Astron. Astrophys. Suppl. Ser. 136, 205-209
Astronomical Observatory of Padova, vicolo dell'Osservatorio 5,
I-35122 Padova, Italy
Received November 12; accepted December 7, 1998
In order to get diffraction limited imaging on large telescopes using Laser Guide Stars one needs to fire several such artificial beacons angularly displaced with respect to the science target. Such displacement scales with the diameter of the telescope. It is pointed out that when this angle exceeds some given figure it can be more efficient to use directly some off-axis Natural Guide Stars. With realistic assumptions it turns out that next generation giant telescopes could benefit from this technique and could not require any Laser Guide Star.
Key words: telescopes -- instrumentation: adaptive optics
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