The Roman Space Telescope will offer a General Observer program that supports community-based observing programs. While the baseline mission emphasizes the dark-energy and exoplanet measurements, the additional surveys carried out via the General Observer program will exploit it's unique capabilities to substantially broaden the science return of the mission. The General Observer program will provide broad support to many fields of astrophysics in the tradition of HST, no doubt with the same astonishing results of new, creative, field-changing science. In an extended mission, the General Observer program would likely become the dominant part of the mission. HST has demonstrated clearly that the combination of a powerful facility and peer-reviewed proposals has the greatest impact in advancing the extraordinarily broad field of astrophysics research.

Appendix A of the Roman Space Telescope SDT (2013) report contains ~ 50 potential GO or Guest Investigator science programs, each described in one page, contributed by members of the broader astronomical community. Here we simply list their titles to illustrate the remarkable range of ideas for scientific investigations enabled by the Roman Space Telescope :

Planetary Bodies

• A Full Portrait of the Kuiper Belt, Including Size Distributions, Colors, and Bimodality
• The Outer Solar System from Neptune to the Oort Cloud
• Free-floating Planets in the Solar Neighborhood
• Measuring Planet Masses with Transit Timing Variations
• Exoplanet Spectroscopy
• Additional Planet Finding Capabilities — Astrometry
• Additional Planet Finding Capabilities — Transits

Stellar Astrophysics

• Stellar and Substellar Populations in Galactic Star Forming Regions
• Identifying the Coldest Brown Dwarfs
• Stellar Fossils in the Milky Way
• The Infrared Color-Magnitude Relation
• Finding the Closest Young Stars
• The Most Distant Star-Forming Regions in the Milky Way
• Super-resolution Imaging of Low-mass Stars with Kernel-phase and Precision Wavefront Calibration with Eigen-phase
• Detecting and Characterizing Neutron Stars, Black Holes with Astrometric Microlensing

Galactic Astrophysics and the Local Volume

• Proper Motions and headeres of Disk and Bulge Stars
• Quasars as a Reference Frame for Proper Motion Studies
• The Detection of the Elusive Stellar Counterpart of the Magellanic Stream
• Near-field Cosmology: Finding the Faintest Milky Way Satellites
• The Mass of the Milky Way
• Distinguishing Between Cold and Warm Dark Matter
• Finding (or Losing) Those Missing Satellites
  
• Mapping the Potential of the Milky Way with Tidal Debris
• Dissecting Nearby Galaxies
• Galaxy Evolution from Resolved Stellar Pops: Halo Age Distributions of the Local Volume
• Substructure Around Galaxies Within 50 Mpc
• Resolved Stellar Populations in Nearby Galaxies
• Deep Surface Photometry of Galaxies and Galaxy Clusters

Extragalactic Astrophysics

• Galaxy Structure and Morphology
• Strong Lensing
• Searching for Extreme Shock-dominated Galaxy Systems from z = 1 — 2
• Mapping the Distribution of Matter in Galaxy Clusters
• Merging Clusters of Galaxies
• Group-Scale Lenses: Unexplored Territory
• The Evolution of Massive Galaxies: The Formation and Morphologies of Red Sequence Galaxies
• Finding and Weighing Distant, High Mass Clusters of Galaxies
• Probing the Epoch of Reionization with Lyman-Alpha Emitters
• Obscured Quasars
• The Faint End of the Quasar Luminosity Function
• Strongly Lensed Quasars
• High-Redshift Quasars and Reionization
• Characterizing the Sources Responsible for Reionization
• Finding the First Cosmic Explosions
• Resolved Stellar Population Studies in z ~ 2 Star Forming Galaxies

General

• Synergy Between LSST and Roman Space Telescope
• Synergies Between Euclid and Roman Space Telescope
• The Shapes of Galaxy Haloes from Gravitational Flexion
• Roman Space Telescope and IRSA: Synergy Between All-Sky IR Surveys
• Near Infrared Counterparts of Elusive Binary Neutron Star Mergers