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Observation Date (UT) Observation Lat

Canonical Name:Cassiopeia A
TeVCat Name:TeV J2323+588
Other Names:Cas A, 3C461,
G111.7-2.1, VER J2323+588
Source Type:Shell
R.A.:23 23 13.8 (hh mm ss)
Dec.:+58 48 26 (dd mm ss)
Gal Long: 111.71 (deg)
Gal Lat: -2.13 (deg)
Distance: 3.4 kpc
Flux:0.03 (Crab Units)
Energy Threshold:250 GeV
Spectral Index:2.3
Extended:No
Discovery Date:2001-04
Discovered By: HEGRA
Green's Catalog:Link
TeVCat SubCat:Default Catalog

Source Notes:

Source position and its uncertainty:
From Ghiotto et al. (2015):
- R.A. (J2000): 23h 23m 20.4s
- Dec. (J2000): 58d 49' 01.2"
- statistical error: 0.006deg, systematic error: 0.014deg
From Acciari et al. (2010):
The derived position of the peak of gamma-ray emission from Cassiopeia
A deviates from the nominal position of the supernova remnant
(Becker, White, & Edwards 1991) (R.A.: 23h 23m 24s, Dec. +58deg 48.9')
by less than RA of 14" and Dec. of 35".
From Albert et al. (2007):
- R.A. (J2000): 23.386 +/- 0.003deg (stat) +/- 0.001deg (syst) (23h 23m 13.8s)
- Dec. (J2000): 58.81 +/- 0.03deg (stat) +/- 0.02deg (syst) (+58d 48' 26")
From Aharonian et al. (2001):
- R.A. (J2000): 23h 23m 24s
- Dec. (J2000): +58d 48' 54"
- no numbers for the statistical errors are quoted
- systematic error on pointing is 25"

Flux:
From Acciari et al. (2010):
- 3% Crab (200 GeV threshold)
From Albert et al. (2007):
- 3% Crab (250 GeV threshold)
From Aharonian et al. (2001):
- 3.3% Crab (1 TeV threshold)

Spectral Index:
From MAGIC Collaboration (2017):
- By combining Fermi-LAT and MAGIC data, the spectrum was derived between
60 MeV and 10 TeV
- "The spectra measured by the LAT and MAGIC telescopes are compatible
within the errors and show a clear turn off (4.6 sigma) at the highest
energies, which can be described with an exponential cut-off at:
3.5 TeV [+1.6 -1.0 (stat)] TeV [+0.8 -0.9 (sys)] TeV."
- "The gamma-ray emission from 60 MeV to 10 TeV can be attributed to a
population of high-energy protons with spectral index or approx. 2.2
and energy cut-off at approx. 10 TeV."
From Ghiotto et al. (2015):
- 2.75 +/- 0.10(stat) +/- 0.20(syst)
From Acciari et al. (2010):
- 2.62 +/- 0.24(stat) +/- 0.2(syst)
From Albert et al. (2007):
- 2.3 +/- 0.2(stat) +/- 0.2(syst)
From Aharonian et al. (2001):
- 2.5 +/- 0.4(stat) +/- 0.1(syst)


Seen by: HEGRA, MAGIC, VERITAS
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