SAS Solar Tracker

SAS Solar Tracker

The SAS Solar Tracker works in conjunction with the Surface Acquisition System (SAS) (measures above-water ocean colour) to maintain the correct pointing angle with respect to the sun, and thus permits autonomous operation.

The SAS Solar Tracker works in conjunction with the Surface  Acquisition  System  (SAS) (measures above-water ocean colour) to maintain  the  correct pointing  angle  with respect to the sun, and thus permits autonomous operation.

Bigelow Laboratory for Ocean Sciences® researchers Dr. Barney Balch, Bruce Bowler and David Drapeau developed the Underway Aiming System (UAS™) software to address the challenge in ocean colour measurement of aiming shipboard optical sensors at optimal viewing angles from the sun. The UAS™ solution uses the real-time date, time, ship’s position and course to determine the angle of the sun from the sensors, and to position the sensors at the optimal azimuth angle.  The UAS™ performs this calculation in real-time in response to the constantly changing relative positions of the sun and sensors so that optical measurements may be made autonomously with improved accuracy.

Satlantic collaborated with the Bigelow Laboratory for Ocean Sciences® to bring the UAS™ technology to the ocean research community in the Satlantic Surface Acquisition System (SAS) Solar Tracker.  The SAS Solar Tracker consists of a radiometer instrument frame, rotator, and controller with data logging, GPS, electronic tilt and compass sensor, and ship navigation data feed.  The SAS Solar Tracker hosts Satlantic ocean colour radiometers, and optional pyrometer for measuring sea surface temperature mounted on the instrument frame and connected to the controller.

The SAS Solar Tracker autonomously performs measurements when the elevation of the sun and the orientation of the ship allow, subject to operator settings. For example, the SAS Solar Tracker would not collect data at night, or in daylight when the sun is too low in the sky, or when due to ship’s course, the ship’s structure would block the required view of the water. With data storage for months of operation, the SAS Solar Tracker’s autonomy frees busy science crew for other tasks and makes it suitable for deployment on volunteer observing ships.


  • Drive Unit to adjust the viewing angle of the frame
  • Frame for mounting the sensors
  • Precision Lt, Li and Es measurements
  • Adjustable viewing angles from Nadir and Zenith
  • Orientation (azimuth, pitch, roll) measurements
  • Sea-surface temperature
  • GPS for geo-referencing and time tagging
  • Flexible configuration
  • Internal data logging
  • Low power consumption
  • Compact system design
  • Easy to deploy