DATABASE: Absorption line strengths

Data files and descriptions

Kyuseok Oh

The OSSY database is consist of 6 files in fits format :
(note that objects are sorted in the same order they appear in all fits files)

  1. OSSY_SDSS_parameters.fits  [Download: 36MB] [description]
    : General information describing objects.

  2. OSSY_absorption.fits  [Download: 187MB] [description]
    : Stellar absorption line strengths.

  3. OSSY_emission_flux_errors.fits  [Download: 405MB] [description]
    : Intrinsic emission-line fluxes and errors. The values of Emission line strengths are derived from 'intrinsic' shape of spectra, which is affected by both galactic and internal reddening.

  4. OSSY_emission_aon_ew_sky.fits  [Download: 359MB] [description]
    : Gaussian Amplitude / Noise (AON) of the emission-lines, Equivalent Widths (EWs), and flags for the sky contamination. Skyline contamination (λ5577.0, λ6300.0, λ6363.0Å) is provided with '0' (telluric-free) or '1' (contaminated).

  5. OSSY_emission_observed_flux.fits  [Download: 396MB] [description]
    : Emission-line fluxes as observed. The reddening attenuation (i.e., internal reddening) factor is not applied.

  6. OSSY_quality_assessment_continuum.fits  [Download: 28MB] [description]
    :Nσ is a measure of the continuum fitting quality, derived indicating the distance of the given object from the median line in the Figure shown below, in units of sigma. For example, Nσ=3 indicates that there are 99.73% probabiity that the object was a true outlier and only a 0.27% probability of being the result of random fluctuation.

# Name Data Type/Units Description
0 SDSS ID string[1] 18-digit
1 rN_SN float[1] Residual noise / statistical noise ratio
2 S_SN float[1] Signal / statistical noise
3 NSIGMA float[1] Deviation from the median distribution in units of sigma, Nσ.

Figure: Quality assessment for continuum with examples inducing bad fits. This figure shows a quality assessment for a continuum region using randomly selected ~46,000 objects. Red crosses on the central panel denote the median (lower) and 1 σ(upper) distribution for each S/sN bin and orange solid lines fit (note that there is a demarcation line for 1 σ in the direction of larger rN/sN.). The vertical dashed lines indicate a specific bin and its Gaussian distribution has been inserted on the top side as an example. The color filled dots correspond to the colored left and right panels and clarify the trend for quality assessments. The black solid lines represent the observed spectra and the coloured lines are the fits. Furthermore, the top and bottom examples with gray fits are the major reasons for the bad fits. These telluric contaminated spectra (top) and Broad Line Regions (bottom) are marked with black crosses on the central panel. A minor reason which brought about bad fits is also denoted by red and green filled dots.