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Pan-STARRS

Pan-STARRS. Context . National Academy’s Decadal Review recommended a ‘large synoptic survey telescope’ (LSST) 6m class aperture dedicated wide-field optical imager all-sky survey to enable multiple science goals applications from solar system to cosmology strategic emphasis in NEO threat

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Pan-STARRS

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  1. Pan-STARRS

  2. Context • National Academy’s Decadal Review recommended a ‘large synoptic survey telescope’ (LSST) • 6m class aperture • dedicated wide-field optical imager • all-sky survey to enable multiple science goals • applications from solar system to cosmology • strategic emphasis in NEO threat • LSST is assumed to accept natural seeing • for many applications the figure of merit is then simply the etendue: A W  / dW • an alternative to a single 6m telescope is an array of smaller telescopes with the same total area A • many pros and cons, the major advantages are: • single: no duplication of detectors, can go fainter faster • distributed: cheaper, faster to build, more flexible

  3. Pan-STARRS Design Philosophy • Given the following constraints: • Construction time ~ 1 year per meter aperture • Telescope cost rises faster than D2 • Pixel size limited to >10mm, desire 0.3” pixels requires a focal length of <8m • Optical design for a large  becomes very expensive for fast f-ratios • Costs of CCD detectors have been falling • (O)MEGACAMs: ~$8-10M for ~3x108 pixel or ~2-3c/pixel • Today it is possible to do a factor of 10 better • We believe it is cheaper and better to build an a survey instrument from an array of telescopes and detectors.

  4. Telescopes Four 1.8m R-C + corrector 7 square degree FOV Sited on Mauna Kea or Haleakala Operation mode: Broad band optical imaging Four telescopes view the same field to detect transient or moving objects and build up a deep image of the sky Partners: IfA: science, detectors, pipelines MHPCC: production DP, infrastructure SAIC: databases and mass storage systems MIT-Lincoln Lab: detectors Detector and controllers 109 0.3” pixels per camera Image motion compensation 512 channel controller 2 second readout 4e- read-noise Data-Processing System Multicolor summed images Difference images for detection of moving and variable objects Catalogs of static, moving, transient objects Science: “Killer Asteroids” (PHAs) Huge range of other science topics – presently imagination limited Pan-STARRS in a Nutshell

  5. Pu`u Poliahu UH 0.6-m UH 2.2-m UH 0.6-m

  6. CFHT UKIRT

  7. Science Overview Observing Programs Science Programs • Time domain astronomy • Transient objects • Moving objects • Variable objects • Static sky science • Enabled by stacking repeated scans to form a collection of ultra-deep static sky images • Very extensive overlaps between observational requirements of science programs!

  8. Pan-STARRS Surveys • Solar System (Ecliptic Plane) – used primarily to satisfy the observing requirements imposed by the PHO, NEO, MBA, KBO and other SS programs. • 3 – used primarily to satisfy the observing requirements of the WL, LSN census, and EG object detection & classification programs; primary cadence drivers are the LSN census (and other proper motion studies) • Medium-Deep – the SNe, LSS, and the EG object detection & classification programs; primary cadence driver being SNe • Ultra-Deep – EG object detection & classification and, to some extent, SNe programs • Object Variability/Auxiliary – mostly user-defined supporting programs such as stellar variability and the search for extra-solar planets

  9. Design Reference Mission 5- limit (AB) Total int. (min)

  10. Science with Pan-STARRS • Moving Object Science • NEO – Near Earth Object threat • OSS/MBO – Main Belt and Other Solar System science • KBO – Kuiper Belt Objects • SOL – Solar Neighborhood (parallaxes and proper motions) • Static and Invariable Object Science • WL – Weak Lensing • LSS – Large Scale Structure • LSB – Low Surface Brightness and dwarf galaxies • SPH – Spheroid formation • EGGS – Extragalactic and Galactic Stellar science • Transient and Variable Object Science • AGN – Active Galactic Nuclei • SNE – Supernovae • GRB – Gamma Ray Bursts and afterglows • EXO – Exoplanets (from occulation) • YSO – Young Stellar Objects • VAR – Variability Science (especially stars) • TGBN (Things that go Bump in the Night)

  11. Near Earth Asteroids Size 100m 1km 10km Time Interval 103 2x105 5x108 year 105 102 Energy 108 Mton Global Regional Local

  12. Damage vs Size

  13. Risk Reduction vs Time (1000m) (500m) (200m) LINEAR PS LSST (50m)

  14. Inner Solar System Science • ~107 asteroids • Families • Orbit parameter space structure • ~104 NEOs • Phase-space distribution • Hazardous asteroids • Comets

  15. Outer Solar System Science • Kuiper Belt Objects • Orbital distribution • Formation and evolution • Trans-Neptunian Objects • Interlopers on hyperbolic orbits

  16. Parallax survey Complete stellar census to 100pc Proper motions Formation history Other goals: Stellar variability Low mass stars Extra-solar planets Stars and the Galaxy

  17. Moving Objects • KBO – 20,000 KBOs over 10 years; all sky, unbiased. • ~100 in binary pairs • OSS – many more asteroids and comets (~20x) • 5x106 million main belt, 105 Jupiter Trojans, etc. • SOL – parallaxes to ~100pc in 10 years • Best substellar IMF available (better than UKIDSS) • 10-100x more brown dwarfs than SDSS or 2MASS • EGGS – proper motions of most stars in the Milky Way • Accuracy of 2.5 km/s at 1kpc.

  18. Cosmology – Weak Lensing • Total mass power spectrum P(k) to large scales • Test of inflation theory • Evolution of P(k) • Higher order statistics • Gravitational instability theory • Cluster mass function • Cosmology • Cosmological parameters • Geometric tests • World model

  19. Static and Invariable Objects • WL – Weak lensing over 1000 sq deg. • Large-scale structure of mass on large scales (wide area) and small scales (high density of objects) as a function of redshift, evolution of mass clustering. • Mass profiles of galaxies • SPH, LSB, AGN – Evolution of galaxies • Pan-STARRS will survey 4x the area of SDSS, will have the same photometric accuracy but 3-4 mag fainter, good sensitivity at 1um (y band). • Reionization, metal formation, spheroid formation, AGN activity, galaxy merging, and cluster formation.

  20. Cosmology – Supernovae • Hubble diagram • Dark energy equation of state w(z) • Cosmological parameters • Supernova physics • Star formation history

  21. Transient and Variable Objects • SNE – 10,000’s of SNIa to z=1 • Measure time (redshift) evolution of dark energy • AGN – Dropouts to z=7, variability identification • Reionization, metals, spheroid formation, nature of radio sources, stellar disruptions, etc. • GRB – Optical counterparts (~100 per year) • Possibly V~8 declining to V~20 in one day • EXO – Occultations of stars by planets • Pan-STARRS is sensitive to Jupiters around sub-solar mass stars or Earths around brown dwarfs. • VAR – Stellar variability • White dwarfs, binaries, Cepheids, Miras, RR Lyrae, microlensing, supergiants, etc, etc.

  22. TGBN • The Pan-STARRS survey is 10-20 times SDSS, Megacam survey, Vista, etc. in extent, but… • We are repeating it 30 – 500 times! • We will be the first to have extensive time domain information, designed with useful and interesting cadences, well controlled selection and systematics, and huge samples. • There is a high likelihood for unanticipated discoveries • Unexpected variable objects • Extremely rare objects • Very large scale patterns

  23. Data Volume • Expect 700 images = 6 Tb per night raw; 3 Tb per night = 1 Pb per year reduced! • We have to be prepared not to “save the bits” • We must create a reliable enough pipeline that we tap all the science we want as the data flow through, and then throw the bits on the floor. (This has never been achieved before.)

  24. Image Processing Pipeline Telescope Cameras Interface 1 Interface 7 Interface 4 Interface 3 Interface 5 Interface 6 Interface 2 Chip Level Chip Level Telescope and System Level System Level System Level System Level Image Capture Phase 0 Phase 4 Augmented Image Processing Phase 5 Science Client Product Generation Phase 6 Science Client Interfaces Phase 1 Detector Calibration (Calibration and Instrument Correction Processes) Phase 2 Map and Warp to Sky (Image Manipulation Processes) Phase 3 Create Sky Image (Image Combination Processes) Science Clients Scheduler Data Storage Data Storage Data Storage Data Storage Data Storage Data Storage TCS and Environment Monitoring Internal Product Generation Internal Product Generation NB: specifics have changed! Mission Planning…pre-staging of each night’s scheduling and supporting data…TBD

  25. Confusing Issues • LSST should not be discussed as an either – or competitor to Pan-STARRS; Pan-STARRS will exist before LSST begins construction. Therefore: • Astro-photo precursor survey will have been done, • A robust data pipeline will have been shaken down, • 50% of 300m PHAs will have been discovered, etc, etc. • What etendue is really needed? • Etendue is A W  / dW: those last two factors are important! • SDSS at A W =7.5, CFHT at 10, Suprime at 13 cannot approach LSST science because of limited  and/or dW. • Pan-STARRS at A W = 50 is designed to have superb  and dW and the software and scheduling to maintain LSST science. • Pan-STARRS will improve on the present state of the art (SDSS, upcoming synoptic surveys) by at least an order of magnitude in science productivity.

  26. Design Reference Mission 5- limit (AB) Total int. (min)

  27. Final Data Products • Sky, the wallpaper: • 10 Tpix x 6 colors x N versions • Sky, the movie: • 10 Tpix x 6 colors x 50 epochs • Sky, the database: • 2x1010 objects (x 6 colors x 20-60 epochs) • Photometry to < 0.01 mag, astrometry to < 50 mas • Photometric redshifts of most of these objects • 109 proper motions (complete over 3) • 108 variable stars and AGN • 107 asteroids (104 NEO/PHA) • 107 transients (SN, GRB, etc.) • 3x105 stars within 100 pc (with good parallax)

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