CARA Science: AST/RO Heterodyne Receivers
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The Antarctic Submillimeter Telescope and Remote Observatory (AST/RO)
is a 1.7-meter telescope and it has been in operation since January 1995.
It is a general-purpose telescope for astronomy and
aeronomy studies at wavelengths between 200 and 2000 microns
(Stark 1997a). The telescope
operates continuously through the austral winter, and has been available for
use on a proposal basis by all astronomers since 1998.
AST/RO studies have
concentrated on spectroscopic observations of submillimeter-wave transitions
of atomic carbon and carbon monoxide in molecular clouds and photon-dominated
regions of the Milky Way. In addition, submillimeter sky characteristics
have been measured using AST/RO (Chamberlin 1997, Lane 1998).
AST/RO's receivers are:
There are also two acousto-optical
spectrometers (AOS) with 1.07 MHz resolution, 1.1 GHz
bandwidth, and 2048 channels each, and one high-resolution
AOS with 44 kHz resolution, 64 MHz bandwidth, and 2048 channels.
- 230 GHz SIS receiver: 120 K DSB noise temperature.
- 460-492 GHz SIS waveguide receiver: 120-170 K DSB noise temperature.
- 460-492 GHz SIS quasi-optical receiver: 165 K DSB noise temperature
- 460-500 GHz Schottky-barrier diode receiver: 950 K DSB noise temperature.
(This receiver will work without a liquid Helium supply).
AST/RO invites observing proposals from
the astronomical community. Since travel to the South Pole is
not possible during Austral winter (Feb.-Oct.), observations on
AST/RO are performed by a winterover scientist in residence at
Over its lifetime, AST/RO has concentrated on three types of projects:
1) observatory projects proposed and decided upon by consensus during numerous
bi-annual meetings of the extended AST/RO group representing eight different
institutions; 2) graduate student thesis projects, two of which have been
completed using AST/RO data and two more which are approaching the final
stages; and 3) external proposals submitted in response to three general
solicitations to the worldwide astronomy community. Major accomplishments
in each category include:
AST/RO data have been obtained and
distributed to the following external PIs: W. Reach (CI emission
from a translucent cloud in Chamaeleon); M. Marx (CI emission from
cold, quiescent atomic clouds in the LMC); P. Wannier (CI emission
across cloud boundaries in the Southern Coalsack and Chamaeleon regions);
T. Bourke (CI and CO J=4-3 maps of the globule/high-velocity
outflow BHR71); F. Scappini (CO J=4-3 observations of Bok globules);
and D. Clemens (CO J=4-3 survey for dense gas in high-mass star-forming
- First detection of [CI] emission in the Magellanic Clouds
(Stark 1997b, Bolatto 1998a).
- First detection of [CI] in absorption (Staguhn 1997).
- Survey of [CI] and CO J=4-3 emission from the HII region/molecular
cloud complex NGC 6334 (Jackson 1998a).
- Survey of [CI] emission in the inner few degrees of the Galaxy, to
CI/CO ratio as a function of metallicity through comparisons with the LMC/SMC
and the solar neighborhood (Ojha 1998a).
- Survey of CO J=4-3 emission in the inner few degrees of the Galaxy
- Survey of [CI] and CO J=4-3 emission in strips across the Galactic plane
- Survey of [CI] and CO J= 4-3 emission from the Carina spiral arm region near
the bright Eta Carina nebula (Zhang 1999, see
- J. Staguhn completed his Ph.D. thesis at U. Cologne based in part on AST/RO
observations of [CI] interacting with non-thermal filaments in the Galactic
Center (Staguhn 1996, 1998a).
- J. Ingalls completed his Ph.D. thesis at Boston U. on a study of the
properties of C+, CI, CO, and dust in a sample of high-latitude clouds in the
Milky Way (Ingalls 1999a, 1997a, 1998a, 1999b).
- A. Bolatto is completing a Ph.D. thesis at Boston U. based on mapping of
[CI] and CO emission in the Magellanic Clouds
- M. Huang is completing a Ph.D. thesis at Boston U. on the properties
of C+, CI, and CO in a sample of southern HII regions (Huang 1999, 1998b).
For more information
The group has a website at
AST/RO is based at the Harvard Smithsonian Center for Astrophysics.
For more information, contact Adair Lane,