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Paper: Reference Object Identification: Pattern-matching or First-guess Model? A Procedure to Determine the Spectral Format of X-Shooter Takes Advantage of Both Techniques
Volume: 411, Astronomical Data Analysis Software and Systems XVIII
Page: 458
Authors: Modigliani, A.; Bristow, P.D.; Izzo, C.
Abstract: X-Shooter is a wide-band (320-2500 nm), intermediate-resolution, (R = 4, 000-14, 000) single-object, three-arm spectrograph for the VLT. It starts commissioning late in 2008. X-Shooter data reduction, particularly the wavelength calibration, will be supported by an instrument physical model which provides both predictive power and physical understanding of the instrument behavior during operation. Reference spectral line identification is made robust with the help of pattern-matching techniques. Non-negligible spectral format shifts may arise from the optimization of the instrument configuration performed during commissioning phases, maintenance or from macro earthquake events. Hence a procedure is required to reliably recover the spectral format via the automatic identification of reference spectral lines in calibration lamp exposures that may have changed location by tens or even hundreds of pixels. The predictive power and accuracy provided by the instrument physical model, together with the robustness of a 2D pattern matching algorithm, can cope with significant spectral format changes. We describe the implemented procedure.
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