SAM science verification: Call for Proposals

The SOAR Adaptive Module (SAM) is a laser guide star adaptive optics system that improves natural seeing at the 4.1-m SOAR telescope. The instrument is equipped with a CCD imager (pixel scale 0.045 arcsec, field of view 3 arcmin). SAM commissioning is almost complete, and we are ready to begin Science Verification (SV) testing as a final step prior to offering SAM on a shared risk basis in Semester 2013B.

Through this call for proposals (CfP), we solicit proposals for short (<0.5 night) science projects which could be executed as part of this SV testing process. This solicitation is open to investigators from all SOAR partners including the US, Brazilian and Chilean open access communities.

The SAM SV program is intended to demonstrate the ability of the instrument to produce scientifically useful images. Ideally an SV proposal would test as many aspects as possible of SAM's performance, such as image quality and its uniformity over the field, gain in limiting magnitude, photometric accuracy, and astrometric calibration. This SV process is complementary and parallel to shared risk proposals to use SAM during 2013B, which may be submitted in response to the normal 2013B CfP to be released on 1 March 2013 (NOAO) and 15 March 2013 (Brazil and Chile).

The SAM SV program will use up to 6 nights of engineering time during the 2013A Semester (March to July) including some nights which will be partly dark. Observations will be executed in service mode, with a possibility of remote participation by the proposers.

SAM performance

The performance of SAM depends on the turbulence profile: seeing improvements are larger when the majority of the natural seeing results from low-altitude ("ground layer") turbulence that SAM is designed to compensate for. Under median conditions the FWHM resolution might be 0.4, 0.45, 0.5, and 0.55 arcsecond in the I,R,V,B filters. The best resolution achieved so far under good conditions is 0.25 arcsecond in the R and I bands. The PSF can be modeled by a Moffat function with beta=1.5. In addition to the laser, the tip-tilt compensation requires two natural guide stars brighter than R=18 located within a 5x5 arcmin square field around the science target. Such guide stars are available for most of the sky.

The SAM imager is equipped with standard B, V, R, I filters, an Halpha filter (656/64nm) and can also use other 3" and 4" filters available at CTIO and the SOI filters 4" filters, see
However observations in filters which transmit 355nm, the wavelength of the laser, such as U and u', are not possible.

How to propose

Proposals should contain about 1 page of text describing briefly the science objective, the technical aspects of SAM which will be tested, data to be taken (objects, filters, exposure times, total requested time), and contact information of the proposer. Each proposal should request no more than 5 hours of observing time, including 15 minutes setup for each pointing. Further details of the programs accepted will be obtained from the proposers at a later time.

We will begin reviewing SV proposals on February 15, 2013, and those requiring SV time in March must be received by that date; we will continue to accept proposals for the remainder of the semester until the deadline of March 15, 2013. Proposals should be sent by e-mail to . Selection of the SV proposals for execution will be done internally, with most weight given to how the proposal will contribute to the overall technical goals of the SV process. Time allocated to SV is being accounted as engineering, not science time; because of the special technical needs time allocations may not be strictly proportional to the SOAR partner's telescope time shares.

The images obtained with SAM will be processed (bias and flat field, plus basic astrometric calibration) at SOAR and delivered to the proposers. The proposers are asked to evaluate the data as soon as possible after receipt, and provide a report quantitatively assessing the quality of the SAM data, their suitability for the science project, and their compliance with the requirements, and describing any problems encountered. Ideally, the results of successful SV projects would be published by the proposers in some way.

Additional information

SAM web page:
SAM performance predictions:
Recent results:
NOAO Newsletter article (September 2012):

Last modified: January 24, 2013