the GRB). The
seeing during the observations was around 1".

We do not detect any object within the enhanced Swift-XRT error circle
(Mangano et al., GCN 13053
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 ) down to approximate limiting magnitudes of
r'>23.5 and z'>22.2 (calibrated against the SDSS catalog).

V. Mangano (INAF-IASFPA), A. Melandri (INAF-OAB), B. Sbarufatti
(INAF-OAB/PSU), J.A. Kennea (PSU), M.C. Stroh (PSU), D.N. Burrows
(PSU), A.P. Beardmore (U. Leicester), P.A. Evans (U. Leicester), O.M.
Littlejohns (U. Leicester) and M. Stamatikos report on behalf of the
Swift-XRT team:

We have analysed 9.9 ks of XRT data for GRB 120312A (Stamatikos  et al.
GCN Circ. 13049
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 ), from 112 s to 19.6 ks after the  BAT trigger. The
data are entirely in Photon Counting (PC) mode. Using 2188 s of PC mode
data and 2 UVOT images, we find an enhanced XRT position (using the
XRT-UVOT alignment and matching UVOT field sources to the USNO-B1
catalogue): RA, Dec = 251.78816, +23.85817 which is equivalent to:

RA (J2000): 16h 47m 09.16s
Dec(J2000): +23d 51' 29.4"

with an uncertainty of 1.6 arcsec (radius, 90% confidence).

The light curve can be modelled with  a power-law decay with a decay
index of alpha=1.28 (+0.14, -0.13).

A spectrum formed from the PC mode data can be fitted with an absorbed
power-law with a photon spectral index of 1.54 (+0.26, -0.25). The
best-fitting absorption column is  1.4 (+0.9, -0.8) x 10^21 cm^-2, in
excess of the Galactic value of 4.1 x 10^20 cm^-2 (Kalberla et al.
2005). The counts to observed (unabsorbed) 0.3-10 keV flux conversion
factor deduced from this spectrum  is 4.9 x 10^-11 (5.7 x 10^-11) erg
cm^-2 count^-1. 

A summary of the PC-mode spectrum is thus:
Total column:	     1.4 (+0.9, -0.8) x 10^21 cm^-2
Galactic foreground: 4.1 x 10^20 cm^-2
Excess significance: 2.1 sigma
Photon index:	     1.54 (+0.26, -0.25)

The results of the XRT-team automatic analysis are available at
http://www.swift.ac.uk/xrt_products/00517566.

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

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. B. Markwardt (GSFC), 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-240 to T+736 sec from the recent telemetry downlink,
we report further analysis of BAT GRB 120312A (trigger #517566)
(Stamatikos, et al., GCN Circ. 13049
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 ).  The BAT ground-calculated position is
RA, Dec = 251.812, 23.881 deg, which is 
   RA(J2000)  =  16h 47m 14.8s 
   Dec(J2000) = +23d 52' 50.3" 
with an uncertainty of 2.1 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 35%.
 
The mask-weighted light curve shows a single slightly symmetric peak
starting at ~T-10 sec, peaking at ~T+0.5 sec, and ending at ~T+35 sec.
T90 (15-350 keV) is 14.2 +- 3.4 sec (estimated error including systematics).
 
The time-averaged spectrum from T-1.42 to T+15.87 sec is best fit by a simple
power-law model.  The power law index of the time-averaged spectrum is
1.72 +- 0.23.  The fluence in the 15-150 keV band is 5.7 +- 0.8 x 10^-7 erg/cm2.
The 1-sec peak photon flux measured from T+0.95 sec in the 15-150 keV band
is 1.3 +- 0.3 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/517566/BA/

M. Stamatikos (OSU/NASA/GSFC), S. Campana (INAF-OAB),
M. M. Chester (PSU), V. D'Elia (ASDC), N. Gehrels (NASA/GSFC),
S. T. Holland (STScI), J. A. Kennea (PSU), V. Mangano (INAF-IASFPA),
F. E. Marshall (NASA/GSFC), A. Maselli (INAF-IASFPA),
A. Melandri (INAF-OAB), J. P. Osborne (U Leicester),
K. L. Page (U Leicester), D. M. Palmer (LANL),
P. Romano (INAF-IASFPA), B. Sbarufatti (INAF-OAB/PSU),
M. H. Siegel (PSU), M. C. Stroh (PSU), C. A. Swenson (PSU),
G. Tagliaferri (INAF-OAB) and B.-B. Zhang (PSU) report on behalf of
the Swift Team:

At 16:06:28 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 120312A (trigger=517566).  Swift slewed immediately to the burst. 
The BAT on-board calculated location is 
RA, Dec 251.764, +23.857 which is 
   RA(J2000) = 16h 47m 03s
   Dec(J2000) = +23d 51' 24"
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty).  The BAT light curve showed a single-peaked FRED
structure with a duration of 12 about sec.  The peak count rate
was ~1300 counts/sec (15-350 keV), at ~0 sec after the trigger. 

Using promptly downlinked data we find an uncatalogued X-ray source
with an enhanced position: RA, Dec 251.7885, 23.8586 which is
equivalent to:
   RA(J2000)  = 16h 47m 09.23s
   Dec(J2000) = +23d 51' 30.8"
with an uncertainty of 2.1 arcseconds (radius, 90% containment). 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 (4.08 x
10^20 cm^-2, Kalberla et al. 2005), with an excess column of 1.7
(+1.51/-1.34) x 10^21 cm^-2 (90% confidence). 

UVOT took a finding chart exposure of 150 seconds with the White filter
starting 112 s 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
0.07. 

Burst Advocate for this burst is M. Stamatikos (Michael.Stamatikos-1 AT nasa.gov). 
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.)