A geologist and fellow of the Royal Astronomical Society, Isaac Roberts (1829-1904) made significant contributions to the photography of star-clusters and nebulae. By championing reflecting rather than refracting telescopes, Roberts was able to perceive previously unnoticed star-clusters, and was the first person to identify the spiral shape of the Great Andromeda Nebula. Roberts' use of a telescope for photographing stars, and a long exposure time, provided greater definition of stellar phenomena than previously used hand-drawings. Although Roberts' conclusions about the nature of the nebulae he photographed were not always correct, the book is significant for the possibilities it suggests for nebular photography. Published in 1893 and 1899, the two-volume Photographs of Stars represents the summation of his work with his assistant W. S. Franks at his observatory in Crowborough, Sussex. Volume 2 contains 29 plates of stars, and his conclusions about their origins and nature.
A geologist and fellow of the Royal Astronomical Society, Isaac Roberts (1829-1904) made significant contributions to the photography of star-clusters and nebulae. By championing reflecting rather than refracting telescopes, Roberts was able to perceive previously unnoticed star-clusters, and was the first person to identify the spiral shape of the Great Andromeda Nebula. Roberts' use of a telescope for photographing stars, and a long exposure time, provided greater definition of stellar phenomena than previously used hand-drawings. Although Roberts' conclusions about the nature of the nebulae he photographed were not always correct, the book is significant for the possibilities it suggests for nebular photography. Published in 1893 and 1899, the two-volume Photographs of Stars represents the summation of his work with his assistant W. S. Franks at his observatory in Crowborough, Sussex. Volume 2 contains 29 plates of stars, and his conclusions about their origins and nature.
Inhaltsverzeichnis
Preface; List of the plates; Instruments; List of abbreviations adopted in this work; 1. The negatives; 2. Epoch of the Fiducial stars, A.D. 1900; 3. Table for converting the measured right ascensions; 4. Deterioration of the negatives; 5. Effects of atmospheric glare and of diffraction upon the films of photographic plates; 6. Arrangement of the plates; 7. Method for micro-puncturing the photographic discs of stars on plates; 8. Star catalogues and photographic charts; 9. Duration of the effective exposures given to photographic plates in the 20-inch reflector; 10. Are the millions of stars and the numerous nebulosities limited in number and extent; 11. The evolution of stellar systems; 12. Inferences suggested by examination of the photographs; 13. Description of the photographs; 14. M.31. Andromedae; 15. M.99 Virginis; 16. M.51 Canum Venaticorum; 17. Region of 7 Cassiopeiae; 18. Nebulae in the Pleiades; 19. M.42. Orionis; 20. General conclusions concerning the evolution of stellar systems.
