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BEGIN:VEVENT
DTSTART;TZID=Atlantic/Canary:20131205T223000
DTEND;TZID=Atlantic/Canary:20131205T233000
UID:iactalks-571
X-WR-CALNAME: IAC Talks: Open Astronomy Seminars
X-ORIGINAL-URL: /iactalks/Talks/view/571
CREATED:2013-12-05T22:30:00+00:00
X-WR-CALDESC: IAC Talks upcomming talks
SUMMARY:Imfit: A fast, flexible new program for fitting galaxy images
DESCRIPTION:Imfit: A fast, flexible new program for fitting galaxy images\n
 Dr. Peter Erwin\n\nI will discuss a new, open-source astronomical image-fi
 tting program,  specialized for galaxies, which is fast, flexible, and hig
 hly  extensible. A key characteristic is an object-oriented design which  
 allows new types of image components (2D surface-brightness functions)  to
  be easily written and added to the program. Image functions provided  wit
 h the program include the usual suspects for galaxy decompositions  (Sersi
 c, exponential, Gaussian), along with Core-Sersic and  broken-exponential 
 profiles, elliptical rings, and components which  perform line-of-sight in
 tegration through 3D luminosity-density models  of disks and rings seen at
  arbitrary inclinations. Minimization can be  done using the standard chi^
 2 statistic (using either data or model  values to estimate per-pixel erro
 rs) or the Cash statistic, which is  appropriate for Poisson data in low-c
 ount regimes; different  minimization algorithms allow trade-offs between 
 speed and decreased  sensitivity to local minima in the fit landscape.  I 
 will also show that  fitting low-S/N galaxy images by minimizing chi^2 can
  lead to  significant biases in fitted parameter values, which are avoided
  if the  Cash statistic is used; this is true even when Gaussian read nois
 e is  present.
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