| Canonical Name: | 3C 66A |
| TeVCat Name: | TeV J0222+430 |
| Other Names: | |
| Source Type: | IBL |
| R.A.: | 02 22 41.6 (hh mm ss) |
| Dec.: | +43 02 35.5 (dd mm ss) |
| Gal Long: | 140.15 (deg) |
| Gal Lat: | -16.76 (deg) |
| Distance: | z=0.34 |
| Flux: | 0.06 (Crab Units) |
| Energy Threshold: | 200 GeV |
| Spectral Index: | 4.1 |
| Extended: | No |
| Discovery Date: | 1998-03 |
| Discovered By: | Crimea |
| TeVCat SubCat: | Default Catalog |
Source Notes:
Source Position and its uncertainty:
From
Acciari et al.(2009):
- R.A. (J2000): 02h 22m 41.6s +/- 1.7s
- Dec. (J2000): 43d 02" 35.5' +/- 21"
Spectral Index:
From
Aleksic et al. (2011):
- 3.64 +/- 0.39(stat) +/- 0.25(syst)
From
Acciari et al. (2009):
- 4.1 +/- 0.4(stat) +/- 0.6(syst)
Distance:
The redshift of this blazar (often quoted as 0.444) is disputed - the
authors of the paper that reported this redshift quoted it as "highly
uncertain".
The redshift was updated from unknown to z=0.340 on 171013.
From
Torres-Zafra et al. (2017):
- The authors have firmly established the presence of a galaxy group at
z = 0.3400 +/- 0.0006 in the close environment of 3C 66A and propose that
the host galaxy of 3C 66A belongs to this galaxy cluster.
- A redshift lower limit of z >= 0.33 is also set for 3C 66A.
- "we have analysed spectro-photometrically the environment of 3C66A,
with the goal of finding the galaxy group hosting this blazar. This
study was made using optical images of a 5.5 x 5.5 arcmin^2 field
centred on the blazar, and spectra of 24 sources obtained with
Gemini/GMOS-N multi-object spectroscopy. We found spectroscopic
evidence of two galaxy groups along the blazar's line of sight: one at
z of approximatemy 0.020 and a second one at z of approximately
0.340. The first one is consistent with a known foreground structure,
while the second group here presented has six spectroscopically
confirmed members. Their location along a red sequence in the
colour-magnitude diagram allows us to identify 34 additional candidate
members of the more distant group. The blazar's spectrum shows broad
absorption features that we identify as arising in the intergalactic
medium, thus allowing us to tentatively set a redshift lower limit at
z >= 0.33 (for 3C 66A). As a consequence, we propose that 3C66A is
hosted in a galaxy that belongs to a cluster at z=0.340."
From
Paiano et al. (2016):
"
Miller et al. (1978) proposed a redshift of z = 0.444, on the basis
on one emission line attributed to Mg II 2800 Ang. A value considered
by the authors as tentative and highly uncertain. No other optical
spectroscopy was done for thirty years. More recently
Finke et al.
(2008) showed an optical spectrum in the range from 4200 to 8500
Ang with no detectable optical features. The featureless spectrum was
also confirmed by
Shaw et al. (2013). Our high signal-to-noise (∼
200) GTC spectrum is also featureless. Based on our procedure of
redshift lower limits estimated by EW_min, due to the relatively
bright source we can set only a modest lower limit of z > 0.10. We are
not able to confirm the Mg II emission proposed by
Miller et al.
(1978) because it is out of our spectral range. However at z =
0.444 we would expect to observe HBeta emission line at 7020 Ang,
where we do not detect any line with EW > 0.2Ang. We conclude that the
redshift of this source is still unknown."
From
Furniss et al. (2013):
- HST/COS data were used to seek the redshift of this object.
- "The data show a smooth continuum with intergalactic medium
absorption features which can be used to place a firm lower limit on
the blazar redshift of z >= 0.3347. An upper limit is set by
statistically treating the non-detection of additional absorbers
beyond z = 0.3347, indicating a redshift of less than 0.41 at 99%
confidence and ruling out z >= 0.444 at 99.9% confidence."
From
Shaw et al. (2013):
- an upper limit of z < 1.67 was quoted
- no redshift could be determined
From
Yang & Wang (2010):
- an upper limit of 0.58 on the redshift of this object is derived.
From
Finke et al. (2008):
- " Our spectrum’s wavelength range does not cover the range of the
Miller et al. (1978) feature, so we are unable to confirm or refute
their detection; however, we were able to constrain 0219+428’s
redshift to z >= 0.096"
From
Miller et al. (1978)
- the authors reported the detection of a MgII emission line at 4044
Ang leading them to quote a tentative redshift of z=0.444 for this
object - they flag this redshift as being "highly uncertain" in their
paper.
Flux:
The flux from this object has been found to be variable (see references).
Seen by: Crimea, VERITAS
-
Optical circular polarization induced by axion-like particles in blazars
Yao, Run-Min et al., arXiv e-prints parXiv:2209.14214 (2022) [LINK]
-
Dual-high-frequency VLBI study of blazar-jet brightness-temperature gradients and collimation profiles
Burd, P.R. et al., arXiv e-prints parXiv:2112.04403 (2021) [LINK]
-
Studies of extragalactic background light with TeV BL Lacertae objects
Longhua, Qin et al., MNRAS 499 p2662-2671 (2020) [LINK]
-
Quasi-periodic behaviour in the optical and gamma-ray light curves of blazars 3C 66A and B2 1633+38
Otero-Santos, J. et al., MNRAS p122 (2020) [LINK]
-
Search for spectral features in extragalactic background light with gamma-ray telescopes
Korochkin, A. et al., arXiv e-prints parXiv:1906.12168 (2019) [LINK]
-
Optical Variability of TeV Blazars on long time-scales
Gaur, H. et al., arXiv e-prints p (2019) [LINK]
-
Long-term optical monitoring of TeV emitting blazars. I. Data analysis
Nilsson, K. et al., A&A 620 pA185 (2018) [LINK]
-
Multi-color optical monitoring of ten blazars from 2005 to 2011
Meng, N. et al., ArXiv e-prints p (2018) [LINK]
-
Constraining the redshifts of TeV BL Lac objects
Qin, L. et al., ArXiv e-prints p (2017) [LINK]
-
Radio and optical intra-day variability observations of five blazars
Liu, X. et al., ArXiv e-prints p (2017) [LINK]
-
Optical intra-day variability in 3C 66A: 10 years of observations
Kaur, N. 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]
-
On the redshift of TeV BL Lac objects
Paiano, S. et al., ArXiv e-prints p (2017) [LINK]
-
Redshift determination of the BL Lac object 3C66A by the detection of its host galaxy cluster at z=0.340
Torres-Zafra, J. et al., ArXiv e-prints p (2017) [LINK]
-
VERITAS Observations of Very High Energy Blazars and Potential for Cosmological Insight
Amy Furniss for the VERITAS Collaboration, ArXiv e-prints p (2015) [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]
-
A Study of the Long-term Spectral Variations of 3C 66A Observed with the Fermi and Kanata Telescopes
Itoh, R. et al., ArXiv e-prints p (2013) [LINK]
-
On the Redshift of the Very High Energy Blazar 3C 66A
Furniss, A. et al., ArXiv e-prints p (2013) [LINK]
-
Spectroscopy of the Largest Ever Gamma-Ray-selected BL Lac Sample
Shaw, M.S. et al., ApJ 764 p135 (2013) [LINK]
-
Observation of selected IBLs and LBLs with VERITAS
Majumdar, P. and for the VERITAS Collaboration, ArXiv e-prints p (2011) [LINK]
-
Stereoscopic Observations of the Blazar 3C 66A with the MAGIC Telescopes
Klepser, S. et al., ArXiv e-prints p (2011) [LINK]
-
VHE Blazar Discoveries with VERITAS
Wystan Benbow for the VERITAS Collaboration, ArXiv e-prints p (2011) [LINK]
-
Rapid optical variability of TeV blazars
Gopal-Krishna et al., ArXiv e-prints p (2011) [LINK]
-
Observations of the Blazar 3C 66A with the Magic Telescopes in Stereoscopic Mode
Aleksic, J. et al., ApJ 726 p58-+ (2011) [LINK]
-
Multi-frequency emission analysis and constraining redshift of 3C 66A
Yan, D. et al., ArXiv e-prints p (2010) [LINK]
-
Multi-wavelength Observations of the Flaring Gamma-ray Blazar 3C 66A in 2008 October
The Fermi-LAT collaboration, the VERITAS collaboration, the GASP-WEBT consortium & Multi-wavelength partners, ArXiv e-prints p (2010) [LINK]
-
ERRATUM: ''Veritas Observations of a Very High Energy Gamma-ray Flare from the Blazar 3C66A'' (2009, ApJ, 693, L104)
Acciari, V.A. et al., ApJ 721 pL203-L204 (2010) [LINK]
-
Redshifts of distant blazar limited by Fermi and VHE Gamma-ray observations
Yang, J. and Wang, J., ArXiv e-prints p (2010) [LINK]
-
Discovery of a Very High Energy Gamma-Ray Signal from the 3C 66A/B Region
Aliu, E. et al., ApJ 692 pL29-L33 (2009) [LINK]
-
Mechanism of very high energy radiation in BL Lacertae object 3C 66A
Yang, J. and Wang, J., ArXiv e-prints p (2009) [LINK]
-
Veritas Observations of a Very High Energy Gamma-Ray Flare From the Blazar 3C 66A
Acciari, V.A. et al., ApJ 693 pL104-L108 (2009) [LINK]
-
Redshift limits of BL Lacertae objects from optical spectroscopy
Finke, J.D. et al., A&A 477 p513-516 (2008) [LINK]
-
The WEBT Campaign on the Intermediate BL Lac Object 3C66A in 2007-2008
Boettcher, M. and Fultz, K., ArXiv e-prints p (2008) [LINK]
-
Discovery of >100 GeV Gamma-ray Emission from the Blazar 3C66A by VERITAS
Swordy, S., The Astronomer's Telegram 1753 p1-+ (2008) [LINK]
-
Results of observation of Cyg gamma-2, BL Lac, 3C66A, Mk 501, and the Crab nebula by the GT-48 gamma-ray telescope in 2006
Neshpor, Y.I. et al., Bulletin Crimean Astrophysical Observatory 104 p141-144 (2008) [LINK]
-
On the correlation between the very-high-energy gamma-ray and X-ray fluxes from the blazar 3C 66A
Fidelis, V.V., Astronomy Letters 32 p91-95 (2006) [LINK]
-
The Active Galaxy 3C 66A: A Variable Source of Very High-Energy Gamma-Rays
Neshpor, Y.I. et al., Astronomy Reports 44 p641-646 (2000) [LINK]
-
Blazar 3C 66A: Another extragalactic source of ultra-high-energy gamma-ray photons
Neshpor, Y.I. et al., Astronomy Letters 24 p134-138 (1998) [LINK]
-
Optical spectra of BL Lacertae objects
Miller, J.S. et al., p176-187 (1978) [LINK]
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