  Adaptive optics (AO) systems allow a telescope to reach its diffraction limit
at near infrared wavelengths. But to achieve this, a bright natural guide star
(NGS) is needed for the wavefront sensing, severely limiting the fraction of
the sky over which AO can be used. To some extent this can be overcome with a
laser guide star (LGS). While the laser can be pointed anywhere in the sky, one
still needs to have a natural star, albeit fainter, reasonably close to correct
the image motion (tip-tilt) to which laser guide stars are insensitive. There
are in fact many astronomical targets without suitable tip-tilt stars, but for
which the enhanced resolution obtained with the Laser Guide Star Facility
(LGSF) would still be very beneficial. This article explores what adaptive
optics performance one might expect if one dispenses with the tip-tilt star,
and in what situations this mode of observing might be needed.
