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As you are aware, we are working with the community to prepare a long-term plan for the scientific program of the Green Bank Observatory and the GBT for the period 2020 – 2030.

Currently, Green Bank staff are engaged with the community to develop a number of technical and State of the Profession white papers for the decadal survey (see below). If you would like to co-author or endorse a white paper underway, or suggest a new topic, please fill out the form at http://tiny.cc/GBT2020. If you are interested in this information or have questions, please send an email to gbo_2020@nrao.edu.

Science White Papers

Of the 570 unique science white papers submitted to the Astro2020 decadal survey committee, 38 (7%) explicitly requested use of the GBT, and a total of 86 papers (15%) described science which either requires the use of a GBT-like instrument or is best done with the GBT. 

The chart below breaks down those papers by science category, showing explicit GBT requests (blue), implicit GBT requests (grey; e.g. noting the need for a large single dish telescope similar to the GBT), and describing GBT science (orange).  Note that only the first two categories listed by a paper are used for this plot.

Distribution of white papers versus science categories for the submitted papers requesting the GBT or describing science that is well and readily done by the GBT. A complete list of all science white papers can be found on the National Academies site.

Projects, Activities and the State of the Profession

The Astro2020 Decadal Survey chairs have solicited white papers on activities, projects, or state of the profession considerations, referred to as APC white papers. Green Bank Observatory is working with the community on a number of white papers which reflect the community’s decadal goals. Below is a list of the currently planned white papers, with a link to further information as well as the contacts for anyone interested in contributing to the white papers.

If you are planning or interested in working on, or endorsing, any of the white papers listed below, or are involved in a project, activity, or state of the profession white paper topic for Green Bank Observatory which is not listed below, we’d love to hear form you. Please fill out the form at http://tiny.cc/GBT2020 or email us at astro2020@gbobservatory.org.

Additional information on Green Bank Observatory Future Instrumentation.

Further information on the white papers and the Astro2020 process can be found on the National Academies site.)

Project and Activity White Papers

  1. The Case for a Fully Funded GBT
  2. The Advanced GBT
  3. Argus+
  4. GBT Planetary Radar
  5. K-Band Phased Array Feed

State of the Profession White Papers:

  1. The Role of Observatories in Professional Astronomy Training
  2. Green Bank Observatory: Broader Impact


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