Ground-based Observatories - Instrumentation and Detector

Systems

Doug Simons (Gemini Observatory)

Paola Amico (Keck Observatory)

Scientific Detector Workshop - 2005Photo Courtesy Akihiko Miyashita, Subaru Telescope

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Coauthor ListCoauthor ListDietrich Baade, European Southern Observatory

Sam Barden, Anglo Australian ObservatoryRandall Campbell,W.M. Keck Observatory

Gert Finger, European Southern ObservatoryKirk Gilmore, Stanford/SLAC

Roland Gredel, Calar Alto ObservatoryPaul Hickson, University of British Colombia

Steve Howell, National Optical Astronomy ObservatoryNorbert Hubin, European Southern Observatory

Andreas Kaufer, European Southern ObservatoryRalk Kohley, GranTeCan/ Instituto de Astrofisica de Canarias

Philip MacQueen, University of TexasSergej Markelov, Russian Academy of Sciences

Mike Merrill, National Optical Astronomy ObservatorySatoshi Miyazaki, Subaru TelescopeHidehiko Nakaya, Subaru Telescope

Darragh O'Donoghue, South African Astronimical ObservatoryTino Oliva, INAF/ Telescopio Nazionale Galileo

Andrea Richichi, European Southern ObservatoryDerrick Salmon,Canada France Hawaii Telescope

Ricardo Schmidt, National Optical Astronomy ObservatoryHomgjun Su, National Astronomical Observatory of China

Simon Tulloch, ISAAC Newton Group/ Instituto de Astrofisica de CanariasMark Wagner, Large Binocular Telescope

Olivier Wiecha, Lowell ObservatoryBinxun Ye, National Astronomical Observatory of China

PosterOral

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A World-wide Sample of A World-wide Sample of InstrumentsInstruments

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SummarySummary

Survey conducted world-wide to develop a “snap shot” of instrumentation used today and planned for tomorrow

Intent is to use this database to Explore “where we are” now in astronomy Extrapolate to the future Help bridge gap between astronomical

community and manufacturers about what types of detectors are needed

Not intended to be a detailed description of any institution’s instruments No single observatory is large enough to

“dominate” the database

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Survey DetailsSurvey Details Instrument name Observing Modes Start of operations Wavelength Coverage Field of View Instrument cost Multiplex gain Spatial [“]/Spectral

resolution # Detectors Detector Format Detector size

Buttability Pixel size Pixel scale Electronics Noise Readout Time Dark Current Full well Cost per pixel Comments or

additional parameters

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Survey DetailsSurvey Details

25 institutions polled as part of a world-wide survey of ground-based instrumentation Compiled instrumentation database for

telescopes with 3.5 m aperture

Compiled data on ~200 instruments through this survey Enough to probe various trends in

instrumentation and the detector systems in use today at major astronomy facilities, worldwide

Detailed results will be published via the Proceedings of this conference

Represents a unique source of information about instrumentation in astronomy, both existing and planned

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Wavelength Wavelength CoverageCoverage

The “great divide” between optical and infrared is obvious

Basically a bimodal distribution, separated at 1 µm

This divide is artificial - it’s technology driven, not science driven

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Currently astronomy is pretty heavily dominated by optical instruments, with ~2 out of 3 instruments using CCDs

Optical, Near-Infrared, or Mid-Optical, Near-Infrared, or Mid-Infrared?Infrared?

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MIR NIR OPT

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The next-generation of instruments will consist of nearly equal numbers of optical and NIR instruments

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In both cases MIR instruments occupy a very small part of the “market” This is due to many reasons

includingA relatively small MIR

communityA historically specialized field

technically to get intoThe need for special

telescope systems (chopping), etc.

The lack of MIR instruments reflects a relatively “untapped” science frontier, not lack of scientific importance

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Optical, Near-Infrared, or Mid-Optical, Near-Infrared, or Mid-Infrared?Infrared?

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MIR NIR OPT

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Spectrometers remain the most popular type of instrument in astronomy (~60%), with imagers a distant second (~25%) Most spectrometers also have

an imaging mode, at least to support a target acquisition mode, so imaging systems are important

Among the spectrometers built, not surprisingly the most popular type remains the “simple” long slit spectrometer An equal number of MOS and

IFU based systems are either built or planned

Given the large multiplex gain of these systems, MOS and IFU spectrometers tend to require the largest focal planes

What Modes are Most What Modes are Most Commonly Used?Commonly Used?

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Imager Spectrometer Other

Primary Instrument Modes

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MOS IFU Long Slit

Spectrometer in Use

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Top histogram shows dominant manufacturers used in various instruments Effectively assumes 1

detector per instrument “Others” are in many cases

are one-off devices in specialized instruments which together account for ~20% of all instruments

Bottom plot tallies all detectors sampled in survey so is a true “head count” of detectors in use

Current Market Share by Current Market Share by Various ManufacturersVarious Manufacturers

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Regardless of how market share is assessed, E2V detectors are the most commonly used in ground-based astronomy Nearly half of all science

detectors in instruments sampled are made by E2V

Linked to previous plots demonstrating popularity of optical instruments in astronomy

Large CCD mosaics that have been built no doubt enable E2V market share compared to NIR manufacturers, where comparably large mosaics have not been built

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Current Market Share by Current Market Share by Various ManufacturersVarious Manufacturers

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Most instruments use (surprisingly) small pixels, most at ~0.1” Lack of >1” pixels is

probably due to not sampling small telescopes which often have large fields

Plate Scale and Field of Plate Scale and Field of ViewView

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Plate Scale (arcsec/pixel)

Clearly a “sweet spot” in field size of instruments for fields in the 10-100 arcmin2 range

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Extremely small fields are pretty much exclusively domain of AO

Can’t correct over large fields

Extremely large fields on the right are mainly due to future ultra wide field instruments involving enormous CCD focal planes

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NIR instruments have pretty much locked into 18-27 µm pixel format

The the future, pixels of this size will remain popular

Likewise MIR instruments have adopted pixels 2-3 times bigger, consistent with larger point spread function at these longer wavelengths

Shifting to considerably smaller pixels to reach larger array formats may pose problems for optical designs of infrared instruments Drives builders to faster optical

systems and reduced tolerances which may be non-trivial to achieve in cryogenic instruments

Typical Infrared Pixel Size Now Typical Infrared Pixel Size Now and Tomorrow…and Tomorrow…

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Pixel Size (µm)

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Similarly, current and future optical instruments have pretty much “standardized” on 13-15 µm pixels 86% of current

instruments use 13-15 µm pixels

In all cases 15 um is the most often used, with

73% of future instruments sampled will use 13-15 um pixels

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Pixel Size (µm)

Typical CCD Pixel Size Now and Typical CCD Pixel Size Now and Tomorrow…Tomorrow…

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1024x1024 is the “standard” format used in NIR arrays today 2048x2048x devices likely

have not been around long enough to become well established, with only ~15% of the market share

In the future, the community clearly wants to switch to larger format device, with 75% of the future instruments sampled going with 2k NIR arrays

Again, astronomers will take advantage of larger format IR detectors, when they become available

Typical Infrared Array Format, Typical Infrared Array Format, Now and Tomorrow…Now and Tomorrow…

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2x4k building block is, not surprisingly, by far the most popular current CCD format

Future planned instruments will baseline 4x4k detectors as much as the more established 2x4k detectors 77% of future instruments

expect to use either 2x4k or 4x4k CCDs

Clearly astronomers are eager to use ever larger CCDs…

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Typical CCD Format, Now and Typical CCD Format, Now and Tomorrow…Tomorrow…

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Total Pixel “Inventory”, Now Total Pixel “Inventory”, Now and Tomorrow…and Tomorrow…

Total of ~1.9 Gpixels found in current instruments sampled by this survey Essentially all IR focal

planes are <10 Mpixel Most optical focal

planes are also <10 Mpixel, though some are much larger

Have merged NIR+MIR into “Infrared”

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OpticalInfrared

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Total Pixel “Inventory”, Now Total Pixel “Inventory”, Now and Tomorrow…and Tomorrow…

The future looks similar in the infrared with most instruments having modest size focal planes

The future at optical wavelengths include a lot more large focal planes

The future market includes ~7.7Gpixels of science grade detectors, >90% of which is in the form of CCDs in the future “More” category (>100 Mpixel focal planes)

Note that lack of planned IR large format focal planes isn’t due to lack of ambition on the part of IR astronomers - it’s due to lack of money…

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OpticalInfrared

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Includes all instruments (current and future) in survey

SDSU clearly the most commonly used controller in astronomy, with ~1 in 4 controllers being an SDSU system

Huge range in controllers being used - total of 44 different controllers identified in survey

This is an area where we would all benefit from an “industry standard” Closest thing we have is

SDSU

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Instrument CostsInstrument Costs

Most participants in the survey did not include a cost and, in general, it is difficult to make a detailed “apples to apples” comparisons due to various assumptions Does cost include labor, overhead, all parts, etc?

Instead, have only assessed median costs of current and future instruments to look for basic trends

Optical Infrared

Current$400,000

$3,750,000

Future$6,600,000

$5,000,000

Median Instrument Cost Summary

Future Trends in Future Trends in Science and Science and Technology…Technology…

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““Cosmic Convergence”Cosmic Convergence”

Tracing the physical origin, evolution, and large scale structure of matter and energy, from the Big Bang, to present, remains one of highest priority research areas in all of science

Many organizations are working in this field in a global effort to unravel the most fundamental aspects of the universe

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Key Epochs in the Early Key Epochs in the Early UniverseUniverse

Reionization in the Early Universe

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Photons from this scattering surface are what we now see as the Cosmic Microwave Background (CMB)

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““First Light” in a Dark First Light” in a Dark UniverseUniverse

Simulation of an Ultra Deep NIR Image of the First Stars

Using current and/or next-gen telescopes, we will, for the first time, detect the first luminous objects in the universe – the “First Light”

The discovery and analysis of the first stars is arguably one of the “holy grails” in astronomy

The light from these distant objects is red shifted to 1-2 µm, hence the need for large format, low noise, NIR detectors in the future

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Boundaries on Research Boundaries on Research FrontiersFrontiers

Astronomy is fundamentally a technology driven and limited field of science and detectors always have and always will play a central role in what we can learn about the universe

As an example…

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The Galactic Center: Discovery The Galactic Center: Discovery Strip ChartStrip Chart

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The Galactic Center: Becklin & The Galactic Center: Becklin & Neugebauer 1975Neugebauer 1975

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The Galactic Center: Forrest et The Galactic Center: Forrest et al. 1986al. 1986

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The Galactic Center: Rigaut et The Galactic Center: Rigaut et al. 1997al. 1997

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The Galactic Center: Recent ESO The Galactic Center: Recent ESO ResultsResults

Zeroing in on a Massive Black Hole…

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The 25 Year “Evolution” of the The 25 Year “Evolution” of the Galactic Center...Galactic Center...

Our basic understanding of key areas in astronomy is clearly a function of current technology

What took us perhaps 25 years to achieve before, may only take ~10 years with the rapid acceleration of technology available to astronomers

Advancements in science detectors have made this all possible…

25 y

rs

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Boundaries on Research Boundaries on Research FrontiersFrontiers

ELT’s and the next generation of ultra wide field instruments are examples of next-generation ground-based facilities that will revolutionize our understanding of the universe

The years ahead in astronomy will include explorations of very large and very small structures

In either case, large scale, high performance, affordable optical and infrared science detectors will be necessary

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The Future is Both Large The Future is Both Large and Smalland Small

The next generation of ELT’s will provide unprecedented “views” of the universe

Given the extreme apertures of these telescopes, when coupled with AO systems that allow ELT’s to work at their diffraction limits, they will yield data with spatial resolutions far greater than what is possible with the current generation of 8-10 m telescopes

TMT

OWL

The ELT’s Windowon the Universe...

~1”

~1”

Target: Galactic Cores

Objective: Detect signaturesof black holes in compactgalactic nuclei

Target: Io

Objective: Remote seismicmonitoring & planetarymineralogy

Target: Forming Planetary Systems

Objective: Measure SED offorming stars, planets & surrounding gas, binary fractions, disk evolution,Dust & gas dynamics, MF, etc.

Target: First Stars

Objective: Morphology, spectra, and luminosity of first luminous objects in the universe

Target: -ray bursters

Objective: Identify andmeasure distance & SEDof hosts; detect the “first” GRBs in the universe

Target: Extra-solar planets

Objective: Direct imaging and spectroscopy of planetary systems beyond our own

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Future Wide Field Future Wide Field FacilitiesFacilities

LAMOST ProjectThe Large Sky Area Multi-Object

Fiber Spectroscopic Telescope

Pan-STARRS

LSST

Hyper-SUPRIME + WFMOS

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Future ResearchFuture Research

These facilities will be used to perform enormous surveys to answer major questions in astronomy and fundamental physics, of interest to all of humanity

Galaxy Genesis

Dark Matter

Dark Energy

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The Destiny of the The Destiny of the UniverseUniverse

Matter/Gravity Overcome theInitial Expansion from the Big Bang

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The Destiny of the The Destiny of the UniverseUniverse

Universe “Coasts” Outward, with Matter/GravityIn Approximate Equilibrium with Big Bang Expansion

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The Destiny of the The Destiny of the UniverseUniverse

Expansion of the Universe Accelerates, UltimatelyShredding Its Material Contents

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The Destiny of the The Destiny of the UniverseUniverse

Expansion of the Universe Accelerates, UltimatelyShredding Its Material Contents

With the discovery of Dark Energythis now appears to be possible.

Next-generation detectors willplay a key role in solving this mystery

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Summary ThoughtsSummary Thoughts

Detectors in 180 instruments in use today have been surveyed to perform a “bottom-up” assessment of detector systems in use now or planned in the near future in astronomyOptical detectors currently dominate those used in

ground-based astronomy, and will remain the most commonly used detector throughout the next ~decade

Planned future instruments will need Gpixel class optical focal planes and many are migrating to 40962 format

Most infrared detectors used now have a 10242 format, but many instrument builders are migrating to the buttable 20482 format detectors now available

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Summary ThoughtsSummary Thoughts A “top-down” approach is used to forecast the

future in ground based astronomy (~5-15 years) ELTs: Large infrared focal planes will be needed to

sample diffraction limited fields of enormous telescopes of the future

Wide Field Facilities: Large optical focal planes will be used to survey millions of stars and galaxies at modest to high spectral resolution

Cosmology: Frontier science is being red shifted to the near-infrared as telescopes get larger, which will drive NIR detectors to have low noise and low dark current in often “photon starved” applications

The science horizon in astronomy is exciting and compelling, but our discoveries will only be as remarkable as the science detectors we use to explore the universe