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Regular proposals

Our regular proposal for observations is a formal request submitted by astronomers and researchers seeking to observe with the EVN. These proposals cover a variety of observational modes, including both disk-recorded and real-time electronic (e-EVN) sessions, following the current capabilities of the network. They are evaluated based on their scientific merit and technical feasibility, and successful proposals are granted access to the EVN's array of telescopes spread across Europe and beyond. We encourage you to explore our website and learn more about the EVN and our proposal process.

If you have any questions or need further information, please don't hesitate to contact us.

Regular proposals include the following observing modes:


Standard observations

For science cases where there is no time constraint on when the observations should be conducted, or the required epochs are already known at the time of proposal submission. This implies observations that can be scheduled during a regular EVN or e-EVN session.

Standard observations can be conducted in either disk-recording or real-time EVN (e-EVN) operational modes, including both continuum and/or spectral line observations, and any of the currently available observing modes.

Proposals for standard observations need to follow the instructions detailed below.

Trigger observations

Provide a rapid response to follow up on transient events or time-varying astrophysical sources in a timely manner. For observations that need to be conducted shortly after an expected astrophysical event has occurred, or after the target source displayed a particular state transition or intrinsic change.

Continuum or spectral line observations requiring a single correlator pass can be requested as trigger proposals. But note that multiple correlator passes are not available in this mode (e.g. it is not possible to simultaneously obtain both continuum and spectral line modes).


Once the proposal is accepted and the trigger observations are awaiting, the PI can request to activate them once the target met the required criteria set in the proposal (see more below):

  • Trigger requests on e-EVN runs, including accurate target source coordinates, required calibrators, and phase-referencing cycle (if needed), must be sent to the Chair of the EVN Programme Committee (with the EVN Scheduler and EVN User Support in copy) and received no later than 8:00 UT of the day before the e-VLBI run.
  • Trigger requests on an EVN-lite subarray day should be sent and received no later than 8:00 UT three days before the EVN-lite subarray run. Note that EVN-lite observations are done at a central frequency of 21 cm. Stations may have limitations in changing frequency bands for EVN-lite triggers.
  • Trigger requests during regular EVN sessions are also possible with the following restrictions:
    • Performed on best effort basis; only if there is an available observing slot in the right frequency range and if media resources are sufficient.
    • Performed in disk-recording only.
    • Trigger activation should be done at least one week before the start of the desired frequency block in the schedule by writing a mail to the PC Chair.



The submitted proposal must clearly justify why trigger observations are requested and why the target of opportunity mode is not suitable, including:

  • A list of potential targets, if known at the time of the proposal submission, with an explanation of how these sources form a coherent set for achieving the goals of the proposal. If the proposal will trigger on targets that are not known beforehand (e.g. triggering on new gamma-ray bursts), the authors need to state how many possible targets will be triggered.

  • Well-defined trigger criteria, specified for each class of sources separately, if necessary. This criteria can arise from both, an astrophysical or observational motivation.

  • Minimum number and configuration of telescopes required.

  • Desired period for which the proposal will be active (maximum duration of 1 year, or 9 months for automatic trigger proposals).

  • Maximum number of trigger events to be observed.

  • Demonstrate capability of proposers to locate and respond to triggering events within the active period of the proposal. Specify which data or monitoring campaign will provide the required information to be able to trigger the proposal.

  • Required sensitivity, resolution, or other constraints that the final data must comply.

  • Minimum/maximum observing time.

  • Justification as to why standard e-VLBI observations or target of opportunity are not suitable.


Large observations proposals

Large observation proposals are intended for projects that request observing time of more than 48 hours. These proposals are subject to more detailed scrutiny by the EVN Programme Committee, but otherwise follow the same rules that apply to the standard proposals.

For projects with several observing epochs, the EVN Programme Committee may request a progress report.

Global proposals
Global proposals are those requesting telescopes from the NRAO (i.e. VLBA and/or VLA) and GBO (Green Bank Telescope) telescopes. These proposals are discussed together with the NRAO and GBO Time Allocation Committees (TACs). The e-MERLIN array observing time, which can also be requested within the EVN observations, has to be granted by the e-MERLIN TAC and proposals should therefore include a clear justification for its inclusion. All these telescopes can be requested within the same EVN proposal. Global proposals are judged in the same manner as regular proposals by the EVN committee. NRAO, GBO and e-MERLIN TACs have their own procedures for evaluation. The PI of the proposal will receive a unified feedback from this proposal corresponding with the outcome of the different TACs.
Out-of-session observations

For science cases that require specific observing epochs that do not lie within the standard regular EVN or e-EVN sessions.

The maximum observing time available for out-of-session projects is 144 hours per year. Out-of-session observing blocks are longer than 12 hours (although individual observations can be shorter) and only up to 10 sessions can be scheduled each year (up to a maximum of 144 hours).

Out-of-session proposals can be requested for either disk-recording or e-EVN observations.

The scientific (and technical) justification should include an explanation as to why out-of-session observations are requested instead of in-session observations.

The proposal must include:

  • Required observing dates.

  • GST ranges.

  • Minimum number of telescopes (and any specific telescopes if necessary).

Successful proposals will be scheduled following the regular EVN session, which occurs after the proposal review.

Correlator-only proposals

With a correlator-only proposal, investigators apply for time on the JIVE SFXC correlator to correlate their observations. These observations may include 'non-EVN' stations. The correlator-only proposal cannot ask for any observing time on EVN antennas via the EVN Programme Committee (nor will this be granted). The EVN PC's acceptance of a correlator-only proposal does therefore not result in any time being subtracted from an Observatory's commitment of time to the EVN.

The actual observations must be organised by the Principal Investigator, in separate coordination with the desired participating observatories themselves. In the proposal, the Principal Investigator must thus:

  • Discuss the observations organised by the proposal team themselves, and demonstrate the availability of recording the raw data of the observations for each telescope (correlator-only projects are not allowed to access the EVN disk pool).
  • Comment on the plan/estimated timeline for observations, data delivery to JIVE, and the correlation preparation (including the timely notification of the correlation to JIVE science operations).

If accepted, these proposals will be recognised as EVN projects.

EVN Lite proposals

EVN-lite subarray observations started in February 2023. These provide additional opportunities for trigger projects, outside of the regular disk-recording or e-VLBI sessions. Projects that require a limited EVN sub-array, but flexible triggering, may benefit from this. The dates of EVN-lite observations are publicly listed. This is a best-effort service for projects requiring a small number of stations, preferably in the 18 or 21-cm bands. Note that the EVN-lite triggers must be received by 8:00 UT three days before the observations. Teams interested in proposing an EVN-lite background project should consult the EVN PC Chair. Find here the EVN-lite policy document.


Requesting additional telescopes

Observations with the EVN can incorporate and include other VLBI networks or specific antennas.

The NRAO stations and the Green Bank Observatory

In addition to the EVN antennas, proposals can also request some or all of the NRAO antennas (VLBA and VLA) and/or the Green Bank Telescope (GBT). Justification for their need and a plan for their use must be clearly outlined in the proposal.

The proposal, submitted via the standard EVN channels, is automatically (and internally) sent to the NRAO, and is assessed separately by the EVN Programme Committee and the NRAO. The PI does not need to perform any extra step, and will receive a unique (combined) feedback from the programme committee.


e-MERLIN stations can be included in any proposal requesting disk-recording or e-VLBI observations. Their inclusion must be clearly justified in the proposal. The proposal is judged by both the EVN Programme Committee and the e-MERLIN time allocation committee.

EVN affiliated stations

EVN affiliated stations are antennas of the NASA Deep Space Network (e.g. Robledo in Spain) and the Australian Long Baseline Array (LBA). Proposals can request to include these antennas in the EVN network, but their inclusion must be clearly justified in the proposal.

In the NorthStar submission tool, the LBA can be selected under 'Other' in the telescope-selection box.

Note that proposals including the LBA need to also submit independently a proposal to the LBA for their subsequent deadline.

Non-EVN stations

In the proposal, it needs to be specified which non-EVN stations will be included in the observations.

The investigators must send a copy of the proposal to the director/scheduler of the included observatory and arrange all aspects of the observatory's participation in the EVN observations (including acquiring telescope time from the observatory, observing support, disk supply, etc.).

More information on including non-EVN stations is given in the Code of Practice for Non-EVN observatories.


General information about the proposal submission

  • Read the current call for proposals.
  • Check the current capabilities of the EVN.
  • The proposals are submitted via the NorthStar proposal tool (requires registration).
  • The proposal should include:
    • A four-page PDF including the scientific and technical justifications (up to two pages), and relevant figures, tables, and references (remaining two pages).
    • The requested network of telescopes.
    • Request observing band.
    • Preferred observing dates (if any).
    • Number of epochs (if any).
    • Recording setup.
    • Correlator information.
    • Target sources (coordinates, total flux density, correlated flux density, required signal-ton=-noise ratio, and required field of view).
    • Phase-referencing source and cycle (if any).  Check here for more information on possible phase calibrator sources.
    • Additional information such as the students involved in the proposal, linked proposals and relevant previous allocations.
  • Further instructions regarding submitting a proposal are given in the NorthStar help file (the Read me first! link after you login).
  • Retraction, editing and resubmission of proposals until the deadline is possible.
  • An email will automatically be sent to all co-investigators following submission.

If you require assistance at any stage of this process, contact us!


Data policy

Investigators named on an EVN or global VLBI proposal have the sole right of access to the data obtained for that proposal for 12 months after the distribution of the data to the Principal Investigator. If the proposal comprises multiple observations, then the 12 month period begins from the distribution of the final observation associated with the proposal.

One month prior to the public release of data from a proposal, JIVE will inform the Principal Investigator (at the last known e-mail address) about the impending action. Under exceptional circumstances the Principal Investigator can request a short delay in the release date. All such requests should be made to the Chair of the EVN Programme Committee.

The abstracts of successful proposals are published in the EVN Data Archive upon the completion of observations. Following the expiry of the proprietary period for a proposal, all data related to it will be publicly accessible.