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 (except AMBER observations with more than one spectral band).
  • Concatenated OBs prepared with P2PP3 that will take longer than one hour to execute (except CRIRES observation of science and telluric concatenated OBs which can be as long as 1.5 hour). 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. For CRIRES, OBs with multiple grating settings can be submitted without the 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.

Additional conditions for Waiver Requests regarding CRIRES

In addition to the general Phase 2 Waiver Request policies, waiver requests have to be submitted for any of the following conditions:

  • if a concatenation of a science-telluric OB pair takes longer than 1.5 hours to be executed.
  • if a DIT larger than 600s (typically 900s) is used,
  • if a DIT larger or equal than 60s is used that is different from the recommended values 60, 90, 120, 180, 300, or 600s,
  • if a slit width of 0.0 arcsec is used (for obtaining SV images),
  • if the AO guide star has a distance to the target in between 20 and 25 arcsecs,
  • if the finding chart should be skipped, which only is possible if the following conditions are met:
    • there is no other source within the 50" x 50" field that has a magnitude similar (within 2 mag) to the target star in the observed band (this applies to science targets as well as telluric standards),
    • the target/telluric is not variable (to avoid confusion with fainter stars at the faint passage through the variability curve),
    • the present day position of a high proper motion target with respect to the surrounding sources fulfills the first condition.
    Note that, if the waiver was granted, but nevertheless the target appears double or ambiguous during observations, the night astronomer will either pick one source according to his/her best judgment, or cancel the OB.

No waiver for skipping finding charts is necessary for the submission of placeholder-OBs of a ToO programme that targets a moving or unknown source. However, when the ToO observation is activated, Paranal expects to get a finding chart (see the ToO instructions).

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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