The method used to align two images is based on normalized cross-correlation, and is a widely used method in many disciplines, including astronomy (please see the article ``Proceedings of the SPIE, Advanced Signal Processing Algorithms, Architectures, and Implementations XV1, Vol. 6313, pp. D1-D13, San Diego, CA, Aug. 2006.) It should be noted that this functionality is new in Version 2, and since only a limited amount of testing has been done it should be used with caution. The correlation images should be examined to check that there is a good peak and the computed offsets checked.
The following command-line, ommosaic imagesets=''image1 image2 ...'' mosaicedset=mosaicedimage.fits mincorr=0.5 correlset=correl.fits attempts to align the images image1, image2, stacks the images that have been successfully aligned (ie those with a computed correlation coefficent of at least equal to 0.5, stores the stacked image in the file mosaicedimage.fits and the correlation images in the file correl.fits.