Preparing for operations with the European Extremely Large Telescope Fernando Comerón.

Preparing for operations withthe 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 conditionsCoverage 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 conditionsVirtually 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?”

ESO 1968-2018:50 years operating leading observatories