An Etymological Dictionary of Astronomy and Astrophysics
English-French-Persian

The quality of an imaging system which is characterized by → isoplanatism.

From → iso- "equal, uniform" + Gk. plane "wandering," from planasthai "to wander" + -tic adjective-forming suffix, → -ic.

Izobirâh, from izo-, → iso-, + birâh "a devious path; a wanderer, who deviates, errs."

The angle in which the → point spread function of the atmosphere/telescope system is space invariant. Because of the presence of → turbulence in high layers of the atmosphere, this angle is extremely small, often only a few seconds of arc at visible wavelengths. See also → aplanatism.

→ isoplanatic; → angle.

The spatial region where the variation of the → point spread function of an imaging system is considered negligible.

→ isoplanatic; → patch.