Spectra from "Average Spectra of Massive Galaxies in the SDSS"
by D. Eisenstein, D. Hogg, et al, in the Astrophysical Journal.

In this tar package, you will find 88 files in addition to this
readme documentation.  These files contain the average spectra,
the errors, and the residual emission line spectra described
in the paper.  The format is ASCII.

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With the exception of the files "spectrum_svd.data" and 
"spectrum_svdZ.data", the format is as follows:

The file names are a series of terms:

ellip:	These are drawn from the MAIN sample (described in the paper).
lrg:	These are drawn from the LRG  sample (described in the paper).

0701a.05: This marks the sample and reduction number for my pipeline.
	You can ignore it.

lum205, lum210, lum215, lum220: These indicate the luminosity bin, 
	-20.5 to -21, -21 to -21.5, -21.5 to -22, -22 to -22.5 in M_r
lum218: This indicates M_g < -21.8 for the LRG sample.

n0_3, n4_9, n10: This indicates the environment bin, 0<=N<=3, 4<=N<=9, 
	and N>=10. Omitted for the full sample (i.e. luminosity selection 
	without environment selection).

template: This is a special file containing an expanded wavelength coverage
	for LRGs in the redshift range 0.3<z<0.35.  This is used in 
	Figure 4 in the paper.

faruv: Special wavelength range (in the UV) for very high redshift LRGs.
	This is used in Figure 11 in the paper.

This defines the sample.  The analysis was run separately on each sample.


For each sample, there are multiple files:

spave1: This is the average spectrum for the chosen sample.

sperr: This is the error on the average spectrum, as computed from splitting
	the data in two parts by even & odd plate numbers.

spem:  This is the residual between the average and median spectrum, 
	showing an emission line spectrum.

spave1.325: This is the average spectrum smoothed to 325 km/s.

All of the files within a sample have the same relative normalization.
The spectra are always F_lambda units.


These files are all ASCII. They contain a header line and then many lines
of two column format: wavelength and spectrum (or error).  The wavelengths
are spaced on the usual SDSS grid, namely a grid of 0.0001 in log10(lambda).

The header line contains 6 or 7 numbers.
1) The number of spectra in the sample
2) The number of wavelength bins
3) The number of PCA eigenspectra included in the average
4) The lower wavelength
5) The upper wavelength
6) The flags that control my processing (ignore)
7) The S/N of the spectrum is given in the sperr file

The spave1.325 files didn't copy this information correctly, but
they do include the Gaussian velocity dispersion by which they have 
been smoothed.

Further details of the samples and methods should be in the paper.
If you want tables in electronic form, they are in separate files
in the astro-ph LaTeX source.

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The files "spectrum_svd.data" and "spectrum_svdZ.data" contain the
vectors from Figures 8 and 10, in which the average spectra themselves
were subjected to PCA.  These files have a separate format, which is
documented in the files themselves.

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The file "stacked_spectrum.tar.gz" is a tarball containing all of
the other files in the directory.

Contact me (deisenstein@as.arizona.edu) if you have any questions.  Enjoy!

Daniel Eisenstein
Steward Observatory
December 16, 2002