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%astro-ph/0911.1912

\documentclass[twocolumn,floatfix]{revtex4}
\usepackage{natbib}
\usepackage{amsmath}
\usepackage{graphicx}
\usepackage{wasysym}

\bibpunct{(}{)}{;}{a}{}{,}

\newcommand{\romn}[1] {{\mathrm #1}}
\newcommand\fs{\hbox{$.\!\!^{\romn s}$}}
\newcommand\farcm{\hbox{$.\mkern-4mu^\prime$}}
\newcommand\farcs{\hbox{$.\!\!^{\prime\prime}$}}

\newcommand{\gr}{$\gamma$-ray}
\newcommand{\grs}{$\gamma$-rays}
\newcommand{\hess}{H.E.S.S.}
\newcommand{\hgcfull}{HESS~J1745-290}
\newcommand{\hgc}{HESS~J1745-290}
\newcommand{\astar}{Sgr~A$^*$}
\newcommand{\aeast}{Sgr~A~East}
\newcommand{\pwn}{G359.95-0.04}
\newcommand{\position}{$\alpha=17^\mathrm{h} 45^\mathrm{m} 39\fs6\pm 0
\fs4_\mathrm{stat}\pm 0\fs4_\mathrm{sys}$, 
  $\delta=-29^\circ 0' 22''\pm 6''_\mathrm{stat}\pm 6''_\mathrm{sys}$}
\newcommand{\distToAStar}{$8''\pm 9''_\mathrm{stat}\pm 9''_
\mathrm{sys}$}

\begin{document}

\title{Localising the VHE $\gamma$-ray source at the Galactic Centre}

\author{HESS Collaboration}
\author{F.~Acero$^{15}$}
\author{F. Aharonian$^{1,13}$}
\author{A.G.~Akhperjanian$^{2}$}
\author{G.~Anton$^{16}$}
\author{U.~Barres de Almeida$^{8}$} \thanks{supported by CAPES
Foundation, Ministry of Education of Brazil}
\author{A.R.~Bazer-Bachi$^{3}$}
\author{Y.~Becherini$^{12}$}
\author{B.~Behera$^{14}$}
\author{K.~Bernl\"ohr$^{1,5}$}
\author{A.~Bochow$^{1}$}
\author{C.~Boisson$^{6}$}
\author{J.~Bolmont$^{19}$}
\author{V.~Borrel$^{3}$}
\author{I.~Braun$^{1}$}
\author{J.~Brucker$^{16}$}
\author{F. Brun$^{19}$}
\author{P. Brun$^{7}$}
\author{R.~B\"uhler$^{1}$}
\author{T.~Bulik$^{29}$}
\author{I.~B\"usching$^{9}$}
\author{T.~Boutelier$^{17}$}
\author{P.M.~Chadwick$^{8}$}
\author{A.~Charbonnier$^{19}$}
\author{R.C.G.~Chaves$^{1}$}
\author{A.~Cheesebrough$^{8}$}
\author{J.~Conrad$^{31}$}
\author{L.-M.~Chounet$^{10}$}
\author{A.C.~Clapson$^{1}$}
\author{G.~Coignet$^{11}$}
\author{M. Dalton$^{5}$}
\author{M.K.~Daniel$^{8}$}
\author{I.D.~Davids$^{22,9}$}
\author{B.~Degrange$^{10}$}
\author{C.~Deil$^{1}$}
\author{H.J.~Dickinson$^{8}$}
\author{A.~Djannati-Ata\"i$^{12}$}
\author{W.~Domainko$^{1}$}
\author{L.O'C.~Drury$^{13}$}
\author{F.~Dubois$^{11}$}
\author{G.~Dubus$^{17}$}
\author{J.~Dyks$^{24}$}
\author{M.~Dyrda$^{28}$}
\author{K.~Egberts$^{1}$}
\author{P.~Eger$^{16}$}
\author{P.~Espigat$^{12}$}
\author{L.~Fallon$^{13}$}
\author{C.~Farnier$^{15}$}
\author{S.~Fegan$^{10}$}
\author{F.~Feinstein$^{15}$}
\author{A.~Fiasson$^{11}$}
\author{A.~F\"orster$^{1}$}
\author{G.~Fontaine$^{10}$}
\author{M.~F\"u{\ss}ling$^{5}$}
\author{S.~Gabici$^{13}$}
\author{Y.A.~Gallant$^{15}$}
\author{L.~G\'erard$^{12}$}
\author{D.~Gerbig$^{21}$}
\author{B.~Giebels$^{10}$}
\author{J.F.~Glicenstein$^{7}$}
\author{B.~Gl\"uck$^{16}$}
\author{P.~Goret$^{7}$}
\author{D.~G\"oring$^{16}$}
\author{M.~Hauser$^{14}$}
\author{S.~Heinz$^{16}$}
\author{G.~Heinzelmann$^{4}$}
\author{G.~Henri$^{17}$}
\author{G.~Hermann$^{1}$}
\author{J.A.~Hinton$^{25}$}
\author{A.~Hoffmann$^{18}$}
\author{W.~Hofmann$^{1}$}
\author{P.~Hofverberg$^{1}$}
\author{M.~Holleran$^{9}$}
\author{S.~Hoppe$^{1}$}
\author{D.~Horns$^{4}$}
\author{A.~Jacholkowska$^{19}$}
\author{O.C.~de~Jager$^{9}$}
\author{C. Jahn$^{16}$}
\author{I.~Jung$^{16}$}
\author{K.~Katarzy{\'n}ski$^{27}$}
\author{U.~Katz$^{16}$}
\author{S.~Kaufmann$^{14}$}
\author{M.~Kerschhaggl$^{5}$}
\author{D.~Khangulyan$^{1}$}
\author{B.~Kh\'elifi$^{10}$}
\author{D.~Keogh$^{8}$}
\author{D.~Klochkov$^{18}$}
\author{W.~Klu\'{z}niak$^{24}$}
\author{T.~Kneiske$^{4}$}
\author{Nu.~Komin$^{7}$}
\author{K.~Kosack$^{1}$}
\author{R.~Kossakowski$^{11}$}
\author{G.~Lamanna$^{11}$}
\author{J.-P.~Lenain$^{6}$}
\author{T.~Lohse$^{5}$}
\author{V.~Marandon$^{12}$}
\author{O.~Martineau-Huynh$^{19}$}
\author{A.~Marcowith$^{15}$}
\author{J.~Masbou$^{11}$}
\author{D.~Maurin$^{19}$}
\author{T.J.L.~McComb$^{8}$}
\author{M.C.~Medina$^{6}$}
\author{J. M\'ehault$^{15}$}
\author{R.~Moderski$^{24}$}
\author{E.~Moulin$^{7}$}
\author{M.~Naumann-Godo$^{10}$}
\author{M.~de~Naurois$^{19}$}
\author{D.~Nedbal$^{20}$}
\author{D.~Nekrassov$^{1}$}
\author{B.~Nicholas$^{26}$}
\author{J.~Niemiec$^{28}$}
\author{S.J.~Nolan$^{8}$}
\author{S.~Ohm$^{1}$}
\author{J-F.~Olive$^{3}$}
\author{E.~de O\~{n}a Wilhelmi$^{1}$}
\author{K.J.~Orford$^{8}$}
\author{M.~Ostrowski$^{23}$}
\author{M.~Panter$^{1}$}
\author{M.~Paz Arribas$^{5}$}
\author{G.~Pedaletti$^{14}$}
\author{G.~Pelletier$^{17}$}
\author{P.-O.~Petrucci$^{17}$}
\author{S.~Pita$^{12}$}
\author{G.~P\"uhlhofer$^{18}$}
\author{M.~Punch$^{12}$}
\author{A.~Quirrenbach$^{14}$}
\author{B.C.~Raubenheimer$^{9}$}
\author{M.~Raue$^{1,33}$}
\author{S.M.~Rayner$^{8}$}
\author{O.~Reimer$^{30}$}
\author{M.~Renaud$^{12}$}
\author{F.~Rieger$^{1,33}$}
\author{J.~Ripken$^{31}$}
\author{L.~Rob$^{20}$}
\author{S.~Rosier-Lees$^{11}$}
\author{G.~Rowell$^{26}$}
\author{B.~Rudak$^{24}$}
\author{C.B.~Rulten$^{8}$}
\author{J.~Ruppel$^{21}$}
\author{F.~Ryde$^{32}$}
\author{V.~Sahakian$^{2}$}
\author{A.~Santangelo$^{18}$}
\author{R.~Schlickeiser$^{21}$}
\author{F.M.~Sch\"ock$^{16}$}
\author{A.~Sch\"onwald$^{5}$,}
\author{U.~Schwanke$^{5}$}
\author{S.~Schwarzburg$^{18}$}
\author{S.~Schwemmer$^{14}$}
\author{A.~Shalchi$^{21}$}
\author{M. Sikora$^{24}$}
\author{J.L.~Skilton$^{25}$}
\author{H.~Sol$^{6}$}
\author{{\L}. Stawarz$^{23}$}
\author{R.~Steenkamp$^{22}$}
\author{C.~Stegmann$^{16}$}
\author{F. Stinzing$^{16}$}
\author{G.~Superina$^{10}$}
\author{I.~Sushch$^{5}$}
\author{A.~Szostek$^{23,17}$}
\author{P.H.~Tam$^{14}$}
\author{J.-P.~Tavernet$^{19}$}
\author{R.~Terrier$^{12}$}
\author{O.~Tibolla$^{1}$}
\author{M.~Tluczykont$^{4}$}
\author{C.~van~Eldik$^{1}$} \email{Christopher.van.Eldik@mpi-hd.mpg.de}
\author{G.~Vasileiadis$^{15}$}
\author{C.~Venter$^{9}$}
\author{L.~Venter$^{6}$}
\author{J.P.~Vialle$^{11}$}
\author{P.~Vincent$^{19}$}
\author{M.~Vivier$^{7}$}
\author{H.J.~V\"olk$^{1}$}
\author{F.~Volpe$^{1}$}
\author{S.J.~Wagner$^{14}$}
\author{M.~Ward$^{8}$}
\author{A.A.~Zdziarski$^{24}$}
\author{A.~Zech $^{6}$}

\vspace{9mm}

\affiliation{
$^1$
Max-Planck-Institut f\"ur Kernphysik, P.O. Box 103980, D 69029
Heidelberg, Germany} \affiliation{
$^2$
 Yerevan Physics Institute, 2 Alikhanian Brothers St., 375036 Yerevan,
Armenia} \affiliation{
$^3$
Centre d'Etude Spatiale des Rayonnements, CNRS/UPS, 9 av. du Colonel
Roche, BP
4346, F-31029 Toulouse Cedex 4, France} \affiliation{
$^4$
Universit\"at Hamburg, Institut f\"ur Experimentalphysik, Luruper
Chaussee
149, D 22761 Hamburg, Germany} \affiliation{
$^5$
Institut f\"ur Physik, Humboldt-Universit\"at zu Berlin, Newtonstr. 15,
D 12489 Berlin, Germany} \affiliation{
$^6$
LUTH, Observatoire de Paris, CNRS, Universit\'e Paris Diderot, 5 Place
Jules Janssen, 92190 Meudon, 
France} \affiliation{
$^7$
IRFU/DSM/CEA, CE Saclay, F-91191
Gif-sur-Yvette, Cedex, France} \affiliation{
$^8$
University of Durham, Department of Physics, South Road, Durham DH1 3LE,
U.K.} \affiliation{
$^9$
Unit for Space Physics, North-West University, Potchefstroom 2520,
    South Africa} \affiliation{
$^{10}$
Laboratoire Leprince-Ringuet, Ecole Polytechnique, CNRS/IN2P3,
 F-91128 Palaiseau, France} \affiliation{
$^{11}$ 
Laboratoire d'Annecy-le-Vieux de Physique des Particules,
Universit\'{e} de Savoie, CNRS/IN2P3, F-74941 Annecy-le-Vieux,
France} \affiliation{
$^{12}$
Astroparticule et Cosmologie (APC), CNRS, Universite Paris 7 Denis
Diderot,
10, rue Alice Domon et Leonie Duquet, F-75205 Paris Cedex 13, France
\thanks{UMR 7164 (CNRS, Universit\'e Paris VII, CEA, Observatoire de
Paris)}} \affiliation{
$^{13}$
Dublin Institute for Advanced Studies, 5 Merrion Square, Dublin 2,
Ireland} \affiliation{
$^{14}$
Landessternwarte, Universit\"at Heidelberg, K\"onigstuhl, D 69117
Heidelberg, Germany} \affiliation{
$^{15}$
Laboratoire de Physique Th\'eorique et Astroparticules, 
Universit\'e Montpellier 2, CNRS/IN2P3, CC 70, Place Eug\`ene Bataillon,
F-34095
Montpellier Cedex 5, France} \affiliation{
$^{16}$
Universit\"at Erlangen-N\"urnberg, Physikalisches Institut,
Erwin-Rommel-Str. 1,
D 91058 Erlangen, Germany} \affiliation{
$^{17}$
Laboratoire d'Astrophysique de Grenoble, INSU/CNRS, Universit\'e Joseph
Fourier, BP
53, F-38041 Grenoble Cedex 9, France } \affiliation{
$^{18}$
Institut f\"ur Astronomie und Astrophysik, Universit\"at T\"ubingen, 
Sand 1, D 72076 T\"ubingen, Germany} \affiliation{
$^{19}$
LPNHE, Universit\'e Pierre et Marie Curie Paris 6, Universit\'e Denis
Diderot
Paris 7, CNRS/IN2P3, 4 Place Jussieu, F-75252, Paris Cedex 5, France}
\affiliation{
$^{20}$
Charles University, Faculty of Mathematics and Physics, Institute of 
Particle and Nuclear Physics, V Hole\v{s}ovi\v{c}k\'{a}ch 2, 180 00}
\affiliation{
$^{21}$
Institut f\"ur Theoretische Physik, Lehrstuhl IV: Weltraum und
Astrophysik,
    Ruhr-Universit\"at Bochum, D 44780 Bochum, Germany} \affiliation{
$^{22}$
University of Namibia, Private Bag 13301, Windhoek, Namibia}
\affiliation{
$^{23}$
Obserwatorium Astronomiczne, Uniwersytet Jagiello{\'n}ski, ul. Orla 171,
30-244 Krak{\'o}w, Poland} \affiliation{
$^{24}$
Nicolaus Copernicus Astronomical Center, ul. Bartycka 18, 00-716 Warsaw,
Poland} \affiliation{
 $^{25}$
School of Physics \& Astronomy, University of Leeds, Leeds LS2 9JT, UK}
\affiliation{
 $^{26}$
School of Chemistry \& Physics,
 University of Adelaide, Adelaide 5005, Australia} \affiliation{
 $^{27}$ 
Toru{\'n} Centre for Astronomy, Nicolaus Copernicus University, ul.
Gagarina 11, 87-100 Toru{\'n}, Poland} \affiliation{
$^{28}$
Instytut Fizyki J\c{a}drowej PAN, ul. Radzikowskiego 152, 31-342
Krak{\'o}w,
Poland} \affiliation{
$^{29}$
Astronomical Observatory, The University of Warsaw, Al. Ujazdowskie
4, 00-478 Warsaw, Poland} \affiliation{
$^{30}$
Institut f\"ur Astro- und Teilchenphysik, Leopold-Franzens-Universit
\"at 
Innsbruck, A-6020 Innsbruck} \affiliation{
$^{31}$
Oskar Klein Centre, Department of Physics, Stockholm University,
Albanova University Center, SE-10691 Stockholm, Sweden} \affiliation{
$^{32}$
Oskar Klein Centre, Department of Physics, Royal Institute of Technology
(KTH),
Albanova, SE-10691 Stockholm, Sweden} \affiliation{
$^{33}$
European Associated Laboratory for Gamma-Ray Astronomy, jointly
supported by CNRS and MPG
}

\begin{abstract}

  The inner 10~pc of our galaxy contains many counterpart candidates
  of the very high energy (VHE; $> 100$~GeV) gamma-ray point
  source HESS J1745-290.  Within the point spread function of the
H.E.S.S.
  measurement, at least three objects are capable of accelerating
  particles to very high energies and beyond, and of providing the
observed
  gamma-ray flux. Previous attempts to address this source confusion
  were hampered by the fact that the projected distances between those
  objects were of the order of the error circle radius of the emission
  centroid (34'', dominated by the pointing uncertainty of
  the H.E.S.S. instrument). Here we present H.E.S.S. data of the
Galactic
  Centre region, recorded with an improved control of the instrument
  pointing compared to H.E.S.S. standard pointing procedures. Stars
  observed during gamma-ray observations by optical guiding cameras
mounted
  on each H.E.S.S. telescope 
  are used for off-line pointing calibration, thereby decreasing the
  systematic pointing uncertainties from 20'' to 6'' per axis. The
position of
  HESS J1745-290 is obtained by fitting a multi-Gaussian profile to the
  background-subtracted gamma-ray count map. A spatial 
  comparison of the best-fit position of HESS J1745-290 with the
position and
  morphology of candidate counterparts is performed.  The position is,
  within a total error circle radius of 13'', coincident with the
  position of the supermassive black hole Sgr A* and the recently
  discovered pulsar wind nebula candidate G359.95-0.04. It is
significantly
  displaced from the centroid of the supernova remnant Sgr A East,
  excluding this object with high probability as the dominant
  source of the VHE gamma-ray emission.\\\\

  Key words:
  Galaxy: centre -- 
  ISM: individual: Sgr~A~East --
  ISM: individual: Sgr~A* --
  ISM: individual: G~359.95-0.04 --
  gamma-rays: observations
\end{abstract}