Astronomical image

The astronomical image may be any suitable image, provided it has WCS information. It should be as large as the size of the map to be made. The WCS is used unless the source is a moving object (listed above). The image must be an NDF. It is recommended that the image pixel scale be set to be much less than the likely output map pixel spacing (typically 3 arcsec at 850 $\mu$m, 1 arcsec at 450 $\mu$m) to avoid imaging and sampling artefacts.