Photochart of polar stars. 19th-century series of photographs for a region of the northern polar skies, showing some 1270 stars. Three types of photog

---

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 20 to 60 seconds (silver bromide prints) and 3 to 30 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 transparencies, see image C024/9978.

---

Size: 4664px × 3745px
Photo credit: © ROYAL ASTRONOMICAL SOCIETY/SCIENCE PHOTO LIBRARY / Alamy / Afripics
License: Licensed
Model Released: No

Keywords: -, 14, 1800s, 1888, 19th, astronomical, astronomy, astrophysical, astrophysics, august, black--white, british, bromide, century, chart, diffused, english, engravings, european, exposure, gaslight, hemisphere, historical, history, isaac, monochrome, negative, night, northern, photochart, photographic, photozincograph, platinotype, polar, prints, projection, region, roberts, silver, skies, sky, star, stars, sunlight, times