GRB 120815A

C. Pagani (U Leicester), S. D. Barthelmy (GSFC),
N. Gehrels (NASA/GSFC), F. E. Marshall (NASA/GSFC),
K. L. Page (U Leicester), D. M. Palmer (LANL) and
M. Stamatikos (OSU/NASA/GSFC) report on behalf of the Swift Team:

At 02:13:58 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 120815A (trigger=531003).  Swift will execute a delayed slew
due to Earth-limb observing constraint.  The BAT on-board calculated location
is RA, Dec 273.955, -52.134, which is 
   RA(J2000)  =  18h 15m 49s
   Dec(J2000) = -52d 08' 02"
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty).  The BAT light curve shows a single pulse 
with a duration of about 10 sec.  The peak count rate
was ~1500 counts/sec (15-350 keV), at ~1 sec after the trigger. 

Due to an observing constraint, Swift will not slew until T0+40.6
minutes. There will be no XRT or UVOT data until this time. 

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.)

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 120815A detected by SWIFT
(trigger 531003) with the TAROT robotic telescope (D=25cm)
located at the European Southern Observatory,
La Silla observatory, Chile.

The observations started 34.7s after the GRB trigger
(15.4s after the notice). The elevation of the field decreased from
65 degrees above horizon and weather conditions
were good.

The first image is trailed with a duration of 60.0s
(see the description in Klotz et al., 2006, A&A 451, L39).
We do not detect any OT with a limiting magnitude of:
t0+34.7s to t0+94.7s : R > 16.3

The second image is 30.0s exposure in tracking mode:
t0+108.0s to t0+138.0s : R > 18.4

We co-added a series of exposures from t0+108s to t0+1605s.
Due to the annouced slew delay announced by Pagani et
al. (GCNC 13645), we analyze the BAT error box.
We compared the co-added TAROT images with the
NOMAD1 catalog sources. Three non catalogued sources
could be an optical counterpart candidate:

ID ra(J2000)    dec(J2000)  Rmag
T1 18:15:57.33 -52:07:35.6  18.5
T2 18:15:58.58 -52:07:27.5  19.0
T3 18:15:35.22 -52:05:21.4  18.3

These sources does not appear in the R filtered DSS image.
The sources does not show any significant brightness
variation durong 20 min. but they are close to the
limiting magnitude in the individual images.
Few other fainter sources are also present in the
TAROT image.

More informations can be found at the following URL:

http://cador.obs-hp.fr/grb120815a

Magnitudes are not corrected for galactic dust extinction.

N.B. Galactic coordinates are lon=342.0422 lat=-15.9869
and the galactic extinction in R band is about 0.3 magnitudes
estimated from D. Schlegel et al. 1998ApJ...500..525S.

This message may be cited.

J.A. Kennea (PSU), G. Cusumano (INAF-IASF PA), M. Perri (ASDC), P.A.
Evans (U. Leicester), J.P. Osborne (U. Leicester) and D.N. Burrows
(PSU) report on behalf of the Swift-XRT team:

The XRT began observing the field of GRB 120815A at 02:58:45.5 UT,
2686.8 seconds after the BAT trigger. Using promptly downlinked data we
find an uncatalogued X-ray source located at RA, Dec 273.95896,
-52.12978 which is equivalent to:
   RA(J2000)  = 18h 15m 50.15s
   Dec(J2000) = -52d 07' 47.2"
with an uncertainty of 3.6 arcseconds (radius, 90% containment). This
location is 17 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 (8.55 x
10^20 cm^-2, Kalberla et al. 2005), with an excess column of 1.6
(+1.61/-1.45) x 10^21 cm^-2 (90% confidence).

V. Sudilovsky (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 120815A (Swift trigger 531003; Pagani
et al., GCN 13645
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 ) simultaneously in g'r'i'z'JHKs 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 150 seconds after the BAT
trigger, and were obtained at airmass 1.1 and a mean seeing of 1".3.

Based on exposures of 142 seconds in g'r'i'z' and 240 seconds in JHK
centered 348 seconds after the trigger, we detect an uncataloged source in
all bands at

RA (J2000): 18:15:49.82
DEC (J2000): -52:07:52.1

with an uncertainty of 0.3".

This position is close to the Swift XRT position (J. A. Kennea et al., 
GCN 13647
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 ).

We measure a preliminary magnitude:

i' ~ 17.6

The magnitudes are derived based on GROND zeropoints (g'r'i'z') and 2MASS
stars (JHK).

D. Malesani (DARK/NBI), S. Schulze (PUC and MCSS), A. de Ugarte Postigo 
(IAA/CSIC and DARK/NBI), D. Xu (WIS), V. D'Elia (INAF/Roma and 
ASI/ASDC), J. P. U. Fynbo (DARK/NBI), N. R. Tanvir (Univ. Leicester), 
report on behalf of a larger collaboration:

We observed the field of GRB 120815A (Pagani et al., GCN 13645
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 ) with the 
VLT/X-shooter spectrograph. We confirm the presence of a bright, 
uncatalogued object consistent with the GROND position (Sudilovsky et 
al., GCN 13648
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 ). From the acquisition images, we measure R = 18.9 for 
the afterglow at an epoch of 1.67 hr after the GRB (calibrated to nearby 
USNO stars).

Our spectra cover the wavelength range 3000-25000 AA, and were taken 
starting on 2012 Aug 15.163 UT (1.69 hr after the GRB), for a total of 
40 min exposure. Continuum from the afterglow is detected with high S/N 
in all of the UVB, VIS, and NIR arms.

The spectrum shows a wide trough and a multitude of strong absorption 
lines, which we interpret as due to a DLA and metal transitions of N V, 
S II, Si II, O I, C IV, Si IV, Fe II, Al II, Al III, Mn II, Mg II, Mg I, 
among others, at a common redshift z = 2.358. At the same redshift, we 
also detect fine-structure lines of Ni II and Fe II, thus confirming 
conclusively that this is the GRB redshift. We also detect intervening 
systems at z = 1.539, 1.693, and 2.00. In particular, the system at z = 
1.539 displays exceptionally strong Mg II, Mg I, and Fe II absorption.

We acknowledge the expert support of the VLT observing staff at Paranal, 
in particular Maja Vuckovic, Marcelo Lopez, and Thomas Rivinius.
We also thank Alex Kann for discussion on the afterglow identification.

[GCN OPS NOTE(15aug12): Per author's request, ML and TR were added to the
last paragraph.]

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

Using 1694 s of XRT Photon Counting mode data and 6 UVOT
images for GRB 120815A, 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 = 273.95807, -52.13142 which is equivalent
to:

RA (J2000): 18h 15m 49.94s
Dec (J2000): -52d 07' 53.1"

with an uncertainty of 1.6 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), N. Gehrels (GSFC), H. A. Krimm (GSFC/USRA),
C. Pagani (U Leicester), 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-239 to T+963 sec from recent telemetry downlinks,
we report further analysis of BAT GRB 120815A (trigger #531003)
(Pagani, et al., GCN Circ. 13645
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 ).  The BAT ground-calculated position is
RA, Dec = 273.976, -52.125 deg, which is 
   RA(J2000)  =  18h 15m 54.4s 
   Dec(J2000) = -52d 07' 29.0" 
with an uncertainty of 1.8 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 28%.
 
The mask-weighted light curve shows a FRED pulse starting at ~T-0.3 sec,
peaking at ~T+0.5 sec, and ending at ~T+30 sec.  T90 (15-350 keV) is
9.7 +- 2.5 sec (estimated error including systematics).
 
The time-averaged spectrum from T-0.24 to T+11.97 sec is best fit by a simple
power-law model.  The power law index of the time-averaged spectrum is
2.29 +- 0.23.  The fluence in the 15-150 keV band is 4.9 +- 0.7 x 10^-7 erg/cm2.
The 1-sec peak photon flux measured from T+0.17 sec in the 15-150 keV band
is 2.2 +- 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/531003/BA/

C. Pagani (U Leicester) reports on behalf of the Swift-XRT team:

We have analysed 8.5 ks of XRT data for GRB 120815A (Pagani  et al. GCN
Circ. 13645
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 ), from 2.7 ks to 39.5 ks after the	BAT trigger. The data
are entirely in Photon Counting (PC) mode. The enhanced XRT position
for this burst was given by Goad et al. (GCN. Circ 13650).

The light curve can be modelled with  a power-law decay with a decay
index of alpha=0.89 (+/-0.07).

A spectrum formed from the PC mode data can be fitted with an absorbed
power-law with a photon spectral index of 1.85 (+0.12, -0.11). The
best-fitting absorption column is  5.5 (+4.2, -3.8) x 10^21 cm^-2, at a
redshift of 2.358, in addition to the Galactic value of 8.6 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 4.0 x
10^-11 (5.0 x 10^-11) erg cm^-2 count^-1. 

A summary of the PC-mode spectrum is thus:
Galactic foreground: 8.6 x 10^20 cm^-2
Intrinsic column:    5.5 (+4.2, -3.8) x 10^21 cm^-2 at z=2.358
Photon index:	     1.85 (+0.12, -0.11)

The results of the XRT-team automatic analysis are available at
http://www.swift.ac.uk/xrt_products/00531003.

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

S. T. Holland (STScI) and
C. Pagani (U Leicester)
report on behalf of the Swift/UVOT team:

     The Swift/UVOT observed the field of GRB 120815A starting 2672 s
after the BAT trigger (Pagani et al., 2012, GCNC 13645).  Settled
observations started at 2690 s.  We detect an uncatalogued source
inside the UVOT-enhanced XRT error circle (Goad et al., 2012, GCNC
13650) with preliminary coordinates

   RA (J2000.0)  18:15:49.88  =  273.95783 (deg)
  Dec (J2000.0) -52:07:52.1   =  -52.13114 (deg)

and an estimated uncertainty of 0.6 arcsec (radius, 90% confidence,
statistical + systematic).  The UVOT detection is consistent with the
optical afterglow reported by Sudilovsky et al. (2012, GCNC 13648)
Source magnitudes and 3-sigma upper limits at this location are given
below.  The afterglow is 4.27 arcsec northeast of the USNO-B1.0 source
0378-0977505, so the following photometry should be considered
preliminary.

Filter       TSTART   TSTOP   Exp Time       Mag  Err  Sigma
------------------------------------------------------------
    v         2847     3046        100     19.34 0.29    3.9
    b         3667     4120        226     20.11 0.24    4.7
    u         3462     3661        100    >20.5
 uvw1         3257     3457        100    >20.2
 uvm2         3052     3252        100    >19.9
 uvw2         4330     4530        100    >20.3
white         2690     2840         75     19.94 0.19    5.8
------------------------------------------------------------

    The quoted magnitudes and upper limits have not been corrected for
the Galactic extinction along the line of sight to this burst of
E_{B-V} = 0.10 mag (Schlafly et al. 2011, ApJS, 737, 103).

H. Levato and C. Saffe
Instituto de Ciencias Astronomicas, de la Tierra y del Espacio (ICATE)

C. Mallamaci, C. Lopez and F. Podest
Observatorio Astronomico Felix Aguilar (OAFA)

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

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

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

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

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


MASTER-ICATE robotic very wide field cameras (FOV=2x384 square degrees, 
D=72mm,
f/1.2, 1 pix = 22 arcsec, http://observ.pereplet.ru) located in Argentina
(Observatorio Astronomico Felix Aguilar, http://93.180.27.230:8080/) were
pointed to the GRB120815A (C. Pagani, GCN 13645
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 ) 37 s after notice
time and 60 s after GRB time at 2012-08-15 02:13:58 UT. We haven`t found 
optical transient  within
SWIFT error-box  our first (5 s exposure) set. The 5-sigma upper limit has 
been about 12.0 mag
The 5-sigma upper limit on coadd first 30 images is about 13.0 mag.

Our cameras are continuously imaging the sky with 5 sec exposures.

This message can be cited.