Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Modelling high resolution Echelle spectrographs for calibrations: Hanle
  Echelle spectrograph, a case study   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.

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The categories of this paper are: cmp-lg
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The categories of this paper are: econ
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The categories of this paper are: quant-ph
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The categories of this paper are: math
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The categories of this paper are: nlin
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The categories of this paper are: chem-ph
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The categories of this paper are: alg-geom
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The categories of this paper are: comp-gas
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The categories of this paper are: solv-int
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The categories of this paper are: bayes-an
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The categories of this paper are: q-alg
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The categories of this paper are: chao-dyn
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The categories of this paper are: math-ph
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The categories of this paper are: physics
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The categories of this paper are: cs
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The categories of this paper are: funct-an