A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
From: Frank Reed
Date: 2016 Oct 5, 11:34 -0700
Mark, that's simply a sign convention to match the signs of the Nautical Almanac correction tables and the choice of signs in the series expansion. It's no big deal, and you should treat it as a pure "recipe rule". Bear in mind that other versions of the series expansion methods adopt other conventions on the signs.