What's where at Lick Observatory on Mt. Hamilton

For over a century there have been various astronomical instruments located on Mt. Hamilton. Some of the earliest instruments and their sites remain, others have been obliterated. During the passage of years many instruments and sites have been added.

While writing code for real-time atmospheric refraction corrections for the MOS it became evident that there was no complete, self-consistent, and accurate set of positions for the telescopes on Mt. Hamilton. In looking at the published positions it became evident that there has been widespread confusion about the origin of coordinates at Lick Observatory. Few of the measurements shared a common reference frame, and it was not immediately obvious when they did.

Thus this became a historical exercise in finding as many published positions as possible, determining who measured what and when, distinguishing one dome site from another after a century of confusion, marching around the mountaintop, and interpreting the assumptions used in the original calculations. With the story of each of the characters in hand, getting their precise positions turned out to be the easiest part.

Fortunately, Lick Observatory provides a particularly favorable scenario for geodetic purposes. The first director of the observatory was also the president of the University of California, and he had strong ties to civil engineers. He was arranged to have Mt. Hamilton included in the geodetic effort for the first transcontinental triangulation by the USC&GS, and he also had teams of students run levelling lines to the mountain top. As a result, structures on Mt. Hamilton have been used as geodetic reference points for over 110 years.

Digital Maps of Mt. Hamilton

Instruments on Mt. Hamilton

Sites of Instruments (&c.)

Geodetic Positions of Sites

Notes on the Geodetic Positions

Astronomical Positions of Sites

History of Published Positions



WWW users with table- and image-capable browsers may be interested in taking a virtual tour of Mt. Hamilton.
Steve Allen <sla@ucolick.org>