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Observation Date (UT) Observation Lat

Canonical Name:Centaurus A
TeVCat Name:TeV J1325-430
Other Names:NGC 5128
Source Type:FRI
R.A.:13 25 26.4 (hh mm ss)
Dec.:-43 00 42 (dd mm ss)
Gal Long: 309.51 (deg)
Gal Lat: 19.43 (deg)
Distance: z=0.00183
Flux:0.08 (Crab Units)
Energy Threshold:250 GeV
Spectral Index:2.7
Extended:Yes
Size (X):0.04 (deg)
Size (Y):0.00 (deg)
Discovery Date:2009-03
Discovered By: H.E.S.S.
TeVCat SubCat:Default Catalog

Source Notes:

The detection of this source by H.E.S.S. was announced at the Moriond 2009 conference.
It had previously been claimed to be a TeV emitter in 1975 by Grindlay et al. (4.5 sigma).
Evidence for extension of the TeV emission from this source was reported by Sanchez et al. (2018)
making this the first extragalactic TeV source for which an extension has been reported.

Source position and its uncertainty:
From Aharonian et al. (2009):
- R.A. (J2000): 13h 25m 26.4s +/- 4.6s(stat) +/- 2.0s(syst)
- Dec. (J2000): -43d 0.7' +/- 1.1'(stat) +/- 30''(syst)

Source Extension:
From Sanchez et al. (2018):
Evidence for extension with an elliptical shape is presented:
- the Gaussian width of the semi-major axis is 0.044 +/- 0.012 deg
- the emission is point-like in the tranvers direction
- the extension is aligned with the radio jets

Distance:
From H.E.S.S. Collaboration (2018):
- "at a distance of approx. 3.8 Mpc Harris et al. (2010), Centaurus A is
the nearest active galaxy Israel (1998)"

Spectral Information:
From H.E.S.S. Collaboration (2018):
In this paper data taken betweeen 2004 and 2010 are
analysed/re-analysed. Two datasets are defined:
- Data set A was taken between April 2004 and July 2008 (these data were previously published)
- Data set B was taken between 2009 and 2010
Spectral indices:
- Data set A: 2.51 +/- 0.19 (stat) +/- 0.20 (syst)
- Data set B: 2.55 +/- 0.19 (stat) +/- 0.20 (syst)
- Combined data sets A and B: 2.52 +/- 0.13 (stat) +/- 0.20 (syst)
Normalisation constants:
- Data set A: 1.44 +/- 0.22 (stat) +0.43 (syst) -0.29(syst) e-13 cm-2 s-1 TeV-1 at E0 of 1 TeV
- Data set B: 1.50 +/- 0.22 (stat) +0.45 (syst) -0.30(syst) e-13 cm-2 s-1 TeV-1 at E0 of 1 TeV
- Combined data sets: 1.49 +/- 0.16 (stat) +0.45 (syst) -0.30(syst) e-13 cm-2 s-1 TeV-1 at E0 of 1 TeV

Flux:
From H.E.S.S. Collaboration (2018):
- "Cen A is a weak VHE source with a measured integral flux above 250 GeV
of about 0.8% of the flux of the Crab Nebula"

Source Properties: From H.E.S.S. Collaboration (2018):
- "An updated Fermi-LAT analysis provides evidence for spectral
hardening by approximately 0.4 +/- 0.1 at gamma-ray energies above 2.8
+1.0 −0.6 GeV at a level of 4.0 sigma. The fact that the spectrum
hardens at GeV energies and extends into the VHE regime disfavour a
single-zone SSC interpretation for the overall spectral energy
distribution (SED) of the core and is suggestive of a new gamma-ray
emitting component connecting the high-energy emission above the break
energy to the one observed at VHE energies. The absence of significant
variability at both GeV and TeV energies does not yet allow
disentanglement of the physical nature of this component, though a
jet-related origin is possible and a simple two-zone SED model fit is
provided to this end"


Seen by: H.E.S.S.
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