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WFMOS as a Bridge to the Future for Gemini & Subaru Doug Simons Director, Gemini Observatory Three Presentations – One Message… WFMOS in the Aspen Context Gemini Fundamentals Gemini Design Collaborations – Overarching Considerations WFMOS – Current Status & Next Steps WFMOS Negotiations

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wfmos as a bridge to the future for gemini subaru

WFMOS as a Bridge to the Future for Gemini & Subaru

Doug Simons

Director, Gemini Observatory

three presentations one message
Three Presentations – One Message…

WFMOS in the Aspen Context

Gemini Fundamentals

Gemini Design

Collaborations – Overarching Considerations

WFMOS – Current Status & Next Steps

WFMOS Negotiations

Gemini/Subaru Science & Instrumentation

Kentaro Motohara

Chris Packham

two telescopes one observatory


Cerro Pachon, Chile


Mauna Kea, Hawaii

Two Telescopes - One Observatory
  • To our community, Gemini appears and functions as a single observatory - the only major ground based observatory that is capable of targeting any object in the sky
gemini observatory management structure

Gemini Board

NSF, STFC, NRC, etc.

Executive Agency






Gemini Observatory Management Structure
  • The Gemini Director has many bosses, some real, others virtual, all important…
    • Requires careful attention, clear communication, and regular interaction with many key stakeholders
    • Gemini Board has ultimate authority
    • AURA provides the business and legal framework within which Gemini functions
current status












Mauna Kea

Cerro Pachon

Current Status

Baseline Modes Commissioned

Instrument Under Development

aspen instrument program








Aspen Instrument Program










aspen instrument program9




  • Conceptual design studies completed successfully
  • Instrument procurement canceled due to lack of funding and higher priority given to WFMOS
  • High performance coronagraph
    • ~107 contrast ratio
  • Being built by a number of institutions – led by LLNL
  • Scheduled for deployment at Gemini-South in 2011





Aspen Instrument Program

  • AAO and JPL are now completing competitive design studies for WFMOS
  • Conceptual design studies will be reviewed Feb. 09
  • Gemini Board decision regarding proceeding with WFMOS - May 09






  • UH completed site testing in 2008
  • Results indicate that a GLAO system at Gemini-N would be powerful
  • Decision to proceed with GLAO 2010?





ir optimized telescope design

IR Optimized Design

  • f/16 secondary
    • tip/tilt
    • chopping
  • Telescope structure
    • Designed to reduce thermal inertia
  • Relies on active optics that are always “on”

Primary mirror rests above elevation

axis to increase wind flushing & Cassegrain payload

IR Optimized Telescope Design
ir optimized telescope design11
IR Optimized Telescope Design

4-Layer Protected Silver Coatings

~3% total emissivity

ir optimized telescope design12
IR Optimized Telescope Design
  • Reduced cross-section secondary mirror supports designed to minimize diffracted light in PSF

Typical strehl achieved is

60-75% @ 10 m

ir optimized telescope design13
IR Optimized Telescope Design
  • However, the same design features which allow Gemini to excel as an infrared optimized telescope make it difficult to support prime focus instruments (like WFMOS…)
some overarching considerations
Some Overarching Considerations…
  • There is an inevitable trend in science toward international collaboration and Gemini and Subaru are uniquely poised to lead the way among 8-10 m class facilities worldwide
  • Subaru and Gemini each have unique capabilities that would help the “other” community
    • Subaru – world class wide field instrumentation (optical and NIR)…
    • Gemini – IR optimization, all-sky access; fast response modes…
some overarching considerations16
Some Overarching Considerations…
  • In general scientific collaborations should be –
    • Mutually beneficial
    • Founded on fair and equitable terms
    • Designed to provide partners with research opportunities that they would not otherwise have
    • Take advantage of natural synergies
    • Tailored to avoid costly capability duplication between observatories
some overarching considerations17
Some Overarching Considerations…
  • In many ways the WFMOS initiative is just a catalyst for fostering a scientific collaboration between the Subaru and Gemini communities
  • If we do not proceed with WFMOS, for any reason, I urge that we continue to nurture future scientific collaboration based on other capabilities unique to Subaru and Gemini
wfmos negotiations
WFMOS Negotiations
  • Discussion topics to date have included –
    • Duration of agreement
    • Cost sharing
    • Time exchange parameters
    • Commissioning and maintenance considerations
    • Other related issues…
  • Motohara-san will summarize negotiations in more detail in the next presentation

Nov. 2008

Dec. 2008

Oct. 2008

wfmos baseline design guidelines
WFMOS Baseline Design Guidelines
  • Wavelength Range: 0.39 – 1.0 µm
  • Field of View: ~1.5 deg diameter
  • Spatial Sampling: ~1 arcsec fiber entrance
  • Spectral Resolution: R~1800 – 3500 (~3000 fibers) and R~40,000 (~1500 fibers)
  • One-shot wavelength coverage: ~0.39 to 1.0 µm (low resolution spectrographs), >100 Å (high resolution spectrographs)
  • Simultaneous stellar targets: ~4500
  • Detector operating modes: standard readout or “nod & shuffle” as required to achieve the science goals.
wfmos trade studies
WFMOS Trade Studies
  • WFMOS teams will include in their proposals a number of trades studies to determine the optimal WFMOS design/cost needed to support the science goals of the instrument
  • Trades can include many things including -
    • Acquisition field size
    • Vignetting
    • Multiplex gains
    • Total survey time
    • Fiber manipulation schemes
    • Manufacturing risks for key components
    • Science impact of cost-saving reductions in the baseline WFMOS capabilities
two wfmosconceptual design study teams
JPL Team

PI Richard Ellis


Penn State


Cambridge IofA

U. College London

LNA Brazil

AAO Team

PI Sam Barden


U. Oxford/RAL

U. Portsmouth

U. Durham

Johns Hopkins U.


Two WFMOSConceptual Design Study Teams

Two competitive conceptual design studies are being performed by large, international teams. They will be completed in Feb. 2009

wfmos decision process
WFMOS Decision Process
  • After the WFMOS Conceptual Design Review (Feb. 22-23) a number of discussions will be held leading to a May Gemini Board meeting decision about proceeding with WFMOS
    • Gemini and Subaru will consider the review committee report jointly before a recommendation is made to Gemini Board
    • Subaru and Gemini SAC’s will consider science implications of any significant design changes in WFMOS
    • Draft Subaru/Gemini agreement will be negotiated and submitted for consideration by Gemini Board and NAOJ
possible concerns
Possible Concerns
  • Number of fibers in WFMOS
    • The design will include a complex trade between fiber number, throughput, field of view, etc.
    • Together these design parameters determine the amount of telescope time needed to complete a survey and the amount of telescope time needed will not be allowed to be prohibitive as design/cost options are weighed
possible concerns25
Possible Concerns
  • Delay in delivery
    • Historically Gemini instruments have been delivered 1-2 years late
      • Typical of other observatories
      • NIFS (2) and GSAOI were Gemini’s best performers, bHROS and FLAMINGOS-2 our worst
    • It is in the strategic interests of everyone to ensure that WFMOS is deployed on schedule
    • If approved, Gemini will increase the size of its development group to help oversee the timely delivery of WFMOS
    • Gemini and Subaru will interact regularly throughout the development period of the instrument to ensure design trades meet everyone’s needs
possible concerns26
Possible Concerns
  • Funding challenges
    • The global economic crisis is effecting essentially all segments of society and astronomy is no different
    • Gemini funding for WFMOS remains uncertain
      • The US funding situation in particular should be clarified in the next ~2-3 months
      • Funding for Gemini’s operations will be given higher priority than its development program
gemini commitment to wfmos
Gemini Commitment to WFMOS
  • Today, 5 years after the Aspen Workshop, WFMOS remains the highest priority instrument in Gemini’s development program with strong support from the –
    • Gemini Science Committee
    • Gemini Board of Directors
    • Gemini Community
  • Both personally and on behalf of Gemini Observatory, I thank you for the opportunity to share these perspectives on Gemini, WFMOS, and hopefully a long lasting scientific partnership between our observatories