Backup Targets

Introduction and Policy

During a run in Visitor Mode, you are expected to perform the observations described in the approved proposal. This includes the specified targets and instrumental set-up(s).

Changes to the originally described observations have to be approved in advance, if they cover one of the following three aspects: 

  • Additional Targets: In case you need more targets to fill the night, additional targets must be requested and approved in advance.
  • Backup targets: You should have a backup programme in case conditions do not permit your main programme to be executed. In particular, keep in mind that strong wind often comes from the North, so backup targets to the South should be prepared. Backup targets must be requested and approved in advance.
  • Change of instrument set-up: in case you want to use an instrumental set-up not requested in the approved proposal, this must be requested and approved in advance.

In case the changes are not approved, you will have to stick to the original targets and set-up. If these observations cannot be performed (e.g., because of high wind), the telescope will be used by the observatory staff to perform Service Mode observations or Test/Technical operations.

Approval of additional targets, backup targets, or setup changes for Visitor Mode runs must be sought at least two weeks in advance of the observing run, via p2. Requests sent on shorter notice, in particular, less than 48 hours from the start of the run, may not be processed in time. In those cases, the corresponding data will not be accessible from the ESO Science Archive Facility until the request is approved.



The submission of program change requests (backup/additional targets, setup changes) is done from within the p2 user interface. In p2, select the relevant Run to access the Change Request menu on the top right. You will be guided though the submission process.

You will receive an acknowledgement via email, and later a reply indicating whether the change is approved. The telescope will also be notified.