Green Bank 6 cm survey

Green Bank 6 cm survey
Name	Green Bank 6 cm survey
Wavelength	6 cm
Frequency	4.8 GHz
Telescope	Robert C. Byrd Green Bank Telescope
Institution	National Radio Astronomy Observatory
Region	Galactic plane
First release	1990s
Resolution	~3.5 arcmin
Sensitivity	~ mJy

Green Bank 6 cm survey The Green Bank 6 cm survey is a radio continuum survey conducted with the Robert C. Byrd Green Bank Telescope and predecessor facilities, targeting the Galactic plane and selected extragalactic fields. The project produced catalogs used by teams at the National Radio Astronomy Observatory, Harvard University, Princeton University, University of Cambridge, and other institutions to study radio sources, star formation, and Galactic structure. Survey data have been cited alongside results from the Very Large Array, Effelsberg 100-m Radio Telescope, Parkes Observatory, Arecibo Observatory, and space missions such as Infrared Astronomical Satellite and Spitzer Space Telescope.

Overview

The survey mapped emission at 6 cm (≈4.8 GHz) to characterize compact and extended sources across portions of the Milky Way and selected fields associated with Seyfert galaxies, pulsar wind nebulae, supernova remnants, and H II regions. Instrumental heritage includes the legacy of the Green Bank 140-foot telescope, operational ties to the National Science Foundation, and collaborative analyses with groups at California Institute of Technology and University of Manchester. The dataset filled a niche between lower-frequency surveys from the Low-Frequency Array and higher-frequency campaigns by the Atacama Large Millimeter/submillimeter Array.

Survey Design and Observations

Survey strategy borrowed mapping techniques from campaigns at the Westerbork Synthesis Radio Telescope and observing practices developed by teams at the Jodrell Bank Observatory and Max Planck Institute for Radio Astronomy. Observations employed drift-scan and raster-scan modes to obtain contiguous coverage along declination bands intersecting the Galactic Center, Cygnus X complex, and fields near M31 (Andromeda Galaxy). Scheduling accounted for availability at the Green Bank Observatory and coordination with calibrator observations of sources like 3C 286, 3C 48, and 3C 147. Pointing, beam characterization, and scan strategy were informed by prior surveys such as the NRAO VLA Sky Survey and the GB6 catalog.

Data Reduction and Calibration

Data reduction pipelines adapted techniques from the AIPS and CASA frameworks and applied baseline subtraction, RFI excision, and deconvolution tuned for single-dish data used by teams at NASA Jet Propulsion Laboratory and University of Maryland. Flux-density calibration referenced standards tied to the flux scale established by Baars et al. and calibrators monitored by staff at the National Radio Astronomy Observatory. Polarization calibration used observations of polarized sources studied in work at University of Bonn and Leiden Observatory, with imaging products validated against maps from the Effelsberg 21 cm survey and the Planck satellite at microwave frequencies.

Catalogs and Source Properties

Resulting catalogs list compact and extended sources with positions, peak flux densities, integrated fluxes, and deconvolved sizes; follow-up cross-matching was performed with catalogs from IRAS, Two Micron All Sky Survey, Sloan Digital Sky Survey, and the ROSAT and Chandra X-ray Observatory archives. Catalog entries aided identification of counterparts including H II regions cataloged by the WISE team, planetary nebulae from the HASH database groups, and extragalactic radio sources associated with hosts in the 2MASS Extended Source Catalog and FIRST survey. Statistical properties extracted from the catalog informed source counts used in studies by researchers at Princeton University and University of California, Berkeley.

Scientific Results and Applications

The survey enabled multiwavelength studies of massive star formation by linking radio free–free emission to infrared tracers used by teams around Spitzer and Herschel Space Observatory, and provided constraints on synchrotron spectra for supernova remnants compared with observations from the VLA and ATCA. Studies combining the survey with pulsar catalogs from Parkes and timing arrays connected continuum structures to pulsar wind nebulae analyzed at Jodrell Bank. Extragalactic science leveraged cross-identifications with Sloan Digital Sky Survey optical spectroscopy to study radio-loud quasars and Seyfert populations, informing luminosity function measurements undertaken by groups at Johns Hopkins University and Max Planck Institute for Astrophysics.

Limitations and Future Work

Limitations include angular resolution lower than interferometers like the Very Large Array and sensitivity constrained by single-dish system temperature and radio-frequency interference monitored by staff from the Federal Communications Commission and the Green Bank Observatory. Future work proposed by collaborations involving NRAO, Square Kilometre Array pathfinder teams, and university groups calls for reprocessing with modern RFI mitigation, combination with interferometric data from the VLA Sky Survey and incorporation into multiwavelength databases curated by the Centre de Données astronomiques de Strasbourg and the International Virtual Observatory Alliance.

Category:Radio astronomy surveys Category:Green Bank Observatory