First Data Release of the COSMOS Lyman-Alpha Mapping And Tomography
  Observations: 3D Lyman-$\alpha$ Forest Tomography at 2.05 < z < 2.55
  Faint star-forming galaxies at $z\sim 2-3$ can be used as alternative
background sources to probe the Lyman-$\alpha$ forest in addition to quasars,
yielding high sightline densities that enable 3D tomographic reconstruction of
the foreground absorption field. Here, we present the first data release from
the COSMOS Lyman-Alpha Mapping And Mapping Observations (CLAMATO) Survey, which
was conducted with the LRIS spectrograph on the Keck-I telescope. Over an
observational footprint of 0.157$\mathrm{deg}^2$ within the COSMOS field, we
used 240 galaxies and quasars at $2.17<z<3.00$, with a mean comoving transverse
separation of $2.37\,h^{-1}\,\mathrm{Mpc^3}$, as background sources probing the
foreground Lyman-$\alpha$ forest absorption at $2.05<z<2.55$. The
Lyman-$\alpha$ forest data was then used to create a Wiener-filtered
tomographic reconstruction over a comoving volume of $3.15\,\times
10^5\,h^{-3}\,\mathrm{Mpc^3}$ with an effective smoothing scale of
$2.5\,h^{-1}\,\mathrm{Mpc}$. In addition to traditional figures, this map is
also presented as a virtual-reality YouTube360 video visualization and
manipulable interactive figure. We see large overdensities and underdensities
that visually agree with the distribution of coeval galaxies from spectroscopic
redshift surveys in the same field, including overdensities associated with
several recently-discovered galaxy protoclusters in the volume. This data
release includes the redshift catalog, reduced spectra, extracted
Lyman-$\alpha$ forest pixel data, and tomographic map of the absorption.
