George R. Wallace, Jr., Astrophysical Observatory

The George R. Wallace, Jr., Astrophysical Observatory (WAO) is MIT's local teaching and research optical observatory located in Westford, Massachusetts. Professor James Elliot ('65) is the director, Dr. David Osip ('89) serves as the assistant director/manager, and beginning in the spring of last year, Ms. Chelsey Logan has served as the on site observatory specialist. Other staff, usually undergraduate student observers and graduate thesis students, are coordinated through research programs. Undergraduates working on the various projects are funded in part by an NSF's Research Experiences for Undergraduates (REU) program and in part by NASA and NSF research grants to Professor Elliot and Dr. Osip. The site observing facilities consist of a 24-inch reflecting telescope and a 16-inch reflecting telescope, each in their own domes, a four-bay shed with roll-off roof housing three Celestron 14-inch Cassegrain telescopes (C-14) and a computer controlled Meade 8-inch Cassegrain telescope, and several Celestron 8-inch Cassegrain portable telescopes. Additional infrastructure includes a building housing electronics workshop, data analysis computer facilities, and an office for the observatory specialist. The primary instrument for the 24-inch telescope has now been upgraded to a high sensitivity back-illuminated CCD camera system from Apogee, mated to a computer controlled three slot filter slide from Optec. All other telescopes are equipped with CCD (charge-coupled device) camera systems as well and dedicated control computers. Additional instruments used during the past year include several photographic cameras, and a moderate-resolution fiberoptic spectrograph.

A major facility upgrade was completed in the past year at WAO. As part of this process, the entire 24-inch telescope was disassembled for the first time since it was built 30 years ago. A new drive system has been constructed with close-looped encoded stepper-servo motors mated to custom 10:1 reduction gearing for both axes. A new telescope control system known as MOVE (designed originally at Lowell Observatory) has also been implemented. This new drive system allows full computer control of all telescope motions tracking at both sidereal and non-sidereal (for solar system objects) rates with positional accuracy of better than an arcsecond. The primary and secondary mirror have been tested, re-figured, polished, and re-coated; they were re-installed in the newly completed telescope late last summer. The resulting optical configuration is a substantial improvement over the previous system and should provide excellent seeing limited performance. In late October 2001, the 24-inch telescope was fully reassembled. Over the fall semester and IAP, the telescope balance and motion were refined. The mirrors were laser collimated during the spring semester. Home and limit switches were installed to allow the telescope to move (and stop) under computer control. The camera and filter slide were tested and calibrated in lab and then mounted on the telescope. In the spring semester, and accurate pointing map for the telescope was developed using the Apogee camera at the Cassegrain focus and an additional 5-inch Schmidt-Cassegrain finder scope for initial field corrections. A majority of the telescope upgrade and performance verification of the combined camera/telescope system constituted the masters thesis project of Janet Wu ('00,'02) under the supervision of Dr. Osip and Professor Elliot.

Last summer, PCCD (the portable CCD system that had served as the observatories work-horse camera for several years) went through its own system upgrades in preparation for an occultation observing campaign (the original purpose for the portable system). Graduate student Michael Person ('94) and undergraduate James Pate ('03) carried out the PCCD work under the supervision of Professor Elliot. The system was then deployed last August in South Africa for observations of the occultation of a star by Neptune's moon, Triton. The results of this successful observing campaign are being incorporated in Person's PhD Thesis.

Student participation at the observatory was once again robust over the past year with several organized events with the campus chapter of SEDS (Students for the Exploration and Development of Space). Professor Elliot's fall laboratory course 8.287J-12.410J Observational Techniques of Optical Astronomy drew 14 students, who used the Wallace facilities for a variety of astronomical projects, including broadband imaging of star clusters to construct color-magnitude diagrams and wide field astrometric imaging of asteroids and planetary satellites. In addition, the new fiberoptic spectrograph systems were used for low and moderate resolution single target spectroscopy observations. Doctors Andrew Rivkin and Joanna Thomas-Osip offered 12.409 Observing the Stars and Planets in the fall and spring semester, where an additional 20 students used the observatory for laboratory work.

David J. Osip
Assistant Director

More information about the Wallace Astrophysical Observatory can be found online at


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