The Grism Lens-Amplified Survey from Space (GLASS). XIII. G800L optical
  spectra from the parallel fields
  We present a catalogue of 22755 objects with slitless, optical, Hubble Space
Telescope (HST) spectroscopy from the Grism Lens-Amplified Survey from Space
(GLASS). The data cover $\sim$220 sq. arcmin to 7-orbit ($\sim$10 ks) depth in
20 parallel pointings of the Advanced Camera for Survey's G800L grism. The
fields are located 6' away from 10 massive galaxy clusters in the HFF and CLASH
footprints. Thirteen of the fields have ancillary HST imaging from these or
other programs to facilitate a large number of applications, from studying
metal distributions at $z\sim0.5$, to quasars at $z\sim4$, to the star
formation histories of hundreds of galaxies in between. The spectroscopic
catalogue has a median redshift of $\langle z\rangle=0.6$ with a median
uncertainty of $\Delta z / (1+z)\lesssim2\%$ at $\rm F814W\lesssim23$ AB.
Robust continuum detections reach a magnitude fainter. The 5 $\sigma$ limiting
line flux is $f_{\rm lim}\approx5\times10^{-17}\rm~erg~s^{-1}~cm^{-2}$ and half
of all sources have 50% of pixels contaminated at $\lesssim$1%. All sources
have 1- and 2-D spectra, line fluxes/uncertainties and identifications,
redshift probability distributions, spectral models, and derived narrow-band
emission line maps from the Grism Redshift and Line Analysis tool (GRIZLI). We
provide other basic sample characterisations, show data examples, and describe
sources and potential investigations of interest. All data and products will be
available online along with software to facilitate their use.
