an instrument for observing and photographing the sun's corona, consisting of a telescope fitted with lenses, filters, and diaphragms that simulate an eclipse.
Origin of coronagraph
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019
an optical instrument used to simulate an eclipse of the sun so that the faint solar corona can be studied
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012