Comparison of CCD astrolabe multi-site solar diameter observations

Andrei A., Boscardin S., Chollet F., Delmas C., Golbasi O., Jilinski E., ...More

ASTRONOMY & ASTROPHYSICS, vol.427, no.2, pp.717-723, 2004 (SCI-Expanded) identifier identifier

  • Publication Type: Article / Article
  • Volume: 427 Issue: 2
  • Publication Date: 2004
  • Doi Number: 10.1051/0004-6361:20041334
  • Journal Name: ASTRONOMY & ASTROPHYSICS
  • Journal Indexes: Science Citation Index Expanded (SCI-EXPANDED), Scopus
  • Page Numbers: pp.717-723
  • Keywords: Sun : general, Sun : fundamental parameters, Sun : photosphere, Sun : activity, RADIUS, SUN
  • Akdeniz University Affiliated: No

Abstract

Results are presented of measured variations of the photospheric solar diameter, as concurrently observed at three sites of the R2S3 (Reseau de Suivi au Sol du Rayon Solaire) consortium in 2001. Important solar flux variations appeared in that year, just after the maximum of solar activity cycle 23, make that time stretch particularly promising for a comparison of the multi-site results. The sites are those in Turkey, France and Brasil. All observations are made with similar CCD solar astrolabes, and at nearby effective wavelengths. The data reductions share algorithms, that are alike, the outcomes of which are here treated after applying a normalization correction using the Fried parameter. Since the sites are geographically quite far, atmospheric conditions are dismissed as possible causes of the large common trend found.