| Canonical Name: | W Comae |
| TeVCat Name: | TeV J1221+282 |
| Other Names: | VTS J1221+281,
ON 231,
B2 1219+28 |
| Source Type: | IBL |
| R.A.: | 12 21 31.7 (hh mm ss) |
| Dec.: | +28 13 59 (dd mm ss) |
| Gal Long: | 201.73 (deg) |
| Gal Lat: | 83.29 (deg) |
| Distance: | z=0.102 |
| Flux: | 0.09 (Crab Units) |
| Energy Threshold: | 200 GeV |
| Spectral Index: | 3.81 |
| Extended: | No |
| Discovery Date: | 2008-08 |
| Discovered By: | VERITAS |
| TeVCat SubCat: | Default Catalog |
Source Notes:
Source position and its uncertainty:
From
Acciari et al. (2008):
"The mean position of the W Com excess is derived by fitting a 2D Gaussian
function to the uncorrelated excess sky map and is found to be compatible
within errors with the nominal position of W Com"
- no information on the magnitude of the positional uncertainty is provided
- the source position provided by
NED is used here
From
Acciari et al. (2009):
- "The position of the peak of the gamma-ray excess, reconstructed by
fitting a two-dimensional Gaussian function to the uncorrelated excess
sky map, is in agreement with the position of the radio source
associated with W Com (
Fey et al. (2004)): Difference in
RA=40"+/-31"(stat); Difference in Dec=-55"+/-41.4"(stat). The
systematic uncertainty on the . pointing, verified with optical
pointing monitors, is less than 50". The morphology of the excess is
compatible with the distribution expected from a point source."
Spectral Properties:
From
Acciari et al. (2008):
- Spectral index: 3.81 +/- 0.35(stat) +/- 0.34(syst)
From
Acciari et al. (2009):
- Spectral index (flare): 3.68 +/- 0.22(stat) +/- 0.3(syst)
Flux:
The flux from this source has been found to be variable (see references).
From
Acciari et al. (2008):
- a flux at a level of 9% that of the Crab was reported
From
Acciari et al. (2009):
- a flare with a flux at a level of ~25% that of the Crab was reported
Seen by: VERITAS
-
Studies of extragalactic background light with TeV BL Lacertae objects
Longhua, Qin et al., MNRAS 499 p2662-2671 (2020) [LINK]
-
Swift and XMM-Newton monitoring of the ISP blazar ON 231 in outburst state
Kalita, Nibedita and Sawangwit, Utane, arXiv e-prints parXiv:1906.01964 (2019) [LINK]
-
Signature of Stochastic Acceleration and Cooling Processes in an Outburst Phase of the TeV Blazar ON 231
Kalita, Nibedita et al., ApJ 880 p19 (2019) [LINK]
-
Multi-color optical monitoring of ten blazars from 2005 to 2011
Meng, N. et al., ArXiv e-prints p (2018) [LINK]
-
Long-term optical monitoring of TeV emitting blazars. I. Data analysis
Nilsson, K. et al., A&A 620 pA185 (2018) [LINK]
-
On the redshift of TeV BL Lac objects
Paiano, S. et al., ArXiv e-prints p (2017) [LINK]
-
Signature of Inverse Compton emission from blazars
Gaur, H. et al., ArXiv e-prints p (2017) [LINK]
-
VHE Analyses of Long-Term Low-Flux-State Observations by VERITAS of Intermediate-Frequency-Peaked BL Lacertae Sources: 3C 66A and W Comae
Juliana Vievering for the VERITAS Collaboration, ArXiv e-prints p (2015) [LINK]
-
The Blazar Emission Environment: Insight from Soft X-ray Absorption
Furniss, A. et al., ArXiv e-prints p (2013) [LINK]
-
Emission from Hot Dust in the Infrared Spectra of Gamma-ray Bright Blazars
Malmrose, M. et al., ArXiv e-prints p (2011) [LINK]
-
Rapid optical variability of TeV blazars
Gopal-Krishna et al., ArXiv e-prints p (2011) [LINK]
-
Observation of selected IBLs and LBLs with VERITAS
Majumdar, P. and for the VERITAS Collaboration, ArXiv e-prints p (2011) [LINK]
-
VHE Blazar Discoveries with VERITAS
Wystan Benbow for the VERITAS Collaboration, ArXiv e-prints p (2011) [LINK]
-
Detection of Intra-day Variability Timescales of Four High-energy Peaked Blazars with XMM-Newton
Gaur, H. et al., ApJ 718 p279-291 (2010) [LINK]
-
Multiwavelength observations of a TeV-Flare from W Com
Maier, G. and Pian, E., ArXiv e-prints p (2009) [LINK]
-
Multiwavelength Observations of a TeV-Flare from W Comae
Acciari, V.A. et al., ApJ 707 p612-620 (2009) [LINK]
-
A synchrotron self-Compton scenario for the very high energy gamma-ray emission of the intermediate BL Lacertae object W Comae
Zhang, J., Research in Astronomy and Astrophysics 9 p777-782 (2009) [LINK]
-
VERITAS Discovery of >200 GeV Gamma-Ray Emission from the Intermediate-Frequency-Peaked BL Lacertae Object W Comae
Acciari, V.A. et al., ApJ 684 pL73-L77 (2008) [LINK]
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