The raw data

Origin of data

We have used the redshifts from spZbest files and the spectra were downloaded from the SDSS DAS as spPlate files. The photometric data provided for reference below has been taken from the FNAL tsObj files provided per plate in spectro/2d_26.

Spectrum normalisation

The SDSS DR7 includes a different spectrophotometric calibration, and as a result the overall normalisation of the spectra matches the PSF magnitudes (see this page for more details). This is correct for point sources but is not easily interpreted for extended sources. As a consequence we have renormalised our flux outputs to match the photometric fiber magnitude in the r-band. This is done by calculating synthetic r-band magnitudes from the spectra and matching these to the outputs of photo. The scale applied is kept as the key SPECTOFIBER in the gal_line file below.

General notice: Please note that our line fluxes where given, are all corrected for foreground (galactic) reddening using the O'Donnell, J.E., 1994, ApJ, 422, 158. If you have any questions about this please feel free to contact us.

About error estimates

Note: This section has not yet been updated to reflect DR7 spectra but we espect small changes.

The quoted uncertainties (e.g. *_FLUX_ERR are formal uncertainties). These are, however, underestimates of the true uncertainties and this should be taken into account in most work. To estimate the true uncertainties we have used the duplicate observations of galaxies, to compare the empirical spread in value determinations with the random errors. These uncertainties will include both errors in the spectrophotometry etc which are not included in the spectro2d pipeline, but more importantly they also include continuum subtraction uncertainties which are otherwise very hard to quantify (note in particular the substantial adjustment of the Ha flux errors below).

Since this procedure cannot be carried out on a galaxy-by-galaxy basis, there is a certain amount of residual uncertainty here, but the following table of conversions seems to give very good fits to our emission line models and we have adopted these - in particular all the derived data have been calculated with the emission line flux errors adjusted according to the following table:

Emission line Scale uncertainty by
[O II]3727 2.199
[Ne III]3869 1.731
Hbeta 1.882
[O III]4363 1.306
[O III]4959 1.573
[O III]5007 1.566
[O I]6300 1.378
HeI 5876 1.501
Halpha 2.473
[N II]6584 2.039
[S II]6716 1.621
[S II]6731 1.621

That said, it is of course entirely up to the individual whether to adopt these scalings or not, but we would in general recommend it. The quantities in the following files are the quantities given by our pipeline so have not been scaled in any way.

The FITS tables with data

The files below are substantial so you might prefer direct access to the datafiles through this link.