The precision of the ISO pointing has implications for the performance
of the SWS, which requires a pointing jitter 
and a similar pointing drift. For a discussion of pointing, and the problems
that occur due to mis-pointing, see the ISO Satellite Data Users Manual (ISO
DUM, SAI/95-218/Dc) and the SWS Data User Manual (SWS IDUM, SAI/95-221/Dc).
These are distributed on the CD-ROMs and are also available on the ISO WWW
site (http://www.iso.vilspa.esa.es/).
Observing with SWS requires a pointing
accuracy of a few arcseconds in order to bring a source to the center of the
fields of view that range in size between 
and 
and to prevent errors in flux and wavelength calibration.
Observers have to provide source positions accurate to about 1'' with their proposal. In particular, IRAS positions are not accurate enough for SWS follow up and need to be improved by independent preparatory data.
Observers do not have to take into account offsets that originate in the drift of the boresight between the SWS optical axis and the startrackers used for pointing. These will be calibrated regularly by the Science Operations Team, resulting in pointing accurate to a few arcsec on given absolute positions.