Observing > Call For Proposals > Call For Proposals: Semester 2016B > Green Bank Telescope (GBT) Proposals

Green Bank Telescope (GBT) Proposals

by Davis Murphy last modified Jan 05, 2016


The 1 February 2016 deadline is for the Semester 2016B GBT observing period: 1 August 2016 – 31 January 2017.

Details of all GBT observing modes are in the The Proposer's Guide for the Green Bank Telescope. Proposers should also consult the more general document The Performance of the GBT: A Guide for Planning Observations. Proposers should make sure that they are familiar with the latest versions of these documents before writing their proposal.

The GBT receivers, backends, and observing modes that are available in Semester 2016B are listed in Tables 1 and 2 below.

Table 1: GBT Receivers

Receiver Frequency Range
Prime Focus 1 290-920 MHz
Prime Focus 2 910-1230 MHz
L-band 1.15-1.73 GHz
S-band 1.73-2.60 GHz
C-band (linear only - see below) 3.8-8.0 GHz
X-band 8.0-11.6 GHz
Ku-band 12.0-15.4 GHz
K-band Focal Plane Array (7 pixels) 18.0-26.0 GHz
Ka-band 26.0-39.5 GHz
Q-band 38.2-49.8 GHz
W-band 67-93.3 GHz
ARGUS (shared risk - see below) 80-115.3 GHz, Private PI instrument

Table 2: GBT Backends and Observing Modes

Backend Observing Modes
Versatile Green Bank Astronomical Spectrometer (VEGAS) Continuum (see below), spectral line
Digital Continuum Receiver (DCR) Continuum
Green Bank Ultimate Pulsar Processing Instrument (GUPPI) Pulsar
Mark V Very Long Baseline Array Disk Recorder Very Long Baseline Interferometry
Caltech Continuum Backend (CCB) Continuum
JPL Radar backend Private PI instrument - Open for Public Use
Radar Private PI instrument

C-band:  Proposals wishing to use the GBT C-band receiver should only use linear polarization outputs.  The circular polarization of the receiver is currently not preforming correctly and we will not accept any proposals to use the circular polarization output of this receiver.

C-band VLBI on the GBT: NRAO will only accept proposals for VLBI Stokes I continuum observations using the GBT C-band receiver.  All other VLBI observations requesting the C-band receiver on the GBT will be disregarded.  Please see the HSA section of the call for proposals for more details.


Continuum: All modes of VEGAS may now be used for continuum observations.  We were not able to update the Proposal Submission Tool to reflect this situation before the proposal call was released.  Proposers should use the spectral line modes of VEGAS to choose the desired bandwidth and then note in the technical justification that the observations will be for continuum measurements.

Pulsar: VEGAS pulsar modes are not yet released for use.  Proposals for VEGAS pulsar observations will not be accepted.

ARGUS: Observers interested in shared-risk observations using the ARGUS instrument should see http://www.gb.nrao.edu/argus/ for further information.  All ARGUS proposals must have permission from the instrument development team.

VLBI: All Very Long Baseline Interferometry (VLBI) proposals requesting the GBT should include any needed setup and overhead time in the time request of their proposals.  HSA proposals requesting the GBT should provide a justification for needing large aperture antennas. C-band VLBI observers should see C-band note above.

470-700 MHz RFI Digital TV transmissions above 470 MHz will make observing very difficult with the 450 and 600 MHz  feeds of the PF1 receiver. Available RFI plots do not show the strength of these signals as they overpower the system: they are too low by a factor of 10 to 50. Observers should consult the GBT support scientists before submitting a proposal for these feeds.

MUSTANG: NRAO will not accept any proposals to use MUSTANG, MUSTANG1.5 or MUSTANG2.0 at the 1 February 2016, deadline.

Mapping If you are considering mapping with the GBT such that there are major turns or moves (end of rows in raster map, change in position for pointed maps, etc.) that occur with a cadence faster than every 30 seconds, you will need to consult with a GBT support scientist to ensure that the GBT can safely withstand the stresses induced by the mapping motions.


The GBT is scheduled by the Dynamic Scheduling System (DSS). The DSS system is fully described in the GBT Proposer's Guide and the GBT Observer's Guide.

GBT Proposal Preparation

Proposers should consult the The Performance of the GBT: A Guide for Planning Observations and the GBT Observer's Guide. All proposers, including pulsar proposers, should use the GBT Sensitivity Calculator. Please see the Calculator’s User's Guide for instructions. The Sensitivity Calculator results can be cut and pasted into the Technical Justification section of the proposal. This will streamline the creation of your Technical Justification and will increase your chances of getting a positive technical review.  If you are planning on making maps with the GBT, you should use the GBT Mapping Calculator tool.

The GBT observing policies describe the telescope's remote observing restrictions.

Proposers requesting GBT participation in High Sensitivity Array (HSA), Very Long Baseline Array (VLBA), or Global Millimeter Very Long Baseline Interferometry (GMVA) observations should consult the VLBA, HSA, and GMVA section of this Call.

GBT Shared Risk Observing

Observers requesting instruments that are shared-risk will be expected to travel to Green Bank for observations. The observers will be expected to help commission the instruments, to help debug observing and data reduction software, as well as helping to develop data reduction and calibration schemes.

Proposals to use ARGUS (80-115.3 GHz) will be accepted with the instrument development team's permission.  NRAO will consider shared-risk proposals for Semester 2016B observations with this instrument.

Limited Time for "Fixed" and "Windowed" Observations

Due to varied pressures on the GBT's schedule, the amount of time that can be accepted for fixed time observations (e.g. VLBI, pulsar transit observations, etc.) and windowed observations (e.g. monitoring observations) will be limited for the proposal call.  Proposals needing fixed and windowed observations will likely have to be ranked at least in or near the top decile in order to be accepted.

Limited Receiver Availability

Due to contractual obligations, the Prime Focus 800 MHz feed will only be available for approximately two weeks each month.  The Prime Focus 342 MHz feed will only be available for approximately one week per month.  The other Prime Focus feeds (450, 600 and Prime Focus 2) will likely only be considered for installation if a proposal requesting one of those feeds is ranked in the top decile of proposals and there is a significant time request for that receiver from all accepted proposals.

Other GBT Gregorian receivers may only be available during a few short, two or three week periods during the semester.