The Goodman Spectrograph is an imaging, multi-object spectrograph for the SOuthern Astrophysical Research telescope (SOAR). It is one of the first designed to take advantage of Volume Phase Holographic (VPH) gratings by employing an articulated camera. This aspect of the mechanical design has had complicating effects on a number of usually simple systems, and has led to some unorthodox solutions. The spectrograph is also highly optimized for efficiency from 320 to 850 nm, and designed for rapid configuration changes, so that its throughput makes it competitive with instruments on larger telescopes. We present the high level requirements that have driven the mechanical and electronic systems, and show their implementation in the completed instrument. It is too early to assess the overall system performance, but tests of the modular subsystems show promising results. We discuss the expected overall performance and discuss mitigation strategies should that performance fall short of our goals.
Travel from North America to the 4.1m SOAR telescope atop Cerro Pachon exceeds $1000, and takes >16 hours door to door (20+ hours typically). SOAR aims to exploit best seeing, requiring dynamic scheduling that is impossible to accomplish when catering to peripatetic astronomers. According to technical arguments at www.peakoil.org, we are near the peak rate of depleting world petroleum, so can expect travel costs to climb sharply. With the telecom bubble's glut of optical fiber, we can transmit data more efficiently than astronomers and "observe remotely". With data compression, less than half of the 6 Mbps bandwidth shared currently by SOAR and CTIO is enough to enable a high-fidelity observing presence for SOAR partners in North America, Brazil, and Chile. We discuss access from home by cable modem/DSL link.
The Goodman spectrograph is an all-refracting articulated-camera high-throughput imaging spectrograph for the SOuthern Astrophysical Research telescope (SOAR). It is designed to take advantage of Volume Phase Holographic (VPH) gratings. Due to the high level of mechanical complexity, a fully graphical control system with parallel motor control was developed. We have developed a software solution in LabVIEW that functions as a control system, component management tool, and engineering platform. A modular software design allows other instrument projects to easily adopt our approach. Distinguishing features of the control system include automated configuration changes, remote capability, and PDA control for component swaps.
The SOAR telescope will begin science operations in 3Q 2003. From the outset, astronomers at all U.S. research universities will be able to use it remotely, avoiding 24+ hrs of travel, and allowing half-nights to be scheduled to enhance scientific return. Most SOAR telescope systems, detector array controllers, and instruments will operate under LabVIEW control. LabVIEW enables efficient intercommunication between modules executing on dispersed computers, and is operating-system independent. We have developed LabVIEW modules for remote observing that minimize bandwidth to the shared LAN atop Cerro Pachon. These include control of a Polycom videoconferencing unit, export of instrument control GUI's and telescope telemetry to tactical displays, and a browser that first compresses an image in Chile by a factor of 256:1 from FITS to JPEG2000 and then sends it to the remote astronomer. Wherever the user settles the cursor, a region-of-interest window of lossless compressed data is downloaded for full fidelity. As an example of a dedicated facility, we show layout and hardware costs of the Remote Observing Center at UNC, where instruments on SOAR, SALT, and other telescopes available to UNC-CH astronomers will be operated.