SUSI Images

SUSI stands for the Sydney University Stellar Interferometer, a new and unique astronomical instrument of unprecedented angular resolving power. The instrument is located at the Paul Wild Observatory, near Narrabri in northern New South Wales, alongside the Australia Telescope.

SUSI uses modern technology in the form of lasers, adaptive optics, computers etc. to overcome the problems posed by atmospheric turbulence to make measurements which would otherwise require a telescope with a mirror 640m in diameter! Although limited to observations of stars and stellar systems, SUSI will measure stars of all types - young, old, light, massive, cool and hot. It will enable fundamental properties like temperature, size and mass to be determined. It will also allow detailed studies of the atmospheres and interiors of stars and their evolution.

Funded jointly by the Australian Research Council and the University of Sydney, SUSI is being progressively commissioned and is now operating with a resolving power equivalent to an 80m telescope. It will ultimately reach its full 640m resolving power - equivalent to measuring the thickness of a human hair at a distance of 100km.


SUSI seen from the north end of the 640m baseline.


Looking north along the SUSI baseline from the central stations. Each siderostat station (right) has a smaller electronics box alongside. The C14 dome and SUSPECT building are on the left, with AT antennas in the background.


Another view of the central portions of the SUSI baseline, showing one station forming the stub of an eastern arm.


A siderostat station, showing the 20cm mirror in its alt-az mounting (the siderostat), which feeds starlight into one the north or south periscopes mounted on either side of it.


The Beam Reducing Telescope is composed of a large parabolic mirror (seen from the rear) and a smaller paraboloid (on the green mount seen in the distance. In the foreground are the mirrors of the tilt correction system and the mounts of the atmospheric corrector (with no optics in place).


The Beam Reducing Telescope is composed of a large parabolic mirror (seen in the distance) and a smaller paraboloid (on the green mount with the motorised focus control seen in the foreground). In the background are the carriages on the rails of the path length compensation system.


The intensified video camera of the Star Acquisition System. Behind it are the mirrors forming the top part of the periscopes that lift the light from the outside (in the grey pipes) to the level of the beam Reducing Telescope.


The 70m long path compensation system has carriages that move to equalise the light paths in the two arms of the interferometer. This view shows the fine compenation carriage on the righthand rails. The optics in the foreground is mostly part of the infrared pathlength monitoring interferometer which keeps precise track of where the carriage is along the rails.


Not a very good view of the fine compensation carriage.


Train coming!


The main optical table in SUSI contains the optics to combine the "blue" light beams and detect the interference signal. It also has the optics and detectors to use half the light to remove image motion (tip-tilt correction), plus optics to inject an alignment beam into the system from the "back end". The other aperture wheels and shutters visible in this picture allow remote operation of all these systems from the control room.