SDSS-IV eBOSS emission-line galaxy pilot survey
  The Sloan Digital Sky Survey IV extended Baryonic Oscillation Spectroscopic
Survey (SDSS-IV/eBOSS) will observe 195,000 emission-line galaxies (ELGs) to
measure the Baryonic Acoustic Oscillation standard ruler (BAO) at redshift 0.9.
To test different ELG selection algorithms, 9,000 spectra were observed with
the SDSS spectrograph as a pilot survey based on data from several imaging
surveys. First, using visual inspection and redshift quality flags, we show
that the automated spectroscopic redshifts assigned by the pipeline meet the
quality requirements for a reliable BAO measurement. We also show the
correlations between sky emission, signal-to-noise ratio in the emission lines,
and redshift error. Then we provide a detailed description of each target
selection algorithm we tested and compare them with the requirements of the
eBOSS experiment. As a result, we provide reliable redshift distributions for
the different target selection schemes we tested. Finally, we determine an
target selection algorithms that is best suited to be applied on DECam
photometry because they fulfill the eBOSS survey efficiency requirements.
