Cherenkov Telescope Array

HEGRA Data Processing

HEGRA Atmospheric Cherenkov Telescope System

The HEGRA experiment was located on the Canary Island of La Palma (28.75 N, 17.89 W, 2200 m a.s.l.) and consisted of several parts, including the HEGRA Atmospheric Cherenkov Telescope System.

In 1992 the first HEGRA prototpye telescope CT1 started operation. The full HEGRA system consisted of 5 identical telescopes, each having 8.5 square meters mirror reflector area and a camera of 271 pixels, made of photomulipliers. The telescopes were arranged on a square of 100 m side length with an additional telescope in the center of the square. HEGRA was operated until 2002.

HEGRA Data Processing

The read_dst program calculates the event parameters (event ASCII file) from the image parameters (dst file) with the help of some configuration files. These event parameters are first stored in an ASCII format. They are then reformatted to the standard astronomical data format FITS by the evt_ascii2fits program. This enables the usage of standard FTOOLS to examine the HEGRA event data.

Trigger files, available for each source, define the list of event files used to produce the results. For every trigger file, i.e. for every source, the event2result program calculates three images and three light curves for different energy bands. The results, images as well as light curves, are stored in FITS files.