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SDSS Web Services
Tamás BudaváriJohns Hopkins University
Coding against the UniverseCoding against the Universe
SC4DEVO-1 Tamás Budavári (JHU) 2
OutlineSDSS Primer
Technology
Web ServicesData Access• Images• Spectra• Catalog
Higher Level
SC4DEVO-1 Tamás Budavári (JHU) 3
SDSS Imaging Survey2.5m telescope
Apache Point, NM5 photometric bandsDrift scan operation
Photo pipeline100,000,000 galaxiesAutomated reductionCatalog archive server
SC4DEVO-1 Tamás Budavári (JHU) 4
NGC 2068
SC4DEVO-1 Tamás Budavári (JHU) 5
UGC 3214
SC4DEVO-1 Tamás Budavári (JHU) 6
NGC 6070
SC4DEVO-1 Tamás Budavári (JHU) 7
SDSS SpectropscopyTwo spectrographs
Red and blue partOptical fibers 640 in each bundlePlugged manually
Automatic reduction2D and 1D pipelinesCatalog archive server
SC4DEVO-1 Tamás Budavári (JHU) 8
SC4DEVO-1 Tamás Budavári (JHU) 9
Developing Web ServicesWe chose the .NET Framework
The C# programming languageExtensive class library (for free)Simple and efficient database accessFast imaging and graphics routinesRapid development in Visual StudioVery easy Web Services programming
Use CVS for versioning
SC4DEVO-1 Tamás Budavári (JHU) 10
Custom Tools and PackagesWrapper for CFITSIOCFITSIO by Vivek Haridas (JHU)
Access to FITS tables and images from C#XML Web Services return FITS in attachment
Scientific PlottingUsing TeeChart LiteFast plotting of online data
SC4DEVO-1 Tamás Budavári (JHU) 11
Available Web ServicesSDSS Web Services
Field Finder and SIAPSDSS Image CutoutSpectrum and Filter ServicesScientific Catalog ArchiveDensityMap Services
Other Relevant ServicesNED Services WrapperCosmic Distances
SC4DEVO-1 Tamás Budavári (JHU) 12
SDSS Fields and SIAField Images
Search for fields (HTM)Get all info, e.g. WCSReturns links to FITS
Simple Image AccessWrapper on top of FieldsReturns links in VOTable
SC4DEVO-1 Tamás Budavári (JHU) 13
SDSS Image CutoutBuild JPEG mosaics
For given (RA, Dec)Arbitrary zoom levelsOverplot catalog dataOverplot geometryMapQuest like navigationList of objects
Proper WSJPEG returned in DIMEor byte array
SC4DEVO-1 Tamás Budavári (JHU) 14
Spectrum ServicesPublic repository
500,000 spectra (2B row)Spatial search and moreRegister & submit yours
Web siteOn-the-fly plottingBuilding composites
Web servicesMore options and tools
SC4DEVO-1 Tamás Budavári (JHU) 15
SDSS Catalog ServicesCasJobs
Access to a 1TB of data80M unique galaxiesQueue system for SQLMyDB• 500MB remote DB• Upload and extract
Web servicesWeb site interfaceCommand-line client
SC4DEVO-1 Tamás Budavári (JHU) 16
SDSS DensityMap ServicesA SQL query to image converter
Select x,y,f and build color coded f(x,y) image
SC4DEVO-1 Tamás Budavári (JHU) 17
Other ServicesWrapper for NED
Name resolver functionSearch by coordinate
Available from
Cosmic DistancesVarious distance measuresUsing ΛCDM cosmology
NED ned = new NED();ObjInfo o = ned.ObjByName(“m101”);/* Use o.ra, o.dec, etc… */
Distance d = new Distance();float z=0.1, h=0.7, m=0.3, l=0.7;float r = d.Luminosity(z,h,m,l);
http://www.voservices.org
SC4DEVO-1 Tamás Budavári (JHU) 18
Consuming Web Services
SC4DEVO-1 Tamás Budavári (JHU) 19
ConclusionsSDSS Web Services……provide access to scientific data and tools…are (very) easy to consume…are being used :-)
Development coordinated w/ IVOAOpen SkyQuery for federating archivesSDSS Open SkyNode
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