This page provides useful information for General Investigators preparing proposals, with references to the Core Community Surveys (CCS) and the first General Astrophysics Survey (GAS), the Roman Galactic Plane Survey. It includes brief summaries of each survey along with links to the dedicated pages where they are described in more detail.

Core Community Surveys

Three Core Community Surveys (CCS) have been defined by three committees through a process that solicited broad input from the astronomical community. The goal of this process was to arrive at a set of core surveys that would enable a broad range of astrophysical investigations while meeting Roman’s scientific mission requirements in cosmology and exoplanet demographics. The three Core Community Surveys are the High-Latitude Wide-Area Survey, the High-Latitude Time-Domain Survey, and the Galactic Bulge Time-Domain Survey. As all Roman data will be publicly available, the large volume of data produced by these surveys will enable many and different scientific investigations and it is expected that a large fraction of Roman users will interact primarily, or exclusively, with Roman’s data archive using the CCS data through analysis proposals solicited in this and future calls.  

High-Latitude Wide-Area Survey

Roman’s High-Latitude Wide-Area Survey (HLWAS) will deliver high-resolution imaging and slitless grism spectroscopy with unprecedented area, resolution, and depth. Observations will be conducted throughout Roman’s five-year prime mission. The HLWAS is a multi‑tiered imaging and spectroscopic program that will map ~5,100 deg², or about 12% of the sky. The HLWAS enables comprehensive, multi‑probe constraints on dark energy and dark matter, leveraging weak lensing, baryon acoustic oscillations, redshift-space distortions, galaxy clustering, and strong gravitational lensing. The HLWAS will also enable a wide variety of scientific investigations from the study of solar system objects, to stars and stellar systems in the Milky Way and nearby galaxies, to star-forming and active galaxies and quasars in the early Universe. More information about the HLWAS is available at this RDox page.

High-Latitude Time-Domain Survey

Roman’s High-Latitude Time-Domain Survey (HLTDS) provides time-series photometry and slitless spectroscopy at HST-like resolution and sensitivity across tens of deg², obtaining multi-band color information and spectroscopy on a 5-day cadence. Most observations will occur over a two-year window in the middle of Roman’s five-year primary mission. The HLTDS will monitor fields in both hemispheres, with observations optimized to detect and characterize Type Ia supernovae (SNe Ia) over redshifts from ~0.5 to > 2.5. As one of Roman’s Core Community Surveys, HLTDS is central to meeting the mission’s science requirements: by using SNe Ia to trace the expansion history of the Universe, it will probe the origin of cosmic acceleration and the nature of dark energy. Beyond SNe Ia, HLTDS will chart the transient near-infrared sky, enabling the detection and characterization of rare, high-redshift events, core-collapse SNe, tidal disruption events, super-luminous SNe, kilonovae, pair-instability SNe, active galactic nuclei, dust-extinguished sources, and cool, red objects. The survey will also deliver deep co-added imaging and slitless spectroscopic data, enabling studies of faint and distant galaxy populations. More information about the HLTDS is available at this RDox page.

Galactic Bulge Time Domain Survey

Roman's Galactic Bulge Time Domain Survey (GBTDS) will obtain high cadence, high-precision time-series photometry over 1.7 deg² in the Milky Way's bulge. The observations will be obtained throughout Roman's five-year prime mission at either 12-minute (high cadence seasons) or five-day cadence (low cadence seasons). By using microlensing, it will enable demographic studies of exoplanets comparable to those in our solar system in both mass and orbital distance. The GBTDS is also anticipated to discover over 100,000 transiting exoplanets. Beyond exoplanets, the GBTDS will enable a sensitive search for stellar mass black holes via microlensing and astrometry, enable asteroseismology of several hundred thousand red giants, monitor the supermassive black hole at the Milky Way's center, and enable studies of neutron stars, white dwarfs, and high energy X-ray binaries. More information about the GBTDS is available at this RDox page.

General Astrophysics Surveys

Galactic Plane Survey

The Galactic Plane Survey (GPS) is an Early-Definition General Astrophysics Survey defined and recommended by the community that features wide-field mapping, time-domain observations, and deep-field/spectroscopic measurements of the Galactic Plane. With imaging and spectroscopy components, the GPS will deliver the highest-angular-resolution panoramic map of the Milky Way to date, covering ~35% of the Galactic plane at near-infrared wavelengths to reveal stars within and behind high-extinction regions. It is anticipated to reach over an order of magnitude deeper than any previous infrared survey of the Galactic plane, to yield a catalog of ~20 billion sources, an order of magnitude larger than previous surveys, and to measure proper motions for billions of Milky Way stars. Science enabled by the GPS includes investigations into Galactic structure and dynamics, star formation, the interstellar medium, dust, star clusters, evolved stars, low-mass stars, and brown dwarfs. A time-domain component further expands the scientific scope, enabling the identification and characterization of compact binaries, free-floating planets, and eruptive and pulsational variables. More information about the GPS can be found on RDox.

WFI Parallel Observations

WFI operates continuously during Coronagraph observations to provide fine pointing control. While the coronagraph is active, WFI collects science-quality data which is referred to as WFI parallel observations. The specific WFI pointings during parallel operations are not known prior to Cycle 1, though they are expected to use multiple filters and sum to roughly 90 days of data. Science observations for a single target typically span one or more calendar days.

Scheduling of the Core Community and Galactic Plane Surveys

The Roman Space Telescope observing plan includes three Core Community Surveys, the community defined Galactic Plane Survey, Coronagraph observations, and General Astrophysics Surveys selected through this and future General Investigator calls for proposals. In addition, there are also routinely executed calibration observations that are part of the calibration plan (and expected to yield scientifically valuable data).

Although the community surveys are fully defined, the exact scheduling of specific observations is uncertain, as it depends on the start of Roman operations, the specific details of the selected GAS requesting new observations, and the targets and timing of the Coronagraph observations (which are still being discussed).

A high-level summary of the time range when different components of the community surveys are expected to execute is available at this observing plan page and can be used for planning purposes for proposers responding to this call for proposals. Please note that this summary is expected to be updated as more information becomes available; proposers are advised to check regularly the Late Breaking News section of the Call for any updates.

Data Products and Product Availability

The Roman calibration pipeline developed by the SOC, romancal, processes Roman WFI data automatically as data is received from the telescope, producing prompt data products that are made available in the MAST archive on the timescale of a few days.

All WFI data are calibrated to Level 2 (L2), which are count rate images with detector-level calibrations applied. All WFI imaging data except Galactic Bulge Time Domain Survey data are subsequently combined by the SOC pipeline to produce mosaics (i.e. Level 3 or L3 data) as well as catalogs (i.e. Level 4 or L4 products). Prompt L3 products are co-adds of exposures only in the same visit (including mosaics), while L4 catalogs are single band and will include positions, photometric measurements, and shapes. WFI spectroscopy mode prompt science data are processed by the SSC Wide Field Spectroscopy pipelines to produce calibrated, extracted spectra and spectral catalogs (Level 4 data) for all grism and prism observations. Galactic Bulge time domain data are processed by the SSC Galactic Bulge Survey pipelines. More information about the calibration and processing of Roman WFI prompt data products is available on RDox.

The Science Centers will also produce survey-specific Data Release products and make them available in the MAST archive, approximately every 6 to 12 months. Data release L3 products will include exposures co-added across multiple visits, thus producing deeper images, while data release L4 catalogs will be multi-band, deeper, and with more sources than the prompt L4 catalogs, and include photometric redshifts. Data release spectra will incorporate multi-band imaging and multiple rolls for more precise decontamination and spectral extraction. The timing and processing of data releases are contingent on the details of the scheduling of the observations. More details on data releases are available on RDox.