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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?

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Do you understand that the word "telescope" applied to non-optical light means a general instrument for detecting the emissions named and does not imply something like putting a gamma ray detector was put on the end of the Palomar scope? Indeed, some people describe IceCube as a "neutrino telescope" and it consists of a cubic kilometer of instrumented, deep, Antarctic ice. – dmckee♦ Jun 1 '12 at 14:02
But how else were Gamma Ray Bursts discovered, if not for telescopes? You can't deny that extremely distant (undetectable to the human eye) Supernovae were sighted only with the help of powerful telescopes. And presumably GRB were discovered at the same time due to simultaneous occurrence. – Graviton Jun 1 '12 at 14:10
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I was asking if you understand what the phrase "gamma-ray telescope" implies? The nature and phrase of your questions suggest--to me--that you many have misunderstood what that instrument is and how it works. Neither optical nor radio telescopes where involved in the discovery of GRBs. – dmckee♦ Jun 1 '12 at 14:14
I guess the core of the question is: is top limit of gamma caused by nature or by capability of instruments ? – Rocket Surgeon Jun 2 '12 at 17:26
Not exactly, I'm pretty sure the maximum limit occurs naturally. The question is not about existence, but perception. – Graviton Jun 2 '12 at 18:00

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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.

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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.

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