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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-recording and e-VLBI observations.

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

The proposal must include:

  • A scientific justification.
  • A technical justification, outlining:
    • Required telescopes - specifying key telescopes and the minimum acceptable number of telescopes.
    • Observing frequency and bandwidth.
    • The desired timescale for scheduling as a range of dates with UT time intervals.
    • Optionally, inclusion of figures, tables and references.

Proposals should be 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 of the Science and Technical justification and 2 pages of figures, tables and references.​ Figures and tables may be mixed with the text as long as the specified page limits are not exceeded.


ToO in e-VLBI or regular sessions

When the ToO observation can be conducted within one of the regular EVN or e-EVN sessions, the proposal must be sent to:


ToO as out-of-session observations

Out-of-session ToO observations are organised in an ad-hoc manner 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:


ToO policy

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.

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