Introduction

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The National Radio Astronomy Observatory (NRAO) invites scientists to participate in the Semester 2027A Call for Proposals for the Karl G. Jansky Very Large Array (VLA), the Robert C. Byrd Green Bank Telescope (GBT), and the Very Long Baseline Array (VLBA), High Sensitivity Array (HSA), and Global mm VLBI Array (GMVA).

The submission deadline for Semester 2027A proposals is Wednesday, 29 July 2026, at 17:00 EDT (21:00 UTC).

Starting in 27A the GBT will join the VLA to include constraints for proposals with a PI from a non-US institution  (see What's New in 27A).

For the VLA, the B and A-configurations will be available. It is anticipated there will be around 3300 hours on the VLA, 2000 hours on the GBT, and 965 hours on the VLBA available for science observing. Opportunities for Joint proposals will be available for ALMA, JWST, HST, Swift, Chandra, XMM-Newton, and IXPE. Joint Proposals with ALMA or JWST need to be submitted to the facility requesting the larger amount of observing time.

The array configurations available for joint ALMA/VLA will be: ALMA C-1 to C-10 and VLA B, A, and D-configurations.

The NRAO 2027A Call for Proposals is for observations with the VLA, GBT, and VLBA/HSA/GMVA.  

A detailed timeline for the 27A Proposal Call is available here and summarized in the table below:

 
Date Action
24 June 2026 NRAO Call for Proposals
29 July 2026 NRAO Proposal Deadline @ 17:00 EDT
27 August 2026 Individual Science Reviews Completed
11 September 2026 Science Review Panel (SRP)  Meetings Completed
14-15 October 2026 Telescope time allocation committee (TAC) meeting
10 November 2026 Disposition Letters Sent

Connect with NRAO

The NSF National Radio Astronomy Observatory and NSF Green Bank Observatory are facilities of the U.S. National Science Foundation operated under cooperative agreement by Associated Universities, Inc.

Founded in 1956, the NSF NRAO provides state-of-the-art radio telescope facilities for use by the international scientific community. NSF NRAO telescopes are open to all astronomers regardless of institutional or national affiliation. Observing time on NSF NRAO telescopes is available on a competitive basis to qualified scientists after evaluation of research proposals on the basis of scientific merit, the capability of the instruments to do the work, and the availability of the telescope during the requested time. NSF NRAO also provides both formal and informal programs in education and public outreach for teachers, students, the general public, and the media.

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