Abstract
We reduce and analyze, in a uniform way, all of the data obtained by the Solar Disk Sextant (SDS) experiment, concerning high-precision measurements of the solar radius and oblateness, in the bandwidth 590 {–} 670 nm, made onboard stratospheric balloons during a series of flights carried out in 1992, 1994, 1995, and 1996. The measured radius value appears anti-correlated with the level of solar activity, ranging from about 959.5 to 959.7 arcsec. Its variation from year to year is outside the error range, which is mostly due to a systematic diurnal behavior, particularly evident in the 1996 flight. The oblateness shows an analogous temporal behavior, ranging from about (4.3 to 10.3) × 10−6.
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We regret that Prof. Caccin died on June 19, 2004.
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Egidi, A., Caccin, B., Sofia, S. et al. High-Precision Measurements of the Solar Diameter and Oblateness by the Solar Disk Sextant (SDS) Experiment. Sol Phys 235, 407–418 (2006). https://doi.org/10.1007/s11207-006-0073-x
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DOI: https://doi.org/10.1007/s11207-006-0073-x