Controllers Help Peer into Universe

Dec. 8, 2008

Astronomers working for University of California Observatories (UCO), a multi-campus research unit, are creating the first comprehensive survey and map of the distant universe. Called the Deep Extragalactic Evolutionary Probe (DEEP), the team uses telescopes in Hawaii and California, as well as the orbiting Hubble Space Telescope, to collect light emitted from stars or galaxies 14 billion years ago.

Barry Alcott, development engineer at UCO, is using Galil’s RIO Pocket PLC to automate portions of the manually operated Hamilton Spectrograph system, the first cross-dispersed spectrograph installed at the Lick Observatory. It operates by having light fed to a grating that sends it in one direction and then immediately feeds it to a prism that disperses it at a 90° angle, resulting in very high-resolution spectra.

Alcott configured the multiple I/O points provided by the RIO to automatically control four pneumatic stages used for moving an iodine cell into a beam, opening a light port, moving a mirror into a beam and opening a mirror cover. The logic control provided by the RIO ensured proper sequencing of events. All communication for the motion and I/O control is Ethernet.

“A major benefit of automating the control of these functions is the ability to enable our astronomers to remotely control the telescope instruments from a home base,” says Alcott.