A Peek into the Past

Astronomy at Pomona College

Brackett Observatory was built in 1908 and named after Pomona College's esteemed Frank P. Brackett (one of the first three professors of Pomona College). Dr. Brackett used the facility in 1908 to study the sun with the spectrohelioscope and the horizontal solar telescope. A transit telescope was also part of the original complement of instruments at Brackett Observatory.

The horizontal solar telescope still resides at Brackett Observatory in Claremont

Since those times, the on-campus facililty has been upgraded and expanded to include a new classroom and two fully automated computer-controlled 14" telescopes. In addition the original solar telescope and a variety of smaller telescopes are available for student use. Additional information on the Brackett Observatory can be found using the link at left.

As the light levels from nearby Los Angeles increased, Dr. Robert J. Chambers, who was the main astronomer at Pomona from 1964 until 1992, worked hard to find a nearby dark site for students to observe galaxies and perform research. His efforts paid off when he found that the Jet Propulsion Laboratory had developed a site at Table Mountain, near Wrightwood, which offered dark viewing at approximately 7600 feet. He arranged to develop a 1-meter telescope at the site and obtained permission from the Forest Service and JPL to build a new dome which would house the 1-meter telescope. Dr. Chambers then used his training as a mechanical engineer to design the telescope from the ground up, including custom designed gearboxes for both axes, a telescope support system designed on a Surrier truss design, and counterbalancing and preload systems for both axes.

This telescope was then assembled after a heroic effort of the Pomona College Physics and Astronomy Department. The machinists Steve Porter and Glenn Flohr assembled the telescope from components machined in Claremont, and matched the telescope and gear assemblies to parts acquired from a decommisioned Schmidt Camera telescope donated to the college. The telescope was installed on the site by Dr. Chambers in 1985, assisted by Karen Black, Frank Nilon and other students.

After the successful construction of the telescope, a series of Pomona undergraduates including Jim Willis and Jim Di Shaw developed a control system for the telescope and electronics for moving the stepper motors on both axes. Initial tests showed promise, but the mirror was found to be of insufficient quality to perform research observations. This mirror was a light-weight borosilicate glass mirror which suffered from thermal expansion and distortion.

In 1994, through the efforts of the Harvey Mudd College astronomer Dr. Shane Burns, and Pomona College astronomer Dr. Bryan Penprase a grant from NSF ILI was received to create a new mirror for the telescope. This grant was supplemented by funds from JPL to enable upgrades of the control system, and matching funds from Pomona College, Harvey Mudd College and the Joint Sciences Division of the Claremont Colleges. Additional help from Dr. Alma Zook, and Dr. Steve Naftilan was essential for this upgrade grant.

The new optics were received on June 24, 1997, and first light was acheived on June 25 1997. The new primary is a 40.5" diameter Corning ULE mirror, and the secondary is a 12" mirror made of Zerodur Glass. The mirrors were fabricated by Dave Anderson of Rayleigh Optical Company in Tucson, Arizona, and have rms wave errors of 0.038 wavelengths of visible light.

 

Picture of the upgrade installation crew in front of the telescope, which includes (from back row) Tony Grigsby, Glen Flohr, Dave Anderson, (front row) Bryan Penprase, and Eirik Harris. Mike Wheeler from HMC also assisted in the installation.
	First light image with the new 1-meter optics, June 25, 1997. Five minute exposure of M57 taken by Bryan Penprase and Pomona student Eirik Harris.

The telescope renovation is very nearly complete; only some minor upgrades to the telescope control software are left to be implemented. Work is underway on constructing a 2-micron camera for the telescope under a separate grant to Dr. Alex Rudolph of Harvey Mudd College. The telescope will be used for the research and teaching of Claremont College students and collaborators, as well as for JPL researchers, who are entitled to 3/7 of the telescope time in return for their generous assistance in building and operating the facility..