Facilities
Sawyer 24-in Reflector
The 24-in reflector at Whitin Observatory,
built by Boller and Chivens in 1966,
was a gift from Mrs. Margaret Sawyer.
Its f/13.5 Ritchey-Chrétien Cassegrain optics are
presently used with an additional focal length reduction lens
yielding an effective focal ratio of f/9.6.
The primary imaging CCD instrument presently on the telescope is an Apogee Instruments CCD camera which has been in use since summer 2011. The GAM filter wheel in front of the camera holds six 50-mm square filters, selected from among a set of broadband photometric UBVRI and colorless filters from Omega Optical plus 890-nm methane absorption and hydrogen-alpha band filters.
The 24-in telescope and its instrumentation has been used since it was installed in 1966 to teach observational astronomy techniques to intermediate and advanced students. It's also heavily used to carry out research programs at the Whitin Observatory. At present the main research observing program is an ongoing study of the spin properties of Koronis family asteroids. Past projects include long-term observations of symbiotic binary star systems, variable star and supernova monitoring, and study of extrasolar planets by detecting transits in front of the orbited stars.
In 1991, the original telescope drives and relay control system were replaced with a computerized retrofit motion control system by DFM Engineering. Several subsequent improvements were made to the telescope during the summer of 1995, including a DFM upgrade to the control system, installation of a DFM “Guide-Acquire Module” (GAM), and changes to the dome and structure to improve the seeing. In 2003 December the control system was upgraded to a Windows-based version of the DFM software.
The original instrumentation accompanying the telescope was a Boller and Chivens 4 × 5-in photographic plate camera. Other instruments that have been used on the telescope in the past include a photoelectric photometer (ca. 1969), an Optomechanics Research Model 10C Grating Spectrograph (ca. 1982), a Photometrics 512×512 “PM512” CCD camera for electronic imaging (1990), and a successor Photometrics/SITe 1024×1024, 16-bit, back-illuminated, Metachrome-coated “TK1K” CCD camera (1995-2011).
(next page: Fitz/Clark 12-in refractor)
