Proposals for the use of North American NRAO facilities - the GBT, VLA, and VLBA - are organized according to one of the following scientific categories:

SSP - Solar system, stars, planetary systems: Sun, planets, comets, IPM; exoplanets; main sequence stars; active stars; stellar winds; AGB & post-AGB stars; PNe; novae

GWT - Gravitational waves and energetic transients: supernovae, gravitational wave sources, gamma-ray bursts, tidal disruption events, fast radio bursts, exotic/unknown transients

PCO - Pulsars and compact objects: millisecond pulsars, cataclysmic variables, black hole and/or neutron star x-ray binaries, pulsar timing, pulsar proper motion

SFM - Star formation: young stellar objects; protostars; jets, outflows; T Tauri stars; circumstellar disks; protoplanetary systems; astrochemistry

ISM - Interstellar medium: galactic HI & OH; ISM magnetic field; SNRs; HII regions; astrochemistry

NGA - Normal galaxies, clusters, and groups: Galaxies (continuum), including galaxies in groups & clusters: disk emission; star formation; magnetic fields; galactic winds; starbursts; intracluster emission & ICM astrophysics

EGS - Extragalactic structure: Galaxies (line): galaxy structure; galaxy kinematics and dynamics; galaxy chemistry; gas in galaxies

HLA - High-Luminosity AGN: AGN, high-luminosity: FR II radio galaxies, quasars, QSOs, blazars, BL Lacs

LLA - Low-Luminosity AGN: AGN, low-luminosity: FR I radio galaxies, FR 0 radio galaxies, Seyfert galaxies, quiescent SMBH, Sgr A*

HIZ - High redshift and source surveys: High-z objects; extragalactic source surveys; galaxy formation; gravitational lenses; large-scale structure & clusters (as cosmological probes); CMB; early universe

Change to take effect from 1 July 2022

The AGN science category will be split into two in order to manage the increasing number of proposals received in this science area. The new categories will be

HLA - High-Luminosity AGN: AGN, high-luminosity: FR II radio galaxies, quasars, QSOs, blazars, BL Lacs

LLA - Low-Luminosity AGN: AGN, low-luminosity: FR I radio galaxies, FR 0 radio galaxies, Seyfert galaxies quiescent SMBH, Sgr A*

All proposals submitted on or after 1 July 2022 will need to specify one of the following ten science categories: SSP, GWT, PCO, SFM, ISM, NGA, EGS, HLA, LLA, or HIZ.

Change to take effect from 4 January 2019

The ETP science category will be split into two in order to manage the increasing number of proposals received in this science area. The new categories will be

GWT – Gravitational Waves and Energetic Transients: supernovae, gravitational wave sources, gamma-ray bursts, tidal disruption events, fast radio bursts, exotic/unknown transients

PCO – Pulsars and Compact Objects: millisecond pulsars, cataclysmic variables, black hole and/or neutron star x-ray binaries, pulsar timing, pulsar proper motion

All proposals submitted on or after 4 January 2019 will need to specify one of the following nine science categories: SSP, GWT, PCO, SFM, ISM, NGA, EGS, AGN or HIZ.