Pulkovo Observatory

Struve and the capital of astronomy

Tsar Nicholas I approved the new observatory in 1834 and Friedrich Georg Wilhelm von Struve, who had directed the Dorpat Observatory, designed it and became its first director; it opened in 1839. Pulkovo was built for precision: its meridian instruments sat on stone piers insulated from the building, and its 15-inch refractor was, on completion, one of the largest in the world.

Struve's work on the parallax of Vega and on double stars made the observatory's name. The star catalogues that followed, for epochs 1845, 1865, 1885, 1905 and 1930, became references used around the world. Astronomers from many countries visited.

The Struve arc

Struve also initiated a chain of triangulation to measure the shape of the Earth, from Hammerfest in Norway to the Black Sea, running some 2,800 kilometres through ten countries. UNESCO inscribed the Struve Geodetic Arc on the World Heritage List in 2005,. In 1885 a 30-inch refractor was installed, then the largest in the world.

Destruction and rebuilding

Pulkovo stood on the front line in the siege of Leningrad, from 1941 to 1944, and its buildings were destroyed. Parts of the library and some instruments had been evacuated before the siege. Reconstruction began in 1946 and the observatory reopened in 1954. It remains the Central Astronomical Observatory of the Russian Academy of Sciences, and is listed with historic Saint Petersburg as a World Heritage site.

The cost of a precise site

Pulkovo's catalogues were as good as they were because the instruments were isolated and the observers were trained. The observatory's quality depended on the institution, and when the institution was cut off by war, the work stopped. Its postwar reconstruction took years, and the observatory returned to a changed field in which satellite positioning and radio techniques had taken over from the meridian circle for fundamental positions. Pulkovo's modern work covers solar physics, stellar and galactic astronomy, and reference frames. What its history shows is the vulnerability of an observatory sited near a city, on a front line or in a capital, and the importance of the records kept elsewhere.

Instruments and technologies

• Meridian instruments Transit instruments and meridian circles on isolated stone piers, for fundamental star positions.
• 15-inch refractor (1839) A refractor by Merz and Mahler, used for double stars and for parallax.
• 30-inch refractor (1885) A large refractor with a lens by Alvan Clark and Sons, installed in 1885.

The people

• Friedrich Georg Wilhelm von Struve Founder and first director; double stars, stellar parallax and the geodetic arc.

Timeline

• 1839 Observatory opens with Struve as first director.
• 1885 30-inch refractor installed.
• 1941 Buildings destroyed during the siege of Leningrad (1941–1944).
• 1946 Reconstruction begins.
• 1954 Observatory reopens.

Key lessons for observation today

• Plan for evacuation of what matters Instruments and records were saved even though buildings were not. A site resilience plan names what must leave first and where it goes.
• Isolate the instrument from the building Independent piers kept vibration out. The same principle applies to a seismometer vault or a GNSS monument.
• A reference catalogue is infrastructure Pulkovo's catalogues were a standard others calibrated against. Reference data need a steward and a schedule.

Sources

• Wikipedia, Pulkovo Observatory
• Pulkovo Observatory of the Russian Academy of Sciences
• Wikipedia, Friedrich Georg Wilhelm von Struve
• Nature (1954), Pulkovo Observatory
• UNESCO World Heritage Centre, Struve Geodetic Arc