Director's Discretionary Time Proposals

Up to 5% of the available general observing time may be used for Director's Discretionary Time Proposals (DDTs).
A DDT proposal must necessarily belong to one of the following categories:

  • proposals of ToO nature requiring the immediate observation of a sudden and unexpected
    astronomical event (clearly indicate the urgency in Box 5 - Special Remarks),
  • proposals requesting observations on a hot and highly competitive scientific topic,
  • proposals asking for follow-up observations of a programme recently conducted from ground-based and/or space facilities, where a quick implementation should provide break-through results,
  • proposals of a somewhat risky nature requesting a small amount of observing time to test the feasibility of a programme.

DDT proposals can only be carried out in Service Mode. Proposers can view the schedule of the observatory using the link: In particular, service mode slots for a particular telescope can be identified  by selecting 'Service Slots' under 'Observing Mode' as well as the relevant telescope.

Very few non-time-critical DDT proposals are foreseen to be approved. Therefore proposers should provide a very clear justification (in Box 8 B of the application form) why the programme should be considered for DDT allocation and was not submitted through the normal OPC procedure. In the absence of such a justification, the proposal will not be considered for DDT allocation, and the proposers will be encouraged to resubmit their proposals for the next appropriate OPC submission deadline.

DDT proposals time may be submitted any time. They must be written using the special current ESOFORM DDT template.

Please note that you now require an ESO User Portal account in order to submit proposals. You can get an account and submit proposals using the following link:

Once you have logged in, you can select the option, "Submit a proposal", from the menu on the left-hand side. You should then upload the LaTeX file of your proposal and follow the rest of the upload instructions.

DDT proposals will be subject to the normal proposal validation procedure.

In Box 5 of the proposal form applicants have to indicate whether the proposed DDT observations were already submitted in a proposal to the OPC. If yes, the respective proposal number has to be indicated.

Normally DDT proposals will be reviewed by the Director's Discretionary Time Committee (DDTC). Once received and validated, a copy of the proposal will automatically be forwarded to the Director of the La Silla and Paranal Observatory who, in exceptional cases where a proper review by the DDTC would delay time-critical, urgent observations, may decide to carry out the observations prior to a DDTC review. Such urgent requests must be clearly identified in Box 5 (Special Remarks) of the application form.

Please note that within one month following the observations, the PI's of accepted DDT proposals have to submit a report on the achieved science to the account -