altitude circle

altitude circle

[′al·tə‚tüd ‚sər·kəl]
(astronomy)
(electromagnetism)
A bright circle which surrounds the central dark portion of a plan position indicator display or photograph, and results from ground clutter.
References in periodicals archive ?
We flew the low altitude circle and enjoyed the spectacular early morning view (see photo) before lining up and landing.
In fact, the TABULAR DATA OMITTED equal altitude circle covers a range about ten times greater than the latitude range in the table--1,050 miles.
The horizontal sky lines that divide up our zones, incidentally, are called almucantars, an old Arabic term for the altitude circles of the altazimuth coordinate system.