aura 2 sep 2004. context national academy’s decadal review recommended a ‘large synoptic survey...
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AURA 2 Sep 2004AURA 2 Sep 2004
AURA 2 Sep 2004AURA 2 Sep 2004
ContextContext
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 • 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
AURA 2 Sep 2004AURA 2 Sep 2004
Pan-STARRS Design PhilosophyPan-STARRS Design Philosophy
Given the following constraints:• Construction time ~ 1 year per meter aperture• Telescope cost rises faster than D2
• Pixel size limited to >10m, 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.
AURA 2 Sep 2004AURA 2 Sep 2004
Pan-STARRS in a NutshellPan-STARRS in a Nutshell
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
AURA 2 Sep 2004AURA 2 Sep 2004
Pu`u Poliahu
UH 0.6-m
UH 0.6-m
UH 2.2-m
AURA 2 Sep 2004AURA 2 Sep 2004
UKIRT
CFHT
AURA 2 Sep 2004AURA 2 Sep 2004
Science OverviewScience Overview
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
Observing Programs
Science Programs
Very extensive overlaps between observational requirements of science programs!
AURA 2 Sep 2004AURA 2 Sep 2004
Pan-STARRS SurveysPan-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
AURA 2 Sep 2004AURA 2 Sep 2004
Design Reference MissionDesign Reference Mission
Mode PSY Area Cad. w g r i z y
SSNEO
1.1d 0.2b
7000 h/d/m27.3 300
SSKBO
1.0d 0.2b
3 hdmy26.3 60
Var.0.8d 0.8b
133 4 min29.222000
28.67400
28.54400
24.94400
3 1.3d 2.5b
3 14d25.9 30
25.6 30
25.4 60
23.9 20
22.3 30
Med. Deep
0.6d 0.9b
1200 4d27.1 271
27.0 460
27.31200
25.01900
24.0 600
Ultra Deep
0.5d 0.7b
28 4d29.110000
29.018000
28.06300
27.06700
26.026000
5-5- limit (AB) limit (AB)
Total int. (min)Total int. (min)
AURA 2 Sep 2004AURA 2 Sep 2004
Science with Pan-STARRSScience 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)
AURA 2 Sep 2004AURA 2 Sep 2004
Near Earth AsteroidsNear Earth Asteroids
Local
Regional
Global108 Mton105
103
102
100m 1km 10km2x105 5x108 year
SizeTime Interval
Energy
AURA 2 Sep 2004AURA 2 Sep 2004
Damage vs SizeDamage vs Size
AURA 2 Sep 2004AURA 2 Sep 2004
Risk Reduction vs TimeRisk Reduction vs Time
(200m)(200m)
(50m)(50m)
(500m)(500m)
(1000m)(1000m)
PSPSLINEARLINEAR
LSSTLSST
AURA 2 Sep 2004AURA 2 Sep 2004
Inner Solar System ScienceInner Solar System Science
~107 asteroids• Families• Orbit parameter
space structure
~104 NEOs• Phase-space
distribution• Hazardous
asteroids
Comets
AURA 2 Sep 2004AURA 2 Sep 2004
Outer Solar System ScienceOuter Solar System Science
Kuiper Belt Objects• Orbital distribution• Formation and
evolution Trans-Neptunian
Objects Interlopers on
hyperbolic orbits
AURA 2 Sep 2004AURA 2 Sep 2004
Stars and the GalaxyStars and the Galaxy
Parallax survey• Complete stellar census to 100pc
Proper motions• Formation history
Other goals:• Stellar variability• Low mass stars• Extra-solar planets
AURA 2 Sep 2004AURA 2 Sep 2004
Moving ObjectsMoving 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.
AURA 2 Sep 2004AURA 2 Sep 2004
Cosmology – Weak LensingCosmology – 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
AURA 2 Sep 2004AURA 2 Sep 2004
Static and Invariable ObjectsStatic 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.
AURA 2 Sep 2004AURA 2 Sep 2004
Cosmology – SupernovaeCosmology – Supernovae
Hubble diagram• Dark energy equation
of state w(z)• Cosmological
parameters Supernova physics Star formation history
AURA 2 Sep 2004AURA 2 Sep 2004
Transient and Variable ObjectsTransient 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.
AURA 2 Sep 2004AURA 2 Sep 2004
TGBNTGBN
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
AURA 2 Sep 2004AURA 2 Sep 2004
Data VolumeData 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.)
AURA 2 Sep 2004AURA 2 Sep 2004
Image Processing PipelineImage Processing Pipeline
Phase 1 Detector
Calibration (Calibration
and Instrument CorrectionProcesses)
Phase 2 Map and
Warp to Sky(Image
Manipulation Processes)
Phase 3 Create Sky
Image (Image
CombinationProcesses)
Inte
rfac
e 1
Inte
rfac
e 2
Inte
rfac
e 3
Inte
rfac
e 4
Inte
rfac
e 5
Data Storage
Data Storage
Data Storage
Telescope Cameras
ScienceClients
Phase 6ScienceClient
Interfaces
TCS andEnvironmentMonitoring
Phase 4 Augmented
Image Processing
Data Storage
Inte
rfac
e 7
Chip Level Chip Level Telescope and System Level
Inte
rfac
e 6
Phase 5 Science Client
Product Generation
Data Storage
Data Storage
System Level System Level System LevelImage Capture
Scheduler
Phase 0
Internal Product
Generation
Internal Product
Generation
Mission Planning…pre-staging of each night’s scheduling and supporting data…TBD
NB: specifics have changed!
AURA 2 Sep 2004AURA 2 Sep 2004
Confusing IssuesConfusing 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 those last two factors are important!• SDSS at A CFHT at 10, Suprime at 13 cannot
approach LSST science because of limited and/or• Pan-STARRS at A is designed to have superb
and 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.
AURA 2 Sep 2004AURA 2 Sep 2004
Design Reference MissionDesign Reference Mission
Mode PSY Area Cad. w g r i z y
SSNEO
1.1d 0.2b
7000 h/d/m27.3 300
SSKBO
1.0d 0.2b
3 hdmy26.3 60
Var.0.8d 0.8b
133 4 min29.222000
28.67400
28.54400
24.94400
3 1.3d 2.5b
3 14d25.9 30
25.6 30
25.4 60
23.9 20
22.3 30
Med. Deep
0.6d 0.9b
1200 4d27.1 271
27.0 460
27.31200
25.01900
24.0 600
Ultra Deep
0.5d 0.7b
28 4d29.110000
29.018000
28.06300
27.06700
26.026000
5-5- limit (AB) limit (AB)
Total int. (min)Total int. (min)
AURA 2 Sep 2004AURA 2 Sep 2004
Final Data ProductsFinal 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)