Proc. Neutrino Astrophysics - MPP Theory Group

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Crab flux
Figure 4: Gamma-ray flux above 1.5 TeV from the direction of the active galaxy Mkn 501,
determined with the HEGRA telescope 1. The various symbols are for different modes of
operation with and without ambient moon light. The time axis is given in mean Julian days
and extends from March 8 to October 13, 1997 (courtesy D. Kranich).
Projects for the Future
VHE astrophysics seems to be in a similar state as X-ray astronomy in the 1960s. The next
generation of telescopes which will combine higher angular resolution, larger mirror area and
stereoscopic imaging [15]. It will probably allow to detect on the order of hundreds of sources
and lower the energy threshold thus closing the present “gap” in detectable primary gamma
energy between satellites (up to 20 GeV presently) and ground based devices.
References
[1] T.C. Weekes et al., VERITAS proposal (1996).
[2] T.C. Weekes, Space Science Rev. 75, 1 (1996); M.F. Cawley, T.C. Weekes, Exp. Astr. 6,
7 (1996).
[3] D. Petry et al., Proc. Workshop “Towards a Major Atmospheric Cherenkov Detector
IV”, Padova, ed. M. Cresti, 141, (1995).
[4] M. Rivoal et al., Proc. 25th ICRC (Durban), 5, 145 (1997).
[5] W. Hofmann, astro-ph/9710297 (1997).