ETVS UNIVERSITY BUDAPEST Department of Physics of Complex

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EÖTVÖS UNIVERSITY BUDAPEST Department of Physics of Complex Systems Spectrum Services 2007 László Dobos

EÖTVÖS UNIVERSITY BUDAPEST Department of Physics of Complex Systems Spectrum Services 2007 László Dobos (ELTE) [email protected] elte. hu Tamás Budavári (JHU), István Csabai (ELTE) VO Spectroscopy Workshop, ESAC 2007 1

MOTIVATIONS • SDSS Data Archive Server offers very limited possibility to search among spectra

MOTIVATIONS • SDSS Data Archive Server offers very limited possibility to search among spectra • Sky. Server has nice search features, but does not contain the spectra • Observed spectra are in many formats: – – binning wavelength scale (air / vacuum) extinction correction file format VO Spectroscopy Workshop, ESAC 2007 2

SPECTRUM & FILTER SERVICES • • Database of spectra Wide range of search possibilities

SPECTRUM & FILTER SERVICES • • Database of spectra Wide range of search possibilities Preprocessing spectra on the fly Data analysis Access to data in many file formats Plot spectra Web interface Web service to program against • Filter service: database of optical instrument band-pass curves VO Spectroscopy Workshop, ESAC 2007 3

VO Spectroscopy Workshop, ESAC 2007 4

VO Spectroscopy Workshop, ESAC 2007 4

VO Spectroscopy Workshop, ESAC 2007 5

VO Spectroscopy Workshop, ESAC 2007 5

AVAILABLE SPECTRA • Repository of observed and theoretical spectra – – SDSS DR 1

AVAILABLE SPECTRA • Repository of observed and theoretical spectra – – SDSS DR 1 -DR 5 (1 M spectra in DR 5 only) 2 d. F (250 k) Ba. Se. L stellar library Bruzual-Charlot stochastic burst model library (100 k) • 'My Spectrum' is a public repository where users can upload their own measurements or save results of spectrum processing. VO Spectroscopy Workshop, ESAC 2007 6

SEARCH POSSIBILITIES • • • Cone search - search by coordinates and radius ID

SEARCH POSSIBILITIES • • • Cone search - search by coordinates and radius ID search - if you know the database identifier (ie. from Sky. Server) Object search - by a list of coordinates Redshift search Advanced search - with many basic options • Region search - gives back spectra of objects in a complex, arbitrary area • Similarity search - based on PCA VO Spectroscopy Workshop, ESAC 2007 7

3. REGION SEARCH • The new Footprint Service allows defining complex regions on the

3. REGION SEARCH • The new Footprint Service allows defining complex regions on the sphere • Spectrum Services link to the Footprint Service to get region description • Spectra observed in the given region can be retrieved from the database VO Spectroscopy Workshop, ESAC 2007 8

VO Spectroscopy Workshop, ESAC 2007 9

VO Spectroscopy Workshop, ESAC 2007 9

4. SIMILAR SPECTRUM SEARCH • Spectra are expanded on a predefined basis PCA (see

4. SIMILAR SPECTRUM SEARCH • Spectra are expanded on a predefined basis PCA (see Ching-Wa's talk) or model spectra • Coefficients are stored in a multi-dimensional database • Database is indexed by special spatial indices • N-Nearest neighbour search in the coefficient space • Not necessarily physical, still interesting VO Spectroscopy Workshop, ESAC 2007 10

GALAXIES VO Spectroscopy Workshop, ESAC 2007 11

GALAXIES VO Spectroscopy Workshop, ESAC 2007 11

PREPROCESSING TOOLS • General functions to convert spectra to the same format to use

PREPROCESSING TOOLS • General functions to convert spectra to the same format to use in analysis • Functions: – – – Correction for galactic extinction Rest frame Normalization Rebinning Vacuum - Air wavelength conversion • Download preprocessed spectra (XML, VOTable, ASCII) • Store them in 'My. Spectrum' for later use VO Spectroscopy Workshop, ESAC 2007 12

ANALYSIS TOOLS • Composite spectrum: – average, median • Convolution with filters from Filter

ANALYSIS TOOLS • Composite spectrum: – average, median • Convolution with filters from Filter Service synthetic magnitude calculation • Continuum and line fitting • The new version will be really fast: – Parallel computation on multiple processor – optimized LAPACK libraries VO Spectroscopy Workshop, ESAC 2007 13

VO Spectroscopy Workshop, ESAC 2007 14

VO Spectroscopy Workshop, ESAC 2007 14

SUMMARY & FUTURE WORKS • Spectrum database and public repository • Web site &

SUMMARY & FUTURE WORKS • Spectrum database and public repository • Web site & web service • Integration with other VO services: – Filter Service, Footprint Service • Preprocessing and analyzis tools • Improved line fitting algorithm • Make similarity search public • Latest VO standard implementation VO Spectroscopy Workshop, ESAC 2007 15

URLs OF INTEREST • Spectrum Services http: //voservices. net/spectrum • Filter Service http: //voservices.

URLs OF INTEREST • Spectrum Services http: //voservices. net/spectrum • Filter Service http: //voservices. net/filter • Footprint Service http: //voservices. net/footprint VO Spectroscopy Workshop, ESAC 2007 16

VO Spectroscopy Workshop, ESAC 2007 17

VO Spectroscopy Workshop, ESAC 2007 17

Distribution of SDSS objects in the space of SDSS galaxy eigenspectra Galaxies Stars QSOs

Distribution of SDSS objects in the space of SDSS galaxy eigenspectra Galaxies Stars QSOs VO Spectroscopy Workshop, ESAC 2007 18

WEB INTERFACE • For interactive use by humans • Concept: try the functions on

WEB INTERFACE • For interactive use by humans • Concept: try the functions on the web page, but use the web service for batch processing • Register / login • Search and display results in a nice format • 'Wizards' to guide users through the pages of many parameters of scientific functions • Download spectra in XML, VOTable, ASCII • (No implementation of the latest DM yet) VO Spectroscopy Workshop, ESAC 2007 19

2. SPEEDING UP SPECTRUM SERVICES • Objective: processing hundreds of thousands of spectra •

2. SPEEDING UP SPECTRUM SERVICES • Objective: processing hundreds of thousands of spectra • Moved to. Net 2. 0 - Better computing performance • Streamlined processing of spectra – Minimal memory usage – No upper limit for number of spectra • Multi-processor support – parallel execution of processing routines • Optimized LAPACK integration: – MKL (intel), ACML (AMD) VO Spectroscopy Workshop, ESAC 2007 20

4. 1 THE ECOEFF SPACE • DR 4 galaxy eigenspectra used as basis (Yip

4. 1 THE ECOEFF SPACE • DR 4 galaxy eigenspectra used as basis (Yip et. al 2002) from gappy PCA algorithm • All spectra (even stars and QSOs) are expressed on this basis • Our method: minimal χ2 fitting (with masks etc. ) • Applied to: – SDSS DR 5 – Charlot's stochastic 100 k spectrum set • Objective: find physical parameters very quickly VO Spectroscopy Workshop, ESAC 2007 21