Unique Cherenkov telescopes have successfully been installed at the Ondřejov Observatory near Prague. There are two telescopes at the site, which are now the largest optical telescopes in the Czech Republic. They have been developed in the frame of the Cherenkov Telescope Array Observatory, and evaluated as performing telescopes in the high energy region above 1 TeV.
Using the telescopes, researchers have begun to observe night sky in order to detect the first sources of high energy gamma rays, with the main interest being now the remnants of a supernova SN 1054. This catastrophic death of star was observed e.g. by Chinese astronomers in the year 1054, and it is now known as the Crab Nebula.
The observation of the target is performed by both telescopes at the same time. This makes it possible for the researchers from the Czech Academy of Sciences to get a more precise reconstruction of the observed showers initiated by high energy gamma-ray photons. The combination of images taken by the telescopes provides the researchers with a 3D image of a secondary particle shower, enabling them to determine very precisely which direction the original gamma photon has come from.
“The telescope observation programme will help us answer some key question we have about the universe. Our main goal is to understand the way cosmic photon sources work. Their energy is very high – around 1 TeV (1 teraelectronvolt, 1012 eV, which is almost a trillion times larger than that of the visible light photons),” says the head of the SST-1M research team from the Institute of Physics of the Czech Academy of Sciences, Dr. Petr Trávníček.
After the apparatus is tested at the Ondřejov Observatory, the SST-1M Consortium aims to relocate the telescopes to another observation site located at a higher altitude. “The SST-1M Consortium was born out of an idea to create a 4m diameter telescope in a well-known optics configuration for a gamma-ray telescope, named Davies-Cotton. Our innovation effort concentrated on the telescope’s camera. The University of Geneva has expertise in project management, system engineering, photosensors, telescope control and data analysis,” says professor Teresa Montaruli from the Geneva University, the principal investigator of the international SST-1M project, about the involvement of the University of Geneva in the SST-1M Consortium.
The construction of the SST-1M telescopes would not have been possible without the involvement of Polish researchers. They managed to successfully resolve the telescope mechanical structure and the digital camera electronics. “The H. Niewodniczański Institute of Nuclear Physics in Poland has extensive experience in dealing with telescope motorised control and operation, as well as with the design of their mechanical structure. The University in Cracow has then developed the camera digital electronics,” says professor Jacek Niemiec from the Polish Academy of Sciences.
The optical part of the telescopes, including the manufacturing of high-quality reflective layers and precise alignment of all mirror segments, was the responsibility of researchers and technicians from the Institute of Physics of the Czech Academy of Sciences and the Palacky University who worked together with experts from the Astronomical Institute of the Czech Academy of Sciences to prepare the observation location at the Ondřejov site and to perform the telescope commissioning process.
More about the telescopes
The cooperation project to develop the SST-1M Cherenkov telescopes has been a joint effort of the Institute of Physics and the Astronomical Institute of the Czech Academy of Sciences, the Palacky University in Olomouc, the Henryk Niewodniczański Institute of Nuclear Physics of the Polish Academy of Sciences, University of Geneva and other institutions participating in the SST-1M Consortium.
The first telescope has been in its observation mode since 23 February 2022 when it detected its “first light”. The second telescope has detected its first cosmic ray showers on 19 April 2022 already in a linked observation mode (with both telescopes targeting the same source on the sky).