| Canonical Name: | Cassiopeia A |
| TeVCat Name: | TeV J2323+588 |
| Other Names: | Cas A, 3C461,
G111.7-2.1, VER J2323+588
1LHAASO J2323+5854 |
| 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
Cao et al. (2025):
- The best-fit position of the source is given as:
- R.A. (J2000): 350.87 deg +/- 0.07 deg (stat) = 23h 23m 28.8s
- Dec. (J2000): 58.75 deg +/- 0.04 deg (stat) = +58d 45m
... assuming a power law spectrum"
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
Cao et al. (2025):
- "we find that its spectrum is significantly softer than those
obtained with Imaging Air Cherenkov Telescopes (IACTs) and its flux
near approx. 1 TeV is about two times higher. In combination with
analyses of more than 16 years of Fermi-LAT data covering 0.1GeV - 1TeV,
we find that the spectrum above 30 GeV deviates significantly from a
single power-law, and is best described by a smoothly broken power-law
with a spectral index of 1.90 +/- 0.15 (stat) (3.41 +/- 0.19 (stat) )
below (above) a break energy of 0.63 +/- 0.21 (stat) TeV. Given
differences in the angular resolution of LHAASO-WCDA and IACTs, TeV
gamma-ray emission detected with LHAASO may have a significant
contribution from regions surrounding the SNR illuminated by particles
accelerated earlier, which, however, are treated as background by
IACTs."
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, LHAASO
-
Revisiting X-ray polarization of the shell of Cassiopeia A using spectropolarimetric analysis
Mercuri, Alessandra et al., arXiv e-prints parXiv:2504.07051 (2025) [LINK]
-
Broadband gamma-ray spectrum of supernova remnant Cassiopeia A
Cao, Zhen et al., arXiv e-prints parXiv:2502.04848 (2025) [LINK]
-
Cassiopeia A's Reverse Shock and its Effects on the Expanding SN Ejecta
Fesen, Robert A. et al., arXiv e-prints parXiv:2501.07708 (2025) [LINK]
-
The First LHAASO Catalog of Gamma-Ray Sources
Cao, Zhen et al., ApJS 271 p25 (2024) [LINK]
-
Spectrum and location of ongoing extreme particle acceleration in Cassiopeia A
Woo, Jooyun et al., arXiv e-prints parXiv:2410.16522 (2024) [LINK]
-
Identifying a point-symmetric morphology in supernova remnant Cassiopeia A: explosion by jittering jets
Bear, Ealeal and Soker, Noam, arXiv e-prints parXiv:2403.07625 (2024) [LINK]
-
A JWST Survey of the Supernova Remnant Cassiopeia A
Milisavljevic, Dan et al., arXiv e-prints parXiv:2401.02477 (2024) [LINK]
-
Far-infrared polarization of the supernova remnant Cassiopeia A with SOFIA HAWC +
Rho, Jeonghee et al., MNRAS 522 p2279-2296 (2023) [LINK]
-
X-ray polarization detection of Cassiopeia A with IXPE
Vink, Jacco et al., arXiv e-prints parXiv:2206.06713 (2022) [LINK]
-
An Asymmetrical Model for High Energy Radiation of Cassiopeia A
Zhan, Shihong et al., arXiv e-prints parXiv:2204.02664 (2022) [LINK]
-
The auto and cross angular power spectrum of the Cas A supernova remnant in radio and X-ray
Saha, Preetha et al., MNRAS p (2021) [LINK]
-
Formation pathway for lonely stripped-envelope supernova progenitors: implications for Cassiopeia A
Hirai, Ryosuke et al., MNRAS 499 p1154-1171 (2020) [LINK]
-
Detection of the Red Supergiant Wind from the Progenitor of Cassiopeia A
Weil, Kathryn E. et al., arXiv e-prints parXiv:2002.08442 (2020) [LINK]
-
Evidence for proton acceleration up to TeV energies based on VERITAS and Fermi-LAT observations of the Cas A SNR
Abeysekara, A.U. et al., arXiv e-prints parXiv:2003.13615 (2020) [LINK]
-
Three-Dimensional Kinematic Reconstruction of the Optically-Emitting, High-Velocity, Oxygen-Rich Ejecta of Supernova Remnant N132D
Law, Charles J. et al., arXiv e-prints parXiv:2004.00016 (2020) [LINK]
-
Search for Continuous Gravitational Waves from the Central Compact Objects in Supernova Remnants Cassiopeia A, Vela Jr. and G347.3-0.5
Alessandra, Papa et al., arXiv e-prints parXiv:2005.06544 (2020) [LINK]
-
Mapping the radio to mid-infrared spectral index of Cas A: evidence for flattening and a cooling break
Domcek, V. et al., arXiv e-prints parXiv:2005.12677 (2020) [LINK]
-
Highlights of Galactic Physics with VERITAS
Richards, G., 36th International Cosmic Ray Conference (ICRC2019) 36 p773 (2019) [LINK]
-
GeV light curves of young supernova remnants
Petruk, O. et al., arXiv e-prints parXiv:1912.06452 (2019) [LINK]
-
Is Supernova Remnant Cassiopeia A a PeVatron?
Zhang, X. and Liu, S., arXiv e-prints p (2019) [LINK]
-
Vortical amplification of magnetic field at inward shock of supernova remnant Cassiopeia A
Fraschetti, F. et al., ArXiv e-prints p (2018) [LINK]
-
On the search for Galactic supernova remnant PeVatrons with current TeV instruments
Cristofari, P. et al., ArXiv e-prints p (2018) [LINK]
-
Deep observations of Cas A with MAGIC indicate it is no PeVatron
Guberman, D. et al., ArXiv e-prints p (2017) [LINK]
-
X-ray Measurements of the Particle Acceleration Properties at Inward Shocks in Cassiopeia A
Sato, T. et al., ArXiv e-prints p (2017) [LINK]
-
A cut-off in the TeV gamma-ray spectrum of the SNR Cassiopeia A
MAGIC Collaboration et al., ArXiv e-prints p (2017) [LINK]
-
3D simulations of young core-collapse supernova remnants undergoing efficient particle acceleration
Ferrand & Safi-Harb, ArXiv e-prints p (2016) [LINK]
-
Hard X-ray emissions from Cassiopeia A observed by INTEGRAL
Wang, W. and Li, Z., ArXiv e-prints p (2016) [LINK]
-
A Deep Observation of Gamma-ray Emission from Cassiopeia A using VERITAS
Ghiotto, A. and for The VERITAS Collaboration, ArXiv e-prints p (2015) [LINK]
-
A detailed study of Gamma-ray emission from Cassiopeia A using VERITAS
Kumar, S. and for the VERITAS Collaboration, ArXiv e-prints p (2015) [LINK]
-
Locating the most energetic electrons in Cassiopeia A
Grefenstette, B.W. et al., ArXiv e-prints p (2015) [LINK]
-
Origin of gamma-ray emission in the shell of Cassiopeia A
Saha, L. et al., ArXiv e-prints p (2014) [LINK]
-
Fermi-LAT Detection of a Break in the Gamma-Ray Spectrum of the Supernova Remnant Cassiopeia A
Yuan, Y. et al., ArXiv e-prints p (2013) [LINK]
-
Modeling the Shell of Cassiopeia A to find the TeV Gamma-ray Emission Region
Ergin, T. et al., ArXiv e-prints p (2013) [LINK]
-
A statistical study of Galactic SNR source spectra detected at >GeV energies
Mandelartz, M. and Becker Tjus, J., ArXiv e-prints p (2013) [LINK]
-
Gamma Rays from Cosmic Rays in Supernova Remnants
Dermer, C.D. and Powale, G., ArXiv e-prints p (2012) [LINK]
-
Unified model for the gamma-ray emission of supernova remnants
Yuan, Q. et al., ArXiv e-prints p (2012) [LINK]
-
Observations of the shell-type SNR Cassiopeia A at TeV energies with VERITAS
The VERITAS Collaboration et al., ApJ 714 163 (2010) [LINK]
-
Fermi-LAT discovery of GeV gamma-ray emission from the young supernova remnant Cassiopeia A
Funk, S. & Uchiyama, Y. for the Fermi-LAT Collaboration, ArXiv e-prints p (2010) [LINK]
-
The Three-dimensional Structure of Cassiopeia A
DeLaney, T. et al., ApJ 725 p2038-2058 (2010) [LINK]
-
Evidence for Cosmic Ray Acceleration in Cassiopeia A
Araya, M. and Cui, W., ApJ 720 p20-25 (2010) [LINK]
-
Suzaku X-Ray Imaging and Spectroscopy of Cassiopeia A
Maeda, Y. et al., PASJ 61 p1217- (2009) [LINK]
-
VERITAS Observations of Supernova Remnants and Pulsar Wind Nebulae in the Fermi Era
Humensky, T.B. and for the VERITAS Collaboration, ArXiv e-prints p (2009) [LINK]
-
Spitzer Spectral Mapping of Supernova Remnant Cassiopeia a
Smith, J.D.T. et al., ApJ 693 p713-721 (2009) [LINK]
-
Characterizing the Nonthermal Emission of Cassiopeia A
Helder, E.A. and Vink, J., ApJ 686 p1094-1102 (2008) [LINK]
-
Jets as Diagnostics of the Circumstellar Medium and the Explosion Energetics of Supernovae: The Case of Cassiopeia A
Schure, K.M. et al., ApJ 686 p399-407 (2008) [LINK]
-
Observation of VHE gamma-rays from Cassiopeia A with the MAGIC telescope
Albert, J. et al., A&A 474 p937-940 (2007) [LINK]
-
Evidence for TeV gamma ray emission from Cassiopeia A
Aharonian, F. et al., A&A 370 p112-120 (2001) [LINK]
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