Photospheric Faculae and the Solar Oblateness: a Reply to "faculae and the Solar Oblateness" by R. H. Dicke

Abstract

Dicke has recently contested our statement in an earlier paper that faculae could account for a large part, if not all, of the solar oblateness signal measured by Dicke and Goldenberg in 1966. Using the facular oblateness signal published in our earlier paper and some hitherto unpublished data from his 1966 observations, he concludes that faculae account for only a small part (11 percent) of the observed excess oblateness. His analysis considers data only from a restricted 48-day sample and is based on the assumption that only the observed oblateness signal is subject to error. Our analysis considers data from all 64 days on which observations were made, and is based on the assumption that both the observed oblateness signal and the facular signal are subject to error. We find that faculae account for at least one-third to one-half of the observed excess oblateness, depending on whether 48 days or 64 days are used in the analysis. Moreover, faculae may account for all of the observed excess oblateness provided the facular error is sufficiently large. Thus faculae cannot be excluded as the major source of Dicke and Goldenberg's 1966 oblateness signal.