2ddata_centroid

List of centroid software

from email to astropy list (subject: got centroid?):

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import scipy.ndimage as snd labels, num = snd.label(imageData > (2.*sigma), np.ones((3,3))) starCoordinates = snd.center_of_mass(imageData, labels, range(1,num+1))

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You can get the entire webbpsf package from http://www.stsci.edu/jwst/software/webbpsf, but as that's overkill for this purpose I attach here just the one relevant file.

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One option is PyGuide: http://www.astro.washington.edu/users/rowen/PyGuide/Manual.html

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sextractor wrappers: https://gitorious.org/pysextractor http://supernovae.in2p3.fr/~llg/SExtractor/sextractor.tgz

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astropysics.utils.centroid

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I found an interesting algorithm for calculating star centroids in the following paper, appendix B. http://lanl.arxiv.org/pdf/astro-ph/9907229v1.pdf -- maybe in aspylib.com

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A PhD student here, Nate Lust, has spent considerable time evaluating centering (not centroiding) algorithms. The quickest and worst is the usual center-of-light algorithm. He has a fast Python/C implementation of the Gunn-Owen least-asymmetry algorithm that he may be willing to share. The other easy one is simply fitting a Gaussian + constant offset to the inner part of the PSF. Nate is working on a paper that evaluates these vs. real and synthetic data. He and Kevin Stevenson published preliminary results in the Supplementary Information to:

Stevenson, K. B., J. Harrington, S. Nymeyer, N. Madhusudhan, S. Seager, W. C. Bowman, R. Hardy, D. Deming, E. Rauscher, and N. Lust 2010. Possible thermochemical disequilibrium in the atmosphere of the exoplanet GJ 436b. Nature 464, 1161–1164.

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drizzlepac package available from STScI: http://stsdas.stsci.edu/irafx