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Imaging Surveys: Goals/ChallengesImaging Surveys: Goals/Challenges

May 12, 2005

Luiz da Costa European Southern Observatory

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OutlineOutline

Past & Future Imaging Surveys

The EIS project experience: lessons learned

EIS Data Reduction System

Applications

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MotivationMotivation

Large-aperture telescopes (Keck, VLT, OWL?)

Expanded MOS capabilities

Space Missions: HST, Chandra, XMM, Spitzer, Galex

Advent of wide-field imagers (optical/infrared)

enabling to probe new regions of parameter space

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Science GoalsScience Goals

Galaxy Evolution

Constrain Dark Energy

– Abundance and clustering evolution of galaxy clusters

– Weak gravitational lensing on large scales

– Evolution of the spatial distribution of galaxies

– Luminosity distances of Type 1a SNe

Transient phenomena

– Solar system probes: asteroids, comets, TNOs

– Variable stars/galaxies

– Gamma-ray bursts

Extreme (cool, distant, unknown) rare objects which require depth and area

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Recent SurveysRecent Surveys

General purpose surveys

– NOAO

– INT

– EIS

Targeted surveys (deep, space/ground)

– COMBO-17

– FORS

– SUBARU

– FIRES

– GOODS

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Optical Near IR

SDSS

DLS

NWDS

BTC

NWDS

Some Recent Optical and Near IR Surveys

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Next Generation (Optical)Next Generation (Optical)

CFHTLS

– 4-m; MegaCam 36 CCD 1 x 1 degrees fov

– Very wide 1300 sq degrees 3-bands

– Wide 170 sq degrees 5-bands i’=24.5 (lensing, LSS)

– Deep 4 square degrees r=28 (gal. evolution)

VST

– 2.5m; OmegaCam 32 CCD 1 x 1 square degree fov

– Vesuvio 100 square degrees 5-bands R=26

– OmegaCam survey 1000 sq.deg. 5-bands r’=24 AB

– Data rate from observation 0.84 Mpix/sec

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Next Generation (Optical)Next Generation (Optical)

Dark Energy Survey (DES)

– Blanco telescope 60 CCD 3 square deg. 500 Mpixels

– 4000 sq. deg 4-bands R=24

– complement SZ cluster survey South Pole Telescope

Pan-STARRS (Panoramic Rapid Response)

– 4 small wide-field telescopes

– 6000 sq deg per night r=24

LSST (Large Survey Synoptic Telescope)

– 8-m telescope, 3 sq.deg fov; 3200 Mpixels

– 5-band; 18,000 sq.deg; 26.5 AB

– 10 Petabyte/year; 100 Mpixels/sec (2012) !!!

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Next Generation (IR)Next Generation (IR)

UKIDSS

– UKIRT 4-m; 4 2k x 2k Rockwell devices 0.21 sq.deg.

– LAS 4000 sq.deg K =18.4

– GPS 1800 sq.deg K=19.0

– GCS 1400 sq.deg K=18.7

– DES 33 sq.deg. K=21

– UDS 0.77 sq.deg. K=23.0

VISTA

– 4-m telescope; 1 sq.deg. Fov; 16 2k x 2k

– Data rate from observations 1.28 Mpix/sec

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Optical Near IR

QUEST

SDSS

CFH-L

LSST

DLS

NWDS

GOODS

BTC

CFH-L NWDS

UDFHDF

VST

PS

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ChallengesChallenges

Cope with :– large data rates and volumes– different instruments and/or strategies– archival data

Enable re-calibration (tests) of large sets and comparison with previous versions (talk to 2MASS and SDSS people)

Ensure quality of large volume and diverse nature of products– Reduced (nightly), subtracted, stack and mosaic images;– single-band, color catalogs– galaxy and star catalogs, clusters of galaxies, color-selected objects

Administrate & distribute data/products/information timely

Small budgets for operation

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In other words …In other words …

How to enable relative small teams to efficiently provide reliable data from which to extract science from manysimultaneous SLOANS (in volume) using different instruments and observing techniques

Not even with several graduate students !!!

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Basic RequirementsBasic Requirements

High-throughput, instrument-independent image processing system– keep up with input data rate– handle time critical observations (SN searches, short-period variability)– integrate scheduling & reductions to optimize observations

Administrative layer for: data management, consolidated procedures, and bookkeeping

Re-calibration: associated database enabling version; history; comparison

Well-defined interfaces between processes to:– Ensure quality & consistency of survey products– Provide support for configurable workflows – Avoid relying on individuals

Software enabling un-supervised operations in 24/7 duty-cycle over long stretches of time

Flexible hardware architecture to optimize operations (beowulf x cluster)

The EIS experienceNew Science requires new techniques