48" Samuel Oschin Telescope Reference Information

Configuration History

  • POSS I: Single element corrector at center of curvature of the primary.
  • POSS II: Doublet corrector by Grubb Parsons in a new cell at the center of curvature of the primary.
  • JPL, NEAT, 3 Banger:(Steve Pravdo)CCD's using the telescope optics of POSS II.
  • QUEST: (Charlie Baltay and Dave Rabinowitz) CCD Array with monolithic field flattener. Rabinowitz found that performance could be improved by moving the Grubb Parsons Corrector closer to the primary. Will Emmet of Indiana designed a new cell which was built on the Caltech campus. It moved the corrector 75.75mm (2.982 inch) closer to the primary. This necessitated removing the internal telescope shutters used in POSS. The corrector is currently cemented into this new cell. Assy dwg of cell attached (Autocad format) which shows old and new locations.
  • PTF Camera The CFHT 12k array used for the current PTF had a flat window. Viswa Velur did the optical design for the new field flattener/vacuum window with Petrie doing the mechanical design. The new cell gave us the option of spacing the corrector away from the primary with simple pads, so corrector location became a design variable. Petrie retired 6 mos before installation, but Jeff Zolkower (jz474@cornell.edu) remounted the corrector, still in the QUEST Cell, with spacers that moved it 25 mm farther from the primary. Its current location is therefore 50.75 mm closer to the primary than the center of curvature of the primary. Any new design can incorporate corrector location as a variable, moving outward from the QUEST location.

-- RichardDekany - 09 Sep 2008

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Topic revision: r5 - 2015-07-27 - JeffZolkower
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