1 The Large Synoptic Survey Telescope Status Summary Steven M. Kahn SLAC/KIPAC

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The Large Synoptic

Survey Telescope

Status SummarySteven M. Kahn

SLAC/KIPAC

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LSST Technical Concept• 8.4 Meter Primary

Aperture– 3.4 M Secondary– 5.0 M Tertiary

• 3.5 degree Field Of View• 3 Gigapixel Camera

– 4k x 4k CCD Baseline– 65 cm Diameter

• 30 Second Cadence– Highly Dynamic

Structure– Two 15 second

Exposures• Data Storage and

Pipelines Included in Project

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Why is the LSST unique?Primary mirror

diameterField of view

(full moon is 0.5 degrees)

KeckTelescope

0.2 degrees10 m

3.5 degrees

LSST

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Relative Survey Power

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The Essence of LSST is Deep, Wide, Fast!

* Dark matter/dark energy via weak lensing * Dark matter/dark energy via supernovae* Galactic Structure encompassing local group* Dense astrometry over 30,000 sq.deg: rare moving objects* Gamma Ray Bursts and transients to high redshift* Gravitational micro-lensing* Strong galaxy & cluster lensing: physics of dark matter* Multi-image lensed SN time delays: separate test of cosmology* Variable stars/galaxies: black hole accretion* QSO time delays vs z: independent test of dark energy* Optical bursters to 25 mag: the unknown* 5-band 27 mag photometric survey: unprecedented volume* Solar System Probes: Earth-crossing asteroids

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Principle LSST Science Missions• Dark Energy / Matter

– Weak lensing - PSF Shape/ Depth / Area– Super Novae + Photo z – Filters /

• Map of Solar System Bodies– NEA – Cadence – KBO -

• Optical Transients and Time Domain– GRB Afterglows – Image Differencing– Unknown transients -

• Assembly of the Galaxy and Solar Neighborhood– Galactic Halo Structure and Streams from proper motions– Parallax to 200pc below H-burning limit

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LSST and Dark Energy

• LSST will measure 250,000 resolved high-redshift galaxies per square degree! The full survey will cover 18,000 square degrees.

• Each galaxy will be moved on the sky and slightly distorted due to lensing by intervening dark matter. Using photometric redshifts, we can determine the shear as a function of z.

• Measurements of weak lensing shear over a sufficient volume can determine DE parameters through constraints on the expansion history of the universe and the growth of structure with cosmic time.

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Color-redshift

QuickTime™ and aTIFF (LZW) decompressor

are needed to see this picture.

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Cosmological Constraints from Weak Lensing Shear

Underlying physics is extremely simple General Relativity: FRW Universe plus the deflection formula. Any uncertainty in predictions arises from (in)ability to predict the mass distribution of the Universe

Method 1: Operate on large scales in (nearly) linear regime. Predictions are as good as for CMB. Only "messy astrophysics" is to know redshift distribution of sources, which is measurable using photo-z’s.

Method 2: Operate in non-linear, non-Gaussian regime. Applies to shear correlations at small angle. Predictions require N-body calculations, but to ~1% level are dark-matter dominated and hence purely gravitational and calculable with foreseeable resources.

Hybrids: Combine CMB and weak lens shear vs redshift data. Cross correlations on all scales.

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Measurement of the Cosmic Shear Power Spectrum

• A key probe of DE comes from the correlation in the shear in various redshift bins over wide angles.

• Using photo-z’s to characterize the lensing signal improves the results dramatically over 2D projected power spectra (Hu and Keeton 2002).

• A large collecting area and a survey over a very large region of sky is required to reach the necessary statistical precision.

• Independent constraints come from measuring higher moment correlations, like the 3-point functions.

• LSST has the appropriate etendue for such a survey.

From Takada et al. (2005)

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Constraints on DE Parameters

From Takada et al. (2005)

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Optical Design

0.6”

LSST Optical Design

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LSST Camera

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Camera Mechanical Layout

L1L3

Shutter

Filter

L2

Detector array

1.6m

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Focal plane array

3.5° FOV 64 cm

Raft = 9 CCDs + 1cm x 1cm reservedfor wavefront sensors

201 CCDs totalStrawman CCD layout4K x 4K, 10 µm pixels

32 output ports

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LSST Data Management Infrastructure

BaseCampCenter

Mirror Sites

ArchiveComputing

Center

TelescopeSite

PortalUser

101 to 2 kM1.2 GB/s

103 to 4 kM.4 GB/s

103 to 4 kM.35 GB/s

10-1 kM, .6 GB/s

Focal plane

PortalUsers

150 TB disk10 TFLOP

1 PB disk 25 TFLOP*

PortalUsers

GRID, Internet 2

15 TB disk, 5 TFLOP

Notes: B = bytes, b = bits

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LSST Partners• Research Corporation • U of Arizona • National Optical Astronomical Observatory • U. of Washington• Stanford U. • Harvard-Smithsonian• U. of Illinois• U of California – Davis• Lawrence Livermore National Lab• Stanford Linear Accelerator Center• Brookhaven National Lab• Johns Hopkins University

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LSST Project Structure

Camera

Steven Kahn, Sci.Krik Gilmore, Mgr.

Telescope/Site Charles Claver, Sci. Victor Krabbendam,

Mgr.

SystemEngineering

William Althouse

Science Working Groups

Data Management Timothy Axelrod,

Sci.Jeffrey Kantor, Mgr.

Science AdvisoryCommittee (SAC)

System Scientist &Chair of Science

CouncilZeljko Ivezic

Education & Public Outreach

Suzanne Jacoby

LSST Director Anthony Tyson

Steven Kahn, Deputy

Project ManagerDonald Sweeney

Victor Krabbendam, Deputy

LSSTC Board of Directors

John Schaefer, President

SimulationsDepartment

Phil Pinto

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Steering Committee Aronson (BNL) Burke (SLAC) Stubbs (Harvard) Tyson (UC Davis)

Camera Scientist Kahn (SLAC)

Camera Manager Gilmore (SLAC)

Marshall, ThalerSensor Design - GearySensor Deliverables - RadekaFEE - O'ConnorBEE - OliverWFS - (TBD)Guide Sensors - (TBD)Design & Metrology TakacsFEE Crate - O'Connor

Sensor/RaftDevelopmentRadeka (BNL)

Optical Design - SeppalaL1 - WhistlerL2 - WhistlerL3 - WhistlerFilters - RasmussenMechanisms - Hale

Optics Olivier (LLNL)

Integrating Structure - HaleRaft Module IntegrationRasmussenIn situ Monitoring & ActuationPerlThermal Systems - ThurstonFP Motion Control (TBD)

FP DewarAssembly

Schindler (SLAC)

Mechanisms - HaleCamera Body - HaleThermal Design - Thurston& ImplementationFP Motion Design - (TBD)FEA & Modeling - (TBD)Vacuum Systems - (TBD)Camera Electrical Sys. - OliverCooling Design - ThurstonCam/Tel Interface - AlthouseGroundingPower ConditioningWFS & GuidingContamination Analysis& Control (TBD)

Camera Design &Modeling

Gilmore- acting (SLAC)

FP ControlHousekeepingWFS & GuidingPower ConditioningExposure ControlThermal ControlMechanisms

Camera Controlsand Software

Schalk (UCSC-TBC)

Sensor Level - O'ConnorRaft Level - O'ConnorFocal Plane - RasmussenSky Calibration - GilmoreSimulations - Jernigan

CalibrationBurke (SLAC)

LSST CAMERA ORGANIZATION CHART______________________________________________

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SLAC Participation in LSST

• Faculty: Blandford, Burke, Kahn, Perl, Schindler

• Physics Staff: Gilmore, Kim, Lee, S. Marshall, Rasmussen

• Postdoctoral: Bradac, P. Marshall, Peterson

• Engring/Tech: Althouse, Hodgson, Rogers, Thurston

• Computing: Becla, Hanushevsky, Luitz

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Proposed Funding Model for the LSST

• Concept and Development Phase (2004 – 2008)– $15M from LSSTC members and private sponsors – $15M from the NSF– $18M from the DOE

• Construction Phase (2008 – 2013)– $120M from the NSF– $100M from the DOE– $50M from private sponsors

• Operations Phase (2013 – 2023)– ~$20M/year is estimated as total annual operations budget

($10M/yr for the observatory and $10M/yr for data management)

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Proposed funding and management configuration

NOAO

x

LSST Collaboration Institutions

Funding Sources

Potential relationships established by

MoA's

NCSALSSTC Staff

PMO xLSSTC

PMO: Program Management Office

x

SLACBNLLLNL

Universities

Universities

x

DOE NSFLSSTCPrivate

x

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Key R&D Issues• Telescope

1. Implementation of the wavefront sensor and stability of the correction algorithm2. Metrology for the convex, aspheric secondary3. Achieving 5-sec slew-and-settle specification

• Camera1. Development of focal plane sensor meeting all specifications2. Assembly of focal plane meeting flatness specification3. Fabrication of the filters with spatially uniform passband

• Data Management 1. Interfacing an individual investigator with the voluminous LSST data2. Scientific algorithm development for credible prototyping of pipelines3. Establishing catalog feature set and method for querying data base

• System Engineering1. Completing flow-down of scientific mission to perfomance specifications2. Generating a complete end-to-end simulator3. Establishing link between technical performance, cost, and schedule

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FPA Flatness Allocations Established

Sensor Module

5m p-v flatness over entire sensor surface

Raft Assembly

6.5m p-v flatness over entire surfaces of sensors

Focal Plane Assembly

10m p-v flatness over entire surfaces of sensors

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Integrating structure

Raft structure

AlNUP

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LSST highlights during the last year – Camera

• Strawman camera designed with 3 GPixel camera• Flow-down of science requirements to performance

requirements shows focal plane is achievable with CCD array

• Favorable first results with Hybrid CMOS sensors• Preliminary camera optical and mechanical design

completed• Vendor interaction confirms that refractive elements

and filters can be manufactured