Grid-Free Deconvolution Directly From Visibilities
Project description
Spotless - Radio Interferometry Imaging Algorithm
This is a point-source deconvolution algorithm (part of the CLEAN family) that works without gridding. [http://www.iram.fr/IRAMFR/GILDAS/doc/html/map-html/node37.html]
This is essentially a grid-free version of the Cotton-Schwab algorithm with a different convergence an optimization steps. [Relaxing the isoplanatism assumption in self-calibration; applications to low-frequency radio interferometry]
It does not require W-projection and handles non-coplanar antennas without difficulty. It also works on all-sky images just fine.
Spotless works in a similar way to Hogbom's CLEAN algorithm, however
![Dirty, Spotless and Residual][tart_image]
For more information see the TART Github repository
Install Instructions
tart_tools is available from standard python package repositories. Try:
pip install spotless
Running it on live data
spotless --api https://tart.elec.ac.nz/signal --display --show-sources
gridless --api https://tart.elec.ac.nz/signal --display --show-sources
TODO
- Add Gaussian Source Model
- Make explicit the antenna model (gain as a function of angular coordinates). We are assuming it is hemispherical here.
- Prove the relationship between power in the image and visibilty amplitudes. This might only work when the image tends towards a random one. But this is OK since as we remove the sources the residual becomes more and more random.
- Run an MCMC on the multimodel option to estimate uncertainty in the model. Then use this uncertainty as a stopping criterion (when new model components no longer have certain amplitude or position)
Author
- Tim Molteno (tim@elec.ac.nz)
Development work
If you are developing this package, this should be installed using
make develop
in which case changes to the source-code will be immediately available to projects using it.
Changes
- 0.4.1 Use the disko sphere. Clean up unused code. Use harmonics from disko. Specify the --fov and --res as in disko
- 0.4.0 Move to github repository. Add to pypi. Use disko for utility functions. Add a --version CLI argument
- 0.3.0 Update to python3
- 0.3.3 Add a gridless binary to plot a GRIDLESS imaging, add a PDF export option
- 0.3.4 Fix bitrot in multispotless.
Project details
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