AAS Meeting #194 - Chicago, Illinois, May/June 1999
Session 93. Quiet Photosphere, Chromosphere and Transition Region
Display, Thursday, June 3, 1999, 9:20am-4:00pm, Southeast Exhibit Hall

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[93.02] A Search For Variations in the Solar Radius

G. A. Chapman, A.M. Cookson, J.J. Dobias, S.R. Walton (SFO/CSUN)

We report on an ongoing analysis of the radius of solar images from two photometric telescopes at the San Fernando Observatory. Data used from CFDT1 with 5 arc-sec pixels begins in 1986. Data used from CFDT2 with 2.5 arc-sec pixels begins in the summer of 1992. The solar diameter is determined along the length of the linear diode array in the geocentric north-south direction by fitting the entire image as described in Walton, et al. (1998). Previously, we reported a solar radius variation in phase with the solar cycle using data from CFDT1. A reanalysis of those data have resulted in a much smaller radius variation than that reported in Chapman, et al. (1998). We will report on efforts to compare the radius found from CFDT1 images with that from CFDT2 images. The two instruments have undergone improvements but each at different times. We will discuss possible radius variations between the two instruments. This work was supported by NSF grant ATM-9504374 and NASA grant NAG5-4973.

\begin{center} References \end{center}

\noindent Chapman, G.A., Cookson, S.R., Dobias,J.J. and Walton, S.R. 1998, Spring AGU Meeting.

\noindent Walton, S.R., Chapman, G.A., Cookson, A.M., Dobias, J.J. and Preminger, D.G. 1998, Solar Phys. 179, 31.

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