PG 1553+113

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) MACE (32.78) 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:	PG 1553+113
TeVCat Name:	TeV J1555+111
Other Names:	1ES 1553+113, HESS J1555+111
Source Type:	HBL
R.A.:	15 55 44.7 (hh mm ss)
Dec.:	+11 11 41 (dd mm ss)
Gal Long:	21.92 (deg)
Gal Lat:	43.96 (deg)
Distance:	z=
Flux:	0.034 (Crab Units)
Energy Threshold:	300 GeV
Spectral Index:	4.5
Extended:	No
Discovery Date:	2006-03
Discovered By:	H.E.S.S.
TeVCat SubCat:	Default Catalog

Source Notes:

Source position and its uncertainty:

From Aharonian et al. (2008):
- RA (J2000): 15 55 44.7 +/- 3.0s(stat) +/- 1.3s(syst)
- Dec (J2000): +11 11 41 +/- 53"(stat) +/- 20"(syst)

Distance:

The redshift of this source is uncertain.

From Dorigo Jones et al. (2021):
- "Here, we significantly improve the precision of indirect redshift
constraints for blazars based on the edge of the HI-Ly-alpha forest
observed in their UV spectra. We develop a robust technique to
constrain the redshift of a z<0.5 AGN or blazar with a 1 sigma
uncertainty of approx. 0.01 using only the position of its
highest-redshift Ly-alpha absorber with log N_HI/cm^-2 > 12.6."
- "We present new COS NUV data for 1ES1553+113 and confirm its
redshift of z=0.433 using our technique."

From Zahoor et al. (2021):
- In this work, the effect of the absorption of the extragalactic
galactic background light was used to place constraints on the
redshifts of gamma-ray sources.
- "The very high energy (VHE) gamma-ray spectral indices of blazars
show strong correlation with the source redshift. Absence of any such
correlation in low energy gamma rays and X-rays indicate the presence
of Extragalactic Background Light (EBL) induced absorption of VHE
gamma rays. By employing a linear regression analysis, this
observational feature of blazars is used to constrain the redshift of
BL Lac objects which was unknown/uncertain earlier."
- Two different regression relations were used to constrain the source
redshift and the following values were found for PG 1553+113:
- z = 0.38 +/- 0.10
- z = 0.33 +/- 0.08

From Nicastro (2018):
- "In this contribution we first summarize the fidings from our recent
discovery of two intervening OVII-bearing absorption systems along the
line of sight to the blazar 1ES 1553+113, at redshifts z = 0.3551 and
z = 0.4339"

From Abramowski et al. (2015):
- "The most probable redshift found with this method is z = 0.49 +/- 0.04,
in good agreement with the independent measure of Danforth
et al. (2010)."

From Aliu et al. (2014):
- "When accounting for EBL evolution using the approach described (in
reference above), the 95% confidence level upper limit on the redshift
of PG 1553+115 is z<=0.62"

From Landoni et al. (2014):
- "We secured optical and near-infrared medium-resolution spectra of
four bright BL Lac objects of unknown redshift using the spectrograph
X-Shooter at the ESO-VLT."
- "In spite of the high quality of the spectra and the extended
spectral range of the observations, we have not detected intrisic
spectral features for these sources. However, we are able to provide
strigent lower limits to their redshift." (For two TeV sources: PG 1553+113
and H 1722+119)
- For PG 1553+113 they inferred z > 0.30

From Danforth et al. (2010):
- This distance estimate constrains the redshift to z > 0.400,
specifically putting it in the range: 0.43 - 0.58.

From Yang & Wang (2010):
- an upper limit of 0.78 is placed on the redshift of this object.

Spectral Properties:

From Abramowski et al. (2015):
- Spectral index: 4.8 +/- 0.2 (stat) +/- 0.2 (syst) (power law; pre-flare)
... a log-parabola model was also fit to the pre-flare data
- Spectral index: 4.9 +/- 0.3 (stat) +/- 0.2 (syst) (power law; flare)

From Aliu et al. (2014):
- Spectral index: 4.33 +/- 0.09

From Benbow et al. (2011):
- Spectral index: 4.41 +/- 0.14

From Aharonian et al. (2008):
- Spectral index: 4.5 +/- 0.3(stat) +/- 0.1(syst)

From Albert et al. (2008):
- Spectral index: 4.1 +/- 0.3

Flux:

From Aliu et al. (2014):
- Fluxes of between 5.5% and 10.3% of the Crab are reported

From Benbow et al. (2011):
- a flux of 10% that of the Crab is reported

From Aharonian et al. (2008):
- a flux of 3.4% that of the Crab is reported

Information on the jet:

From Lister et al. (2019):
- "We were unable to identify any robust jet features in this BL Lac object."


Seen by: H.E.S.S., MAGIC, VERITAS

• Constraining the redshift of PG 1553+113 using the photohadronic model
  Sahu, Sarira et al., arXiv e-prints parXiv:2503.22874 (2025) [LINK]
  
• Periodic Gamma-ray Modulation of the blazar PG 1553+113 Confirmed by Fermi-LAT and Multi-wavelength Observations
  Abdollahi, S. et al., arXiv e-prints parXiv:2501.08015 (2025) [LINK]
  
• Unveiling the periodic variability patterns of the X-ray emission from the blazar PG 1553+113
  Aniello, T. et al., A&A 686 pA300 (2024) [LINK]
  
• The variability patterns of the TeV blazar PG 1553 + 113 from a decade of MAGIC and multiband observations
  MAGIC Collaboration et al., MNRAS 529 p3894-3911 (2024) [LINK]
  
• X-Ray Spectroscopy of Interstellar Carbon: Evidence for Scattering by Carbon-bearing Material in the Spectrum of 1ES 1553+113
  Staunton, John and Paerels, Frits, ApJ 949 p26 (2023) [LINK]
  
• Evidence of Periodic Variability in Gamma-ray Emitting Blazars with Fermi-LAT
  Pe�il, P. et al., arXiv e-prints parXiv:2211.01894 (2022) [LINK]
  
• Search for periodicities in High Energy AGNs with a time-domain approach
  Rueda, Hector et al., arXiv e-prints parXiv:2206.07614 (2022) [LINK]
  
• High-energy neutrinos from X-rays flares of blazars frequently observed by the Swift X-Ray Telescope
  Stathopoulos, S.I. et al., arXiv e-prints parXiv:2111.09320 (2021) [LINK]
  
• Improving blazar redshift constraints with the edge of the Ly-alpha forest: 1ES 1553+113 and implications for observations of the WHIM
  Dorigo Jones, J. et al., arXiv e-prints parXiv:2111.06927 (2021) [LINK]
  
• Model-independent Redshift Estimation of BL Lac Objects through VHE Observations
  Zahoor, Malik et al., arXiv e-prints parXiv:2110.15953 (2021) [LINK]
  
• The X-ray outburst of PG 1553+113: A precession effect of two jets in the supermassive black hole binary system
  Huang, Shifeng et al., arXiv e-prints parXiv:2110.01769 (2021) [LINK]
  
• Multi-band Variability of the TeV Blazar PG 1553+113 with XMM-Newton
  Dhiman, Vinit et al., arXiv e-prints parXiv:2106.08514 (2021) [LINK]
  
• MAGIC detection of an increased activity from PG 1553+113 in very-high-energy gamma rays
  Blanch, O. on behalf of the MAGIC collaboration, The Astronomer's Telegram 14520 p1 (2021) [LINK]
  
• The implications of the axion like particle from the Fermi-LAT and H.E.S.S. observations of PG 1553+113 and PKS 2155-304
  Guo, Junguang et al., arXiv e-prints parXiv:2002.07571 (2020) [LINK]
  
• A parsec-scale wobbling jet in the high-synchrotron peaked blazar PG 1553+113
  Lico, Rocco et al., arXiv e-prints parXiv:2001.01753 (2020) [LINK]
  
• Systematic search for gamma-ray periodicity in active galactic nuclei detected by the Fermi Large Area Telescope
  Penil, P. et al., arXiv e-prints parXiv:2002.00805 (2020) [LINK]
  
• Multi-band behaviour of the TeV blazar PG 1553+113 in optical range on diverse timescales
  Agarwal, A. et al., arXiv e-prints parXiv:2011.04074 (2020) [LINK]
  
• Gaussian Process Modeling Fermi-LAT gamma-ray Blazar Variability: A Sample of Blazars with gamma-ray Quasi-periodicities
  Yang, Shenbang et al., arXiv e-prints parXiv:2011.10186 (2020) [LINK]
  
• Looking at Blazar Light Curve Periodicities with Gaussian Processes
  Covino, Stefano et al., arXiv e-prints parXiv:2004.10763 (2020) [LINK]
  
• The Physical Origins of the Identified and Still Missing Components of the Warm-Hot Intergalactic Medium: Insights from Deep Surveys in the Field of Blazar 1ES1553+113
  Johnson, Sean D. et al., arXiv e-prints parXiv:1909.11667 (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]
  
• Search for spectral features in extragalactic background light with gamma-ray telescopes
  Korochkin, A. et al., arXiv e-prints parXiv:1906.12168 (2019) [LINK]
  
• Evaluating Quasi-Periodic Variations in the gamma-ray Lightcurves of Fermi-LAT Blazars
  Ait Benkhali, F. et al., arXiv e-prints p (2019) [LINK]
  
• Optical Flux and Spectral Variability of the TeV blazar PG 1553+113
  Pandey, A., Gupta, A.C., Wiita, P.J., et al., arXiv e-prints p (2019) [LINK]
  
• Confirming the Detection of two WHIM Systems along the Line of Sight to 1ES 1553+113
  Nicastro, F., ArXiv e-prints p (2018) [LINK]
  
• The Blazar PG 1553+113 as a Binary System of Supermassive Black Holes
  Tavani, M. et al., ArXiv e-prints p (2018) [LINK]
  
• Quasi-periodicities of BL Lac Objects and Their Origin
  Sandrinelli et al., ArXiv e-prints p (2018) [LINK]
  
• Testing relativistic boost as the cause of gamma-ray quasi-periodic oscillation in blazar
  Yan, D. et al., ArXiv e-prints p (2018) [LINK]
  
• Multi-color optical monitoring of ten blazars from 2005 to 2011
  Meng, N. et al., ArXiv e-prints p (2018) [LINK]
  
• X-ray spectral variability of blazars using principal component analysis
  Gallant, D. et al., ArXiv e-prints p (2018) [LINK]
  
• Gamma-ray quasi-periodicities of blazars. A cautious approach
  Covino, S. 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]
  
• A search for cyclical sources of gamma-ray emission on the period range from days to years in the Fermi-LAT sky
  Prokhorov, D.A. and Moraghan, A., ArXiv e-prints p (2017) [LINK]
  
• Jet Precession Driven by a Supermassive Black Hole Binary System in the BL Lac Object PG 1553+113
  Caproni, A. et al., ApJ 851 pL39 (2017) [LINK]
  
• Highlights of the MAGIC AGN program
  Sitarek, J. and the MAGIC Collaboration, ArXiv e-prints p (2017) [LINK]
  
• Constraining the redshifts of TeV BL Lac objects
  Qin, L. et al., ArXiv e-prints p (2017) [LINK]
  
• Search for Magnetically Broadened Cascade Emission From Blazars with VERITAS
  VERITAS Collaboration et al., ArXiv e-prints p (2017) [LINK]
  
• Synchrotron emission from the blazar PG 1553+113. An analysis of its flux and polarization variability
  Raiteri, C.M. et al., ArXiv e-prints p (2016) [LINK]
  
• Gamma-ray blazar spectra with H.E.S.S. II mono analysis: the case of PKS 2155-304 and PG 1553+113
  Zaborov, D. et al., ArXiv e-prints p (2016) [LINK]
  
• Gamma-ray blazar spectra with H.E.S.S. II mono analysis: the case of PKS 2155-304 and PG 1553+113
  H.E.S.S. Collaboration et al., ArXiv e-prints p (2016) [LINK]
  
• A model for periodic blazars
  Sobacchi, E. et al., ArXiv e-prints p (2016) [LINK]
  
• Hadronic modeling of TeV AGN: gammas and neutrinos
  Cerruti, M. et al., ArXiv e-prints p (2016) [LINK]
  
• Multi-band optical variability of three TeV Blazars on Diverse Timescales
  Gupta, A.C. et al., ArXiv e-prints p (2016) [LINK]
  
• Probing the very high energy gamma-ray spectral curvature in the blazar PG 1553+113 with the MAGIC telescopes
  Aleksic, J. et al., MNRAS 450 p4399-4410 (2015) [LINK]
  
• Multiwavelength Evidence for Quasi-periodic Modulation in the Gamma-Ray Blazar PG 1553+113
  Ackermann, M. et al., ApJ 813 pL41 (2015) [LINK]
  
• The 2012 flare of PG 1553+113 seen with H.E.S.S. and Fermi-LAT
  Abramowski, A. et al., ArXiv e-prints p (2015) [LINK]
  
• Probe of Lorentz Invariance Violation effects and determination of the distance of PG 1553+113
  Sanchez, D.A. et al., ArXiv e-prints p (2015) [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]
  
• The WEBT campaign on the BL Lac object PG 1553+113 in 2013. An analysis of the enigmatic synchrotron emission
  Raiteri, C.M. et al., ArXiv e-prints p (2015) [LINK]
  
• Evidence for Quasi-periodic Modulation in the Gamma-ray Blazar PG 1553+113
  The Fermi Lat collaboration et al., ArXiv e-prints p (2015) [LINK]
  
• The Extragalactic sky with the High Energy Stereoscopic System
  D.A. Sanchez for the H.E.S.S. collaboration, ArXiv e-prints p (2015) [LINK]
  
• VERITAS Observations of the BL Lac Object PG 1553+113
  Aliu, E. et al., ArXiv e-prints p (2014) [LINK]
  
• Spectroscopy of BL Lacertae objects of extraordinary luminosity
  Landoni et al., A&A 570 pA126 (2014) [LINK]
  
• MAGIC and Swift detection of renewed activity from the blazar PG1553+113 during a MWL campaign
  Cortina, J. on behalf of the MAGIC Collaboration, The Astronomer's Telegram 3977 p1 (2012) [LINK]
  
• The MAGIC view of PG 1553+113
  Prandini et al., ArXiv e-prints p (2011) [LINK]
  
• VERITAS Observations of the BL Lac Object PG 1553+113 Between May 2010 and May 2011
  Orr, M. and for the VERITAS Collaboration, 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]
  
• Overview of the results from extra-galactic observations with the MAGIC telescopes
  Berger, K. and for the MAGIC Collaboration, ArXiv e-prints p (2011) [LINK]
  
• Polarization and photometric observations of the gamma-ray blazar PG 1553+113
  Andruchow, I. et al., ArXiv e-prints p (2011) [LINK]
  
• Rapid optical variability of TeV blazars
  Gopal-Krishna et al., ArXiv e-prints p (2011) [LINK]
  
• PG 1553+113: five years of observations with MAGIC
  The MAGIC Collaboration et al., ArXiv e-prints p (2011) [LINK]
  
• Redshifts of distant blazar limited by Fermi and VHE Gamma-ray observations
  Yang, J. and Wang, J., ArXiv e-prints p (2010) [LINK]
  
• Fermi Observations of the Very Hard Gamma-ray Blazar PG 1553+113
  Abdo, A.A. et al., ApJ 708 p1310-1320 (2010) [LINK]
  
• HST/COS Observations of the Ly alpha Forest toward the BL Lac Object 1ES1553+113
  Danforth, C.W. et al., ArXiv e-prints p (2010) [LINK]
  
• A new upper limit on the redshift of PG 1553+113 from observations with the MAGIC Telescope
  Prandini, E. et al., ArXiv e-prints p (2009) [LINK]
  
• Simultaneous multi-frequency observation of the unknown redshift blazar PG 1553+113 in March-April 2008
  MAGIC Collaboration: J. Aleksic et al., ArXiv e-prints p (2009) [LINK]
  
• MAGIC Observations of PG 1553+113 during a Multiwavelength Campaign in July 2006
  MAGIC Collaboration: Albert, ArXiv e-prints p (2008) [LINK]
  
• HESS observations and VLT spectroscopy of PG 1553+113
  Aharonian, F. et al., A&A 477 p481-489 (2008) [LINK]
  
• A method to correct IACT data for atmospheric absorption due to the Saharan Air Layer
  Dorner, D. et al., ArXiv e-prints 808 p (2008) [LINK]
  
• A Hard X-Ray View of Two Distant VHE Blazars: 1ES 1101-232 and 1ES 1553+113
  Reimer, A. et al., ApJ 682 p775-783 (2008) [LINK]
  
• Break in the Very High Energy Spectrum of PG 1553+113: New Upper Limit on Its Redshift?
  Mazin, D. and Goebel, F., ApJ 655 pL13-L16 (2007) [LINK]
  
• Detection of Very High Energy Radiation from the BL Lacertae Object PG 1553+113 with the MAGIC Telescope
  Albert, J. et al., ApJ 654 pL119-L122 (2007) [LINK]
  
• On the distance of PG 1553+11. A lineless BL Lacertae object active in the TeV band
  Treves, A. et al., A&A 473 pL17-L19 (2007) [LINK]
  
• Optical spectroscopy of BL Lacertae objects. Broad lines, companion galaxies, and redshift lower limits
  Sbarufatti, B. et al., A&A 457 p35-43 (2006) [LINK]
  
• Evidence for VHE gamma-ray emission from the distant BL Lac PG 1553+113
  Aharonian, F. et al., A&A 448 pL19-L23 (2006) [LINK]
  

Want a reference added? Send a bibtex entry to the TeVCat Team