Reliable random error estimation in the measurement of line-strength indices



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Cardiel López, Nicolás and Gorgas García, Francisco Javier and Cenarro, J. and González, J. J. (1998) Reliable random error estimation in the measurement of line-strength indices. Astronomy & astrophysics supplement series, 127 (3). pp. 597-605. ISSN 0365-0138

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We present a new set of accurate formulae for the computation of random errors in the measurement of atomic and molecular line-strength indices. The new expressions are in excellent agreement with numerical simulations. We have found that, in some cases, the use of approximated equations can give misleading line-strength index errors. It is important to note that accurate errors can only be achieved after a full control of the error propagation throughout the data reduction with a parallel processing of data and error images. Finally, simple recipes for the estimation of the required signal-to-noise ratio to achieve a fixed index error are presented.

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We are grateful to the referee for useful comments. The JKT is operated on the island of La Palma by the Royal Greenwich Observatory at the Observatorio del Roque de los Muchachos of the Instituto de Astrofísica de Canarias. The Calar Alto Observatory is operated jointly by the Max-Planck-Institute für Astronomie, Heidelberg, and the Spanish Comisión Nacional de Astronomía. This work was supported by the Spanish “Programa Sectorial de Promoción General del Conocimiento” under grant No. PB93-0456.

Uncontrolled Keywords:Old stellar populations; Early-type galaxies; Extragalactic globular-clusters; Early-type systems; Elliptical galaxies; Spectral evolution; K-giants; Gradients; Spectroscopy; Indexes
Subjects:Sciences > Physics > Astrophysics
Sciences > Physics > Astronomy
ID Code:29953
Deposited On:21 May 2015 08:14
Last Modified:10 Dec 2018 15:05

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