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Target of Opportunity proposals

Targets of Opportunity (ToOs) are defined to be extremely rare and/or unpredictable events where there is a limited opportunity to make scientifically important observations. This limited opportunity and the potential scientific impact of the observations together constitute the justification for an exceptional response to a ToO proposal, bypassing the normal EVN review and scheduling procedures.

ToO proposals can be requested for both disk and e-VLBI observations.

For proposal preparation, this latex template (.tex file) must be used to provide the observational details.

The proprietary period for ToO observations, during which the proposer has exclusive access to the data, is six months. This period begins on the date of receipt of the correlated data from the last epoch of a proposal.


The proposal must include:

A scientific justification.

A technical justification, outlining:

  • Required telescopes - specifying key telescopes and the minimum number of telescopes,

  • Observing frequency,

  • The desired timescale for scheduling as a range of dates with UT time intervals.


Inclusion of figures, tables and references is optional.

Proposals are submitted as a single PDF document, consisting of four pages (excluding the cover sheet) in A4 or US Letter format with a font size no smaller than 11 pt. The proposals should have up to 2 pages for the Science & Technical justification and 2 pages for figures, tables and references.​ Figures and tables may be interleaved with the science justification, so that e.g. figures appear close to the location in the text where references are made to them


ToO in e-VLBI or regular sessions:

The proposal must be sent to the Chair of the EVN Programme Committee, with the EVN Scheduler and the Head of Science Operations at JIVE in copy.


ToO as out-of-session observations:

Out-of-session ToO observations are organised in an adhoc way with the Chair of the EVN Programme Committee and the EVN scheduler, in close contact with the Principal Investigator and the Directors of the available/requested telescopes.

Proposals must be sent to:

A copy of the proposal must also be sent to:


ToO policy document:

Here is the full policy document from the EVN CBD about target-of-opportunity observations.