Some Notes on the Use of the Watts Limb-Correction Charts

Grazing and total occultations of stars by the moon have been used to solve for parameters to refine limb- correction data read from Watts' charts of the moon's marginal zone. When using the charts, the following parameter values and standard errors are indicated by this discussion: correction to adopted radius of the datum, -0'.'022+0'.'025; ellipticity (spherical datum minus Watts datum), -0 .15 cos 2 (AA -153 ); correction to Watts angles (WA) to get axis angles (AA), -0?22+0?02; longitude and latitude components of Watts center minus center of mass, +0'.'25+0'.'74 and -0'.'24+0'.'10, respectively; radial component (correction to constant of sine parallax), +0'.'075+0'.'047.