J/A+A/615/A24 Passband reconstruction from photometry (Weiler+, 2018)
Passband reconstruction from photometry.
Weiler M., Jordi C., Fabricius C., Carrasco J.M.
<Astron. Astrophys. 615, A24 (2018)>
=2018A&A...615A..24W 2018A&A...615A..24W (SIMBAD/NED BibCode)
ADC_Keywords: Photometry
Keywords: instrumentation: photometers - techniques: photometric -
techniques: spectroscopic
Abstract:
Based on an initial expectation from laboratory measurements or
instrument simulations, photometric passbands are usually subject to
refinements. These refinements use photometric observations of
astronomical sources with known spectral energy distribution.
This work investigates the methods for and limitations in determining
passbands from photometric observations. A simple general formalism
for passband determinations from photometric measurements is derived.
The results are applied to the passbands of HIPPARCOS, Tycho, and Gaia
DR1.
The problem of passband determination is formulated in a basic
functional analytic framework. For the solution of the resulting
equations, functional principal component analysis is applied.
We find that, given a set of calibration sources, the passband can be
described with respect to the set of calibration sources as the sum of
two functions, one which is uniquely determined by the set of
calibration sources, and one which is entirely unconstrained. The
constrained components for the HIPPARCOS, Tycho, and Gaia DR1
passbands are determined, and the unconstrained components are
estimated.
Description:
In table2, passbands for HIPPARCOS, Tycho B and V, and Gaia DR1 are
presented. Each of these passbands is divided into the parallel and
the orthogonal component, the passbands being the sum of the two
components, respectively. All passbands are normalised to a maximum
value of One.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
passband.dat 102 8321 Passband solutions
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Table 2: The mean wavelength, the pivot wavelength, the zero points in the
VEGAMAG and the AB photometric systems, and the l2-norms of the parallel
and the orthogonal components for the four pass-bands described in this work
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parameter | G | Hp | BT | VT
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lambdamean [nm] | 661.25 | 540.19 | 419.68 | 529.68
lambda_pivot [nm] | 646.78 | 532.74 | 418.91 | 528.34
zero point [VEGA] | 25.853 | 26.006 | 24.996 | 25.040
zero point [AB] | 25.974 | 25.975 | 24.905 | 25.000
l2-norm of the parallel component | 16.8179 | 13.0333 | 7.0095 | 7.8246
l2-norm of the orthogonal component | 4.3186 | 2.0731 | 1.9359 | 3.1433
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Byte-by-byte Description of file: passband.dat
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Bytes Format Units Label Explanations
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1- 6 F6.1 nm lambda Wavelength in nanometers
8- 18 F11.8 --- HPpar Parallel component of HIPPARCOS passband
20- 30 F11.8 --- HPort Orthogonal component of HIPPARCOS passband
32- 42 F11.8 --- BTpar Parallel component of Tycho B passband
44- 54 F11.8 --- BTort Orthogonal component of Tycho B passband
56- 66 F11.8 --- VTpar Parallel component of Tycho V passband
68- 78 F11.8 --- VTort Orthogonal component of Tycho V passband
80- 90 F11.8 --- Gpar Parallel component of Gaia DR1 G passband
92-102 F11.8 --- Gort Orthogonal component of Gaia DR1 G passband
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Acknowledgements:
Michael Weiler, mweiler(at)fqa.ub.edu
(End) Michael Weiler [Univ. Barcelona, Spain] Patricia Vannier [CDS] 12-Feb-2018