Phase 2 constraints must agree with Phase 1 request

At Phase 1 specific observing conditions (lunar phase also known as Fractional Lunar Illumination or FLI, seeing, and transparency) were requested for each observing run. Your run was reviewed and allocated time with these specific conditions in mind.

At Phase 2, you can relax your constraints, but you cannot specify more stringent constraints. For example,

  • if you requested Seeing = 1.0 at Phase 1, you can specify Seeing = 1.2 at Phase 2, but not Seeing = 0.8;
  • if you requested Transparency = CLR at Phase 1, you can specify THN or THK at Phase 2, but not PHO.

The only exception to this is the case in which only a small subset of OBs need to be obtained under photometric conditions in order to provide an accurate flux calibration, such as for instance a deep field in which a network of bright flux reference objects can be set up from a shallow exposure. Such exceptions are accepted only if accurate flux calibration is needed for the scientific goals of the programme, and for an execution time not exceeding 20% of the total allocated time.

Also check the Service Mode guidelines on observing constraints.

Correspondence between Phase 1 and Phase 2 constraints:

  • If you specified Seeing = 'n' at Phase 1, you must specify Seeing = 2.0 or greater at Phase 2 (1.4 for NACO).
  • If you specified Lunar Phase = 'd' at Phase 1, you must specify FLI < 0.4 at Phase 2.
  • If you specified Lunar Phase = 'g' at Phase 1, you must specify 0.4 ≤ FLI ≤ 0.7 and Moon Angular Distance = 120 or less at Phase 2.
  • If you specified Lunar Phase = 'n' at Phase 1, you must specify FLI = 1.0 and Moon Angular Distance = 60 or less at Phase 2. Exceptions to this statement are applicable for infrared observations. If this is the case for your observations, please refer to the instrument-specific service mode rules for observing constraints for full details.

Note that FLI = 0.0 is interpreted as "moon below the horizon".


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