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 NACO

In addition to the general Phase 2 Waiver Request policies, waiver requests have to be submitted if the following condition is met:

  • In imaging or polarimetry, a saturation of factor 10 (even if that saturation is not due to the target itself) is the maximum acceptable without an approved waiver.  In this context the requester should carefully note two things:
    1. The request should contain the estimated factor above saturation that is anticipated, as well as an assessment of the number of affected pixels (in terms of the diameter of the affected region, in pixels).  Both numbers can be obtained through the use of the ETC and the NAOS-PS.
    2. In the event that a saturation waiver request is granted it is always done so conditionally where the following conditions will apply:
      • You must explicitly reference the README the fact that saturation has been approved to a level of a factor of FF and up to a diameter of ~PP pixels.
      • In such cases there will be some remanence (which goes below the noise background only after tens of readouts) at the location of the saturated stars.
      • This will result in 3 electronic ghosts spreading over tens of pixels with a level of a few tens of ADU.
      • If the star saturates by more than expected, the OB will be classified as "out of constraints --- do not repeat" independent of the ambient conditions.
      • If a FixedSkyOffset template is used the sky data will suffer from remanence patterns on their sky frames (which decrease with time).
      • The handling of such saturation requests is under discussion and the policies may change in the future. Thus, an acceptance of the current request should not be construed to imply a similar result for a similar future request.
  • For cases where the target is very bright and believed to be unambiguously identifiable within the field of view one can request to forego submission of a Finding Chart.  Note that this only applies to NoAO observations or AO observations in which the target is the AO reference object.  This should be made clear in the text of the Waiver Request.
  • Starting in Period 99 M' observations are allowed in Service Mode, pending the approval of a Waiver Request.

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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