Yerkes 41-inch reflector is a 40-inch aperture (101.6 cm) reflecting telescope at the Yerkes Observatory, that was completed in 1968. It is known as the 41 inch to avoid confusion with a 40 inch refractor at the observatory. Optically it is a Ritchey–Chrétien design, and the main mirror uses low expansion glass. The telescope was used as a testbed for an adaptive optics system in the 1990s.
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Main article: Yerkes Observatory § 40-inch aperture refractor |
The glass blanks for what would become Yerkes Great Refractor were made in Paris, France by Mantois and delivered to Alvan Clark & Sons in Massachusetts where they were completed.[1]
In the late 1960s a 40-inch reflecting telescope was added, often called the "41 inch" reflector,[2] and in 2002 it was given a new dome over it.[3] The 41 inch was finished by 1968, with overall installation completed by December 1967 and the optics in 1968.[4][5] The telescope had a clear aperture of 40 inches, but was often called the "41 inch" so it would not be confused with the Yerkes 40 inch refractor.[5] Also, the physical diameter of the mirror was 41 inches, even though optical clear aperture was smaller.[4][5]
The 40 inch reflector was of the Ritchey–Chrétien optical design.[6] It systems and the figuring of the glass was mostly completed at the Optical workshop of the Yerkes Observatory.[5] However, the mirror was completed by Tinsley Laboratories, because the person (A graduate student) working on the mirror died unexpectedly.[5] The mirror had a physical diameter of 104 cm and was made from Cer-Vit low-expansion glass.[7] In the 21st century, the 41 inch was placed on the robotic Skynet telescope network, along with a 24-inch telescope at Yerkes.[8]
The telescope is one of three major instruments at the Observatory in the late 20th and 21st century, along with 40-inch refractor and 24-inch reflector; these three telescopes occupy the 3 main telescope domes of the building.[9]
The 41 inch was installed in the southern dome, replacing the old 24-inch (2 foot ) reflecting telescope that dated to the turn of the century.[10] The northern dome housed the new 24 inch, which replaced the Kenwood 12-inch refractor.[10] Both of these domes are on the eastern side of the building along with the meridian transit room.[10] The south-east dome has a diameter of about 30 feet, and was originally designed for 14-inch refractor in the 1890s.[11]
The launch instruments for the 41 inch reflector included:[5]
The telescope was often used as a testbed for a device known as the Wavefront Control Experiment in the 1990s.[12] This was an adaptive optics system that used a deformable mirror to reduce the blurring caused by disturbances in the atmosphere of Earth.[12] One application was the study of combining adoptive optics with fiber optics for high-accuracy spectrographs.[13] That type of data, given enough accuracy can be used to detect exoplanets by doppler shift.[13]
