Abstract
Drift-time measurements of the solar diameter made at Izaña and Locarno in 1990–1992 show a significant increase of the observed angular semidiameter when compared to results obtained at the same two sites in 1981. The observed increase of ≈0.4″ is not due to a systematic (or long-term) variation, but seems to reflect a more complicated behaviour with time: As both series of measurements were made around a maximum of the 11-year cycle, it seems that a variation in phase with solar activity (in the sense of the Secchi-Rosa law) can be ruled out.
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References
Delache, Ph., Gavryusev, V., Gavryuseva, E., Laclare. F., Régulo, C., Roca Cortés, T.: 1993, Astrophys. J. (in press, IAC Preprint 33/92)
Wittmann, A.: 1973, Solar Phys.29, 333
Wittmann, A., Bonet, J.A., Wöhl, H.: 1981, in: L. Cram, J.H. Thomas (ed.),The Physics of Sunspots, p. 424–433, National Solar Observatory
Wittmann, A.D., Alge, E., Bianda, M.: 1991, Solar Phys.135, 243
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Wittmann, A.D., Alge, E. & Bianda, M. Detection of a significant change in the solar diameter. Sol Phys 145, 205–206 (1993). https://doi.org/10.1007/BF00627996
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DOI: https://doi.org/10.1007/BF00627996