The Forgotten 50 cm Cassegrain Telescope of Byurakan Observatory

During one of my visits to the Byurakan Astrophysical Observatory, I had the lucky chance to see the 50 cm Cassegrain telescope. Henrik Sargsyan, the oldest staff member of BAO, guided us there. The building felt like a lighthouse—standing tall, rising high, with endless stairs leading upward. Finally, we reached the telescope. Unlike the 1-meter Schmidt telescope, where the dome opens with motorized force, here everything is done manually, as you’ll see in the video. Let’s talk about it.

The 50 cm Cassegrain telescope at the Byurakan Astrophysical Observatory (BAO) has a rich history tied to the early formative years of the institution. BAO was founded in 1946, and its first wave of instrumental development included several small domes and towers. Among them were the 50 cm Cassegrain and the 40 cm Cassegrain telescopes, installed between 1951 and 1955.

The telescope is housed in one of the iconic tall stone towers near the main administrative building. Like the other early structures at BAO, this building was designed by the renowned Armenian architect Samvel Safarian, who combined Soviet-era functionality with traditional Armenian volcanic tuff stone aesthetics.

The inscription on the façade, ՌՋԾԳ, confirms the completion year of the structure—1953. It also reflects the Armenian numeral system, where letters represent numbers.

Breakdown:

• Ռ (R) = 1000

• Ջ (J) = 900

• Ծ (TS) = 50

• Գ (G) = 3

1000 + 900 + 50 + 3 = 1953

Before more powerful instruments were installed—such as the 53cm and later 1-meter Schmidt telescopes—this instrument served as a true workhorse. It was used for electrophotometric and polarimetric observations, often alongside the nearly identical 40 cm Cassegrain. Together, they contributed to the study of non-stable stars, long-period variables, and flare stars, supporting Viktor Ambartsumian’s groundbreaking ideas on stellar associations and active galactic phenomena.

https://video.wixstatic.com/video/103e0a_b24ecdda3a044af58986f7b1acb988f0/720p/mp4/file.mp4

Today, it stands as a silent witness of a bygone scientific era—waiting for visitors to step inside and shake the dust off history. A quiet reminder of a glorious past, and still a magnet for astronomy lovers and urban explorers.

I’m Suren, a professional urban explorer in Armenia. I offer unique urbex tours to abandoned, hidden, and off-the-map places you won’t find in guidebooks. Want a custom itinerary? Contact me on WhatsApp or Telegram.