Abstract: A solar thermal collector incorporates an extended reflector surface constructed to concentrate radiation from a radiation source along a focal line. The reflector surface is oriented in a generally upward facing direction relative to the earth with the focal line above the reflector surface. A tracking system supports the extended reflector surface for double axis tracking of the sun by relative motion of the reflector surface to different tracking positions for optimizing concentrated radiation at the focal line. The tracking system is constructed to maintain the focal line of the extended reflector surface in a substantially horizontal orientation relative to the earth during tracking. An elongate absorber is positioned substantially at the focal line for absorbing and converting radiation to heat energy. An elongate absorber housing is coupled to the extended reflector surface and is constructed for positioning the elongate absorber substantially along the focal line.