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Session 57 - Instrumentation & Information Science.
Oral session, Thursday, January 08

[57.03] Imaging Spectrophotometry Using a Liquid-crystal Tunable Filter

R. W. Slawson, Z. Ninkov, E. Horch (RIT/CIS)

In this paper we demonstrate the use of a liquid-crystal tunable filter for obtaining wide-field, low resolution spectrophotometry.

The filter used is electronically tunable to any wavelength in the range from 400 to 720\,nm with a nominal passband of 10\,nm \sc FWHM. We repeatedly imaged the central region of the Jewel Box cluster, NGC\,4755, through the filter while stepping its central wavelength from 435 to 720\,nm in successive exposures. Point-spread function fitting photometry was then performed on all the frames and the images stacked into a datacube of instrumental magnitudes versus wavelength. Differential corrections for each frame were estimated by assuming that one star in the field with a known spectral type was well represented by a standard dereddened spectrophotometric scan. Dereddened spectra of other stars in the field were then constructed with an accuracy limited by the match between the reference star's intrinsic and assumed spectrum and any variation in reddening within the cluster.

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Program listing for Thursday