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 VIMOS

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

  • Deviations from the standard configurations or the standard CCD setups for Service Mode. ESO reserves the right to reject such requests if not sufficiently justified or if they risk imposing an excessive operational burden.
  • Violation of the airmass constraints. Please carefully consider the potentially severe and negative effect this will have on the data quality.
  • Requirement of pre-imaging filters other than the R filter. Given that mask-to-CCD transformation is computed only for R-band, the preparation of the MOS configuration using VMMPS and pre-imaging with another filter can lead to imperfect centering of the targets in the slits.
  • Deviation from the default orientations in pre-imaging mode. The default orientations are rotator on sky = 90 or 0 deg for targets with declinations in the range -45<DEC<-5 deg and rotator on sky = 90 deg otherwise. Please carefully consider the potentially severe and negative effect this will have on the data quality.
  • Overriding the limit on the 30 arcsec offset box within a single OB with a well justified reason. However, you should make sure by using the Unified GuideCam Tool in advance to submitting your request that suitable guide stars exist that can be used for all the offset positions, and that any vignetting that may result in the resulting frames is acceptable for the scientific purpose of the observation. Note also that additional overheads will be charged for the acqusition of new guide stars.
  • Due to negligible fringing with new CCDs it is not necessary any more to dither along the slit between the exposures. If offsets perpendicular to the slit are required, they have to be requested through a waiver.
  • Slit widths larger than 4 arcsec cause saturations in the daytime calibrations (in particular flatfields). They can be allowed if the user is aware of the consequences for data reduction.
  • Requirement to not have attached night-time calibrations consisting of one arc and three flat field exposures at the end of each MOS OB, which uses the grisms HR_blue, MR or HR_orange. This waiver request will be rejected unless it can be demonstrated that the daytime wavelength calibration accuracy of 1-2 pixels is accurate enough for the science case and also for archival researchers that may use the service mode observations in the future (see this report for more details).

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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