AAS 206th Meeting, 29 May - 2 June 2005
Session 15 Astronomical Instruments
Poster, Monday, 9:20am-6:30pm, Tuesday, 10:00am-7:00pm, May 30, 2005, Ballroom A

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[15.04] A Technique for Accurate In-situ Instrumental Throughput Determination

C.W. Stubbs (Harvard University/CfA), D. Sherman (Harvard University), J. Tonry (IfA, U of Hawaii), T. Abbott, A. Saha, N. Suntzeff, R. C. Smith (CTIO/NOAO), E. Margalith (Opotek)

We have devised a technique that uses a tunable laser and a calibrated reference photodiode to perform an in-site determination of the relative throughput of an astronomical instrument. This approach measures the combined transmission of the mirrors, optics, filter and detector at a set of discrete wavelengths, relative to a precision calibrated photodiode. This liberates the calibration of an astronomical system from requiring knowledge of the spectral energy distribution of a celestial source, and has the potential for characterizing the instrument at the percent level or better. We will present inital results obtained for the MOSAIC imager on the Blanco telescope at CTIO, in support of the ESSENCE supernova cosmology project. This work is supported by the NSF under grant AST-0443378.

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Bulletin of the American Astronomical Society, 37 #2
© 2005. The American Astronomical Soceity.