Ground-based Observatories - Instrumentation and Detector Systems

1. Ground-based Observatories - Instrumentation and Detector Systems Doug Simons (Gemini Observatory) Paola Amico (Keck Observatory) Scientific Detector Workshop - 2005 Photo Courtesy Akihiko Miyashita, Subaru Telescope

2. Coauthor List Dietrich Baade, European Southern Observatory Sam Barden, Anglo Australian Observatory Randall Campbell,W.M. Keck Observatory Gert Finger, European Southern Observatory Kirk Gilmore, Stanford/SLAC Roland Gredel, Calar Alto Observatory Paul Hickson, University of British Colombia Steve Howell, National Optical Astronomy Observatory Norbert Hubin, European Southern Observatory Andreas Kaufer, European Southern Observatory Ralk Kohley, GranTeCan/ Instituto de Astrofisica de Canarias Philip MacQueen, University of Texas Sergej Markelov, Russian Academy of Sciences Mike Merrill, National Optical Astronomy Observatory Satoshi Miyazaki, Subaru Telescope Hidehiko Nakaya, Subaru Telescope Darragh O'Donoghue, South African Astronimical Observatory Tino Oliva, INAF/ Telescopio Nazionale Galileo Andrea Richichi, European Southern Observatory Derrick Salmon,Canada France Hawaii Telescope Ricardo Schmidt, National Optical Astronomy Observatory Homgjun Su, National Astronomical Observatory of China Simon Tulloch, ISAAC Newton Group/ Instituto de Astrofisica de Canarias Mark Wagner, Large Binocular Telescope Olivier Wiecha, Lowell Observatory Binxun Ye, National Astronomical Observatory of China Poster Oral

3. A World-wide Sample of Instruments

4. Summary • 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

5. 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 Survey Details

6. Survey 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

7. 180 Instrument Number 90 1 0.1 1 10 100 Wavelength Coverage • 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

8. Currently astronomy is pretty heavily dominated by optical instruments, with ~2 out of 3 instruments using CCDs NOW FUTURE Optical, Near-Infrared, or Mid-Infrared? • The next-generation of instruments will consist of nearly equal numbers of optical and NIR instruments

9. In both cases MIR instruments occupy a very small part of the “market” This is due to many reasons including A relatively small MIR community A historically specialized field technically to get into The need for special telescope systems (chopping), etc. The lack of MIR instruments reflects a relatively “untapped” science frontier, not lack of scientific importance Optical, Near-Infrared, or Mid-Infrared? NOW FUTURE

10. 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 Commonly Used?

11. 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 Various Manufacturers

12. 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 Current Market Share by Various Manufacturers

13. Plate Scale and Field of View • 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 • Clearly a “sweet spot” in field size of instruments for fields in the 10-100 arcmin2 range • 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

14. 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 CURRENT FUTURE Typical Infrared Pixel Size Now and Tomorrow…

15. 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 Typical CCD Pixel Size Now and Tomorrow… CURRENT FUTURE

16. 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 CURRENT FUTURE Typical Infrared Array Format, Now and Tomorrow…

17. 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… Typical CCD Format, Now and Tomorrow… CURRENT FUTURE

18. 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” Total Pixel “Inventory”, Now and Tomorrow… Optical Infrared CURRENT FUTURE

19. 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… Total Pixel “Inventory”, Now and Tomorrow… Optical Infrared CURRENT FUTURE

20. 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 Controller Types

21. Instrument 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 Median Instrument Cost Summary

22. Future Trends in Science and Technology…

23. “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

24. Universe Ionized Universe Neutral Key Epochs in the Early Universe Reionization in the Early Universe Photons from this scattering surface are what we now see as the Cosmic Microwave Background (CMB)

25. Simulation of an Ultra Deep NIR Image of the First Stars “First Light” in a Dark Universe • 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

26. Boundaries on Research Frontiers • 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…

27. The Galactic Center: Discovery Strip Chart

28. The Galactic Center: Becklin & Neugebauer 1975

29. The Galactic Center: Forrest et al. 1986

30. The Galactic Center: Rigaut et al. 1997

31. The Galactic Center: Recent ESO Results Zeroing in on a Massive Black Hole…

32. 25 yrs The 25 Year “Evolution” of the 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…

33. Boundaries on Research Frontiers • 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

34. The Future is Both Large and 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 OWL TMT

35. The ELT’s Window on the Universe... ~1”

36. ~1”

37. Target: Galactic Cores Objective: Detect signatures of black holes in compact galactic nuclei

38. Target: Io Objective: Remote seismic monitoring & planetary mineralogy

39. Target: Forming Planetary Systems Objective: Measure SED of forming stars, planets & surrounding gas, binary fractions, disk evolution, Dust & gas dynamics, MF, etc.

40. Target: First Stars Objective: Morphology, spectra, and luminosity of first luminous objects in the universe

41. Target:-ray bursters Objective: Identify and measure distance & SED of hosts; detect the “first” GRBs in the universe

42. Target: Extra-solar planets Objective: Direct imaging and spectroscopy of planetary systems beyond our own

43. LSST LAMOST Project The Large Sky Area Multi-Object Fiber Spectroscopic Telescope Pan-STARRS Hyper-SUPRIME + WFMOS Future Wide Field Facilities

44. Galaxy Genesis Dark Matter Future 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 Dark Energy

45. The Destiny of the Universe Matter/Gravity Overcome the Initial Expansion from the Big Bang

46. The Destiny of the Universe Universe “Coasts” Outward, with Matter/Gravity In Approximate Equilibrium with Big Bang Expansion

47. The Destiny of the Universe Expansion of the Universe Accelerates, Ultimately Shredding Its Material Contents

48. The Destiny of the Universe With the discovery of Dark Energy this now appears to be possible. Next-generation detectors will play a key role in solving this mystery Expansion of the Universe Accelerates, Ultimately Shredding Its Material Contents

49. Summary 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 astronomy • Optical 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

50. Summary 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