A new estimate of the quadrupole moment of the sun

Recent solar observations at Pic du Midi are reported that yield a value of J(2) = (2.57 +/- 2.36) x 10(-6) for the quadrupole moment of the Sun. These observations were conducted from July 1993 to July 1994 after several improvements of the scanning heliometer. This instrument operates by fast photoelectric scans of opposite limbs of the Sun quasi-simultaneously, which provides the distance between both inflection points of the limb profiles. Any number of solar diameters in any position angle can be measured within a time interval short enough to minimize the scattering of the observational parameters. Errors due to atmospheric deterioration are discussed. From our results, compared to previous values obtained by other authors, it can be concluded than an upper limit for J(2) is probably 1.0 x 10(-5).