18B Semester

18B Proposal Call

The Green Bank Observatory (GBO) invites scientists to
participate in the 2018B Semester
Call for Proposals for the Green Bank Telescope (GBT).

The submission deadline for Semester 2018B proposals is
Thursday, 1 February 2018, at 17:00 EST (22:00 UTC).

The entire proposal call can be found on this page.

The Green Bank Observatory encourages proposals that take advantage of the GBT’s unique capabilities. Key science areas include, but are not limited to: astrochemistry, cosmology, fast radio bursts, galaxy and cluster evolution, HI (galactic and extragalactic), pulsars (searches and timing), radio recombination lines, solar system science, and star formation.

All proposals should state why the GBT is necessary for the requested observations in both the abstract and science justification.Triggered proposals can be submitted for studies of transient objects such as fast radio bursts, near Earth asteroids, comets, and other transients.

We strongly encourage proposers to carefully read through the “News and Opportunities” section of the proposal call as there have been a number of changes made to instrument availability. New instruments include Argus, MUSTANG-2, wide bandwidth C-band receiver, VEGAS spectral line and pulsar modes

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.

We wish 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.

Proposal preparation and submission remain via the NRAO Proposal Submission Tool (PST) available at NRAO Interactive Services. Note that use of the PST 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 2018 deadline is for the 2018B Semester observing period on the GBT:
1 August 2018 – 31 January 2019

Details of all GBT observing modes are in 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.

GBT Instruments

The GBT receivers, backends, and observing modes that are available in Semester 2018B are listed in Tables 1 and 2 below.

ReceiverFrequency RangeNote
Prime Focus 1290 – 395 MHz
680 – 920 MHz
L-band1.15 – 1.73 GHz
S-band1.73 – 2.60 GHz
C-band3.8 – 8.0 GHzlinear only, see below
X-band5 – 11.6 GHz
Ku-band12.9 – 15.4 GHz
K-band Focal Plane Array (KFPA)18 – 26.5 GHz7-pixel array
Ka-band26 – 39.5 GHz
Q-band38.2 – 49.8 GHz
W-band67 – 93.3 GHz
Argus80 – 115.3 GHzshared-risk, private PI instrument, 16-pixel array
MUSTANG-290 GHzshared-risk, private PI instrument
Table 1
BackendObserving ModeNote
VEGAScontinuum, spectral line, pulsarshared-risk
JPL Radar backendradarPrivate PI instrument, open for public use
Breakthrough Listen (BTL)Private PI instrument, shared risk
Table 2

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 observing. NOTE: If VEGAS Pulsar Modes are not release by the start of the 18A semester then all projects will be reverted back to using GUPPI where possible.

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 extremely limited as open skies time has been greatly reduced as part of the divestment of the GBT by the NSF. Proposers should only include the GBT in the proposal if it is essential for the science. This should be clearly justified in the text of the proposal. 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 cannot guarantee that MUSTANG-2 will be cold at the start of scheduled observing due to low observing elevations or rotations of the turret from prior observations. Cool down time for MUSTANG-2 observations should be included in the overhead for MUSTANG-2 observations. All MUSTANG-2 proposals must have permission from the instrument development team.

Breakthrough Listen backend: The Breakthrough Listen project is making its backend available for up to 50 hours of shared-risk observations during the 2018A semester. The instrument consists of a cluster of 32 Titan X and 1080 GPU-based servers capturing 8-bit baseband voltages over up to 5 GHz of instantaneous bandwidth. Data rates are typically tens of TB/hr but a pipeline is available to generate spectra with adjustable frequency (> 3 GHz) and time (> 350 μs) resolutions, with possible science applications including fast radio transients, pulsar observations, stellar flares, SETI, etc. Before submitting a proposal, proposers must obtain permission from the Breakthrough Listen team at Berkeley SETI Research Center. The team will consult on poroposal preperation and data analysis. Any data acquired using the backend will be proprietary to the proposer per the standard GBO policies.
More information including a technical description of the backend and team contact details can be found here.

Observing and Scheduling Constraints

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.

Session lengths:  Proposers should be aware that long scheduling blocks (more than 6 hours) may be very difficult to schedule as a result of the reduced open skies time following the divestment of the GBT by the NSF.  Proposers must make clear in the technical justification section how their project can be scheduled in small observing blocks that would more easily fit into the GBT scheduling constraints.   This is especially critical for proposals that require fixed or coordinated observing dates, e.g. VLBI observations, pulsar monitoring, radar, etc.

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.

Limited Time for “Fixed” and “Windowed” Observations: Due to varied pressures on the GBT’s schedule resulting from the reduced open skies time as a result of the divestment of the GBT by the NSF, 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) is limited.  Proposals needing fixed and windowed observations will likely have to be ranked at least in or near the top 10% of all AUI telescope proposals in order to be accepted.

Limited Instrument Availability: Due to existing obligations, the Prime Focus 800 MHz feed will only be available for approximately three weeks each month.  The Prime Focus 342 MHz feed will only be available for approximately one week each month.  The other Prime Focus feeds (450, 600 and Prime Focus 2) are unlikely to be available.  Similarly, the Zpectrometer, Ku-wide and RRI receiver are also unlikely to be available.  The PFS radar backend (PI: Margot) is available only with prior agreement by the PI.

Prime Focus 1450 and 600 feed: 385-690 MHz
Prime Focus 2910-1230 MHz
ZpectrometerPrivate PI instrument, shared risk
Ku-widenot for spectral line use
RRIPrivate instrument, shared risk
RPS RadarPrivate PI instrument

The availability of GBT Gregorian receivers will be based on demand from the accepted proposals.  Some receivers may be available only for a few short, two or three week periods during the semester.

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, we would like to remind all observers that they should not log into any GBO computing system using another person’s account.  Co-Is and students are required to have their own GBO login and account if they are to participate in observing and data reduction.

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 VLBAHSA, and GMVA Proposal Call.


RFI Monitoring Scans: The most recent RFI monitoring scans for the GBT can be found here. These scans provide information on the frequencies that may encounter RFI.

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 the RFI overpowers the system: the plot intensities are estimated to be too low by a factor of up to 10 to 50. Observers should consult the GBT support scientists before submitting a proposal for these feeds. Also, “TV Whitespace” usuage of these frequencies is expected to begin in 2018.

Potential for RFI: It is likely that there will be a major construction project near Green Bank in 2018-2019. For the safety of the workers, a portable radio system at 450 MHz is being proposed for use. Usage would be kept to a minimum, but there will be the potential for interference at 450 MHz and its harmonics during this time period. There remains the potential for RFI at other frequencies from other equipment used in this project.

Schools and Workshops

Observer Training Workshops: The Green Bank Telescope (GBT) Remote Observer Training Workshop will provide the essential skills and knowledge needed to use the GBT and maximize its scientific output. It is intended for experienced astronomers who need to learn the specifics of observing with the GBT. After completing the workshop, an attendee will be certified to use the GBT as a remote observer. The workshop will focus on hands-on training in the observing techniques most relevant to participants (e.g. high frequency map, continuum, pulsar, etc.).
These workshops will be held three times a year and will complement traditional on-site training. The 2018 workshops will be held January 15-18, May 24-25 and September 17-18.

Single Dish Training School: The Green Bank Telescope (GBT) Single Dish Training School will provide graduate students, post-docs, and experts in other fields of astronomy with both knowledge and practical experience of the techniques and applications of single-dish radio astronomy using the GBT as the primary example. The school will be based around an intensive series of lectures from experts, as well as hands-on radio-astronomy projects and tutorials. Topics to be covered include radio telescope fundamentals, key single-dish science areas, observing and calibration techniques, the impact of weather, the GBT observing procedures and software, and data reduction. The school will be held once per year. An intensive GBT remote observer training workshop will be held immediately following the school for those who wish to obtain remote observing certification.
The 2018 single dish school will be held May 19-23.

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 Joint Observations with Fermi 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 that are not time critical or require highly subscribed LST ranges can request designation as a “filler program.” Such programs may be able to take advantage of gaps in the GBT schedule, but there no guarantee that any GBT time will be allocated. Proposals requesting a designation as filler should do so in the proposal abstract and in the science justification. All filler programs will be given a ranking of C

Triggered Proposals: Observations for unknown sources that would be triggered by a celestial event (e.g. near Earth asteroid, comet, fast radio burst, etc.) can be submitted as a triggered proposal. Any accepted triggered proposal will have proprietary rights to observations over any DDT proposal.

18B Proposal Call Results

A total of 97 proposals requesting NSF funded “open skies” time were submitted to the Green Bank Observatory’s Robert C. Byrd Green Bank Telescope (GBT)  for semester 18B.  Proposals are reviewed on a competitive basis with a panel review system (see Proposal Review System).  Below are the statistics by proposal count and hours.  The oversubscription is the ratio of the number of submitted proposals to the number of approved proposals.  The pressure is the ratio of the requested time to the available time in hours.  Here we only include proposals submitted for the 18B semester that have been reviewed by the Green Bank Observatory Telescope Allocation Committee (TAC).

A description of the 18B proposals accepted can be found in our NSF Open Skies Science Program section below.

Total Proposals97
Statistics by Proposal Count
Requested Time6728 h
Available Time2396 h
Approved2715.75 h
Filler437.75 h
Rejected3574.5 h
Statistics by Proposal Hours

GBT Pressure Plots

Observations in high frequency bands require better weather conditions than observations in lower frequency bands. The GBT uses three weather categories:

  • poor – for observations below 8 GHz
  • good – for observations between 8-18 GHz and 26.5 – 50 GHz
  • excellent – for observations in the 18-26.5 GHz band and above 50 GHz

The first three figures below show the pressure plots for each these weather categories.  The last figure includes all weather categories.  The grey horizontal line shows the total available hours.  The letters A, B, and C correspond to the priorities assigned by the TAC where A and B are approved time and C is filler time.  Carryover is time allocated by a TAC from a previous semester that is being executed in the 18B semester.

GBT Observation Preparation

Please use the GBT Dynamic Scheduling System (DSS) to enable observing sessions, select observers for your project, and enter your blackout dates. The DSS Home Page has additional information about the DSS.  See GBT Observing for information about how to prepare for your observations.

Please note that the DSS uses the average Right Ascension (RA) and Declination (Dec) of all sources within a session.  The average RA and Dec will be used to determine when the session can be scheduled.  You will need to carefully check the RA and Dec, along with the minimum and maximum session lengths, to make sure that these values are satisfactory and will allow all your sources to be observed before enabling the session.

18B Science Program

A total of 97 proposals requesting NSF funded “open skies” time were submitted to the Green Bank Observatory’s Robert C. Byrd Green Bank Telescope (GBT) for the February 1, 2018 semester 18B deadline . The table below summarizes the approved observing programs. Listed are the PI name, proposal ID, proposal title, maximum hours approved and proposal type (Regular, Triggered, Large or External). Proposals from previous semesters that were awarded time in the 18B semester are included. The table also includes HSA and GMVA proposals that were awarded time on the GBT as a VLBI station as well as proposal accepted via external agreements with CHANDRA, Hubble Space Telescope, FERMI and Swift.

For each approved program, the Proposal Finder Tool will have access to its author, title, abstract and total approved hours.

A description of the Time Allocation Committee report for 18B can be found in the Proposal Call Results section above.

Anderson, LorenGBT18B-014The GBT Diffuse Ionized Gas Survey (GDIGS)200.5Large
Andreon, StefanoGBT18B-111A intermediate mass cluster kept at the epoch of entropy growth32Regular
Basu, KaustuvGBT18B-263Deep MUSTANG-2 Imaging of the Sausage Relic in the SZ Effect32Regular
Beasley, AnthonyGBT17B-131GBT Observations of 36 GHz Methonal Masers Towards the Galactic Center24Regular
Bing, LongjiGBT18B-216HI Component in A Blue Compact Dwarf with Violent Gas Dynamics3Regular
Britt, ChristopherGBT18B-313Confirming Candidate MSPs in the Galactic Bulge4Regular
Brodwin, MarkGBT18B-215MUSTANG-2 Observations of MaDCoWS, the Most Massive Galaxy Clusters at z > 1126Regular
Caleb, ManishaGBT18B-035A follow-up campaign for MeerTRAP FRBs with the Green Bank telescope75Regular
Cameron, AndrewGBT18A-261Continued timing observations of a new eccentric, relativistic binary pulsar117Regular
Cromartie, ThankfulGBT18B-289Mass Measurements for Four Millisecond Pulsars Using Relativistic Shapiro Delay30Regular
Demorest, PaulGBT18B-226The North American Nanohertz Observatory for Gravitational Waves324Large
Denny, LucasGBT18B-331Constraining the Origin of A Very High-Velocity Cloud Toward M33 with GBT54Regular
Dolch, TimothyGBT18B-321Continuing Monitoring of DM Variations of PSR B2224+65, the Guitar Nebula Pulsar12Regular
Dollhopf, NiklausGBT18B-140The Chemical Complexity of L1157: K-band Survey on the GBT6Regular
Dollhopf, NiklausGBT18B-141Exploring the Asymmetries of the L1157 Outflow: First Look at L1157-R1.25Regular
Fonseca, EmmanuelGBT18B-234High-precision Timing of the Pulsar Triple System in Messier 41.5Regular
Fonseca, EmmanuelGBT18B-280Timing Measurements of Two GBNCC Pulsars in Relativistic Binary Systems9Regular
Forbrich, JanGBT18B-284Dense gas mapping of resolved Giant Molecular Clouds in M3122Regular
Galaz, GasparGBT18A-191Edetecting molecular gas in the giant low surface brightness galaxy Malin 130Regular
Ginsburg, AdamGBT18A-014MUSTANG Galactic Plane survey pilot: Protoclusters & Massive Stars31Regular
Goldsmith, PaulGBT18B-053Accretion onto Molecular Cloud Filaments40Regular
Gomez, Jose L.G18A002Probing the Innermost Regions of AGN Jets and their Magnetic Fields36Regular
Gomez, Jose L.GMVA18B-164Imaging massive binary BH candidates in OJ287 and 3C345 with the GMVA+ALMA23Regular
Hada, KazuhiroGMVA18B-196Imaging Magnetic Acceleration and Collimation of M87 Jet at Scales of 7-150Rs14Regular
Haqq-Misra, JacobGBT18B-150Observing Earth’;s Radio Leakage from Lunar Reflections0Regular
Hilton, MattGBT18B-059Pressure Profiles from MUSTANG-2 for Clusters Detected by AdvACT and Planck33Regular
Issaoun, SaraGMVA18B-240Sharpening the source model for Sgr A*: 3mm VLBI with GMVA+ALMA8Regular
Jackson, JamesGBT16A-353The Radio Ammonia Mid-Plane survey69Large
Karunakaran, AnanthanGBT18B-203Searching for the HI reservoirs of Dwarfs in the Leo Triplet18Regular
Kepley, AmandaGBT17B-151Extragalactic GBT+ARGUS Gas Density Survey85.5Large
Linden, SeanGBT18A-366Building integrated SEDs with the GBT for LIRGs in GOALS9Regular
Lovell, AmyGBT18B-069OH Observations of 46P/Wirtanen and C/2017 S3 PANSTARRS19.25Regular
Lynch, RyanGBT18B-278Exploring the High Frequency Properties of FRB12110226Regular
MacDonald, NicholasGMVA18B-039Disorder vs. Order: Discerning the nature of the magnetic field in PKS 1510-0895Regular
Mantz, AdamGBT18B-221Unveiling the Most Distant Massive Galaxy Cluster with MUSTANG-225Regular
Mason, BrianGBT18A-336Detailed Sunyaev-Zel’dovich Effect Imaging of Z > 1 Galaxy Clusters47.25Regular
McGuire, BrettGBT18B-004A GBT Census of Aromatic Molecules Outside TMC-195Regular
McGuire, BrettGBT18B-007An Extremely Deep K-band GBT Survey of TMC-1418Large
Monson, NathanielGBT18A-400Uniform Silicon Isotope Ratios Across the Milky Way Galaxy15Regular
Mooley, KunalVLBA18B-201Mapping the size and morphology of the GW170817 post-merger fireball39Regular
Moss, VanessaGBT18B-307Uncovering the hidden iceberg structure of the Milky Way halo77.5Regular
Mroczkowski, TonyGBT18A-175A GBT+MUSTANG-2 Measurement the SZ Power Spectrum (continued)58.5Regular
Oslowski, StefanGBT18B-266Continuing follow-up of FRBs discovered by ASKAP126Regular
Pineda, JaimeGBT18B-288Exploring the kinematics of a subsonic dense core38Regular
Ransom, ScottGBT18B-071Continued Timing of a Millisecond Pulsar in a Stellar Triple System65Regular
Ransom, ScottGBT18B-072Long Term Timing of 59 Recycled Pulsars in Bulge Globular Clusters75Regular
Robinson, JustinGBT18B-258HI Spectroscopy of Active Galaxies with Direct Black Hole Mass Measurements165.25Regular
Schisano, EugenioGBT18B-211Filaments in the massive star forming complex G096+1.38: highways in the sky?0Regular
Spekkens, KristineGBT18B-246Atomic Gas in the Host Galaxies of Gravitational Wave Events20Triggered
Swiggum, JosephGBT17B-325Continuing the GBT All-Sky 350-MHz Pulsar Survey234Large
Watson, DarachGBT18A-230Detecting CO in a normal galaxy at Z=7.13268Regular
White, JacobGBT18A-329Measuring the Emission from Sirius A’s Stellar Atmosphere4Regular
Wilkins, OliviaGBT18B-025Complex Organic Formation in Protostellar Environments6.25Regular
Williams, GwenllianGBT18B-220Interaction of two IRDC hubs: A complete evolutionary study of the SDC13 region3.5Regular

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