The 53 cm Schmidt Telescope at Byurakan Astrophysical Observatory

During one of my many visits to Byurakan Astrophysical Observatory—where I regularly guide visitors—I asked Henrik Sargsyan, the observatory’s oldest staff member, to show us the 53 cm Schmidt telescope. Sargsyan has worked at BAO since 1958. Warm, generous, and deeply devoted to science, he gladly agreed. Seeing yet another instrument that shaped modern astronomy was pure joy.

Byurakan is home to several major telescopes, including the ZTA-2.6 and the famous 1-meter Schmidt telescope, which I have already covered in detail. This time, the focus is on the 53 cm Schmidt telescope—smaller in size, but no less important in its scientific impact.

The building that houses the 53 cm Schmidt telescope

The telescope is installed at an altitude of 1,398 meters. It features a 53 cm (21-inch) correcting lens and a mirror of the same diameter. The focal length is 180 cm (71 inches), with a fast focal ratio of f/3.4. Its wide field of view—25 square degrees (5° × 5°)—made it especially suitable for survey work, with a plate scale of 114.6 arcseconds per millimeter.

This instrument played a key role in studies of nearby galaxies, particularly in assessing the compactness of their nuclei. In the 1970s and 1980s, it was extensively used to search for flare stars in star clusters and stellar associations. Some of the earliest projects carried out with this telescope focused on detailed colorimetric observations of galaxies, including investigations of color distribution in nearby systems.

Main Observing Programs

Polarization of cometary nebula NGC 2261
Nuclei of nearby Sa and Sb galaxies
Nuclei of nearby Sc galaxies
Search for flare stars in Pleiades
Search for flare stars in Orion
Search for flare stars in NGC 7000 (Cygnus)
Search for flare stars in Praesepe
Search for flare stars in Taurus Dark Clouds
Variability of Markarian galaxies
Monitoring of extragalactic supernovae in certain areas

Quietly working in the shadow of larger instruments, the 53 cm Schmidt telescope has left a solid scientific legacy—and remains an essential part of Byurakan’s astronomical history.