Abstract
The Crab Nebula is one of the most studied objects in astrophysics with observations extending over the complete detectable range of the electromagnetic spectrum, from radio waves to TeV γ-rays. Its broad spectral energy distribution is unique and is mainly attributed to non-thermal, synchrotron and inverse Compton, emission processes. Of the confirmed sources of TeV γ-rays, the Crab Nebula is the only object with both steady and strong emission. Consequently, in addition to its use as an important astrophysical laboratory, it has become the de facto calibration source in TeV astrophysics. The Crab is regularly observed by all atmospheric Cherenkov telescopes, with the goal of refining the observing techniques.
Observations by the Solar Tower Atmospheric Cherenkov Effect Experiment (STACEE) in 1998 and 1999 yielded a solid excess of 6.8 σ from the Crab Nebula in 43 hours of on-source exposure. Since then the STACEE detector has undergone several important optical and electronic upgrades, including a doubling of the number of heliostats from 32 to 64 and installation of Flash Analog-to-Digital Convertors (FADSs). During the 2002-2003 and 2003-2004 observing seasons, the upgraded STACEE detector, known as STACEE-64, undertook observations of the Crab Nebula and Pulsar. The primary motivation for these observations was to aid in the characterization of the upgraded instrument, while simultaneously providing data for a pulsed emission analysis. We report here on a detection of the Crab Nebula using these data and on the result of our search for pulsed emission from the Crab Pulsar.
