The Australian Astronomical Observatory's TAIPAN instrument deploys 150 Starbug robots to position optical fibres to accuracies of 0.3 arcsec, on a 32 cm glass field plate on the focal plane of the 1.2 m UK-Schmidt telescope. This paper describes the software system developed to control and monitor the Starbugs, with particular emphasis on the automated path-finding algorithms, and the metrology software which keeps track of the position and motion of individual Starbugs as they independently move in a crowded field. The software employs a tiered approach to find a collision-free path for every Starbug, from its current position to its target location. This consists of three path-finding stages of increasing complexity and computational cost. For each Starbug a path is attempted using a simple method. If unsuccessful, subsequently more complex (and expensive) methods are tried until a valid path is found or the target is flagged as unreachable.
The High Efficiency and Resolution Multi Element Spectrograph, HERMES, is a facility-class optical spectrograph for the Anglo-Australian Telescope (AAT). It is designed primarily for Galactic Archaeology, the first major attempt to create a detailed understanding of galaxy formation and evolution by studying the history of our own galaxy, the Milky Way. The goal of the GALAH survey is to reconstruct the mass assembly history of the Milky Way through a detailed chemical abundance study of one million stars. The spectrograph is based at the AAT and is fed by the existing 2dF robotic fiber positioning system. The spectrograph uses volume phase holographic gratings to achieve a spectral resolving power of 28,000 in standard mode and also provides a high-resolution mode ranging between 40,000 and 50,000 using a slit mask. The GALAH survey requires an SNR greater than 100 for a star brightness of V=14 in an exposure time of one hour. The total spectral coverage of the four channels is about 100 nm between 370 and 1000 nm for up to 392 simultaneous targets within the 2-degree field of view. HERMES has been commissioned over three runs, during bright time in October, November, and December 2013, in parallel with the beginning of the GALAH pilot survey, which started in November 2013. We present the first-light results from the commissioning run and the beginning of the GALAH survey, including performance results such as throughput and resolution, as well as instrument reliability.
We present a stable, inexpensive wavelength reference, based on a white-light interferometer for the use on current and future (arrays of) diffraction-limited radial velocity (RV) spectrographs. The primary aim of using an interferometer is to obtain a dense sinusoidal wavelength reference with spectral coverage between 450-650 nm. Its basic setup consists of an unbalanced fiber Mach-Zehnder interferometer (FMZI) that creates an interference pattern in the spectral domain due to superposition of phase delayed light, set by a fixed optical path-length difference (OPD). To achieve long-term stability, the interferometer is actively locked to a stable atomic line. The system operates in closed-loop using a thermo-optic modulator as the phase feedback component. We conducted stability measurements by superimposing the wavelength reference with thorium-argon (ThAr) emission lines
and found the differential RMS shift to be ~5 m s-1 within 30 minute bins in an experiment lasting 5 hours.
We present the opto-mechanical design and the characterization of the Replicable High-resolution Exoplanet and Asteroseismology (RHEA) spectrograph. RHEA is an ultra-compact fiber-fed echelle spectrograph designed to be used at 0.2-0.4 m class robotic telescopes where long term dedicated projects are possible. The instrument will be primarily used for radial velocity (RV) studies of low to intermediate-mass giant stars for the purpose of searching for hot Jupiters and using asteroseismology to simultaneously measure the host star parameters and de-correlate stellar pulsations. The optical design comprises a double-pass (i.e. near Littrow) configuration with
prism cross-disperser and single-mode fiber (SMF) input. The spectrograph has a resolving power of R>70,000 and operates at 430–670 nm with minimum order separation of ~180 μm. This separation allows a 1x6 photonic
lantern integration at a later stage which is currently under development. The current design is built with the aim of creating an inexpensive and replicable unit. The spectrograph is optimised for long-baseline RV observations through careful temperature stabilisation and simultaneous wavelength calibration. As a further improvement the echelle grating is housed in a vacuum chamber to maintain pressure stability. The performance of the current prototype is currently being tested on a 0.4 m telescope at the Macquarie University Observatory.