Gamma Ray Bursts What is the maximum frequency of the Gamma Rays produced during supernovae? And how are these detected by telescopes without getting some serious damage done?
 A: There is the ground based observatory ( nice picture) Veritas.

VERITAS (Very Energetic Radiation Imaging Telescope Array System) is a major ground-based gamma-ray observatory located at the basecamp of the Fred Lawrence Whipple Observatory in southern Arizona, designed to observe and study very-high-energy (VHE) gamma-rays (energies above ~100 GeV).
Because it is very difficult to produce gamma-rays, the objects that emit them are very interesting to astrophysicists. High-energy gamma rays are associated with exploding stars (supernovae), pulsars , quasars , and black holes rather than with ordinary stars or galaxies.

There is the space based Fermi Large Area Telescope

The LAT is an imaging high-energy gamma-ray telescope covering the energy range from about 20 MeV to more than 300 GeV. Such gamma rays are emitted only in the most extreme conditions, by particles moving very nearly at the speed of light. The LAT's field of view covers about 20% of the sky at any time, and it scans continuously, covering the whole sky every three hours.
Currently the LAT scientific collaboration includes more than 400 scientists and students at more than 90 universities and laboratories in 12 countries. The collaboration has published papers on pulsars, active galactic nuclei, globular clusters, cosmic-ray electrons, gamma-ray bursts, binary stars, supernova remnants, diffuse gamma-ray sources and other subjects.

A recent analysis of 130GeV gammas mentioned in a blog drew my attention to it.
So the energies detected go fairly high and there are means of measuring the energetic photons, developed for the earth bound accelerators.
A: A quick Google for "gamma ray burst spectrum" found lots of hits including http://arxiv.org/abs/1201.2981, which contains a collection of spectra from gamma ray bursts in the appendix. The maximum energies detected are around 10MeV, which seems a lot but remember that the LHC accelerates particles to around a million times more energy than this.
Remember that although GRBs are fantastically energetic, they're a long long way away, so by the time the radiation reaches the earth it's so weak that it can't do any damage. Given the debate in the comments about what constitutes a gamma ray telescope you might like to have a look at http://www.nasa.gov/mission_pages/swift/main/index.html. This describe the NASA Swift satellite, which is used to detect GRBs.
