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ASTRO2020 – Preparations

As you are aware, we are preparing a long-term plan for the scientific program of the Green Bank Observatory and the GBT for the period 2020 – 2030. Over the past four months we have solicited both ideas and interest from the scientific community.

We are now forming a number of scientific working groups to better define the long-term scientific goals for the Green Bank Observatory, with the ultimate aim of these groups to produce one or more white papers. Based on your interest in the Observatory, we would like to invite you to join one (or more!) of the groups and help us as we plan for the future of Green Bank.

If you are interested, please send an email to gbo_2020@nrao.edu indicating which of the science discussions you would like to join. If none of the categories adequately describes your interests, please let us know that (and your interests) as well. Finally, of course, if you wish to be removed from these mailings, please let us know.

Additional information on Green Bank Observatory Future Instrumentation.

Green Bank Working Groups:

Note that these are the groups formed to work on various science whitepapers relating to science which would be done at the Green Bank Observatory. Mapping from these groups to the National Academies thematic categories is given within the listing, and the National Academies thematic groups are given below. authors of scientific whitepapers should choose a primary and, if relevant, secondary theme from the National Academies list when writing/submitting papers.

  1. Fundamental Physics & Cosmology (e.g. gravitational waves, general relativity, equivalence principle) → maps to National Academies thematic area 7 (“Cosmology and Fundamental Physics”)
  2. The Transient Sky (e.g. FRBs, SETI, Pulsars ) → maps to National Academies thematic area 4 & 8 (“Formation and evolution of compact objects” and “Multi-Messenger Astronomy and Astrophysics”)
  3. Stars & Star Formation (e.g. turbulence, magnetic fields, multi-scale molecular clouds, diffuse environments, ISM) → maps to National Academies thematic area 2, 3 & 5 (“Star and Planet formation”, “Stars and Stellar Evolution,” and “Resolved stellar populations and their environments”)
  4. Galaxies & Galaxy Clusters (Milky Way and beyond) (e.g. cosmic web, HI extent of galaxies, galaxy structure, galaxy clusters) → maps to National Academies thematic area 5, 6, & 7 (“Resolved stellar populations and their environments,” “Galaxy Evolution,” and “Cosmology (Large Scale Structure)”)
  5. Astrobiology & Astrochemistry (also could include comets, SETI) → maps to National Academies thematic area 1 & 2 (“Planetary Systems” and “Star and Planet formation”)
  6. Planetary Systems (e.g. sun, stars, asteroid, comets, exoplanets, planetary weather/atmosphere) → maps to National Academies thematic area 1 (“Planetary Systems”)

Thematic Areas for Astro2020 Science Whitepaper Submission

(From the National Academies site)

  1. Planetary Systems including solar system bodies (other than the Sun), debris
    disks, and extrasolar planets; exobiology and the search for life beyond the solar system.
  2. Star and Planet formation, formation of stars and clusters, protostellar and protoplanetary disks, planet-disk interactions, molecular clouds and the cold interstellar medium, dust, and astrochemistry.
  3. Stars and Stellar Evolution, including the Sun, stellar astrophysics, the structure and evolution of single and multiple stars, and brown dwarfs.
    1See page xvii in the Preface to New Worlds, New Horizons
  4. Formation and evolution of compact objects, including stellar-mass black holes, neutron stars, white dwarfs, supernovae, mergers of compact objects, gamma-ray bursts, accretion, production of heavy elements and other extreme physics on stellar scales.
  5. Resolved stellar populations and their environments, including the structure and properties of the Milky Way and nearby galaxies, their stellar
    populations and evolution, as well as interstellar media and star clusters.
  6. Galaxy Evolution, including the formation, evolution, dynamics, and properties of supermassive black holes, galaxies, and galaxy clusters, active galactic nuclei and QSOs, mergers, star formation rates, gas accretion, and the circumgalactic and intergalactic media.
  7. Cosmology and Fundamental Physics, including the early universe, the cosmic microwave background, reionization and galaxy formation up to the
    virialization of protogalaxies, large scale structure, the intergalactic medium, determination of cosmological parameters, dark matter and dark energy, astroparticle physics, tests of gravity, and astronomically determined physical constants.
  8. Multi-Messenger Astronomy and Astrophysics, including the sources of gravitational waves, astrophysical and cosmogenic neutrinos, cosmic rays
    and gamma rays, and the coordinated multi-messenger and multiwavelength follow-ups.


Transformative Science Workshop

The workshop Big Questions. Large Problems, and New Instruments is now over, but the work is continuing. Presentations from the workshop are available on our archived page.

The Argus receiver highlighting the amplifier modules at top and the 4 x 4-pixel card array.

The Argus+ Project at the GBT

The GBT is now into its second winter season with Argus, the 16-pixel camera for spectroscopy in the molecule-rich 3mm atmospheric window between 74 – 116 GHz. Argus is the brainchild of Sarah Church of Stanford University and collaborators, who received an NSF ATI grant to design a modular receiver system for the GBT that could be replicated and expanded in a straightforward way. With the unique combination of angular resolution (6.5 – 9 arcseconds), sensitivity, and field of view of the GBT, Argus is being used for ground-breaking surveys of dense gas in galaxies and nearby star-forming regions. Recent Argus results were highlighted at the American Astronomical Society 2018 Winter Meeting in Washington D.C.

Left: Filament in DR21 mapped in 13CO. This map took 40 minutes in only moderate weather (τ=0.4). The footprint of the Argus array is shown upper right. Right: part of OMC-1 mapped by Argus in HNC(1-0). This map took 4.5 hours, including pointing, surface setting and calibration. The white circle shows the Argus beam (figure courtesy of Alvaro Hacar)

The Green Bank Observatory and the original Argus team are now collaborating on an Argus+ project, which would take advantage of the technical development afforded by Argus to produce a camera with ten times the mapping speed and includes a new spectrometer. Argus+ has the capability to routinely produce spectral line maps of key species such as CO, HCN, and HCO+ with a spatial dynamic range (map area / pixel size) of 104 to 105.

As part of the Argus+ project the community will be invited to participate in legacy surveys with the new instrument. There will be a spectroscopic survey of the Gould Belt molecular clouds, and a survey of dense gas tracers in nearby star-forming galaxies. The legacy surveys will produce unique data of lasting value. Argus+ data will also be displayed in exhibits at the GBO Science Center, and will be incorporated into a range of programs in STEM education throughout the region.

The project leverages the NSF’s investment in the prototype Argus to produce a uniquely powerful scientific instrument accessible to the U.S. scientific community. A proposal was submitted to the NSF MSIP program in early 2018 and was well reviewed, but ultimately not funded in this round. The Argus+ team has taken the reviewer comments to create an even stronger proposal for the next funding call and discussion during the upcoming Astro2020 Decadal Review.

Below is a quick comparison of the original Argus and Argus+.

Pixels16144Single Pol
IF Bandwidth1.5 GHz7 GHz 

16 pix x 2 win x 23.4 MHz x 4096 ch
16 pix x 1250 MHz x 1024 ch

144 pix x 600 MHz x 131k ch
16 pix x 1250 MHz x 1024 ch

Receiver Tsys

40 – 80K

30 – 60K

Usable 3mm hours/year



TLS metrology
Frequency Range

74 – 116 GHz

74 – 116 GHz

Map time 6’x6′
dv=0.1 km/sec,
σTb=0.1 K

 53 hours

 5 hours

Includes overhead