spotless 0.4.1

Grid-Free Deconvolution Directly From Visibilities

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 ([e-mail])

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.