Testing GalfitTesting GalfitClemens Trachternach1, Olaf Schmithüsen1, Gijs Verdoes Klein2, Ewout Helmich2, Dominik Bomans1 ,Ralf-Jürgen Dettmar1, Oliver-
Mark Cordes3, Thomas Erben3, Hendrik Hildebrandt3, Patrick Hudelot3, …
1Astronomisches Institut, Ruhr-Uni Bochum
2Kapteyn Instituut, Rijks-Universiteit Groningen
3Argelander Institut für Astronomie, Uni Bonn
21.11.2006 Astro-WISE Workshop 2006 2
CFHTLSCanada France Hawaii Telescope Legacy Survey
• 36 CCDs• 1 deg² FoV• 1.2hr exposure time in
i-band• MagZP = 25.75 mag• Seeing 0.95’’• Comparable to the KIDS
data
21.11.2006 Astro-WISE Workshop 2006 3
Contaminant correction
• Galfit does χ²-minimization “at all costs“• Galfit needs to know that there is a second object (or
third, or…) to fit it with a new component• Need to think of selection criteria for primary AND
secondary objects
One possibility (the one I made my tests with):• Object inside fitting region, near primary object and not
more than “a few“ magnitudes fainter• Object just outside fitting region but brighter than primary
add component
21.11.2006 Astro-WISE Workshop 2006 4
Contaminant correction
Run 1a Run 1b Run 2a Run 2b
DETECT_MINAREA
(min. area for 2nd object)30 50 50 70
MINAREA_PRIMARY 100 100 150 150
Number of objects 35.000 25.000 25.000 20.000
Objects fitted 11367 11453 7239 7278
Needed time 90 h 75 h 80 h 74 h
21.11.2006 Astro-WISE Workshop 2006 5
Profile Expdisk SersicB/D
(Sersic+Expdisk)
total time / time per obj.(2.6GhZ P4 4GB Ram)
39.5 h
~ 12 s
47 h
~ 14.4 s
102 h
~ 32 s
DETECT_MINAREA (for 2nd object): 30
MINAREA_PRIMARY: 100
~35000 objects in catalogue
~ 11800 objects as “primary” objects
Running Galfit with different profiles
21.11.2006 Astro-WISE Workshop 2006 6
Galfit got stuck
21.11.2006 Astro-WISE Workshop 2006 7
Galfit got stuck
• Need a maximum number of iterations
• If this already exists
Check why it didn’t stop
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