GRB 120712A

David Gruber (MPE) reports on behalf of the Fermi GBM Team:

"At 13:42:25.61 UT on 12 July 2012, the Fermi Gamma-Ray Burst Monitor
triggered and located GRB 120712A (trigger 363793348 / 120712571).
which was also detected by the Swift/BAT (Page et al. 2012, GCN 13454
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 ).
The GBM on-ground location is consistent with the Swift position.

The angle from the Fermi LAT boresight is 42 degrees.

This burst was also independently detected by INTEGRAL SPI-ACS.

The GBM light curve consists of two overlapping peaks
with a duration (T90) of about 23 s (50-300 keV).
The time-averaged spectrum from T0-3 s to T0+16 s is
well fit by a Band function with Epeak = 124 +/- 26 keV, 
alpha = -0.6 +/- 0.2, and beta = -1.80 +/- 0.02.

The event fluence (10-1000 keV) in this time interval is
(4.43 +/- 0.05)E-06 erg/cm^2. The 1-sec peak photon flux measured
starting from T0+9.3 s in the 10-1000 keV band
is 3.5 +/- 0.2 ph/s/cm^2.

The spectral analysis results presented above are preliminary;
final results will be published in the GBM GRB Catalog."

S. R. Oates (MSSL-UCL) and M. J. Page (MSSL-UCL)
report on behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 120712A
95 s after the BAT trigger (Page et al., GCN Circ. 13454
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 ).
A source consistent with the XRT position (Osborne et al., GCN Circ. 13456
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 ) 
and the optical position reported by GROND (Elliott et al., GCN Circ. 13457
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 ) 
is detected in the initial UVOT exposures.

The preliminary UVOT position is:
  RA  (J2000) =  11:18:21.25 = 169.58854 (deg.)
  Dec (J2000) = -20:02:01.7  = -20.03380 (deg.)
with an estimated uncertainty of 0.50 arc sec. (radius, 90% confidence).

Preliminary detections and 3-sigma upper limits using the UVOT photometric system
(Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for the early exposures are: 

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

white (FC)         95           245          147        16.95 +/- 0.03
white              861         1010          150        18.93 +/- 0.09
v                  637          657           19        16.79 +/- 0.15
b                  563        18691         1160        >21.8
u                  308        35517         2569        >22.1
w1                 686        35216         3108        >22.0
m2                4818        41481         3296        >22.1
w2                 613        40167         2931        >22.1

The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.04 in the direction of the burst
(Schlegel et al. 1998).

D. Xu (WIS), J. P. U. Fynbo (DARK/NBI), V. D'Elia (ASDC, INAF), N. R.
Tanvir (U. Leicester) report on behalf of the X-shooter GRB GTO
collaboration:

We observed the field of GRB 120712A (Page et al., GCN 13454
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 ) with the
ESO VLT equipped with the X-shooter spectrograph. Observations started
at 00:06 UT on 2012-07-13 (10.4 hr after the BAT trigger), for a total
exposure time of ~60 min in each of the UVB, VIS, and NIR arms,
covering the wavelength range 3000-25000A.

The spectrum exhibits a relatively broad trough (centered at ~6292A)
which we interpreted as Lyman-alpha break. Redward of this feature the
spectrum shows metals lines such as Mg II, Si II, and  Fe II, all at a
common redshift z=4.1745. We also measured the HI column density,
logN(HI)~20.3, from the Lyman-alpha feature.

We acknowledge the excellent support of the ESO observing staff, in
particular Fernando J. Selman.

K.L. Page (U. Leicester), C. Pagani (U. Leicester), B. Sbarufatti
(INAF-OAB/PSU), G. Stratta (ASDC), P. D'Avanzo (INAF-OAB), M.C. Stroh
(PSU), D.N. Burrows (PSU), J.A. Kennea (PSU), A.P. Beardmore (U.
Leicester) and M.J. Page report on behalf of the Swift-XRT team:

We have analysed 6.2 ks of XRT data for GRB 120712A (Page  et al. GCN
Circ. 13454
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 ), from 94 s to 12.9 ks after the  BAT trigger. The data
comprise 90 s in Windowed Timing (WT) mode with the remainder in Photon
Counting (PC) mode. The enhanced XRT position for this burst was given
by Osborne et al. (GCN. Circ 13456).

The light curve can be modelled with an initial power-law decay with an
index of alpha=0.87 (+/-0.06), followed by a break at T+3706 s to an
alpha of 1.80 (+0.33, -0.29).

A spectrum formed from the PC mode data can be fitted with an absorbed
power-law with a photon spectral index of 2.16 (+0.17, -0.14). The
best-fitting absorption column is  5.0 (+3.1, -1.4) x 10^20 cm^-2,
consistent with the Galactic value of 3.6 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 3.3 x 10^-11 (4.0 x
10^-11) erg cm^-2 count^-1. 

A summary of the PC-mode spectrum is thus:
Total column:	     5.0 (+3.1, -1.4) x 10^20 cm^-2
Galactic foreground: 3.6 x 10^20 cm^-2
Excess significance: <1.6 sigma
Photon index:	     2.16 (+0.17, -0.14)

The results of the XRT-team automatic analysis are available at
http://www.swift.ac.uk/xrt_products/00526351.

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

N. R. Tanvir (U. Leicester), A. J. Levan (U. Warwick) and D. Krogsrud (Gemini)
report on behalf of a larger collaboration:

We observed the afterglow of GRB 120712A (Page et al. GCN 12454
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 ;
using the GMOS-S spectrograph on Gemini-South in good conditions.

Observations began at 2012-7-12 23:43 UT, about 10 hr post-burst.
The spectrum reveals a clear Ly-a break, and many other absorption
features.  A provisional reduction gives a redshift of z=4.15, although
this figure will be refined with better calibration.

J. Elliott, P. Schady (MPE Garching), D. A. Kann (TLS Tautenburg) and J.
Greiner (MPE Garching), report on behalf of the GROND team:

We observed the field of GRB 120712A (Swift trigger 526351; Page et al.,
GCN #13454
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 ) simultaneously in g'r'i'z'JHK with GROND (Greiner et al. 2008,
PASP 120, 405) mounted at the 2.2 m MPG/ESO telescope at La Silla
Observatory (Chile).

Observations started at 22:57 UT on 2012-07-12, 9.24 hours after the GRB
trigger, and are continuing. They were performed at an average seeing of
1".12 and at an average airmass of 1.27.

We found a single point source within the 1".5 enhanced Swift-XRT error
circle reported by Osborne et al. (GCN #13456
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 ) at

RA (J2000.0) = 11:18:21.24

DEC (J2000.0) = -20:02:01.4

with an uncertainty of 0".5 in each coordinate.

Based on images of 7.66 min of total exposures in g'r'i'z' and 8 min in
JHK, 9.5 hours post-burst, we estimate preliminary magnitudes (all in AB)
of

g' = 23.1 +/- 0.1,

r' = 21.3 +/- 0.1,

i' = 20.6 +/- 0.1,

z' = 20.5 +/- 0.1,

J  = 20.0 +/- 0.1,

H  = 19.8 +/- 0.2 and,

K  > 19.1.

Assuming no dust the SED is well fit with a spectral index of beta=1.1 +/-
0.1 at a redshift of z=4.0 +/- 0.2. Including host galaxy dust decreases
the redshift, although both solutions remain consistent within 1-sigma.

Given magnitudes are calibrated against GROND zeropoints as well as 2MASS
field stars and are not corrected for the expected Galactic foreground
extinction corresponding to a reddening of E_(B-V)=0.04 mag in the
direction of the burst (Schlegel et al. 1998).

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

Using 5145 s of XRT Photon Counting mode data and 8 UVOT
images for GRB 120712A, 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 = 169.58851, -20.03397 which is equivalent
to:

RA (J2000): 11h 18m 21.24s
Dec (J2000): -20d 02' 02.3"

with an uncertainty of 1.5 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.

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),
M. J. Page (UCL-MSSL), D. M. Palmer (LANL), T. Sakamoto (GSFC/UMBC),
M. Stamatikos (OSU), J. Tueller (GSFC), T. N. Ukwatta (MSU)
(i.e. the Swift-BAT team):
 
Using the data set from T-120 to T+254 sec from recent telemetry downlinks,
we report further analysis of BAT GRB 120712A (trigger #526351)
(Page, et al., GCN Circ. 13454
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 ).  The BAT ground-calculated position is
RA, Dec = 169.598, -20.051 deg, which is 
   RA(J2000)  =  11h 18m 23.6s 
   Dec(J2000) = -20d 03' 02.9" 
with an uncertainty of 1.0 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 55%.
 
The mask-weighted light curve shows two main overlapping peaks starting 
at ~T-5 sec, peaking at ~T+0 and ~T+8 sec, and ending at ~T+20 sec.
T90 (15-350 keV) is 14.7 +- 3.3 sec (estimated error including systematics).
 
The time-averaged spectrum from T-4.57 to T+16.53 sec is best fit by a simple
power-law model.  The power law index of the time-averaged spectrum is
1.36 +- 0.08.  The fluence in the 15-150 keV band is 1.8 +- 0.1 x 10^-6 erg/cm2.
The 1-sec peak photon flux measured from T+7.51 sec in the 15-150 keV band
is 2.4 +- 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/526351/BA/

M. J. Page (UCL-MSSL), A. A. Breeveld (UCL-MSSL), D. N. Burrows (PSU),
V. D'Elia (ASDC), P. A. Evans (U Leicester), N. Gehrels (NASA/GSFC),
N. P. M. Kuin (UCL-MSSL), O. M. Littlejohns (U Leicester),
F. E. Marshall (NASA/GSFC), S. R. Oates (UCL-MSSL),
K. L. Page (U Leicester), D. M. Palmer (LANL) and
V. N. Yershov (UCL-MSSL) report on behalf of the Swift Team:

At 13:42:27 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 120712A (trigger=526351).  Swift slewed immediately to the burst. 
The BAT on-board calculated location is 
RA, Dec 169.605, -20.061 which is 
   RA(J2000)  =  11h 18m 25s
   Dec(J2000) = -20d 03' 38"
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty).  The BAT light curve shows a couple of overlapping
peaks with a total duration of about 25 sec.  The peak count rate
was ~3000 counts/sec (15-350 keV), at ~8 sec after the trigger. 

The XRT began observing the field at 13:43:58.2 UT, 90.9 seconds after
the BAT trigger. Using promptly downlinked data we find an uncatalogued
X-ray source located at RA, Dec 169.59034, -20.03336 which is
equivalent to:
   RA(J2000)  = 11h 18m 21.68s
   Dec(J2000) = -20d 02' 00.1"
with an uncertainty of 4.1 arcseconds (radius, 90% containment). This
location is 111 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.  We cannot determine whether the source is
fading at the present time. 

A power-law fit to a spectrum formed from promptly downlinked event
data gives a column density in excess of the Galactic value (3.60 x
10^20 cm^-2, Kalberla et al. 2005), with an excess column of 3
(+2.23/-1.94) x 10^21 cm^-2 (90% confidence). 

UVOT took a finding chart exposure of 150 seconds with the White filter
starting 95 seconds after the BAT trigger. There is a candidate afterglow in
the list of sources generated on-board at
  RA(J2000)  =	11:18:21.23 = 169.58847
  DEC(J2000) = -20:02:01.8  = -20.03383
with a 90%-confidence error radius of about 1.10 arc sec. This position is 6.5
arc sec. from the center of the XRT error circle. The estimated magnitude is
17.10. No correction has been made for the expected extinction corresponding to
E(B-V) of 0.04. 

Burst Advocate for this burst is M. J. Page (mjp AT mssl.ucl.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.)