Viktor Ambartsumian (1908-1996) was one of the greatest astronomers and scientists of the 20^th century, he revolutionized our views on the evolution and dynamics of the Universe. Our perception and further investigation of the non-stable phenomena in the Universe is due to Ambartsumian’s efforts and contribution in science that is why the anniversary meeting is entitled “Non-Stable Phenomena in the Universe”. Ambartsumian carried out basic research in Astronomy and Cosmogony. It covered Astrophysics, Theoretical Physics and Mathematical Physics, and mostly focused on the physics of nebulae, star systems, and extragalactic astronomy. He particularly developed the theory of the Planetary Nebulae. He is best known for having discovered the Stellar Associations and predicted Activity of Galactic Nuclei, which became the most important topic of the extragalactic astronomy. Ambartsumian introduced important Statistical Methods to predict the total number of eruptive stars in stellar aggregates. In his later career, Ambartsumian held views in contradiction to the consequences of the general relativity, such as rejecting the existence of black holes and suggesting Superdense Matter that conditions the activity of stars and galaxies.

The Byurakan Astrophysical Observatory (BAO) is one of the main observational centers of the Former Soviet Union and is an important observatory with modern facilities in the region. It was founded in 1946 by one of the greatest astrophysicists of the 20^th century V. A. Ambartsumian and at present is recognized as an Armenian National Value. It is well known for its large spectroscopic surveys: First and Second Byurakan Surveys (FBS and SBS), undertaken by B. E. Markarian and his colleagues. BAO hosts a number of medium-size optical telescopes, the most important being the 2.6m classical telescope and 1m Schmidt telescope. BAO holds the Digitized First Byurakan Survey (DFBS, or the Digitized Markarian survey, completed in 2002-2007), containing low-dispersion spectra of ~20,000,000 objects, largest number in the world, which is the basis of the Armenian Virtual Observatory (ArVO, created in 2005), a member of the International Virtual Observatory Alliance (IVOA). In 2011, Markarian Survey has been included in UNESCO’s “Memory of the World” Documentary Heritage International Register. Since 2015, Armenia and BAO also host an IAU South West and Central Asian Regional Office of Astronomy for Development (SWCA ROAD). In frame of this initiative, a number of activities are being held, including regional workshops, conferences for young astronomers, summer schools, exchange of young astronomers, etc. In 2021, BAO was included in the IAU Outstanding Astronomical Heritage (OAH) list.

BAO is famous for organization of Meetings and Summer Schools. 7 IAU meetings (6 Symposia and a Colloquium) have been organized by BAO in 1966, 1986, 1989, 1998, 2001 and 2013, as well as a new IAU Symposium (#365) is being organized on 21-25 August 2023. The European Annual Meeting JENAM was organized in Armenia in 2007 with 8 parallel symposia and 6 special sessions. New initiatives and subjects were introduced here related to inter- and multi- disciplinary sciences. The first International Conference on CETI was organized here in 1971. The conference “Relation of Astronomy to other Sciences, Culture and Society” was held in 2014. The international symposium “Astronomical Surveys and Big Data” (ASBD) was organized in 2015 with participation of astronomers and computer scientists and another such meeting (ASBD-2) was held in 2020. An international conference “Astronomical Heritage of the Middle East” supported by UNESCO was organized in 2017. In 2022, Armenia hosted the European Astronomy & Astrophysics (A&A) journal Board of Directors meeting. In addition, there is a series of Byurakan International Summer Schools (BISS) that started in 2006 and already 8 such schools have been organized in 2006, 2008, 2010 (combined with IAU International School for Young Astronomers, ISYA), 2012, 2016, 2018, 2020 and 2022. We also have organized ESO-Byurakan International School on Observational Astronomy in 1987. The Regional Astronomical Summer School (RASS) series was started in 2019 and such schools are being organized every 2 years between the BISS. The 3^rd RASS will be held on 11-15 Sep 2023.

The Meeting is also linked to the 3^rd Regional Astronomical Summer School (3RASS/1IRASS) to be held on 11-15 Sep 2023 in Byurakan, so that the participants of the School may attend both events, as well as some invited lecturers of the School may participate in the Conference.

The Venue of the meeting is the Byurakan Astrophysical Observatory (BAO). English is the working language of the Conference. Some support is possible for young participants and others in exceptional cases, both waiving the Registration Fees, Accommodation at BAO Guest House and some other local expenses. Please follow the Registration Form.