About SAM



The SOAR Adaptive Module (SAM) is a laser-assisted adaptive optics instrument at the 4.1-m SOAR telescope. By compensating selectively low-altitude turbulence, it improves resolution at visible wavelengths. The instrument contains a 4Kx4K CCD imager covering the 3-arcmin square field.  The paper describing the instrument is Tokovinin et al. (2016).

Images as sharp as 0.3′′ have been obtained under favorable conditions of weak high-altitude turbulence which happen ~50% of the scheduled SAM nights. Under such conditions, the typical FWHM resolution delivered by SAM is 0.4′′ in the I band and 0.5′′ in the V band. The compensation quality is uniform over the field (FWHM variation of few percent). On nights with strong high turbulence (which does not necessarily mean poor seeing), SAM brings only a marginal resolution gain in closed loop and delivers V -band FWHM between 0.6′′ and 1′′.

The first paper using SAM commissioning data on the globular cluster NGC 6496 was published by Fraga et al. (2013, AJ, 145, 165). It demonstrates that the photometric precision and limiting magnitude in crowded stellar fields are improved by using the SAM AO system and that good-quality photometry can be derived from the SAMI images. 

In the figure 1 from Fraga et al. 2013 shown at right,  we show the full-frame image of NGC 6496 in the I-band taken with the SAM Imager (SAMI; north is up, east to the left). The enlarged fragments of 15 × 12 arcsecond size compare closed-loop (upper) and open-loop (lower) images taken with the same exposure time of 120 s and displayed on the same intensity scale, at the center and near the edge of the field.  

SAM in Numbers

Documentation for the SAM User

Documentation for the SAM Operator (SAM Support Scientist)