Photochart of polar stars. 19th-century series of photographs for a region of the northern polar skies,showing some 1270 stars. Three types of photographic prints are shown here: silver bromide prints (exposed using gaslight),platinotype prints (exposed using diffused sunlight),and a photozincograph. The exposure times range from 1 to 5 minutes (silver bromide prints) and 25 to 45 minutes (platinotype prints). Two circular (polar projection) engravings are also shown. The observations were carried out by on 14 August 1888 by British amateur astronomer and engineer Isaac Roberts (1829-1904). For negative prints,see image C024/9977 | |
Licence : | Droits gérés |
Crédit: | Science Photo Library / Royal Astronomical Society |
Taille de l’image : | 4685 px × 3748 px |
Model Release : | Non requis |
Property Release : | Non requis |
Restrictions : | - |