Wednesday 2 December 2020

The Crossley Reflector and Nebula


The Crossley Reflector and Nebulae

The 36 inch Crossley Reflector which had been used by Edward Crossly in Halifax, Yorkshire and was at the time the largest reflecting telescope in England was donated in the 1890s to Lick Observatory in California. The night sky conditions over Halifax in the latter of the 19th century were very poor due to the pollution from all the factories in the town.

The Crossley telescope although not able to be used to its fullest in Halifax was a trail blazer in the early part of the 20th century at Lick. It was at he time the largest reflector in America, not being surpassed until 1916 when the 100 inch reflector was introduced at Mount Hamilton.

In 1912 H D Curtiss made descriptions of 132 nebulae that had been photographed by the Crossley telescope. Curtiss describes the importance of photography to astronomers. He says that in catalogues, NGC 83 has thirteen nebulae listed while using the Crossley he saw at least fifty small nebulae and nebulous stars.

Today we know that NGC 83 is an elliptical galaxy in Andromeda but at that time all nebulae were assumed to be in our galaxy.

Later in 1918 Curtiss used the Crossley to study the forms of 50 planetary nebulae on photographs that had been taken with various exposure times in order to get more detail of the structure of the planetary nebulae. The majority showed a more or less regular ring or shell structure.

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