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Australian Human Resources Institute Diversity Awards 2013 Finalist

Anna Moore, Caltech ()


"The expanding role of image slicer integral field spectrographs in Astronomical science"

Abstract. The first image slicer integral field spectrograph (or IFS) was invented in 1938 by Bowen to increase the spectroscopic resolution of a seeing limited star. The instrument divided the seeing disk into a series of "slitlet" images and, with some clever mirror trickery, recreated a long slit feeding the conventional spectrograph. The past 10-15 years has seen a huge increase in the use of integral field spectrographs (lenslet array and mirror slicer) on forefront optical telescopes. The data product has changed since 1938 - the modern day IFS produces a 3-dimensional data cube with sky spatial coordinates for x and y, and wavelength as the z axis.I present three instruments that adopt the image slicer IFS technique that I am either PI or Project manage. The Cosmic Web Imager (CWI) is a seeing limited image slicer IFS operating in the optical bandpass at the Cassegrain focus of the 200" Hale telescope on Palomar Mountain. The instrument is designed to detect low surface brightness emission with a forefront science goal of direct detection and mapping of Lyman-a emission from the Intergalactic Medium (IGM, or "cosmic web") at z=2-7. The image slicer, located at the focal plane of the telescope, consists of a 24-mirror array that converts the 40arcsec x 60arcsec focal plane into a curved long slit image feeding a R~5000 spectrograph. High throughput is provided by a large Volume Phase Holographic grating operated in the Littrow configuration. CWI has undergone two science runs and has performed superbly. First results are presented.The Antarctic Cosmic Web Imager (ACWI) is a 2m-class telescope and spectrograph to be located at the South Pole Amundsen Scott station. The instrument is specifically designed with an Antarctic location in mind, including a gravity invariant design to enable surface brightness detections an order lower compared to a temperate site. The instrument concept was so compelling that the National Science Foundation funded a prototype site testing instrument, the Gattini South Pole experiment, to be deployed January 2011, to assess the quality of the sky in the bluest wavelengths (300nm - 500nm). A summary of the instrument is presented along with expected performance.Lastly, the Infra-red Imaging Spectrograph (IRIS) is one of the three "first light" instruments for the Thirty Meter Telescope Project (TMT) with first light scheduled in 2018. IRIS is a narrow field adaptive optics instrument that contains a parallel imager and IFS. IRIS will work in conjunction with the NFIRAOS adaptive optics system at near infra-red wavelengths (0.84-2.4microns) and probe user defined spaxel scales of 4mas to 50mas. The power of the IRIS-NFIRAOS system on TMT will enter a new regime of Astronomical observations.


Held in the AAO Conference room at 03:30 PM on Tuesday, 09 November 2010

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