The Following text was taken from the ESA Science site: URL: http://isowww.estec.esa.nl/science/
In this image, a map of the Infra-Red sky has been overlaid with the slew paths used by the ISOPHOT Serendipity Survey. The slew paths have been expanded for clarity, from their actual 3 arcmin width.
The survey is carried out at 175 microns with a point source detection limit of approximately 1 Jy and the surface brightness detection limit 1 MJy/sr. By the end of the mission approximately 125 000 degrees of slew length will have been observed, covering approximately 15% of the sky.
A complete description of the survey can be found in the paper "First data from the ISOPHOT serendipity survey", by S. Bogun, which has been published in an ISO dedicated issue of Astronomy and Astrophysics Letters.
INFRARED PROCESSING AND ANALYSIS CENTER