  A sample of the brightest point-like sources observed with the ROSAT-HRI were
analysed to asses on the intrinsic shape of the ROSAT-HRI Point Spread Function
(PSF). Almost all of the HRI observations collected during the ROSAT lifetime
are found to be artificially broadened by factors up two ~2 due to residual
errors in the ROSAT aspect solution. After correction by departing pointing
positions, the width of the core of the PSF is found to be less than 5 arcsec
(half energy width, HEW). On the basis of these results, an improved analytical
representation of the ROSAT-HRI PSF is provided. However, for most of the new
observations the source countrate is too weak to allow reliable recovering pf
the ROSAT-HRI resolution. Therefore, a series of examples (data, correction,
and theoretical PSF) are given in order to help the ROSAT user in determining
whether "his/her source" is extended or not.
