indexf: Linestrength Indices in Fully Calibrated FITS Spectra
Abstract
This program measures linestrength indices in fully calibrated FITS spectra. By "fully calibrated" one should understand wavelength and relative fluxcalibrated data. Note that the different types of linestrength indices that can be measured with indexf (see below) do not require absolute flux calibration. If even a relative fluxcalibration is absent (or deficient), the derived indices should be transformed to an appropriate spectrophotometric system. The program can also compute index errors resulting from the propagation of random errors (e.g. photon statistics, readout noise). This option is only available if the user provides the error spectrum as an additional input FITS file to indexf. The error spectrum must contain the unbiased standard deviation (and not the variance!) for each pixel of the data spectrum. In addition, indexf also estimates the effect of errors on radial velocity. For this purpose, the program performs Monte Carlo simulations by measuring each index using randomly drawn radial velocities (following a Gaussian distribution of a given standard deviation). If no error file is employed, the program can perform numerical simulations with synthetic error spectra, the latter generated from the original data spectra and assuming randomly generated S/N ratios.
 Publication:

Astrophysics Source Code Library
 Pub Date:
 October 2010
 Bibcode:
 2010ascl.soft10046C
 Keywords:

 Software