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Vulcan South Equipment

Mount

The Vulcan South photometer is mounted on the Australian-built Generic Mount, or Gmount. The mount was originally designed to be used as part of the Automated Astrophysical Site Testing Observatory (AASTO), a joint University of New South Wales (UNW) - Australian National University (ANU) - Center for Astrophysical Research in Antarctica (CARA) initiative. The Gmount was designed to operate on very low power in the extreme cold of the Antarctic Plateau. Site testing at the South Pole from the AASTO was completed in 2003, making the Gmount available for our use.

Photometer

The Vulcan South Photometer is essentially a large precise light-meter that measures the brightness of thousands of stars simultaneously. It is called a photometer because it is designed for precise brightness measurements rather than diffraction-limited imaging like most telescopes. Our system is a refractor using a fast lens and CCD camera detector mounted on a temperature compensated stable optical bench. The optics are enclosed in an insulated and heated shell and look out through a 10-inch optical window.

CCD Camera

The photometer consists of a Roper Scientific 500-series CCD camera with a 4096x4096 pixel Kodak KAF-16800 front illuminated chip with 9 micron pixels. The camera was supplied by Zoran Ninkov and is the same one that was previously used for the Vulcan Camera Project in 1998-2000 and for our test deployment to the South Pole in Feb 2001.

Lens

We are using a surplus Aerojet-Delft reconnaissance lens (S/N 76749). The lens has a 12-inch focal length with an 8-inch aperture (f/1.5). The lens offers a relatively large light gathering capability with a short focal length, allowing us to observe a wide field-of-view while gathering enough photons to keep the intrinsic (Poisson) noise in our measurements small. The lens was purchased through ebay and tested extensively by Zoran Ninkov at the Rochester Institute of Technology and at the Corning Tropel Corporation. Lens test results indicate that the lens provides a well focused image at the red wavelengths where we are observing.

Filters

Our system does not have a filter changer, so we have tried to optimize the single filter given the constraints of our project

  • maximize throughput of starlight,

  • minimize background light (especially aurora),

  • select a wavelength where our optics are optimized,

  • select a wavelength where CCD sensitivity is high.

We have selected a filter from Custom Scientific whose spectral response was chosen to be as wide as possible while avoiding the bright oxygen (OI) line at 6300 angstroms and the night sky lines beyond about 7200 angstroms.

 

 


This material is based upon work supported by the National Science Foundation under Grant No. 0126313. Any opinions, findings and conclusions or recommendations expressed in this material are those of the author(s) and do not necessarily reflect the views of the National Science Foundation (NSF). For questions or comments, please contact Doug Caldwell.