sep 8, 20082008 nvo summer school1 wcsfixer a web-enabled iraf plate solver mike fitzpatrick, noao t...

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Sep 8, 2008 2008 NVO Summer School 1 WCSFixer A Web-Enabled IRAF Plate Solver Mike Fitzpatrick, NOAO THE US NATIONAL VIRTUAL OBSERVATORY

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Page 1: Sep 8, 20082008 NVO Summer School1 WCSFixer A Web-Enabled IRAF Plate Solver Mike Fitzpatrick, NOAO T HE US N ATIONAL V IRTUAL O BSERVATORY

Sep 8, 2008 2008 NVO Summer School 1

WCSFixerA Web-Enabled IRAF Plate Solver

Mike Fitzpatrick, NOAO

THE US NATIONAL VIRTUAL OBSERVATORY

Page 2: Sep 8, 20082008 NVO Summer School1 WCSFixer A Web-Enabled IRAF Plate Solver Mike Fitzpatrick, NOAO T HE US N ATIONAL V IRTUAL O BSERVATORY

Sep 8, 2008 2008 NVO Summer School 2

Motivation and Requirements

• A correct image WCS is fundamental to a lot of VO processing (e.g. Catalog generation and X-match, data quality). So,a service is needed that – Given an image with a poor WCS, will improve it;– Given an image with no WCS, will find one;– Given an image with a non-standard WCS, will

standardize it (e.g. DSS plate solutions)• Must run from a web-browser and return the

corrected image• Provides good feedback to the user about what

was done and the quality of the solution

Page 3: Sep 8, 20082008 NVO Summer School1 WCSFixer A Web-Enabled IRAF Plate Solver Mike Fitzpatrick, NOAO T HE US N ATIONAL V IRTUAL O BSERVATORY

Sep 8, 2008 2008 NVO Summer School 3

Design Goals

NGC3104

• Interactive interface

• Single-page display

• Exploit IRAF capabilities

• More than a simple web-based form

• Should be fun to write

Page 4: Sep 8, 20082008 NVO Summer School1 WCSFixer A Web-Enabled IRAF Plate Solver Mike Fitzpatrick, NOAO T HE US N ATIONAL V IRTUAL O BSERVATORY

Sep 8, 2008 2008 NVO Summer School 4

DEMO

Page 5: Sep 8, 20082008 NVO Summer School1 WCSFixer A Web-Enabled IRAF Plate Solver Mike Fitzpatrick, NOAO T HE US N ATIONAL V IRTUAL O BSERVATORY

Sep 8, 2008 2008 NVO Summer School 5

Technology Used

• SOA – AJAX

Page 6: Sep 8, 20082008 NVO Summer School1 WCSFixer A Web-Enabled IRAF Plate Solver Mike Fitzpatrick, NOAO T HE US N ATIONAL V IRTUAL O BSERVATORY

Sep 8, 2008 2008 NVO Summer School 6

Technology Used

• SOA – AJAX (Simple, Only Apparently AJAX)

Page 7: Sep 8, 20082008 NVO Summer School1 WCSFixer A Web-Enabled IRAF Plate Solver Mike Fitzpatrick, NOAO T HE US N ATIONAL V IRTUAL O BSERVATORY

Sep 8, 2008 2008 NVO Summer School 7

Technology Used

• SOA – AJAX (Simple, Only Apparently AJAX)

• IRAF/CL scripts for plate solution/graphics (~15 separate tasks)

• HTTP/POST service• C-shell CGI script for form processing• HTML iframes for layout• CSS and Javascript for style/dynamic content• Embedded Javascript in return stream for

driving the user interface

Page 8: Sep 8, 20082008 NVO Summer School1 WCSFixer A Web-Enabled IRAF Plate Solver Mike Fitzpatrick, NOAO T HE US N ATIONAL V IRTUAL O BSERVATORY

Sep 8, 2008 2008 NVO Summer School 8

Algorithm

• Verify image is valid (2-D, not an MEF, etc)• Set initial conditions from user input or image header• Generate reference catalog of what should be in the

field• Generate a catalog of detected objects in the image• Cross-match the two catalogs (triangle algorithm, N

brightest objects used)• If (no solution found) {

iterate by searching param space (e.g. No clipping) } else {

compute plate solutionupdate image, data products }

Page 9: Sep 8, 20082008 NVO Summer School1 WCSFixer A Web-Enabled IRAF Plate Solver Mike Fitzpatrick, NOAO T HE US N ATIONAL V IRTUAL O BSERVATORY

Sep 8, 2008 2008 NVO Summer School 9

Why Doesn't it Always Work?

• Too many points• Not enough points• Scale problems lead to bogus solution• Selection Effect• Image Geometry

Page 10: Sep 8, 20082008 NVO Summer School1 WCSFixer A Web-Enabled IRAF Plate Solver Mike Fitzpatrick, NOAO T HE US N ATIONAL V IRTUAL O BSERVATORY

Sep 8, 2008 2008 NVO Summer School 10

Other Astrometry Engines

• Astrometry.net– Downloadable software– Image formats supported– No starting info required

• SCAMP - WCS solutions from SExtractor catalogshttp://terapix.iap.fr

• Automatch - John Thorstensen’s toolshttp://mdm.kpno.noao.edu/Manuals/automatch.html

• Pitt WCS Fixerhttp://nvogre.phyast.pitt.edu/wcs/

Page 11: Sep 8, 20082008 NVO Summer School1 WCSFixer A Web-Enabled IRAF Plate Solver Mike Fitzpatrick, NOAO T HE US N ATIONAL V IRTUAL O BSERVATORY

Sep 8, 2008 2008 NVO Summer School 11

Future Work (Maybe)

• Web-Service interface• Return reference/image catalogs

(VOTable)• Process multiple images (SIAP query

table input instead of single image)• Desktop application via VO Client• Automatically explore parameter space

Page 12: Sep 8, 20082008 NVO Summer School1 WCSFixer A Web-Enabled IRAF Plate Solver Mike Fitzpatrick, NOAO T HE US N ATIONAL V IRTUAL O BSERVATORY

Sep 8, 2008 2008 NVO Summer School 12