Imfit
swMATH ID:  29005 
Software Authors:  Peter Erwin 
Description:  Imfit: A Fast, Flexible New Program for Astronomical Image Fitting. I describe a new, opensource astronomical imagefitting program called Imfit, specialized for galaxies but potentially useful for other sources, which is fast, flexible, and highly extensible. A key characteristic of the program is an objectoriented design which allows new types of image components (2D surfacebrightness functions) to be easily written and added to the program. Image functions provided with Imfit include the usual suspects for galaxy decompositions (Sersic, exponential, Gaussian), along with CoreSersic and brokenexponential profiles, elliptical rings, and three components which perform lineofsight integration through 3D luminositydensity models of disks and rings seen at arbitrary inclinations. Available minimization algorithms include LevenbergMarquardt, NelderMead simplex, and Differential Evolution, allowing tradeoffs between speed and decreased sensitivity to local minima in the fit landscape. Minimization can be done using the standard chi^2 statistic (using either data or model values to estimate perpixel Gaussian errors, or else usersupplied error images) or Poissonbased maximumlikelihood statistics; the latter approach is particularly appropriate for cases of Poisson data in the lowcount regime. I show that fitting lowS/N galaxy images using chi^2 minimization and individualpixel Gaussian uncertainties can lead to significant biases in fitted parameter values, which are avoided if a Poissonbased statistic is used; this is true even when Gaussian read noise is present. 
Homepage:  https://www.mpe.mpg.de/~erwin/code/imfit/ 
Source Code:  https://github.com/perwin/imfit 
Dependencies:  C++ 
Keywords:  Astronomical Image Fitting; Astrophysics; arXiv_astroph.IM; Galaxies; arXiv_astroph.GA; photometry 
Related Software:  FFTW; BUDDA; GALFIT; GIM2D; NumPy; SCons; CxxTest; CFITSIO; MPFIT; NLopt; Sherpa; MGE; GALMORPH; ELLIPSE; LaplaceApproximation; cmaes; LaplacesDemon; R2Cuba; Python; GASPHOT 
Cited in:  0 Documents 
Standard Articles
1 Publication describing the Software  Year 

Imfit: A Fast, Flexible New Program for Astronomical Image Fitting arXiv Peter Erwin 
2014
