4 Cherenkov Telescopes for Optical SETI
25
Compared with the current Cherenkov observatories, which rely on few (2–5) telescopes, CTA represents an impressive leap-forward and will be one of the pillars of
future astronomy. Each observatory will be made up of different types of telescopes,
designed to detect photons of different energies.
Less energetic photons produce a relatively small and faint cone of light. To
detect them very large telescopes, positioned close to each other are needed. More
energetic photons instead produce a more brilliant burst of light which can be detected
by smaller telescopes spread on a large area. Four large-sized telescopes (23 m
diameter) will be placed at the centre of the array, surrounded by a dozen mediumsized telescopes (12 m diameter). In the Southern Hemisphere there will also be
many dozens of small-sized telescopes (4 m diameter) which will be spread out over
a very large area.
All in all, with an enormous collecting area, very big field of view, sensitive
detectors and powerful computers, CTA will bring the search for optical flashes to
an unprecedented level which will certainly open new windows for optical SETI as
well as for time domain astrophysics.
References
1. G. Cocconi, Results and problems concerning the extensive air showers. Rev. Mod. Phys. 21,
26 (1949)
2. G. Cocconi, On the origin of cosmic radiation. Phys. Rev. 83, 1193–1195 (1951)
3. P. Morrison, On gamma-ray astronomy. Il Nuovo Cimento 7, 858–865 (1958)
4. W. Galbraith, J.V. Jelley, Light pulses from the night sky associated with cosmic rays. Nature
171, 349–350 (1953)
5. P.A. Caraveo, The golden age of high-energy gamma-ray astronomy: the Cherenkov telescope
array in the multimessenger era. La Rivista Del Nuovo Cimento 43, 281–318 (2020)
6. G. Cocconi, P. Morrison, Searching for interstellar communications nature, vol. 184 (1959),
pp. 844–846
7. R.N. Schwartz, C.H. Townes, Interstellar and interplanetary communications by optical masers.
Nature 190, 205–208 (1961)
8. C.H. Townes, At what wavelengths should we search for signals from extraterrestrial
intelligence? Proc. Nat. Acad. Sci. 89, 1147–1151 (1983)
9. https://breakthroughinitiatives.org/
10. D. Eichler, G. Beskin, Optical search for extraterrestrial intelligence with air Cerenkov
telescopes. Astrobiology 1, 489–493 (2001)
11. A.U. Abeysekara et al., (VERITAS collaboration) a search for brief optical flashes associated
with SETI target KIC 8462852. ApJ. 818, L33-38 (2016)
12. B.S. Acharya et al., CTA consortium. Intro. CTA Concept Astroparticle Phys. 43, 3–18 (2013)
25
Compared with the current Cherenkov observatories, which rely on few (2–5) telescopes, CTA represents an impressive leap-forward and will be one of the pillars of
future astronomy. Each observatory will be made up of different types of telescopes,
designed to detect photons of different energies.
Less energetic photons produce a relatively small and faint cone of light. To
detect them very large telescopes, positioned close to each other are needed. More
energetic photons instead produce a more brilliant burst of light which can be detected
by smaller telescopes spread on a large area. Four large-sized telescopes (23 m
diameter) will be placed at the centre of the array, surrounded by a dozen mediumsized telescopes (12 m diameter). In the Southern Hemisphere there will also be
many dozens of small-sized telescopes (4 m diameter) which will be spread out over
a very large area.
All in all, with an enormous collecting area, very big field of view, sensitive
detectors and powerful computers, CTA will bring the search for optical flashes to
an unprecedented level which will certainly open new windows for optical SETI as
well as for time domain astrophysics.
References
1. G. Cocconi, Results and problems concerning the extensive air showers. Rev. Mod. Phys. 21,
26 (1949)
2. G. Cocconi, On the origin of cosmic radiation. Phys. Rev. 83, 1193–1195 (1951)
3. P. Morrison, On gamma-ray astronomy. Il Nuovo Cimento 7, 858–865 (1958)
4. W. Galbraith, J.V. Jelley, Light pulses from the night sky associated with cosmic rays. Nature
171, 349–350 (1953)
5. P.A. Caraveo, The golden age of high-energy gamma-ray astronomy: the Cherenkov telescope
array in the multimessenger era. La Rivista Del Nuovo Cimento 43, 281–318 (2020)
6. G. Cocconi, P. Morrison, Searching for interstellar communications nature, vol. 184 (1959),
pp. 844–846
7. R.N. Schwartz, C.H. Townes, Interstellar and interplanetary communications by optical masers.
Nature 190, 205–208 (1961)
8. C.H. Townes, At what wavelengths should we search for signals from extraterrestrial
intelligence? Proc. Nat. Acad. Sci. 89, 1147–1151 (1983)
9. https://breakthroughinitiatives.org/
10. D. Eichler, G. Beskin, Optical search for extraterrestrial intelligence with air Cerenkov
telescopes. Astrobiology 1, 489–493 (2001)
11. A.U. Abeysekara et al., (VERITAS collaboration) a search for brief optical flashes associated
with SETI target KIC 8462852. ApJ. 818, L33-38 (2016)
12. B.S. Acharya et al., CTA consortium. Intro. CTA Concept Astroparticle Phys. 43, 3–18 (2013)