— spectroheliographic /spek'troh hee'lee euh graf"ik/ , adj.
/spek'troh hee"lee euh graf', -grahf'/ , n.
an apparatus for making photographs of the sun with a monochromatic light to show the details of the sun's surface and surroundings as they would appear if the sun emitted only that light.
[ 1890-95; SPECTRO- + HELIOGRAPH ]