2017B Call for Proposals

Green Bank Observatory Call for Proposals: 2017B Semester

The Green Bank Observatory (GBO) invites scientists to participate in the GBO’s 2017B Semester Call for Proposals for the Green Bank Telescope (GBT). Proposals requesting the GBT as part of High Sensitivity Array (HSA), and Global 3mm VLBI Array (GMVA) should be submitted through the Long Baseline Observatory’s call (available here).

The submission deadline for Semester 2017B proposals is Wednesday, 1 February 2017, at 17:00 EST (22:00 UTC).

The GBO wishes to remind proposers of continuing opportunities for joint observations with the Chandra X-ray Observatory, the Hubble Space Telescope, the Swift Gamma-Ray Burst Mission and the Fermi Gamma-ray Space Telescope.

The GBO strongly encourages proposers to carefully read through the News and Opportunities section of the proposal as there have been a number of changes made to instrument availability.

Proposal preparation and submission remain via the NRAO Proposal Submission Tool (PST) available at NRAO Interactive Services. Note that the PST use requires registration. Proposers who need assistance with proposal preparation or have questions regarding the Call or GBT capabilities should contact Observatory staff via the Helpdesk.

News and Opportunities

The 1 February 2017 deadline is for the 2017B Semester observing period on the GBT: 1 August 2017 – 31 January 2018

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.

More Information for Astronomers

The GBT receivers, backends, and observing modes that are available in Semester 2017A are listed in Tables 1 and 2 below.

[table caption=”Table 1″ width=”100%” colwidth=”150|150″ colalign=”left|left”]
Receiver;Frequency Range
Prime Focus 1;290-395 MHz and 680-920 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);18.0-26.5 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, Shared Risk
Mustang2 (shared-risk – see below);90 GHz, Private PI Instrument, Shared Risk

[table caption=”Table 2″ width=”100%” colwidth=”20|100|50″ colalign=”left|left”]
Backend;Observing Modes
Versatile Green Bank Astronomical Spectrometer (VEGAS);Continuum (see below), spectral line, pulsar (shared risk)
Digital Continuum Receiver (DCR);Continuum
Green Bank Ultimate Pulsar Processing Instrument (GUPPI);Pulsar (retiring on February 1, 2018). No new GUPPI proposals will be accepted for observations beyond that date.)
Mark V Very Long Baseline Array Disk Recorder;Very Long Baseline Interferometry
JPL Radar backend;Prive PI Instrument – Open for Public Use

Session lengths: Proposers should be aware that long scheduling blocks (more than 6 hours) will be very difficult to schedule owing to constraints coming from non-NSF GBO partners. Proposers are encouraged to make clear in the technical justification section any constraints about how observing time could be broken into smaller pieces without adversely affecting the proposed science; include information as relevant regarding maximum elapsed time of a split schedule and minimum scheduling block lengths.

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: The GBO will only accept proposals for VLBI Stokes I continuum observations using the GBT C-band receiver (the observations will need to be done using full Stokes just to calibrate Stoke I). All other VLBI observations requesting the C-band receiver on the GBT will be disregarded. Please see the HSA section of the Long Baseline Observatory call (available here) for proposals for more details.

VEGAS Continuum: All modes of VEGAS may now be used for continuum observations. The Proposal Submission Tool has not been updated to reflect this situation. 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.

VEGAS Pulsar: VEGAS pulsar modes will be released for shared risk observing. Proposals requested both VEGAS pulsar modes and GUPPI modes must use the same mode for both instruments. Justification for using both GUPPI and VEGAS pulsar modes simultaneously (such as for transitioning current timing campaigns from GUPPI to VEGAS pulsar modes) must be included in the proposal. Proposals for new pulsar timing campaigns and searches are strongly encouraged to use only the VEGAS pulsar modes. Please review these instructions on the use VEGAS pulsar modes.

GUPPI: The GUPPI pulsar backend will be retired on February 1, 2018.

ARGUS: Observers interested in shared-risk observations using the ARGUS instrument should see the ARGUS website for further information. All ARGUS proposals must have permission from the instrument development team.

VLBI: Time available for VLBI on the GBT will be dramatically reduced compared to past observing semesters due to its new partnership arrangement. Proposers should only include the GBT in the proposal if it is essential for the science and if it is clearly justified in the text of the proposall. 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. C-band VLBI observers should see the C-band VLBI note above.

MUSTANG 2: The GBO will accept proposals for shared risk observations using the MUSTANG 2 instrument at the proposal deadline. The GBO can not guarantee that MUSTANG2 will be cold at the start of scheduled observing. Cool down time for MUSTANG2 observations should be included in the overhead for MUSTANG2 observations. All MUSTANG 2 proposals must have permission from the instrument development team.

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 Proposal Call.

GBT Shared Risk Observing

Observers requesting instruments that are shared-risk will be expected to travel to Green Bank for observations. The observers may 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. Proposals to use MUSTANG 2 will be accepted with the instrument development team’s permission. NRAO will consider shared-risk proposals for observations during the 2017B semester with these instruments.

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 Instrument Availability

Due to existing 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) are unlikely to be considered for installation. Similarly, the Caltech Continuum Backend (CCB), Zpectrometer, Ku-wide and RRI receiver are also unlikely to be considered for installation. The PFS radar backend (PI: Margot) is available only with prior agreement by the PI.

[table caption=”Table 3″ width=”100%” colwidth=”20|100|50″ colalign=”left|left”]
Prime Focus 1;450 and 600 feed: 385-690 MHz
Prime Focus 2;910-1230 MHz
Caltech Continuum Backend (CCB);Continuum
Zpectrometer;26.0-29.5 GHZ, Prived PI Instrument, Shared Risk
Ku-wide;12-18 GHz, not for spectral line use
RRI;Private Instrument, Shared Risk
PFS Radar;Private PI Instrument

Other GBT Gregorian receivers (primarily, but not limited to, Ku, Ka, Q and W) may only be available during a few short, two or three week periods during the semester.

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.

Observer Training:

Due to reductions in the amount of NSF-supported “open skies” time on the GBT for use by the scientific community, it has become increasingly difficult to train new GBT observers in the way we have traditionally done in the past.

We are in the process of re-evaluating our approach to observer training, and as part of this are introducing observer training schools. These will provide an introduction to general radio astronomical techniques as well as onsite training for new GBT observers. These training schools will replace the single-dish summer schools which have held in the past, and will be scheduled two to three times each year.

The next training school will be held May 15-19, 2017 in Green Bank, with the following school September 18-22, 2017.

We still encourage new observers to visit the Observatory, where their projects will receive an increased priority for scheduling and where local staff are on hand to assist in the observations.

While at some point observer training schools may be the primary means to certify new GBT observers, we remain committed to providing all the services necessary to ensure that the GBT remains accessible to the entire scientific community, and ask your patience in this time of transition.

Observing Team Members:

We would like to remind all project teams of the Green Bank Observatory policy that all observers must be listed as a member of the project team in the GBT Dynamic Scheduling System. Also, it is not permissible for an observer to use another person’s computing account to carry out an observation.

Continuing Opportunities:

Joint Observations with Chandra X-ray Observatory

In previous semesters, the community has had the opportunity to propose for observing time on NRAO facilities through a joint program with the Chandra X-ray Observatory. The Green Bank Observatory will continue with this program and will allocate up to 3% of the open skies time to highly ranked proposals that request time on both HST and the GBT. Proposers to the GBO will have the opportunity to request time on Chandra, to be awarded on the recommendation of the GBO Telescope Allocation Committee (TAC) and approved by the GBO Director. Up to 120 ksec will be made available to GBO/LBO/NRAO proposers annually. See the Joint Observations with Chandra page for details.

Joint Observations with the Hubble Space Telescope (HST)

By agreement between the NRAO (and continued honoring by GBO) and the Space Telescope Science Institute, STScI will be able to award up to 3% of the available open skies time to highly ranked proposals that request time on both HST and the GBT. In return, STScI has offered 30 orbits of HST time for allocation by the GBO/LBO/NRAO TAC to proposals submitted for the GBO deadlines for Semester 2017B and Semester 2018A. See the Joint Observations with HST page for details.

Joint Observations with Swift Gamma-Ray Burst Mission

To foster correlative observations, a joint Swift/NRAO observing program was established, detailed in a Memorandum of Understanding. The GBO will continue to honor this agreement. By this agreement, the Swift Program permits GBO/LBO/NRAO to award up to 300 kiloseconds of Swift observing time per year. Similarly, GBO/LBO/NRAO permits the Swift Guest Investigator (GI) Program to award GBO observing time. See the Joint Observations with Swift page for details.

Joint Observations with Fermi Gamma-ray Space Telescope

We remind the community that it is possible to propose for observing time on the GBT through the Fermi Gamma-ray Space Telescope Joint Proposal Opportunity or the Cooperative Proposal Opportunity. See the page for details.

Joint Proposals Between the GBT, LBO, and NRAO

Observing programs that require combinations of the GBT, VLBA, and/or the VLA should submit a proposal for each of the requested telescopes, with a clear justification for each, as has been the case to date. The proposals will be reviewed as before and considered jointly by the Time Allocation Committee. VLBI proposals which request the GBT or VLA (or the HSA, for example) as elements of the VLBI array do not need separate proposals—those telescopes can be selected as separate VLBI stations from a VLBA/HSA proposal.

Other Proposal Opportunities

The GBO would like to make users aware that there are additional proposal opportunities as follows:

  • High Risk Proposals: As a means of maximizing its scientific impact through cutting-edge observations, the Observatory encourages the submission of high-risk/high-reward proposals.
  • Filler Programs: Some programs are not time critical or require highly subscribed LST ranges. Such programs may be able to take advantage of “filler” time. There are opportunities for so-called “filler” programs on the GBT.

Further information about each of these programs can be found here.