1ES 1218+304

Observation Date (UT)	Observation Lat
	ARGO-YBJ (30.11) ASTRI Mini-Array (28.3) CANGAROO (-31.10 ) CAT (42.50) Crimea (45) CTA pSCT (31.68) CTA South (-24.6272) Durham (-30.48) FACT (28.76) H.E.S.S. (-23.16) HAGAR (30) HAWC (19.0) HEGRA (28.76) LHAASO (29.358) LST-1 (28.76) MAGIC (28.76) Milagro (35.88 ) Potchefstroom (-26.9) TACTIC (24.6) TAIGA (103.07) Telescope Array (39.3) Tibet (30.11) VERITAS (31.68) Whipple (31.68)

Canonical Name:	1ES 1218+304
TeVCat Name:	TeV J1221+301
Other Names:	1H 1219+301, H 1219+305
Source Type:	HBL
R.A.:	12 21 26.3 (hh mm ss)
Dec.:	+30 11 29 (dd mm ss)
Gal Long:	186.21 (deg)
Gal Lat:	82.74 (deg)
Distance:	z=0.182
Flux:	0.08 (Crab Units)
Energy Threshold:	120 GeV
Spectral Index:
Extended:	No
Discovery Date:	2006-05
Discovered By:	MAGIC
TeVCat SubCat:	Default Catalog

Source Notes:

Source position and its uncertainty:
From Acciari et al. (2009):
- RA (J2000): 12 21 26.3 +/- 2.8s(stat) +/- 7.0(syst)
- Dec (J2000): +30 11 29 +/- 33"(stat) +/- 1'30"(syst)

Spectral Properties:
From Benbow et al. 2011:
- Spectral index during 2008-09: 3.07 +/- 0.09
From Acciari et al. (2009):
- Spectral index: 3.08 +/- 0.34(stat) +/- 0.2(syst)
From Albert et al. (2006):
- Spectral index: 3.0 +/- 0.4(stat) +/- 0.7(syst) - 0.4(syst)

Flux:
- the flux from this blazar has been found to be variable (see references)
From Acciari et al. (2010):
- the flux peaked at 20% that of the Crab
From Acciari et al. (2009):
- a flux at 6% of the Crab is reported


Seen by: MAGIC, VERITAS

• X-ray Intraday Variability of HBL Blazars with XMM-Newton
  Devanand, P.U. et al., arXiv e-prints parXiv:2209.05515 (2022) [LINK]
  
• Constraints on the extragalactic magnetic field strength from blazar spectra based on 145 months of Fermi-LAT observations
  Podlesnyi, E.I. et al., MNRAS 516 p5379-5388 (2022) [LINK]
  
• The intra-day Optical Monitoring of BL Lacerate Object 1ES 1218+304 at Its Highest X-ray Flux Level
  Sun, S.S. et al., arXiv e-prints parXiv:2104.00920 (2021) [LINK]
  
• Electron-proton co-acceleration on relativistic shocks in extreme-TeV blazars
  Zech, Andreas and Lemoine, Martin, arXiv e-prints parXiv:2108.12271 (2021) [LINK]
  
• Exploring the High-Energy Gamma-Ray Spectra of TeV Blazars
  Feng, Qi, arXiv e-prints parXiv:2108.05333 (2021) [LINK]
  
• Extragalactic background light models and GeV-TeV observation of blazars
  Singh, K.K. and Meintjes, P.J., arXiv e-prints parXiv:2004.01933 (2020) [LINK]
  
• Broadband Study of High-Synchrotron-Peaked BL Lac Object 1ES 1218+304
  Sahakyan, N., arXiv e-prints parXiv:2006.16030 (2020) [LINK]
  
• Studies of extragalactic background light with TeV BL Lacertae objects
  Longhua, Qin et al., MNRAS 499 p2662-2671 (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]
  
• VERITAS Observations of 1ES 1218+304 during the 2019 VHE High State
  Brien, S.O. for the VERITAS Collaboration, 36th International Cosmic Ray Conference (ICRC2019) p755 (2019) [LINK]
  
• Long term multi-wavelength view of the blazar 1ES 1218+304
  Singh, K.K. et al., arXiv e-prints parXiv:1909.02777 (2019) [LINK]
  
• Variability Study of Extreme Blazars with VERITAS
  Gueta, O. for the VERITAS Collaboration, 36th International Cosmic Ray Conference (ICRC2019) 36 p689 (2019) [LINK]
  
• Highlights from the VERITAS AGN Observation Program
  Benbow, Wystan, arXiv e-prints parXiv:1909.05323 (2019) [LINK]
  
• Search for decaying eV-mass axion-like particles using gamma-ray signal from blazars
  Korochkin, A. et al., arXiv e-prints parXiv:1911.13291 (2019) [LINK]
  
• X-ray Flux and Spectral Variability of Six TeV Blazars with NuSTAR
  Pandey, A. 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]
  
• Search for Magnetically Broadened Cascade Emission From Blazars with VERITAS
  VERITAS Collaboration et al., ArXiv e-prints p (2017) [LINK]
  
• The NuSTAR view on Hard-TeV BL Lacs
  Costamante, L. et al., ArXiv e-prints p (2017) [LINK]
  
• Constraints on the Intergalactic Magnetic Field with Gamma-Ray Observations of Blazars
  Finke, J.D. et al., ArXiv e-prints p (2015) [LINK]
  
• Search for TeV Gamma-ray emission from blazar 1ES1218+304 with TACTIC telescope during March-April 2013
  Singh, K.K. et al., ArXiv e-prints p (2014) [LINK]
  
• A hadronic origin for ultra-high-frequency-peaked BL Lac objects
  Cerruti, M. et al., ArXiv e-prints p (2014) [LINK]
  
• VERITAS Long-Term Observations of Hard Spectrum Blazars
  Madhavan, A.S. and for the VERITAS Collaboration, ArXiv e-prints p (2013) [LINK]
  
• Extragalactic magnetic fields constraints from simultaneous GeV-TeV observations of blazars
  Taylor, A.M. et al., A&A 529 pA144+ (2011) [LINK]
  
• X-ray variability patterns in blazars
  Moraitis, K. and Mastichiadis, A., A&A 525 pA40+ (2011) [LINK]
  
• Very high-energy observations of the two high-frequency peaked BL Lac objects 1ES 1218+304 and H 1426+428
  C. Mueller et al., Astroparticle Physics 34 p674 - 678 (2011) [LINK]
  
• Rapid optical variability of TeV blazars
  Gopal-Krishna et al., ArXiv e-prints p (2011) [LINK]
  
• Highlights of the VERITAS Blazar Observation Program
  Wystan Benbow for the VERITAS Collaboration, ArXiv e-prints p (2011) [LINK]
  
• Observation of the BL Lac objects 1ES 1215+303 and 1ES 1218+304 with the MAGIC telescopes
  Colin, P. et al., ArXiv e-prints p (2011) [LINK]
  
• MAGIC Telescopes observation of the BL Lac objects 1ES 1215+303 and 1ES 1218+304
  Lombardi, S. et al., ArXiv e-prints p (2011) [LINK]
  
• Modelling the variability of 1ES1218+30.4
  Weidinger, M. and Spanier, F., A&A 515 pA18+ (2010) [LINK]
  
• Discovery of Variability in the Very High Energy Gamma-Ray Emission of 1ES 1218+304 with VERITAS
  Acciari, V.A. et al., ApJ 709 pL163-L167 (2010) [LINK]
  
• Spectral modelling of 1 ES 1218+30.4
  Ruger, M. et al., MNRAS 401 p973-976 (2010) [LINK]
  
• VERITAS Observations of the BL Lac Object 1ES 1218+304
  Acciari, V.A. et al., ApJ 695 p1370-1375 (2009) [LINK]
  
• VERITAS Observations of the BL Lac Object 1ES 1218+304
  Fortin, P. and for the VERITAS Collaboration, ArXiv e-prints p (2008) [LINK]
  
• Constraints on Energy Spectra of Blazars based on Recent EBL Limits from Galaxy Counts
  Krennrich, F. et al., ApJ 689 pL93-L96 (2008) [LINK]
  
• Suzaku observation of TeV blazar the 1ES 1218+304: clues on particle acceleration in an extreme TeV blazar
  Sato, R. et al., 1085 p447-450 (2008) [LINK]
  
• Discovery of Very High Energy Gamma Rays from 1ES 1218+30.4
  Albert, J. et al., ApJ 642 pL119-L122 (2006) [LINK]
  
• The BeppoSAX View of Extreme BL Lacs
  Costamante, L. et al., p21 (2002) [LINK]
  
• Extreme synchrotron BL Lac objects. Stretching the blazar sequence
  Costamante, L. et al., A&A 371 p512-526 (2001) [LINK]
  

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