Preparing for operations with the European Extremely Large Telescope Fernando Comerón

The E-ELT A 42-m segmented mirror telescope for observations from the blue to the thermal infrared Fully steerable Location still to be decided Aiming for a complement of instruments covering a large parameter space 5-mirror anastigmatic configuration (astigmatism, coma and spherical aberration corrected over a large FoV) Versatile configuration: two Nasmyth foci, two gravity invariant foci, a coude focus The European Extremely Large Telescope being projected by ESO is Europe’s proposal for the next generation of giant optical telescopes expected to operate by the end of the next decade

An adaptive telescope The E-ELT is designed as an adaptive telescope, with a deformable M4 and a tip-tilt M5. Ground-layer AO (GLAO) correction provided by the telescope (3 Natural + 4 Laser Guide Stars) Multi-Conjugate AO (MCAO) or Laser Tomography AO (LTAO) provided by post-focal AO modules Multi-Object AO (MOAO) and Extreme AO (XAO) integrated in some of the proposed instruments

Instrumentation currently under study Eight instruments are currently undergoing Phase A study: EAGLE, multi-IFU NIR spectrograph with MOAO CODEX, high resolution, ultrastable visual spectrograph using GLAO or seeing-limited MICADO, NIR camera using MCAO EPICS, high-contrast imager and spectrograph with XAO HARMONI, single-field, wide-band spectrograph, using GLAO, posibly MCAO/LTAO METIS, mid-infrared imager and spectrograph, using GLAO, possibly LTAO OPTIMOS, wide-field visual multi-object spectrograph, using GLAO, possibly MCAO SIMPLE, high-resolution NIR spectrograph, using GLAO, possibly LTAO Even if only a few are built, this promises variety in wavelengths, techniques, AO modes…

Current status E-ELT project currently undergoing Phase B development Baseline reference design v2.0 prepared in March 2008, v3.0 expected by end of 2008 Phase B budget 57.2 MEur, plus 6.1 MEur in FP7-funded project “Preparing for construction of the E-ELT” Proposal for construction planned for mid 2010 Completion foreseen in 2017

Requirements from the community A multi-purpose facility…  Wide variety of science cases  Reflected in instrumentation studies  Serving a broad community  Offered under conditions similar to other current facilities  No expectation to be executing a single program exclusively for extended periods of time  “Easy” to use, based on known operations principles: “One more telescope” …operating at the limits  Extremely demanding cases in terms of telescope and instrument performance  Operations must ensure that requirements are properly captured, strategies can be implemented, and observation execution can proceed accordingly

Operational requirements on the telescope Several programmes may be executed on any given night Several instruments may be used on any given night, possibly using several AO modes Ability to react to short-time changes in the conditions Best served by extensive use of Service Mode, taking as a base the VLT model Basic requirements on telescope and instruments  Fully steerable  Quick preset time, matched by the dome  Short time needed to switch between instruments  Fast setup of telescope AO  Fast setup of post-focal AO Guaranteed by Basic Reference Design and Top Level Requirements

Dealing with many instruments E-ELT instruments are in principle interchangeable (lifted to Nasmyth platforms, brought to the adapter on carriages on rails) But not on short notice: instrument exchanges must be planned at least days in advance, no use for adapting to changing conditions However, up to ~7 instruments simultaneously mounted still offer lots of flexibility (will more be built?)

Operational requirements on instruments availability Operational efficiency requires a sufficient number of instruments in stand-by at any given time: 1) Guaranteeing suitable scientific exploitation of any atmosphere conditions Coverage of a wide range of parameters (and AO modes) and fast switch- over times 2)Guaranteeing the scientific exploitation of the best conditions. This implies permanent availability of instruments demanding the best conditions (e.g. XAO instrument) 3) No downtime regardless of conditions Virtually ensured by the availability of a large number of focal stations and multi-instrument adapters If instruments need to be exchanged, long-term operations planning will be needed to ensure that all instruments receive the share of time needed (parallel with current situation UT vs. VLTI), determining the planning for transportation of instruments to/from the Nasmyth platforms

Scheduling and AO modes The choice of the most suitable programs will be more complex (and will need more aids) than at the VLT “Given the current turbulence profile (and its evolution over the next hours!), what is the right AO mode to use?” Statistical expectations on the turbulence profile (not just seeing statistics) should become an input of the long- term scheduling

Observing modes Proper exploitation of AO modes requires flexibility in short-term scheduling: rationale for most (all?) available time to be scheduled in service mode. Rationale for programmes in which real-time decisions are needed must be established: Will some programmes require real-time decisions? Will Visitor Mode be justified? Flexibility is required, even in programmes requiring real-time decisions: Possibility to implement hybrid modes combining flexible scheduling with real-time reaction capabilities: for instance, several remotely located observers on-call Effectiveness of flexible remote observing strongly depends on weather forecasting capabilities on a timescale of hours

Tool requirements Scientific performance assessment will need realistic simulation tools with which the user must be able to predict the system output as a function of atmosphere parameters –and specify the relevant constraints Observation preparation tools will need to provide all relevant constraints under which a given observation can be carried out. Observation selection and scheduling tools will need to incorporate atmosphere turbulence assessment and forecast capabilities, relevant to each AO mode.

Ramping up Most E-ELT operations concepts and tools can be developed and tested at the VLT (e.g. “P100 project”) This includes incorporation of atmosphere forecasting tools Planning for E-ELT operations is not about “How would we operate the E-ELT if we had it today?”, but “How will be operate a major ground-based optical facility in ten years from now?”

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