Maximizing GSMT Science Return
This presentation is the property of its rightful owner.
Sponsored Links
1 / 30

Maximizing GSMT Science Return with Scientific Figures of Merit PowerPoint PPT Presentation


  • 87 Views
  • Uploaded on
  • Presentation posted in: General

Maximizing GSMT Science Return with Scientific Figures of Merit. Maximizing value. Who are the interested parties? Scientist users Funding agencies What constitutes value to them? Scientific return Cost What gives greatest value? MAXIMUM SCIENTIFIC RETURN FOR COST. Quantifying value.

Download Presentation

Maximizing GSMT Science Return with Scientific Figures of Merit

An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -

Presentation Transcript


Maximizing gsmt science return with scientific figures of merit

Maximizing GSMT Science Return

with

Scientific Figures of Merit


Maximizing value

Maximizing value

  • Who are the interested parties?

    • Scientist users

    • Funding agencies

  • What constitutes value to them?

    • Scientific return

    • Cost

  • What gives greatest value?

    MAXIMUM SCIENTIFIC RETURN FOR COST


Quantifying value

Quantifying value

Components of value

  • Performance

    • Requirements

    • Goals

  • Cost

    • Build

    • Operations

  • Schedule

    • First light

    • Operating life

R

I

S

K

$$$

Science


Science merit function

Science merit function

Science merit function =  ( Wi x FOMi )

  • Figure of Merit (FOM)

    • For each capability, embodied as instrument + telescope

    • Quantitative, with analytical and numerical components

    • Function of instrument and telescope properties

  • Weight (W)

    • Scientific judgment call


Example 1 gsmt spectroscopic capability

Example 1. GSMT spectroscopic capability


Example 2 celt ir ao system emissivity

Example 2: CELT IR AO system emissivity

  • Cryogenic AO system at prime focus

    • Ultimate performance for emissivity

    • Negative impacts on telescope design, enclosure cost

  • Cryogenic AO system at Nasmyth focus

    • Quantifiably almost as good

    • Expect lower total observatory cost

  • Warm AO system at Nasmyth focus

    • Dramatically reduced performance

    • Low cost, maintains spatial resolution advantage

    • Trades against space platform sensitivity advantage


  • What is the science mission

    What is the science mission?

    Type of mission impacts FOM, weights

    • Design reference mission

      • Total science program specified

    • Timely science mission

      • Maximize science achieved in initial period

    • Scientific capability mission

      • Instrument capabilities for wide range of potential science


    Example ukirt wfcam program

    Example: UKIRT WFCAM program

    • WFCAM: widefield 1-2 m camera on 3.8 m telescope

    • Several large scale surveys over ~10 years (DRM)

    • Quick shallow surveys first (STM)

    • Selected deep fields done repeatedly (STM + DRM)

    • Instrument permits installation of custom filters (SCM)

      http://www.ukidss.org


    Gsmt sample imaging capabilities

    GSMT sample imaging capabilities

    • Enhanced seeing widefield imager

      • Gaussian profile

      • Tens of arcmin FOV

    • Narrow field coronagraph

      • Highest possible Strehl and dynamic range

      • FOV is arcseconds

    • Moderate field, diffraction limited imaging

      • Moderate Strehl over arcminute FOV


    Imaging fom inputs telescope

    Imaging FOM inputs: telescope

    • D, primary mirror diameter

    • TPtel (  ), throughput

    •  ( , , t ),delivered image quality

    • S ( , , t ) , Strehl ratio

    •  (  ) , emissivity

    • Etel , operating efficiency


    Imaging fom inputs instrument

    Imaging FOM inputs: instrument

    • TPinstrl (  ), throughput

    • DQE(  ), detector quantum efficiency

    •  ,pixel sampling

    • , , wavelength coverage and resolution

    • R, D, read noise and dark current

    • Sc, scattered light susceptibility

    • Etel , system efficiency


    Imaging fom inputs multiplex advantages

    Imaging FOM inputs: multiplex advantages

    • , total solid angle field of view

    • n, number of simultaneous spectral channels


    Imaging fom inputs other science value factors

    Imaging FOM inputs: other science value factors

    • Timeliness

      • First light

      • Other facilities

      • Competition

    • Access

      • To facility

      • To data


    Enhanced native seeing imager

    Enhanced native seeing imager

    • Science

      • Distribution of high redshift galaxies

      • Integrated properties of galaxies

    • Programmatic

      • Use at wavelengths where diffraction limit can’t be achieved

      • Use in less favorable conditions, e.g. thin cirrus

    • Implications for FOM

      • Slightly extended sources with some central concentration

      • Wavelength coverage is   1 m


    Enhanced native seeing imager1

    Enhanced native seeing imager

    Background limited, uncrowded field case

    Neglect

    • Emissivity

    • Strehl ratio

    • Read noise, dark current

    • Scattered light

    • Programmatic terms

      Gather terms into a Figure of Merit for (integration time)-1


    Enhanced native seeing imager2

    Enhanced native seeing imager

    Background limited, uncrowded field FOM

    1/time  [ (D2/2) • TPtel () • Etel] •

    [ • DQE • TPtinstr() • Etinstr • f(/) • f(n) • f(, ) ]

    • Track telescope, instrument separately

    • Some factors require simulations to determine appropriate formulations

    • Some factors may include weighting functions

    • Telescope

    • Instrument


    Formulation of image quality

    Formulation of image quality 

    Poor conditions

    1.0

    arcsec

    Good conditions

    0.5

    0

    10

    20

    , arcminutes

    Delivered image quality vs field angle and conditions


    Optimizing

    Optimizing /

    photometry

    Time 

    detection

    1

    2

    3

    4

    /

    /


    Weighting function for

    Weighting function for 

    1

    weight

    0

    0

    20

    , arcminutes

    Tel, atmos rolloffs

    MCAO regime


    Enhanced native seeing imager trades

    Enhanced native seeing imager trades

    Some performance (and cost) trades:

    • D, 

    • , 

    • TPtel () (coatings)

    • n (instrument complexity)

    •  (optics complexity, coatings choices)


    Narrow field coronagraphic imager

    Narrow field coronagraphic imager

    • Science

      • Discovery and characterization of planetary systems

    • Programmatic

      • Diffraction limited, very high Strehl at first light

      • Use in best seeing conditions

    • Implications for FOM

      • Wavelength coverage is 1    5 m

      • Treatment of systematic effects important

      • Independent of telescope design, AO implementation details


    Coronagraphic imager fom additional inputs

    Coronagraphic imager FOM additional inputs

    • d, subaperture size of primary

    • n, number of actuators on deformable mirror

    • , residual wavefront rms error

    • , speckle lifetime (site characteristic)

    • g, gain, ratio of peak intensity to halo level

    • R, amplitude reduction of primary core and halo by coronagraph


    Coronagraphic imager fom

    Coronagraphic imager FOM

    Comparison with enhanced seeing imager:

    • Neglect traditional seeing measure 

    • Include Strehl ratio S, emissivity 

    • Use additional terms to describe AO, coronagraph impacts


    Coronagraphic imager sensitivity fom

    Coronagraphic imager sensitivity FOM

    FOM for sensitivity (SNR):

    sensitivity  [ D2• TP• E •  • DQE• -1 •f(/) • f(n) • f(, ) ]½

    • [ S / (1-S) ] • [ D / d ]2 • [ 1/R ]

    • Includes “traditional” components, Strehl and gain advantages

    • Not yet in right units!

    • How to account for systematic effects?


    Coronagraphic imager systematics

    Coronagraphic imager systematics

    SNR limited by speckle structure in uncorrected halo

    • Pointlike

    • 100% amplitude modulation

    • Persist for time 

      Variety of solutions

    • Decorrelation (large n, kHz AO update rate)

    • Simultaneous differential imaging (NICI)

    • PSF engineering, e.g. speckle sweeping

    • Data taking and reduction methods


    Coronagraphic imager final fom

    Coronagraphic imager final FOM

    • Characterize time – SNR relation by parameter 

    •  = 2 for photon noise limited system, less if residual systematic errors are significant

      1/time  ( previous expression ) 


    Narrow field coronagraphic imager trades

    Narrow field coronagraphic imager trades

    • Mirror segment size d

    • Speckle lifetime  (site characteristics)

    • Emissivity  and Strehl ratio S

    •  error budget allocations

    •  /  with 

    • Suppression of systematic error


    Wide field narrow field comparisons

    Wide field – narrow field comparisons


    Maximizing value redux

    Maximizing value, redux

    Return to performance, cost, schedule, risk mix:

    Is there a similar approach to maximizing value?

    Performance-cost index

    PCI = Science merit function / total cost (capital + ops)

    How to do optimization?


    Maximizing value redux1

    Maximizing value, redux

    • Evaluate a few plausible approaches

      • Telescope type

      • Instruments

    • Trade studies for key parameters

      • Effect on SMF

      • Effect on cost

    • Creative tension between Scientist, Engineer, and Manager


  • Login