Post on 25-Sep-2020
transcript
hips2fits Fast generation ofFITS cutoutsfrom HiPS datasets
Thomas Boch, P. Fernique, F. Bonnarel, Chaitra, C. Bot, F.-X. Pineau, M. Baumann, L. Michel IVOA Interop, Groningen, Apps 2
IVOA Groningen - Oct 2019 - hips2fits - Apps 2
HiPSdatasetscollections
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700+ image HiPS
60+ planetary HiPS
IVOA Groningen - Oct 2019 - hips2fits - Apps 2
Firstimplementations
• AladinDesktopcodebehindTomcatserver—>bilinearresampling
• Othertestsusingstandard reprojectiontools
• Montage
• reproject
• SWarp3
IVOA Groningen - Oct 2019 - hips2fits - Apps 2
Globalarchitecture
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IVOA Groningen - Oct 2019 - hips2fits - Apps 2
Algorithm
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1.Foreach(x,y)pixel:computeα,δ (usingAstropyWCS)
2.RetrieveNlescoveredbythecutout—>quitefastasmostHiPSareavailableormirroredatCDS
3.Foreach(α,δ):retrieverespecNvecontribuNon from4nearestHEALPixcells(usingcdshealpix(Rust-based)Pythonlibrary)
4.ActualbilinearinterpolaNoncomputaNon,acceleratedbyNumbadecorators
5.ReturnFITSimagecutout
WCS, hips
FITS cutout
x, y α, δ
0.3 0.5
0.10.1
value = w1*val1 + w2*val2 + w3*val3 + w4*val4
IVOA Groningen - Oct 2019 - hips2fits - Apps 2
Performances
6
500k pixels per second
IVOA Groningen - Oct 2019 - hips2fits - Apps 2
Serviceupandrunning
• http://alasky.u-strasbg.fr/hips-image-services/hips2fits• testit
• useit
• sendyourfeedback
• Pythonnotebookexample
• generatecutoutsforMgalaxiesinNHiPSdatasets
• Examplesofgeneratedcutouts… …onthedome!
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IVOA Groningen - Oct 2019 - hips2fits - Apps 2
Usageforoutreachneeds
• Generationofphotospheres
• All-skyCARtesianprojectionwithXMPmetadata
—>UsedbyGiuseppeGreco(VIRGO)forGravitationalWavesoutreach
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IVOA Groningen - Oct 2019 - hips2fits - Apps 2
Futureplans
• Accessfromastroquery.cds
• AchieveconvergencewithSODAinterface
• Extensiontocubecutouts
• Assessphotometryconservationquality
• AmessagetoHiPSproducers:
• «please,keepyourFITStiles,theyareprecious!»
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