A Survey for New Stars and Brown Dwarfs in the Ophiuchus Star-forming
  Complex
  We have performed a survey for new members of the Ophiuchus cloud complex
using high-precision astrometry from the second data release of Gaia, proper
motions measured with multi-epoch images from the Spitzer Space Telescope, and
color-magnitude diagrams constructed with photometry from various sources.
Through spectroscopy of candidates selected with those data, we have identified
155 new young stars. Based on available measurements of kinematics, we classify
102, 47, and six of those stars as members of Ophiuchus, Upper Sco, and other
populations in Sco-Cen, respectively. We have also assessed the membership of
all other stars in the vicinity of Ophiuchus that have spectroscopic evidence
of youth from previous studies, arriving at a catalog of 373 adopted members of
the cloud complex. For those adopted members, we have compiled mid-IR
photometry from Spitzer and the Wide-field Infrared Survey Explorer} and have
used mid-IR colors to identify and classify circumstellar disks. We find that
210 of the members show evidence of disks, including 48 disks that are in
advanced stages of evolution. Finally, we have estimated the relative median
ages of the populations near the Ophiuchus clouds and the surrounding Upper Sco
association using absolute K-band magnitudes (M_K) based on Gaia} parallaxes.
If we adopt an age 10 Myr for Upper Sco, then the relative values of M_K imply
median ages of ~2 Myr for L1689 and embedded stars in L1688, 3-4 Myr for
low-extinction stars near L1688, and ~6 Myr for the group containing rho Oph.
