Site meter not updating site updating web
Atmospheric effects overwhelm this, so it becomes important to locate high-resolution instruments at high altitudes in order to avoid as much of the atmosphere as possible.
The Pulkovo site, at 75 m above sea level, was simply not suitable for a high-quality instrument.
For many years the primary world-class observatory in the Soviet Union was the Pulkovo Observatory outside Saint Petersburg, originally built in 1839.
Like many observatories of its era, it was primarily dedicated to timekeeping, weather, navigation and similar practical tasks, with a secondary role for scientific research.
The large size of the dome itself means there are thermal gradients within it that compound these problems.
Refrigeration within the dome offsets some of these issues.
Around its 50th anniversary a new 76 cm telescope, then the world's largest, was installed for deep space observation.
Further upgrades were limited due to a variety of factors, while a number of much larger instruments were built around the world over the next few decades.
If the temperatures of the primary and the outside air differ by even 10 degrees, observations become impossible.
The telescope also suffers from serious thermal expansion problems due to the large thermal mass of the mirror, and the dome as a whole which is much larger than necessary.
Upgrades have taken place throughout the system's history and are ongoing to this day.
A second attempt fared better and was installed in 1975.
BTA's first images were obtained on the night of 28/29 December 1975.