J. M. McKenny

VHE gamma rays from binary systems

With new generation VHE telescopes, X-ray binary systems become very promising targets for VHE γ-ray observations. In particular, if sources with relativistic jets are thought of as galactic analogues of AGNs, the acceleration mechanisms should be similar. We survey the prospects of studying these objects with HESS, particularly in the context of multiwavelength studies.

Atmospheric sensing for atmospheric Cherenkov telescopes

The atmospheric Cherenkov technique is unique in that the atmosphere is an integral part of the detector. A realistic goal for the next generation of telescopes is to make energy assignments and flux determinations to better than 10%. We discuss the requirements for atmospheric monitoring that will be necessary to achieve this and look forward to how these requirements can be implemented.

VHE observations of high energy peak BL Lacs

The Durham Mark 6 Cherenkov telescope has been used to observe a number of high energy peak BL Lacs (HBLs). Upper limits to the very high energy (VHE) gamma ray flux detected from PKS 0548−322, PKS 2005−489 and 1ES 1101−232 are presented. PKS 2155−304, which had previously been detected in VHE gamma rays, was observed in 1999. The data are consistent with possible bursts of VHE emission, but a final statement will only be possible once data from contemporary RXTE pointed observations are available. An upper limit for the average flux output during these observations is presented.

Geomagnetic effects on atmospheric Cherenkov images

Atmospheric Cherenkov telescopes are used to detect electromagnetic showers from primary gamma rays and to discriminate these from cascades due to hadrons using the Cherenkov images. The geomagnetic field affects the development of showers and is shown to diffuse and distort the images and the effects should be included in interpreting the observations.