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Modelling high resolution Echelle spectrographs for calibrations: Hanle Echelle spectrograph, a case study

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dc.contributor.author Anantha, Ch
dc.contributor.author Jones, D
dc.contributor.author Sivarani, T
dc.date.accessioned 2020-11-12T14:53:40Z
dc.date.available 2020-11-12T14:53:40Z
dc.date.issued 2015-06
dc.identifier.citation Experimental Astronomy, Vol. 39, No. 2, pp. 423-443 en_US
dc.identifier.issn 0922-6435
dc.identifier.uri http://prints.iiap.res.in/handle/2248/6939
dc.description Restricted Access © Springer The original publication is available at springerlink.com http://dx.doi.org/10.1007/s10686-015-9457-y en_US
dc.description.abstract We present a modelling scheme that predicts the centroids of spectral line features for a high resolution Echelle spectrograph to a high accuracy. Towards this, a computing scheme is used, whereby any astronomical spectrograph can be modelled and controlled without recourse to a ray tracing program. The computations are based on paraxial ray trace and exact corrections added for certain surface types and Buchdahl aberration coefficients for complex modules. The resultant chain of paraxial ray traces and corrections for all relevant components is used to calculate the location of any spectral line on the detector under all normal operating conditions with a high degree of certainty. This will allow a semi-autonomous control using simple in-house, programming modules. The scheme is simple enough to be implemented even in a spreadsheet or in any scripting language. Such a model along with an optimization routine can represent the real time behaviour of the instrument. We present here a case study for Hanle Echelle Spectrograph. We show that our results match well with a popular commercial ray tracing software. The model is further optimized using Thorium Argon calibration lamp exposures taken during the preliminary alignment of the instrument. The model predictions matched the calibration frames at a level of 0.08 pixel. Monte Carlo simulations were performed to show the photon noise effect on the model predictions. en_US
dc.language.iso en en_US
dc.publisher Springer en_US
dc.subject Astronomical spectrographs en_US
dc.subject Calibration en_US
dc.subject Instrument modeling en_US
dc.subject Physical model based calibrations en_US
dc.title Modelling high resolution Echelle spectrographs for calibrations: Hanle Echelle spectrograph, a case study en_US
dc.type Article en_US


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