The Solar Diameter Monitor measured the duration of solar meridian transits during the 6 years 1981 to 1987 , spanning the declining half of solar cycle 21 .
We have combined these photoelectric measurements with models of the solar limb-darkening function , deriving a mean value for the solar near-equatorial radius of 695.508 \pm .026 Mm .
Annual averages of the radius are identical within the measurement error of \pm .037 Mm .