Calls for Proposals

Proposals are due by 2017 August 1, 17:00 US EDT (21:00 UT).

This deadline applies to the following proposal types:

• Very Long Baseline Array (VLBA) and High Sensitivity Array (HSA) proposals requesting time in Semester 2018A (2018 February 1 - 2018 July 31) or multi-semester proposals.
• Global mm VLBI Array (GMVA) proposals for 2018 Session I  (April 12-17), or later sessions.

Required proposal submission mechanisms are detailed in individual sections below.

VLBA Proposals

The VLBA provides ultra-high angular resolution for astrophysical studies including:

• Non-thermal continuum emission, including polarimetry, from active galactic nuclei (AGN), Galactic micro-quasars, pulsars, and other sources.
• Maser emission 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 numerous thermal absorption lines, in a variety of Galactic and extragalatic circumstances.
• Multiple-phase-center surveys across the primary beam.
• Parallax and proper motion via differential astrometry of a variety of stars, star-forming regions, and nearby extragalactic objects, at accuracies as good as 10 microarcsec.
• Absolute astrometry at accuracies of ~200 microarcsec to expand the International Celestial Reference Frame.

Overall information about the VLBA is available in the VLBA Observational Status Summary (OSS); specific sections relevant to various proposal types are linked below.

The VLBA operates two data systems, a Polyphase Filterbank (PFB), and a Digital Downconverter (DDC).  These are described in detail in Section 5.4 of the VLBA OSS, which also includes suggestions for selecting the optimal observing system for various scientific goals.

For Semester 2018A, we expect no significant GST-related pressure on available VLBA observing time.

VLBA proposals must be prepared and submitted using the NRAO Proposal Submission Tool (PST), accessible via NRAO Interactive Services.  Use of the PST requires registration by all proposers, including co-investigators, in the NRAO User Database.

Proposals requiring significant additional correlator resources, such as multiple phase centers per field or multiple pulsar phase bins, should consider mechanisms to support the correlation without adversely affecting the throughput of other projects.  These should be entered in the technical justification section of the proposal.

High Sensitivity Array (HSA)

The HSA comprises the VLBA, phased VLA, GBT, Effelsberg, and Arecibo telescopes.  All of these are equipped with instrumentation compatible with the VLBA observing capabilities described in Section 5.4 of the VLBA OSS.  Ongoing special considerations for the HSA telescopes are documented in OSS Section 14.2; new features and special cases are cited here.

VLBI observations combining the VLBA with any one or more of the other four HSA stations can be requested in a single HSA proposal.  However, separate proposals must be submitted for any non-VLBI use of any requested telescopes.

HSA proposals must be prepared and submitted using the NRAO Proposal Submission Tool (PST), accessible via NRAO Interactive Services.  Use of the PST requires registration by all proposers, including co-investigators, in the NRAO User Database.  The inclusion of HSA stations should be quantitatively justified in the proposal.

• The phased Very Large Array (Y27) will be available for HSA observing in Semester 2018A, in its A and D configurations.

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

• The Green Bank Telescope, like the VLBA, has transitioned into a new partnership arrangement, the Green Bank Observatory (GBO).  Time available for VLBI on the GBT will be reduced compared to earlier years, and only the most highly rated proposals across all GBT observation types will be awarded time.  Additionally, 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.

Observations using the GBT 6-cm receiver as part of the HSA must be taken, correlated, and calibrated in full Stokes mode.  Due to the large cross talk between polarizations, only total intensity (Stokes I) data will be usable.

• The Effelsberg telescope supports both the PFB and DDC observing systems available on the VLBA.

• The Arecibo 305-m telescope is currently available only with the PFB observing system.  An RSRO project is encouraged to help qualify the 4-channel DDC observing system at Arecibo.

Global 3mm VLBI Array (GMVA), including Phased ALMA

GMVA proposals submitted by the 2017 August 1 deadline will be considered for scheduling in 2018 Session I  (April 12-17), or later sessions.

Complete information on the GMVA is available at the GMVA website.  Ongoing special considerations for the GMVA are documented in Section 14.3 of the VLBA OSS; new features and/or special cases are cited here.

As noted in the HSA section above, GBT time available for VLBI has been reduced due to its new partnership arrangements.

GMVA proposals must be prepared and submitted using the NRAO Proposal Submission Tool (PST), accessible via NRAO Interactive Services.  Use of the PST requires registration by all proposers, including co-investigators, in the NRAO User Database.  The inclusion of GMVA stations should be quantitatively justified in the proposal.  KVN antennas must be specified by entering "KVN" as "Other" entries in the PST.