[ascl:1604.008]
The Tractor: Probabilistic astronomical source detection and measurement

The Tractor optimizes or samples from models of astronomical objects. The approach is generative: given astronomical sources and a description of the image properties, the code produces pixel-space estimates or predictions of what will be observed in the images. This estimate can be used to produce a likelihood for the observed data given the model: assuming the model space actually includes the truth (it doesnâ€™t, in detail), then if we had the optimal model parameters, the predicted image would differ from the actually observed image only by noise. Given a noise model of the instrument and assuming pixelwise independent noise, the log-likelihood is the negative chi-squared difference: (image - model) / noise.

- Code site:
- https://github.com/dstndstn/tractor
- Used in:
- http://adsabs.harvard.edu/abs/2014arXiv1410.7397L http://adsabs.harvard.edu/abs/2016AJ....151...44D

- Bibcode:
- 2016ascl.soft04008L

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