CLARK

The most popular variant to the HOGBOM algorithm is due to Clark (1980). The iterative search for point sources involves minor and major cycles.

In minor cycles,

an HOGBOM search is performed with two limitations: 1) Only the brightest pixels are considered in the above step 1 and 2) the convolution of the found point sources (step 3 above) is done with a spatially truncated dirty beam. Both limitations fasten the search but may lead to difficult convergence in cases where the secondary side lobes are a large fraction (e.g. 40%) of the main side lobe.

In major cycles,

the clean components found in the last minor cycle are removed in a single step from the residual map in the Fourier plane. The use of the Fourier transform enable to clean slightly more than the inner quarter of the map.