Cosmic gamma-rays astronomy studies the most catastrophic events in the Universe.
The flux of cosmic photons of Very High Energies (VHE 1010 -1014 eV) is very small and it could not be measured by any satellite detectors.
In ground-based apparatus the Earth atmosphere is used as a part of the detector to increase an effective area of the telescopes. Usually this kind of detector is an enormous complex composed of different sophisticated instruments (mechanics, optics, electronics, fast data registration and processing). The design, construction and exploration of such complexes is possible only working together inside big international collaborations of scientists.
The technical details and the performance of MAGIC telescopes may be found in:
- MAGIC (Major Atmospheric Gamma Imaging Cherenkov) complex consists of two 17 m diameter, F/D=1.03 Imaging Atmospheric Cherenkov Telescopes (IACT). The system detects cosmic gamma rays in very high energy range (30 GeV to 100 TeV) with the next performance in dark-time observations:
- Sensitivity for point-like sources (<0.1 deg): 0.8% the flux of the Crab nebula above 0.2 TeV in 50 hours of observation
- Energy threshold: ~75 GeV
- Energy resolution: about 20% per incoming gamma ray.
- Angular resolution: better than 0.1 deg per incoming gamma ray.
Three active international Cherenkov telescope experiments H.E.S.S., MAGIC and VERITAS joined their efforts to construct a unique apparatus – Cherenkov Telescope Array (CTA). We have been working on this project since 2009, inside CTA Consortium consisting of 1200 scientists from 32 countries.
The experiment will have two sites: in south hemisphere – Chile Atacama desert near ESO’s Paranal Observatory; in north hemisphere – La Palma island from Canary Islands, close to MAGIC telescopes (
CTA is planning to build 40 Medium-Sized Telescopes (MSTs). Eight Large-Sized Telescopes (LSTs) and 70 Small-Sized Telescopes (SSTs) For more technical details please look the following links:https://www.cta-observatory.org/project/technology/ https://magic.mpp.mpg.de/newcomers/introduction0/
Bulgarian participants of CTA, most of whom have been official members of MAGIC for 15 years, participate mainly in design and construction of northern part of the project. In 2018 there was an official inauguration of the prototype of the Large Size Telescope – LST1.
The commissioning of the telescope will continue for about one year. Many technical tests, corrections and control observation will be done. The simultaneous observation with MAGIC telescopes are already scheduled. There will be joint detection of triggered signals and pointing information from MAGIC and LST1.
Student Astronomical Observatory Plana (SAO Plana)
The observatory is situated close to Sofia in Plana mountain. The main goal of the observatory is to teach student from Sofia University and involve them in real research.
SAO Plana is equipped with a 35 cm Newton telescope (Orion Optics VX14 Newtonian, 350/1600 mm, f/D=4.6) with guiding system and a STL 11000M CCD-camera with UBVRI-band filters. Full automation of the Observatory is currently in place to allow remote observations. The test of the optical system of SAO Plana proved that the obtained astronomical images are with high quality and the data can be used for a wide range of scientific studies. Pixel size is 1.16 arcsec and the useful field of view (not aberrated by optical coma) has a diameter of over 40 arcmin. The wide field of view and the good aperture of the optical system at SAO Plana allow the realization of numerous scientific studies, related to observations of novae in close galaxies, active galactic nuclei, different types of variable stars, exoplanets, Galactic star clusters, Solar System bodies and others. SAO Plana is especially suited for providing optical data while taking part in global multiwavelength observational campaigns, aimed at various astronomical objects.
Here we describe shortly the activity of Bulgarian consortium and equipment we plan to have in our institutes. The main goals of our efforts are:
- to provide the maximum possibility to Bulgarian groups to participate in construction of this unique international observatory (international face-to-face and online meetings with other colleagues, technical and observational shifts on telescopes in situ)
- to train students and young researchers – the project will continue for more than 20 years
- to develop innovative methods (artificial intelligence approaches) for data analysis, which could be used in Cherenkov technique analysis and transferred to other research fields.