Phase 2 Waiver Requests and Programme Change Requests

Phase 2 Waiver Requests

To ensure the observing efficiency and flexibility of Service Mode observing, ESO has implemented a number of rules, procedures and limitations on programmes scheduled for Service mode. Typically, these have to do with OB construction, observing strategy, or instrument modes available.

In some special cases it is possible to admit some justified exceptions to these rules with a reduced operational impact. However, it is necessary that the exceptions have been reviewed and authorized by ESO well in advance. The Phase 2 Waiver Request procedure is the channel to make this possible.

Instrument independent conditions where a Phase 2 Waiver Request is needed

  • OBs that will take longer than one hour to execute.
  • Concatenated OBs that will take longer than one hour to execute . Please note that justifications based on the reduction of execution overheads cannot be accepted, as sequences of OBs decrease the flexibility of Service Mode observing and thus the operational efficiency of the telescopes
  • Concatenated OBs that have large angular separations between the OB targets (>75 deg) which would result in a very difficult scheduling.
  • OBs that contain multiple instrument configurations. As an exception, multiple broad-band filters in a single OB can normally be allowed without a waiver, and for FORS2 up to two interference filters may be used in a single OB without a waiver.
  • Delayed submission of Phase 2 material needed. This is admissible only under exceptional circumstances justified by scientific reasons, such as the need to wait for the outcome of another observing run before preparing the OBs. Users whose schedule prevents them from submitting their Phase 2 package by the due date are strongly encouraged to find a collaborator who can do it, rather than submitting a waiver request, as ESO cannot guarantee the prompt review and validation of Phase 2 packages submitted after the Phase 2 deadline.
  • The time interval between succeeding time-linked OBs is < 1hr.

Submitting Phase 2 Waiver Requests

Waiver requests should be sent to The Subject line of your e-mail should contain only your ESO Observing Run ID. For example:

Subject: 091.A-0123(B)

All Phase 2 procedure waiver requests must be approved by ESO before Phase 2 package submission. Since a Waiver Request can take up to one week to process, please make sure to submit more than one week before the Phase 2 deadline. Waivers received less than five working days before the submission deadline will normally be rejected.

All waiver requests should include:

  • what technical requirement you wish to override
  • a brief (one paragraph) technical and/or scientific justification

Programme Change Requests

The contents of the Phase 2 package must closely follow the project as described in the Phase 1 observing proposal (see Service Mode Policies. Any significant deviations from the approved programme (e.g. new targets, new instrument, new/different observing modes, etc.) must be approved by ESO before the Phase 2 submission process is completed. All approved run change requests should be summarized in your README file. Please note that change requests must imperatively be submitted, together with a scientific justification, through the dedicated web form.

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