Performance of the SOAR adaptive module with UV Rayleigh guide star

The adaptive module of the 4-m SOAR telescope (SAM) has been tested on the sky by closing the loop on natural stars. Then it was re-configured for operation with low-altitude Rayleigh laser guide star in early 2011. We describe the performance of the SAM LGS system and various improvements made during one year of on-sky tests. With acceptably small LGS spots of 1.6′′ the AO loop is robust and achieves a resolution gain of almost two times in the I band, under suitable conditions. The best FWHM resolution so far is 0.25′′ over the 3′ field of the CCD imager.