УДК 520.1 ANCIENT ASTRONOMICAL OBSERVATORIES IN BULGARIA 1P. Maglova*, 2A. Stoev** [email protected],**[email protected] 1Space Research and Technology Institute, Bulgarian Academy of Sciences Zagora Department 2Yuri Gagarin Public Astronomical Observatory Stara Zagora, Bulgaria Abstract. In this paper we consider several types of monuments, which yield evi- dence for the astronomical practices and beliefs of peoples from the Eneolithic (Chalcolith- ic) and later epochs – Belintash, Tatul, Tangarduk Kaya, Harman Kaya, Kovil, and Par- makla Kaya in East Rhodopes, Tsarevi Porti in West Rhodopes, Zaychi Vruh (Cabyle) and Buzovgrad in the Sredna Gora mountain, Markov kamak in the Rila mountain, and Lilyach in the Konyavska mountain. Discussing these specific monuments, we show how astronomy was woven into everyday and spiritual life, revealing insights into people’s concepts of space and time. These monuments, where positional systems for Sun observa- tions are discovered, we call ancient astronomical observatories. Keywords: Ancient astronomical observatories, Rock-cut monuments, sanctuaries, Positional systems for Sun observations, Great Mother-Goddess, equinox and solstice, calendar. For citation: Maglova P.V., Stoev A.D. Ancient astronomical observatories in Bul- garia. Heritage and Modern Times. 2020;3(3):85–98. Introduction People have always contemplated their environment, including the sky and celestial phenomena. They acted in accordance with these phenom- ena, reflected them in their places of habitation and constructed their worldviews. From the Early Prehistory to the Neolithic and Eneolithic basic astronomical knowledge is transformed into suitable systems of time- reckoning and cosmographic models. The Eneolithic age (5000–3000 BC) is one of the brightest periods in Prehistory in the Bulgarian lands. According to experts, in this era very an- cient ethnicity and complex culture was born [1; 2]. Hundreds Eneolithic settlements were found in Bulgaria – they are well built, with streets orient- ed according to the cardinal directions, protected by wooden or clay fence. Further, during the Bronze Age (3100–1200 BC) a process of gradually im- proving of the economy and evolution of the socio-economic life takes place in Bulgarian lands. At that time creation of megalithic and rock-cut monu- ments blossomed [3]. The rock-cut monuments – sanctuaries and tombs are the only almost completely preserved representatives of monumental religious architecture of the ancient people from the Eneolithic to the end of the Iron Age in Ancient Thrace. © Maglova P.V., Stoev A.D., 2020 85 НАСЛЕДИЕ И СОВРЕМЕННОСТЬ 2020;3(3):85–98 Ancient observatories and their archaeoastronomical research The study of the spatial organisation of the monuments and the exist- ence of obvious linear and circular structures offer sufficient and serious data about the existence of orientations, targets and solar-cult architecture. That is why the rock-cut monuments and cave sanctuaries became an object of independent archaeoastronomical research [4]. It is based on our knowledge about the place of astronomy in the culture of ancient archaic societies who lived on these lands, as well as on registration, analysis and interpretation of their structural elements. These investigations allow us to learn about astronomical knowledge, practices, art, belief, custom, under- standings, and values of the societies who lived on Bulgarian lands. For every object, a preliminary investigation of the archaeological data from excavations such as artefacts found on its territory, as well as estimations about its chronological boundaries of existence have been made. The research continues with preparation of a high precision orthogo- nal and tachometric plan of the rock-cut monument by Theo 010 theodolite and measurement of the basic sight directions on its territory. Horizontal and vertical angles are measured and the mean-square error is ± 6 cc. From the place of sighting presumed for the ancient observer a photo panorama of the local horizon has been made. In addition, azimuths of characteristic relief marks from the visible horizon line have been measured in order to find their relation to arrangements and orientations at the investigated site. Geographic coordinates – latitude and longitude of the rock-cut mon- uments have been determined by the help of a GPS receiver and several consecutive observations of α Ursa Minor. The studied rock-cut monuments Positional systems for Sun observations are discovered on the territo- ry of the following rock-cut monuments on Bulgarian lands. Generally, such rock-cut sites are situated on comparatively high places, near settlements and water springs, and have a specific zero position in relation to the local horizon line. The basic rules of shape creation made by ancient builders of megalithic and rock-cut objects are probably based on their knowledge of the organization of forms in living and non-living na- ture connected with the cult of the Heaven and the Sun. Last but not least is the process of creating and maintaining a calendar, especially needed in the social organization and religious practices of the society. Belintash, near the Mostovo village, Plovdiv district. It is situated on a large plateau, high on the Rhodope mountains. Deep river valleys separate it from the higher mountain ranges. The plateau is north-south oriented and its lowest part descends to the Sushitsa River valley, in a narrow stone gorge. 86 Maglova P.V., Stoev A.D. Ancient astronomical observatories in Bulgaria The area is 5–6 acres, the length is about 300 m and the height is 30–40 m. The archaeological explorations proved that the ancient sanctuary dates back to the 5th millennium BC. It is supposed that site played the role of a central sanctuary for a much larger area – the whole territory of the Rhodopes and even the Upper Thracian Plain with the tribes inhabiting it [5]. In 2011, remains of an artificially built wall, located across the Belintash plateau, were found. According to them, the wall has probably separated the most sacred part of the sanctuary from the rest of the territo- ry. The place of a massive entrance door was also found. This is evidenced by cut in the rock footholds of supporting columns and grooves for moving at opening. Ceramic pots and tools, a bronze ornament, and fragments of a ceramic female figurine are also found. According to recent studies, it can be argued that from the 5th century BC until the end of the Bronze Age (2nd millennium BC) and the whole 1st millennium BC, the sanctuary was operating, but as a result of some conflict at the end of the fourth or third century BC, the sacred site was forcibly de- stroyed [6]. There are also traces of the foundations of a facility at the highest point in the central part of the plateau. Cylindrical hollows, which have been used as footholds of wooden supporting columns are cut on an artifi- cially leveled ground. Two basins with precision cylindrical shape with di- ameters of 1.65 and 2.10 meters are cut in the main rock. One of them is lo- cated at the upper end of the northern part of the plateau and the other – at the southern lower end of the central part of the plateau. The two basins are connected with a system of drainage channels and grooves designed to col- lect rainwater. The existing cult to the Sun in the Eneolithic era and later would re- quire objective knowledge of the movement of this central heavenly body, in addition to the religious-mythological notions. The careful view of the cen- tral part of the plateau shows that there is a precisely leveled two-level ground at its highest point. Archaeoastronomical investigations show that it served for observations of sunrises at astronomically significant points on the horizon (solstice and equinox) [7]. Zaychi Vruh (Cabyle), Sredna gora mountain. Zaychi Vruh is an Early Bronze Age megalithic monument situated around the famous Thracian capital of Cabyle. At the end of the 4th, and the beginning of the 3rd c. BC, Cabyle was the capital of the Odrysian dynasty of Spartok. It is located on the east side of the two-peaked hill "Zajchi Vruh", which is in the sights of the acropolis of the ancient city of Cabyle and is the only hill dominating over the Yambol field. The rocks are evened and worked at the top. Mutually perpendicular trenches with a variable depth have been hewn out in the rocks and oriented East – West and North – South. Thus, the massif has adopted a specific cross-like shape. There 87 НАСЛЕДИЕ И СОВРЕМЕННОСТЬ 2020;3(3):85–98 is an exact coincidence of the straight line towards the points of sunrise during vernal and autumnal equinox and the line of the East – West trench. The pro- jection of the main meridian at the place of observation coincides with the North – South trench. Bas-relief image of the Goddess Cybela is found at the south-west cor- ner of the "cross", next to the trench East – West. There is a rock, located di- agonally, following Cybela's image, which is artificially evened out so the first solar rays can illuminate Cybela's image each morning in the period between vernal and autumnal equinox (i.e. during the time of vegetation – half year). Investigations of the North-South trench show, that an observer standing in its maximal depth can see the line of the main meridian at the place of observation. Consequently, he or she can practically establish the culmination moments of such bright luminaries in the sky as the Sun, Moon, planets and bright stars. Using this relatively precise instrument at Cabyle, the ancient observers could have measured time in units larger than a day – a year, half a year, or the duration of the seasons. At the same time, observing the daily solar culmination and some of the brighter stars, they could measure time in units smaller than a day.