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Session 20 - HAD II - New Telescopes and New Tools.
Division, Oral session, Monday, June 08

[20.04] The Great Spherical Aberration Fiasco of 1902 and Its Aftermath: Testing a New Big Telescope in San Diego

D. E. Osterbrock (UCO/Lick Obs./UCSC)

In 1901, W. W. Campbell, the new director of Lick Observatory, planned to build a "big" (0.9-m) new reflecting telescope, to be erected in the Southern Hemisphere. His aim was complete sky coverage for statistical studies of stellar radial velocities. Campbell designed it as a reflector rather than a refractor to save money; when completed it would be the largest professional-quality silver-on-glass reflector in the world. It would be more effective in collecting light, especially photographic light, than any of the big refractors of that era.

The 37-inch primary mirror, when delivered on Mount Hamilton, proved to be afflicted with severe spherical aberration. Like the HST nine decades later, it was not usable. How this happened will be described.

Unlike the HST, this "Mills reflector" was still on the ground in America. The optics were returned to the maker, John A. Brashear, in Allegheny, Pa., and were refigured there. To save time, the final testing and touch-ups of the figure, in January 1903, were moved to San Diego, the clearest accessible site in the United States. The dome, mounting, and other equipment were waiting in a warehouse near the pier in San Francisco, boxed for shipment to Chile. Campbell was badly injured during the testing process, but his assistant, William H. Wright, completed it. James McDowell of the Brashear firm did the final figuring at San Diego, and in February 1903, Wright and Harold K. Palmer (who passed his final Ph.D. oral exam the afternoon before their ship sailed) took the telescope to Santiago and put it into operation there. It proved higly successful for a quarter of a century, in obtaining the observational data for which it was designed.

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