CPLUCY

The plucy method has several disadvantages for some work. Firstly the requirement that points were $\delta$-functions which had to be located at the centres of pixels in the point-source image made setting the correct positions, which could really be anywhere within a pixel, problematic and normally required highly sub-sampled images which led to unrealistically large images. This restriction has been removed in the modified code cplucy. In this case the points are not $\delta$-functions but instead simply X,Y positions at arbitrary sub-pixel positions. At the start of the code the supplied PSF (which should be well-sampled and may be on a finer pixel grid than the data) is shifted to the appropriate position for each point source and a small internal library of correctly positioned PSFs used during subsequent processing. This also allows the PSF images to be much smaller than the full data frames which is normally the case. The cplucy code is available. and will form part of the forthcoming release of the stecf IRAF package along with many of the other tasks described here. An example of using CPLUCY on HST/NICMOS images of the Orion molecular cloud is described in Hook & Stolovy 1998.