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Automated Astrophysical Site-Testing Observatory (AASTO)
The Automated Astrophysical Site-Testing Observatory (AASTO),
is a self-powered, self-heated autonomous laboratory
that hosts a suite of
site-testing instruments. These instruments cover the spectrum from
UV to submillimeter, and are intended to fully characterize potential
astronomical sites at a variety of locations on the high Antarctic
plateau. The CARA AASTO project enjoys strong collaboration with the
of New South Wales and the Mount Stromlo Observatory in Australia.
It is currently operational at South Pole station, and will
later be deployed to remote, uninhabited sites on the high
Antarctic plateau. It has a suite of
astronomical site-testing instruments, so that potential
observatory sites can be fully characterized over a wide range
In addition to the astronomical site-testing data, the AASTO
also collects weather data such as temperature, wind speed and
direction, and atmospheric pressure.
The AASTO package consists of a suite of instruments:
- Near-Infrared Sky Monitor (NISM)
- This is the simplest instrument, with an InSb detector and fixed
2.35 micron filter cooled to 77K by a low-power Stirling cooler. NISM
is designed to make only "Sky-dip" measurements. Placed to one side of
the instrument is a black-body calibration source.
- Mid-Infrared Sky Monitor (MISM)
- The MISM is similar in concept to its near-IR counterpart, but uses a
Stirling-cycle cooled HgCdTe detector. A chopping frequency of 1kHz is used to
avoid 1/f noise. An ambient-temperature filter wheel yields spectral coverage
from 4 to 14 microns.
- Antarctic Fiber-Optic Spectrometer (AFOS)
- The AFOS consists of a small telescope feeding a grating spectrometer
and CCD detector via a bundle of six optical fibers. By observing bright
stars, a direct measure of atmospheric transmission from the UV cut-on
to about 800 nm is obtained. In addition, sky emission arising from
aurorae and airglow can be monitored.
A full description of the AFOS, together with preliminary results, has been
prepared by Boccas et al. (1998).
- Sonic Radar (SODAR)
- Acoustic radar which measures the height of the
turbulent atmospheric boundary layer. Deployed in January 1999, it
acquired several weeks of wind and
microthermal data with 20 meter resolution to a height of up to 800
- Generic Telescope Mount and DIMM (G-MOUNT and ADIMM)
under development by Australian National University for deployment in
January 2000 to measure the seeing.
- Submillimeter Tipper (SUMMIT)
- Constructed by Carnegie Mellon University and the National Radio
Astronomy Observatory and loaned to the AASTO project, the
uses an ambient-temperature pyroelectric detector to monitor 350 micron
radiation. A stepper motor drives an off-axis paraboloid mirror, allowing the
instrument to scan from zenith to horizon. The tipper is currently taking
the roof of the AST/RO building at the South Pole. Modifications to the tipper
are planned to incorporate it within the AASTO package of instruments.
For more information, see the submillimeter tipper website.
The accomplishments of the project include:
- Measurement of the near-infrared sky brightness from
1.5 microns to 5.5 microns and monitoring it throughout an entire year
(Phillips et al 1999).
- Measurement of the mid-infrared sky brightness from
4 microns to 14 microns and monitoring it throughout an entire year
(Chamberlain et al. 1999).
- Measurement of the near-ground microthermal atmospheric turbulence
(Marks et al. 1996).
- Balloon-borne measurement of microthermal turbulence throughout the
atmosphere (Marks et al. 1996).
For more information
The group has a website at
AASTO is based at the University of New South Wales, Australia, as
part of JACARA,
the Joint Australian Center for Astrophysical Research in Antarctica.
For more information, contact Michael Ashley,