2007/09/28 by W. Benbow, HESS Collaboration, C. Boisson +5
Engineering · Physics and Astronomy · #Astronomical Observations and Instrumentation #Astrophysical Phenomena and Observations #Astrophysics (astro-ph) #FOS: Physical sciences #Gamma-ray bursts and supernovae
paper · pdf · doi:10.48550/arxiv.0709.4602
openalex publication_date 2007/09/28 · openalex created_date 2021/02/15 · openalex updated_date 2026/07/28
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.