The forthcoming total solar eclipse termed by some the Great American Eclipse will be on 21 August 2017 and will for sure remain in the history of world astronomy. The reasons: first, this will be the first total sun eclipse for the last 38 years which will be observable from the territory of the United States of America; second, the event is expected to become the most observed astronomical phenomenon since the emergence of human civilization.

The date 21 August 2017 however will also become part of the history of St. Kliment Ohridski University of Sofia. In the State of Nebraska, a Bulgarian expedition is expected. It is going to film the phenomenon, while astrophysicist Gantcho Gantchev will deliver a lecture. The PhD student from the Astronomy Chair at the Faculty of Physics at Sofia University has been involved in research of „luminous blue variables“ /massive stars/ from of Andromeda and Triangulum galaxies. The lecture will be dedicated to the causes of the total solar eclipse, the information that we can get from it and the safe ways of watching it.

Apart from professional research, Gantcho Gantchev has more than 10 years of work in the sphere of astrophotography, and he will also take pictures of the astronomical occurrence. „Planet Earth is the only place in the Solar System where from a total solar eclipse can be observed”, Gantcho Gantchev said.

“The Sun is 400 times bigger in diameter than the Moon and the Moon – 400 times closer to us. This is a perfect combination due to which we can see the Sun’s and the Moon’s discs in the same size. There are measurements though which suggest that this phenomenon will not be observed forever. Every year the Moon shifts a few centimeters away from the Earth. We owe this knowledge to the astronauts from Apollo missions who have left reflectors (mirrors) on the Moon’s surface. Periodically, from different observatories, lasers emit rays to them to clock the time they come back. Data suggests that after about 300 million years the Moon will be so distant from our planet that total solar eclipses will no longer be observed – only ring-like ones.”

Gantcho Gantchev is the only representative of Sofia University in Bulgaria’s Nebraska expedition. Its other five members are from Hunters of Eclipses Society – quite well trained amateur astronomers with strong experience of more than 30 „captured“ solar eclipses including ones in China, Novosibirsk, Turkey and Zambia. The team is going to provide assistance for arranging filming equipment. The idea and organization of the Nebraska visit has come from the society and from Gantcho Gantchev. It took the group two years to prepare and every stage has been carefully planned. The State of Nebraska has not been selected by accident. The staff of the Astronomy Chair at Sofia University selected it after long research. The eclipse watching position has also been fixed – a locality close to the town of Tryon characterized with very low astronomical pollution and with a long duration of the total phase of the eclipse - 2 min. 35 sec. /only 7 sec. shorter than the longest such duration – in Kentucky/.

“I have engaged in a pretty serious job by using several professional reflex cameras at the same time. Some will take a broader view (sky and landscape) and others will be equipped with long-focus lenses aimed at the Sun's corona. Thanks to our sponsor, Canon Bulgaria, we have state-of-the-art equipment”, the young astronomer said.

„The cameras will be synchronized by means of computers so that they could go on shooting unmanned - guided by software. I seek to obtain a large volume of information for the two minutes of the eclipse. This photography is harder than astroscapes. The problem is that during an eclipse the Sun is very bright at the start and then during the total eclipse phase it becomes very dark. To be able to capture its eruptions and at the same time the stars in the middle of the day, I will use both long and very short shots, and changes of aperture and focal lengths. My aim is to have a photo showing the stars, the Sun’s corona and even the reflection of the Earth on the Moon’s dark disc – a gray-bluish image. This is very tough to do but I hope I will succeed with some processing.”

The hall for Gantcho Gantchev’s lecture in the town of Tryon has already been provided and a family from another town, Mullen, has let their home to be used for the needs of the expedition. „How very hospitable people”, exclaimed Gantcho Gantchev and added: „I was e-mailed yesterday by the local sheriff who offered assistance for parking places and installation of equipment. This will allow us to synchronize the presentation and observations even better. I think we communicate very well with the local people – and also I hope we will be able to present in a worthy way both Sofia University’s Faculty of Physics and Bulgaria”, the young astronomer said in conclusion and promised to donate some of the astrophotographs to the Bulgarian National Radio picture library.

English Daniela Konstantinova