Harold Knox-Shaw and the Helwan Observatory

TL;DR

Harold Knox-Shaw's work at Helwan Observatory included pioneering astronomical photography, morphological studies of nebulae, and early identification of elliptical galaxies, leveraging the observatory's advanced equipment and location.

Contribution

First detailed account of Knox-Shaw's pioneering astronomical observations and discoveries at Helwan Observatory, including early elliptical galaxy identification.

Findings

First photograph of Halley's Comet in 1910

Identification of elliptical galaxies as a distinct class

Correlation of nebula brightness changes with light travel time

Abstract

Harold Knox-Shaw (1885-1970) worked at the Helwan Observatory in Egypt from 1907 to 1924. The Observatory was equipped with a 30-inch (76 cm) reflector that was financed and constructed by the Birmingham industrialist, John Reynolds (1874-1949), to benefit from the clearer skies and more southerly latitude compared with Britain. Knox-Shaw obtained the first photograph of Halley's Comet on its 1910 perihelion passage. He also carried out morphological studies on nebulae and may have been the first to identify what later became to be known as elliptical galaxies as a distinct class of object. Photographic analysis of the variable nebula NGC 6729 in Corona Australis enabled him to conclude that the changes in brightness and shape were correlated with the light travel time from the illuminating star, R CrA.