Multi-wavelength Observations of PG 1553+113 with HESS

HESS Collaboration; W. Benbow; C. Boisson; R. Buehler; H. Sol

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arXiv · 0709.4602

Multi-wavelength Observations of PG 1553+113 with HESS

HESS Collaboration·W. Benbow·C. Boisson·R. Buehler·H. Sol

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Abstract

Very high energy (VHE; >100 GeV) gamma-ray observations of PG 1553+113 were made with the High Energy Stereoscopic System (HESS) in 2005 and 2006. A strong signal, ~10 standard deviations, is detected by HESS during the 2 years of observations (24.8 hours live time). The time-averaged energy spectrum, measured between 225 GeV to ~1.3 TeV, is characterized by a very steep power law (photon index of Gamma = (4.5 +- 0.3 {stat} +- 0.1 {syst}). The integral flux above 300 GeV is ~3.4% of the Crab Nebula flux and shows no evidence for any variations, on any time scale. H+K (1.45-2.45 micron) spectroscopy of PG 1553+113 was performed in March 2006 with SINFONI, an integral field spectrometer of the ESO Very Large Telescope (VLT) in Chile. The redshift of PG 1553+113 is still unknown, as no absorption or emission lines were found.

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HESS Collaboration, W. Benbow, C. Boisson, R. Buehler, H. Sol. 2007-09-28. Multi-wavelength Observations of PG 1553+113 with HESS. https://arxiv.org/abs/0709.4602

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