NRAO eNews
Volume 7, Issue 1
3 January 2014

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NRAO Call for Proposals: Semester 2014B

NRAO eNews Volume 7, Issue 1 3 January 2014

NRAO Call for Proposals: Semester 2014B

The NRAO announces the Call for Proposals for the 3 February deadline for Semester 2014B. The call is open now and will close on Monday, 3 February 2014, at 17:00 EST (22:00 UTC).

Proposal preparation and submission are via the NRAO Proposal Submission Tool (PST) available through the NRAO Interactive Services. Important modifications to the PST have been made and will be in place starting 12:00 EST (17:00 UTC) Friday, 3 January 2014. Proposals of type Regular, Large, or Triggered may be submitted. All proposal authors must be registered users. On the registration form you will be asked for contact information that will be used for notification about proposal disposition, observation preparation, etc.

News for Proposers

Plan Ahead

The nominal NRAO deadline for a Semester B is 1 February, which falls on a Saturday in 2014. Following NRAO policy the deadline has been extended to the next workday, Monday, 3 February. The NRAO Helpdesk will be lightly staffed Saturday-Sunday, 1-2 February. Please plan ahead by submitting any Helpdesk tickets in January rather than the first weekend in February. 

Opportunities for Joint Observations with the Hubble Space Telescope (HST)

By agreement between the NRAO and the Space Telescope Science Institute, STScI will be able to award time on NRAO facilities to highly ranked proposals that request time on both HST and NRAO telescopes. NRAO has offered up to 3% of the available time on its North American facilities, namely the Robert C. Byrd Green Bank Telescope (GBT), the Very Large Array (VLA), and the Very Long Baseline Array (VLBA), for allocation by the HST Time Allocation Committee (TAC), subject to a maximum of 5% of the available time in any given VLA configuration. In return, STScI has offered 30 orbits of HST time for allocation by the NRAO TAC to proposals submitted on or before either of the two NRAO semester deadlines. These are Monday, 3 February 2014 for Semester 2014B and Friday, 1 August 2014 for Semester 2015A. Joint HST/NRAO Proposals should be submitted to the observatory that represents the prime science facility (not to both observatories).

NRAO observing time awarded through the HST Cycle 22 review will be implemented during the 2014B and 2015A observing semesters. The award of time on NRAO facilities will be subject to approval by the NRAO Director, after nominal review by the NRAO TAC to avoid duplication of programs. The important additional criterion for the award of NRAO time is that both the HST and the radio data are required to meet the science goals of the project. It is not essential that the project requires simultaneous NRAO and HST observations. Under this agreement, NRAO time will only be awarded in conjunction with new HST observations (and should not be proposed for in conjunction with an Archival Research or Theory Proposal). Major results from these programs would be credited to NRAO and HST.

HST time awarded through the NRAO TAC will be implemented during the course of HST Cycle 22. A total of up to 30 orbits will be awarded by the 2014B and 2015A NRAO TACs. Proposals submitted to the NRAO requesting HST orbits must indicate that the proposal is joint with HST and must specify the number of orbits requested.

Proposers must always check whether appropriate archival data exist, and provide clear scientific and technical justification for any new observations of previously observed targets. Observations awarded time that duplicate observations already approved by HST or NRAO for the same time period may be canceled, or data sharing and cooperation among different groups may be necessary, as determined by the two observatories. This includes triggered proposals with similar trigger criteria, with or without previously known coordinates.

Be aware that some HST targets might not require new NRAO observations because the joint science goals can be met using:

  • non-proprietary archival data from the VLA or VLBA are online
  • VLA continuum images from sky surveys at a wavelength of 20cm and at a FWHM resolution of 45 arcseconds or 5 arcseconds.

All scientific data from NRAO telescopes have a proprietary period where the data are reserved for the exclusive use of the observing team. The data archive policy and proprietary periods are online.

This policy applies to NRAO data taken through the joint HST-NRAO program.

Dissertation Plans

Students planning to use one or more NRAO telescopes for their PhD dissertation must submit a "Plan of Dissertation Research" of no more than 1000 words with their first proposal. This plan musty be referred to in later proposals for time allocations relevant to the thesis work described in the plan.  It is the responsibility of the student to ensure that the information contained in the plan is up-to-date at the time a given proposal is submitted. By the same token, a proposal for work that is relevant to a student thesis should refer to the plan and clearly state the relevance of the proposal to the plan. At a minimum the plan should contain:

  1. An overview of the research program
  2. The thesis timeline, including the expected date of completion
  3. An estimate of the level of NRAO telescope resources needed to complete the program of research
  4. Clear statements about the importance of each proposal to the thesis as a whole.

The plan provides some assurance against a dissertation being impaired by an adverse review of a proposal when the full scope of the thesis is not seen. The plan can be submitted via NRAO Interactive Services. Students are reminded to submit their plan comfortably in advance of the proposal deadline. Thesis plans must be in pdf format so science reviewers can easily access the plans. Students who have not yet graduated but have active plans on file should update those plans to a pdf format if they are not already in that form.

Commensal Proposals

NRAO telescopes and backends are sufficiently flexible in many cases to allow two experiments to run commensally. To the degree that this enhances science return from the telescopes, NRAO wishes to support commensal projects subject to resource and scheduling constraints. Groups wishing to carry out commensal observations should submit independent science cases as separate primary and secondary proposals. A primary proposal will be submitted that controls the telescope pointings and requests the full amount of telescope hours required. Secondary proposals(s) will be submitted that run commensally with the primary pointings but request 0 hours of telescope time. Each proposal must contain estimates of the full resources needed (correlator setup, data rates, etc.) to carry out their specific part of the project.  During the proposal review and time allocation process it will be determined if the combination of the observing set-up and the positions by the primary or secondary proposals conflict with any approved projects. In the case of a conflict, some data restrictions may be applied to the primary and/or the secondary commensal proposal.  If the primary and secondary proposals use the same back-end resources (VLA-WIDAR, GBT-VEGAS, etc.) it may be necessary for technical reasons to require that the investigators on both primary and commensal projects be given full access to all data.

Proposal Finder Tool

The Proposal Finder Tool (PFT) may be used to search cover sheets of proposals approved for time on NRAO telescopes. The PFT returns the proposal's authors, title, abstract, and, if available, approved hours. 

Source Lists

The Observatory requires proposers to specify their source lists in full. This enables the Observatory to identify potential conflicts between observing programs and to better understand scheduling pressure on the instruments it operates. It may be the case that the final target list has not been selected at the time a proposal is submitted. In such cases, all potential targets and fields should be listed. The only exceptions to this requirement are for Triggered proposals to observe targets that are unknown a priori. Proposal source lists are not made public by the Observatory.

Service Observing

In recent Calls for Proposals, the NRAO announced plans to perform service observations of Sgr A* in support of the anticipated encounter of a gas cloud with the supermassive black hole lying at the center of the Milky Way. The details of the service observations were described in the October 2012 eNews. The observations take the form of: (1) baseline measurements in advance of the encounter with the VLA and VLBA; (2) multi-band monitoring of Sgr A* for an extended period of time with the VLA. These data are available to the community on a non-proprietary basis. The first photometric and imaging observations remain available here. The page will be updated until the program ends in April 2014.

In addition to the service observing described above, we encourage proposals from the community on the announced proposal deadlines for scientifically compelling observing programs of this event using ALMA, the GBT, the VLA, and/or the VLBA. These proposals will undergo the normal peer review and time allocation process.

General Information

NRAO Semester-Based Proposal Cycle

Proposal submission deadlines are nominally on 1 February and 1 August each year. At each deadline, proposers may request time on the Karl G. Jansky Very Large Array (VLA), the Very Long Baseline Array (VLBA) and/or the Robert C. Byrd Green Bank Telescope (GBT). The 1 February deadline applies to requests for time from 1 August through 31 January, and the 1 August deadline applies to requests for time from 1 February through 31 July. Further details about proposal submission, proposal evaluation, and time allocation are available here.

Tips for Proposers

The NRAO proposal evaluation and time allocation process is panel based. That is, members of the scientific community are responsible for reviewing proposals based on their scientific merit through eight Science Review Panels (SRPs). As a means of broadening the scientific perspective of its reviewers, and of increasing the participation of the wider astronomy and astrophysics community in the science program of NRAO facilities, SRP membership is deliberately selected to include some colleagues that are not necessarily experts in radio observational techniques. This being the case, we encourage proposers to consider the following when preparing their proposals:

  1. Avoid the use of radio astronomy jargon
  2. Do not assume the reader is familiar with a particular observing technique - explain it briefly
  3. Do not assume the reader is familiar with an earlier rationale for a developing line of research - provide adequate historical context and connect the dots as necessary
  4. Describe previous observations and publications relevant to the proposed observations
  5. If a particular point source or brightness temperature sensitivity is required, justify it.

Filler Time

The Observatory would like to point out that there are opportunities for so-called "filler" programs on all of its telescopes. Observing programs that exploit frequencies below 10 GHz, do not have strong scheduling constraints, and could benefit from short scheduling blocks are encouraged to propose for such opportunities. The proposal should make clear in the abstract and early in the science justification that "filler" time (scheduling priority C) is being requested, not time at scheduling priority A or B.

Triggered Proposals

Those who are planning to submit a proposal of type Triggered are reminded that they must include well-defined trigger criteria and state applicable semesters in their request for telescope time. Furthermore, a Triggered proposal must ask for the full amount of time needed to achieve the science goals, including both initial and follow-up observations. Proposers should not be using Director's Discretionary Time to request follow-up of an event initially observed under a Triggered proposal.

High Risk Proposals

As a means of maximizing its scientific impact through cutting edge observations, the Observatory also encourages the submission of high-risk/high-reward proposals. Such proposals may involve unusual targets, nonstandard observing techniques, new post-observing data reduction and analysis, or supplementary hardware or new back ends. Please contact Science Support and Research prior to submitting such proposals to discuss anticipated resource requirements. Observers contemplating such proposals may also wish to consider submitting an Exploratory Proposal to request Director's Discretionary Time as a means of demonstrating a proof of concept.

Opportunities for Joint Observations with Fermi or Chandra

We remind the community that it is possible to propose for observing time on NRAO facilities through the Fermi Gamma-ray Space Telescope Joint Proposal Opportunity or the Cooperative Proposal Opportunity. For Fermi, which is primarily in sky-survey mode, potential observers may propose for NRAO observations that make use of the Fermi survey data even without re-pointing of the Fermi satellite. The actual amount of NRAO observing time allocated via the Joint Fermi Process depends on the amount of proposal pressure and the scientific quality of the proposals. A maximum of 10% of the NRAO scientific observing time is made available on the VLA, the VLBA and the GBT, or up to 400-650 hours per year on each telescope. Details about joint observations with Fermi and the VLA, the VLBA or the GBT may be found here. The next Fermi proposal deadline is in January 2014. Similarly, the community may propose for observing time on NRAO facilities through a joint program with the Chandra X-ray Observatory. For Chandra, proposals must be for observations that require both Chandra pointing and NRAO observations to carry out a scientific investigation. The NRAO has allocated up to 3% of the observing time on the VLA, the VLBA and the GBT for Chandra joint proposals. Section 4.5.5 of the Chandra call for proposals gives specifics of the joint NRAO/Chandra program. The next Chandra proposal deadline is in March 2014.

Very Large Array (VLA) Proposals

Observing Capabilities for Semester 2014B

The 3 February 2014 deadline covers the observing period 19 September 2014 through 26 January 2015 (Semester 2014B), corresponding to the DnC, C and CnB configurations. Multi-configuration proposals that include DnC, C and/or CnB configurations may also be submitted. In addition, proposals only for configurations that will fall in Semester 2015A or later may be submitted, if the Principal Investigator is a graduate student. NRAO offers this service to provide scientific and technical feedback for students, and to provide them with an opportunity to re-submit their proposals for their principal semester with this information in hand. Students should ensure that their status is up-to-date and correct in the NRAO User Database. All other proposals for configurations not included in Semester 2014B will be held over for review in the appropriate semester. See the VLA Configuration Plans for further information, including plots of the estimated available observing hours as a function of LST for all configurations in the upcoming semester.

Enhanced capabilities offered for 2014B include the simultaneous use of the 3-bit and 8-bit sampler systems through our General Observing (GO) program, and recirculation of up to a factor of 4 is now considered Shared Risk rather than Resident Shared Risk. Details of the general capabilities are given in the VLA Observational Status Summary (OSS), and are summarized below:

Capability Description
8-bit samplers
  • Standard default set-ups for:
    • 2 GHz bandwidth continuum observations at S/C/X/Ku/K/Ka/Q bands (16 x 128 MHz sub-bands)
    • 1 GHz bandwidth continuum observations at L band (16 x 64 MHz sub-bands)
  • Flexible set-ups for spectroscopy, using two independently tunable 1 GHz basebands, each of which can be split into up to 16 flexibly tunable sub-bands
  • Single, dual & full polarization products
  • Up to 16,384 channels (summed over all polarization products)
3-bit samplers
  • Standard default set-ups for:
    • 8 GHz bandwidth continuum observations at K/Ka/Q bands
    • 6 GHz bandwidth at Ku band
    • 4 GHz bandwidth at C/X bands
  • Flexible set-ups for spectroscopy, using four independently tunable 2 GHz basebands, each of which can be split into up to 16 flexibly tunable sub-bands
  • Single, dual & full polarization products
  • Up to 16,384 channels (summed over all polarization products)
Mixed 3-bit and 8-bit samplers
  • Ability to mix 3-bit and 8-bit samplers, to allow for simultaneous continuum and high-resolution spectral line observing
  • Up to 3 independent sub-arrays using standard 8-bit continuum set-ups
Phased array for VLBI
  • See VLBA section of this Call for Proposals

Both single pointing and mosaics with discrete, multiple field centers will be supported. Data rates up to 25 MB/s (90 GB/hour) will be available to all users, and with additional justification, data rates up to 60 MB/s (216 GB/hour) will be available. Correlator integration time limits per band and per configuration also apply, as described in the OSS. The data rate and total data volume required by a proposal will be a consideration in its technical evaluation.

There are some limitations on frequency settings and tuning ranges; please consult the OSS for further details. In addition, special tools are available to assist users with the development of correlator set-ups for the proposal deadline (see VLA Proposal Preparation and Submission), and the Exposure Calculator has been updated. All antennas employ electronics and receiver systems that provide continuous frequency coverage from 1-50 GHz in the following observing bands: 1-2 GHz (L-band); 2-4 GHz (S-band); 4-8 GHz (C); 8-12 GHz (X); 12-18 GHz (Ku); 18-26.5 GHz (K); 26.5-40 GHz (Ka); and 40-50 GHz (Q).

We will continue to offer shared risk programs to our user community for those who would like to push the capabilities of the VLA beyond those offered for general use.

  • Shared Risk Observing: This program allows users access to capabilities that can be set up via the OPT and run through the dynamic scheduler (without intervention), but are not well tested. The following capabilities are offered under the Shared Risk Observing program: correlator dump times as short as 50 ms; use of the new low frequency system in the frequency range 230 to 470 MHz for Stokes I continuum imaging; recirculation of up to a factor of 4. Please refer to the VLA Proposal Preparation and Submission web page for information about tools and other advice on proposing for Shared Risk observing capabilities.
  • Resident Shared Risk Observing (RSRO): This program provides access to extended capabilities of the VLA that require additional testing, in exchange for a period of residence to help commission those capabilities. Capabilities that would fall under the RSRO program include, e.g., correlator dump times shorter than 50 ms; data rates above 60 MB/s; use of recirculation beyond a factor of 4 in the correlator; use of the P-band system for polarimetry or spectroscopy; more than 3 sub-arrays or sub-arrays with the 3-bit system; on-the-fly (OTF) interferometric mosaicing; complex phased array observations (e.g., pulsar and complex VLBI observing modes). A detailed description of the VLA RSRO program for Semester 2014B and beyond is available at the VLA Proposal Preparation and Submission web page.

Low Frequency Observing for Semester 2014B

The new low frequency receiver system developed in collaboration with the Naval Research Laboratory will be available for Stokes I continuum observations at P-band (230 to 470 MHz), through the Shared Risk Observing program. Use of the P-band system for polarimetry and/or spectroscopy will be through the Resident Shared Risk Observing Program. The new receivers also work at 4-band (58 to 84 MHz), and a new feed compatible with the VLA electronics is being developed, but is not yet commissioned. Members of the community interested in helping to commission the 4-band system in return for peer-reviewed telescope time should apply through the RSRO program described above.

Proposal and Observation Preparation

Proposal preparation and submission are via the Proposal Submission Tool (PST) at NRAO Interactive Services. Use of the PST requires registration in the NRAO User Database. There are various tools and documentation to help users in this process. Descriptions of all updated documentation and tools along with an outline of the steps required to write a proposal are available at the VLA Proposal Preparation and Submission web page.

All approved VLA observations are set up using the Observation Preparation Tool (OPT). Most, if not all, projects will be observed dynamically so users should submit scheduling blocks early in the configuration to maximize the opportunity of them being observed. Advice on the optimal length of scheduling blocks and other useful information may be found at the Observing FAQ web page.

Information about VLA capabilities, observing strategies, and calibration overhead can be found in the VLA Observational Status Summary, at the Guide to Observing with the VLA, and at the Observing FAQ web page. Questions may also be directed to the NRAO Helpdesk.

Green Bank Telescope (GBT) Proposals

The 3 February 2014 deadline is for the 2014B Semester observing period: 1 August 2014 through 31 January 2015.

Details of all GBT observing modes are in the GBT Proposer's Guide. 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.

All proposers, including pulsar proposers, should use the GBT Sensitivity Calculator. Please see the GBT Sensitivity Calculator User's Guide for further 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.

Available receivers, backends and observing modes are presented in Tables 1 and 2.

Table 1: GBT Receivers


Frequency Range


290-920 MHz


910-1230 MHz


1.15-1.73 GHz


1.73-2.60 GHz

C (shared risk)

3.8-8.0 GHz




12.0-15.4 GHz

KFPA - seven pixel array

18.0-26.0 GHz


26.0-39.5 GHz


38.2-49.8 GHz


67-93.3 GHz

MBA1.5 - Bolometer Array(shared risk)

80-100 GHz

Table 2: GBT Backends


Observing Modes


Continuum, pulsar, spectral line





Mark Vc





Private PI instrument – contact the NRAO helpdesk for further information


Private PI instrument – contact the NRAO helpdesk for further information

  • The Mustang bolometer array will undergo an upgrade. The receiver cryogenics will be redesigned such that the receiver can be kept cool at all elevations and will allow observations below 30 degrees elevation.We will accept shared-risk proposals to help commission the upgraded Mustang bolometer array in the 2014B Semester.

  • The C-band receiver is being upgraded to cover the 3.8-8 GHz frequency range. We will consider shared-risk proposals for the 3 February 2014 deadline for observations with this receiver.

  • The GBT spectrometer and spectral processor are being replaced by VEGAS and will be retired at the end of the 2014A Semester.

  • All VLBI proposals requesting the GBT should include any needed setup and overhead time in the time request of their proposals.

  • Digital TV transmissions above 470 MHz will make observing very difficult with these two 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 at minimum. Observers should consult the GBT support scientists before submitting a proposal for these feeds.

  • 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.

Proposers requesting GBT participation in High Sensitivity Array (HSA), Very Long Baseline Array (VLBA), or global Very Long Baseline Interferometry (VLBI) observations should consult the VLBA, HSA, and VLBI section below.

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. The GBT observing policies describe the remote observing restrictions.

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

Technical questions, questions about the proposal process or about the PST should be sent to the NRAO helpdesk.

Very Long Baseline Array (VLBA), High Sensitivity Array (HSA), & Very Long Baseline Interferometry (VLBI) Proposals

The 3 February 2014 deadline applies to all types of Very Long Baseline Array (VLBA) and High Sensitivity Array (HSA) proposals requesting time in Semester 2014B (1 August 2014 through 31 January 2015), or multi-semester proposals. It also applies to global mm VLBI proposals for the September 2014, or later, sessions. Please see the instructions for submitting VLBA, HSA, and global VLBI proposals. Requests for resources beyond just the VLBA (i.e., the inclusion of HSA or GMVA stations) need to be quantitatively justified in the proposal.

VLBA Observing Capabilities

The VLBA provides ultra-high angular resolution for observations of non-thermal continuum emission, maser lines of OH (1.7 and 6.0 GHz), CH3OH (6.7 and 12.2 GHz), H2O (22 GHz), SiO (43 and 86 GHz) and other molecules, and absorption-line studies of numerous thermal spectral lines. Following the recent completion of a major upgrade program, the VLBA now operates two new data systems based on modern digital signal processing technology. Details of this instrumentation are available in the VLBA Observational Status Summary. In the following brief summary, an "IF" is one of the four 512 MHz signals carried on cables from the antenna's vertex to the control building, and a "channel" refers to a single contiguous frequency range, of any bandwidth, observed in a single polarization, that is sampled, filtered, and recorded as a separate entity.

  • The Polyphase Filterbank (PFB) observing system provides sixteen 32 MHz channels, with a fixed 2048 Mbps recording rate. The channels can be selected flexibly between two VLBA IF inputs. Channel placement is restricted to 32 MHz steps along the frequency axis.
  • The Digital Downconverter (DDC) observing system is considerably more flexible. As many as eight channels can be selected arbitrarily from up to four VLBA IFs, and placed at 15.625 kHz steps on the frequency axis with bandwidths ranging from 1 MHz to 128 MHz by factors of 2. Extremely narrow bands can be accommodated by observing at 1 MHz bandwidth, and selecting a narrower range using the DiFX correlator's spectral zoom mode. All bandwidths must be identical, and channels cannot span either of two zone boundaries within the IF band, at 640 and 896 MHz. Use of 128 MHz bandwidth is limited to 4 (or fewer) channels by the 2048 Mbps recording rate limitation.

Wideband science is possible using either the PFB observing system, at its fixed 2048 Mbps data rate, or the DDC system at 2048 Mbps or lower rates. We anticipate that our pool of recording media will support the highest data rates for approximately half of all observing hours. Spectroscopic and other narrow-band observations will generally be best supported by the DDC system, which incorporates scientifically compatible counterparts for all modes of the VLBA legacy system, as detailed in the VLBA Observational Status Summary. Inputs to either data system can come from any of the four VLBA IFs. Typically only two are used, in opposite polarizations, but less common modes are also possible, generally dual-polarization dual-frequency cases. The four-IF capability of the DDC allows these modes to be exploited.

High Sensitivity Array (HSA)

The phased VLA ("Y27") will be available for VLBA proposals in Semester 2014B, in configurations DnC/C/CnB. HSA proposals can request the phased VLA in conjunction with the VLBA and other HSA telescopes, subject to availability of matching observing systems (see below). Phased-VLA observing is limited to two independently-tunable VLA subband pairs, one polarization pair (RCP+LCP) in the A0/C0 baseband pair, and the other (RCP+LCP) in the B0/D0 baseband pair. Any matching bandwidths available on the VLA as well as the VLBA DDC data system described above can be used. Bandwidths must be uniform at each station, across the entire VLBI array, and throughout the entire duration of the observation. In particular, VLA phasing and VLBI observing must be carried out at the same bandwidth. Bandwidths of 16 MHz and wider are available as a general capability. Bandwidths narrower than 16 MHz may work if the source is strong enough, but are expected to be of limited use. Further details are available in the VLA section of this Call for Proposals, in the document VLBI at the VLA, and in the VLBA Observational Status Summary.

Observing with a single VLA antenna ("Y1") in conjunction with the VLBA will only be available through the VLBA Resident Shared Risk Observing program.

Proposals to use the GBT as part of the HSA will be considered for Semester 2014B. The GBT is equipped with the full VLBA Sensitivity Upgrade instrumentation, and is able to support all the observing configurations described in the VLBA Observing Capabilities section above. A table of Available Receivers and Bands compares the frequency ranges of GBT receivers with their VLBA counterparts, and includes sensitivity data and special capabilities. Note that all proposals to use the GBT as part of VLBI must include time to set up the telescope (pointing, focus, etc.) prior to the start of the observation. This can take 0.5-1 hr depending on the frequency (see Chapter 6 of the GBT Proposer's Guide).

The Effelsberg and Arecibo HSA stations have also installed the same wideband equipment, but their implementation is not yet complete. An observing mode to match the PFB system works well for continuum science, but there is currently no mode to match the DDC for spectroscopy that has been fully commissioned. The following table summarizes the availability of the various observing systems for HSA stations for 2014B:

HSA station Observing system
Arecibo Y N N
Effelsberg Y RSRO N

where DDC-4 refers to a 4-channel, 2-IF mode, and DDC-8 to the full 8-channel, 4-IF case. Combinations marked "RSRO" are only available through the Resident Shared Risk Observing program (below). The observing system must be identical for all stations in an observation.

Global 3mm VLBI Array (GMVA)

VLBI proposals for observing at 3mm wavelength using the VLBA, GBT, Effelsberg, Pico Veleta, Plateau de Bure, Onsala, and Yebes telescopes should be submitted by 3 February 2014 through the NRAO Proposal Submission Tool. Successful proposals will be considered for scheduling in the September 2014 (or later) session. Proposers should be aware that at some GSTs the available time on the VLBA in the September 2014 session may be limited due to prior commitments (primarily in the Galactic Plane), and that the GBT will only observe at 3mm at night (i.e., 3 hours after sunset until sunrise). In order to maximize the sensitivity for continuum observations the GMVA will record at the highest bit rate which telescope instrumentation and resources permit. All telescopes will record at 2 Gbps (the only exception being Plateau de Bure which will record in a compatible 1 Gbps mode).

For further details on proposing please consult the relevant administrative and technical information hosted at Bonn.

VLBA Filler Project Challenge

NRAO is soliciting proposals for one or more Large projects for up to 750 hours per semester of "filler" time on the VLBA. To be eligible for this large time allocation with FILLER status the project should be flexible enough to be scheduled:

  • under non-ideal weather conditions
  • with less than the full complement of antennas
  • with a target list of source positions around the sky
  • with short duration or variable length scheduling blocks

Teams must provide tools that allow VLBA operations, with minimal effort, to create schedules for arbitrary blocks of time of one hour or more when such time becomes available during dynamic scheduling. Large proposals for VLBA filler time will be subject to the usual NRAO Large Proposal Policy. Multi-semester proposals will be considered.

Types of projects that might use VLBA filler time include, but are not limited to, surveys of many sources, astrometry, geodesy, deep integrations spread over many sessions, and long term monitoring. It is rare for fewer than 6 or 7 antennas to be functional and have good observing conditions, so high frequency projects that can use a reduced array are viable. Proposers should be aware that the available time will not be uniformly spread across the sky because of the high demand for galactic time from high priority programs. Proposals that require much greater correlator resources than typical projects (such as multiple phase centers per field) should address mechanisms to support the correlation without adversely affecting the throughput of other projects.

Regular proposals that can utilize the same sort of VLBA filler time continue to be encouraged.

VLBA Resident Shared Risk Observing Program

The VLBA Resident Shared Risk Observing (RSRO) program provides users with early access to new capabilities in exchange for a period of residency in Socorro to help commission those capabilities. The phased-VLA system was developed through RSRO programs, and NRAO encourages additional RSRO proposals to expand the phased-VLA capabilities. A number of additional areas are suggested at the VLBA RSRO program webpage, including the development of Y1 with the VLBA. We encourage other innovative ideas for new VLBA observing modes from the community as well.

Proposal Preparation

Proposal preparation and submission for the VLBA, HSA, and GMVA are via the Proposal Submission Tool (PST) at NRAO Interactive Services. Use of the PST requires registration in the NRAO User Database.

Information about VLBA capabilities can be found in the VLBA Observational Status Summary Questions may also be directed to the NRAO Helpdesk.

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