asteroid detection with the large synoptic survey ... detection with the large synoptic survey...

Asteroid Detection with the Large Synoptic

Survey Telescope (LSST)Lynne Jones (University of Washington/LSST)

XXIX IAU - Honolulu - 8/3/2015

Planetary science & LSST

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Currently Known*

LSST Discoveries**

Median number of observations+

Observational arc length+

Near Earth Objects (NEOs) 12,832 100,000 (D>250m) 60 6.0 years

Main Belt Asteroids (MBAs) 636,499 5,500,000 (D>500m) 200 8.5 years

Jupiter Trojans 6,387 280,000 (D>2km) 300 8.7 years

TransNeptunian Objects (TNOs) + Scattered Disk

Objects (SDOS)1,921 40,000 (D>200km) 450 8.5 years

Plus: comets, irregular satellites, Earth minimoons and temporary satellites .. 10-100x increase in sample size for every

small body population in the Solar System

* As reported by the MPC ** Expected by end of survey +For the brightest objects (near 100% completeness)

XXIX IAU - Honolulu - 8/3/2015 3

L A R G E S Y N O P T I C S U R V E Y T E L E S C O P E


L A R G E S Y N O P T I C S U R V E Y T E L E S C O P E

Explore dark energy and dark matter

Map the Milky Way and Local Volume

Explore the transient sky

Inventory the Solar System


• 8.4m (6.7m effective) diameter primary• Deep individual images, in

ugrizy

• 9.6 square degree FOV camera• Large survey footprint

• Rapid cadence• 2x15s exposures• 2 visits per night• Return every ~4 nights

Science drivers to design

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3.5 degrees

(Full moon is 0.5 degrees)

LSST FOV

u g r i z y# visits 70 100 230 230 200 200m5 depth 23.9 25.0 24.7 24.0 23.3 22.1


LSST data processing - a complete survey project

Nightly Operations :Each 15s exposure =

6.44 GB (raw)2x15s = 1 visit, 800 visits/night.

Release “Alerts” within 60 seconds

(~106 per night)

Daily Operations:Moving Object

Processing.Transfer 15 TB/night of

image data to US.

At Data Archive:Yearly reprocessing of all data,

Generates calibrated, query-able catalogs: +20 PB end of 10 years

Generates processed images:+50 PB end of 10 years

Start of operations: 2022 End of operations: 2032


LSST data processing - a complete survey project

Nightly Operations :Each 15s exposure =

6.44 GB (raw)2x15s = 1 visit, 800 visits/night.

Release “Alerts” within 60 seconds

(~106 per night)

Daily Operations:Moving Object

Processing.Transfer 15 TB/night of

image data to US.

At Data Archive:Yearly reprocessing of all data,

Generates calibrated, query-able catalogs: +20 PB end of 10 years

Generates processed images:+50 PB end of 10 years

Start of operations: 2022 End of operations: 2032

See Mario Juric’s talk tomorrow!


LSST Performance

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Effective Mirror Diameter

6.7 mField of view 9.6 sq degExposure (‘Visit’) Time 2x15 s /visitSurvey length 10 yearsData rate ~15 TB/nightSky coverage ~18,000 sq

degSite Cerro PachonFilters ugrizyTypical seeing 0.7”Photometric accuracy 10 mmagAstrometric accuracy 50 masAstrometric precision 10 mas

LSST will measure the characteristics of about 10B galaxies and 10B stars, but it will also open an unprecedented window on transient and changing phenomena in the night sky.

u g r i z y# visits 70 100 230 230 200 200m5 depth 23.

925.0

24.7 24.0 23.3 22.1


Detecting moving objects

LSST will detect and link the detections of

millions of small moving objects across the Solar System, 10-100x more than currently known.


Planetary science & LSST

8

Currently Known*

LSST Discoveries**

Median number of observations+

Observational arc length+

Near Earth Objects (NEOs) 12,832 100,000 (D>250m) 60 6.0 years

Main Belt Asteroids (MBAs) 636,499 5,500,000 (D>500m) 200 8.5 years

Jupiter Trojans 6,387 280,000 (D>2km) 300 8.7 years

TransNeptunian Objects (TNOs) + Scattered Disk

Objects (SDOS)1,921 40,000 (D>200km) 450 8.5 years

Plus: comets, irregular satellites, Earth minimoons and temporary satellites .. 10-100x increase in sample size for every

small body population in the Solar System

* As reported by the MPC ** Expected by end of survey +For the brightest objects (near 100% completeness)


• Planetary migration• Nice model• Slow migration of giant

planets• Planetesimal formation

• Collisional evolution• Distribution of primordial

material

• More ‘test particles’ = much stronger constraints on these models

Formation and evolution of the Solar System

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Nice model - giant planet migration(movie credit: Hal Levison, SwRI)


Collisional history and size distribution

The semi-major axis vs. inclination: color-coded using opticalcolors measured by SDSS

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Color-coded with SDSS optical

colors

Main belt asteroids detected in the Sloan Digital Sky Survey (SDSS), color coded according to their observed colors — 88,000 MBAs(Parker et al 2008)

Identify families, see compositional trends, determine size distribution - understand collisional history of asteroids.

With LSST - 50x better resolution


Collisional history and size distribution

The semi-major axis vs. inclination: color-coded using opticalcolors measured by SDSS

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Color-coded with SDSS optical

colors

Main belt asteroids detected in the Sloan Digital Sky Survey (SDSS), color coded according to their observed colors — 88,000 MBAs(Parker et al 2008)

Identify families, see compositional trends, determine size distribution - understand collisional history of asteroids.

With LSST - 50x better resolution

5.4 The Main Belt: Collisional Families and Size Distributions

Figure 5.7: Illustration of the decomposition of the Main Belt asteroid population into families and backgroundobjects using proper orbital elements and color (adapted from Parker et al. 2008). The top three panels show thesine of the orbital inclination vs. orbital eccentricity diagrams for three regions of the Main Asteroid Belt definedby semi-major axis range (see the top labels). Each dot represents one object, and is color-coded according to itscolor measured by SDSS (see also Figure 5.5 for a “zoomed-out” view). The three middle panels show objects from37 identified families, and the bottom three panels show the background population. Examples of size distributionsfor several families are shown in Figure 5.8. These results are based on about 88,000 objects. The LSST data setwill include several million objects and will also provide exquisite time domain information.

Previous surveys have shown that the albedo distribution of asteroids is bimodal, with one peakhaving a mean albedo of 0.06 while the other peak has a mean of 0.20 in g or about 0.25 in r or i.These two di�erent albedo peaks are correlated with asteroid color, representing their taxonomictypes. Low albedo MBAs are C-, D-, and P-types asteroids, while those MBAs with higher albedosare S-, R-, V-, E-, and M-type asteroids.

LSST data can be used to measure MBA taxonomies, which may be used to constrain the albedos

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• Sparse lightcurve inversion can provide shapes for 10,000-100,000 NEOs and MBAs

• Learn about physical properties, help us understand effect of non-gravitational forces

Lightcurves, spin periods, and shapes


• Surface activity can be due to collisions or outbursts• Outbursts let us learn about physical properties,

collisions tell us about the size distribution of very small objects

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Outbursts and collisional activity


• Retrograde objects • Families of small objects • Active asteroids • Trojans (Neptune, Uranus, Mars, Earth)• Earth mini-moons • Objects with extreme colors (space weathering,

composition)• Binaries (not so rare, but better sampling)

• 10-100x more asteroids, with photometry accurate to 10mmag, astrometry accurate to 50mas, and 100’s of measurements in multiple colors

Rare and unusual objects

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asteroid detection with the large synoptic survey ... detection with the large synoptic survey...

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