Guidelines for measuring solar radius with Baily beads analysis

  • Costantino Sigismondi


By inspection of central eclipses videorecords, data of Baily beads timings are retrievable. Knowing the lunar limb profile at the moment of the eclipse we evaluate the excess or defect of solar limb when the Sun is assumed at its standard radius. Two procedures of data analysis are here presented: one based on limb heights and the other on times. While these methods are based upon Occult 4 software, they can be used with other ephemerides and new lunar profiles. The example of 2006 total eclipse data, with its remarkably negative value of ΔR= − 0.41“± 0.04”, is presented.


solar eclipses observations ephemerides solar radius variations 


  1. 1.
    Baily F. On a remarkable phenomenon that occurs in total and annular eclipses of the Sun. Mon Not R Astron Soc, 1836, 4: 15–19ADSGoogle Scholar
  2. 2.
    Baily F. Observations of the solar eclipse, May 15, 1836. Mon Not R Astron Soc, 1836: 3: 199–200ADSGoogle Scholar
  3. 3.
    Halley E. Observation of late total solar eclipse on the 22nd April [...]. Phil Trans R Soc Lon XXIX, 1714–1716: 245–262Google Scholar
  4. 4.
    Dunham D W, Sophia S, Fiala A D, et al. Observations of a probable change in the solar radius between 1715 and 1979. Science, 1980, 210: 1243–1245CrossRefADSGoogle Scholar
  5. 5.
    Newcomb S. Reports on observations of the eclipse of August 7, 1869. U. S. Naval Observatory, 1870: 15–22Google Scholar
  6. 6.
    Sofia S, Dunham D W, Dunham J B, et al. Solar radius change between 1925 and 1979. Nature, 1983, 340: 522–526CrossRefADSGoogle Scholar
  7. 7.
    Herald D. Observations of baily’s beads from near the northern limit of the total solar eclipse of June 20, 1974. The Moon, 1976, 15: 91–107CrossRefADSGoogle Scholar
  8. 8.
    Fiala A D, Dunham D W, Sofia S. Variation of the solar diameter from eclipse observations. Sol Phys, 1994, 152: 97–104CrossRefADSGoogle Scholar
  9. 9.
    Dunham D W, Thompson J R, Sofia S, et al. Accuracy of solar radius determinations from solar eclipse observations, and comparison with SOHO Data, 2005. Proc. of SORCE Science Meeting, Durango, ColoradoGoogle Scholar
  10. 10.
    Kubo Y. Position and radius of the Sun determined by solar eclipses in combination with lunar occultations. Publ Astron Soc Jpn, 1993, 45: 819–829ADSGoogle Scholar
  11. 11.
    Watts C B. The U.S. Naval Observatory survey of the marginal zone of the moon. U.S. Naval Observatory, 1962: 59–61Google Scholar
  12. 12.
    Morrison L V, Appleby G M. Analysis of lunar occultations. Mon Not R Astron Soc, 1981, 196: 1013–1020ADSGoogle Scholar
  13. 13.
    Nugent R. GPS camera synchronization analysis, 2008. In: Proc. of 26th IOTA Annual Meeting September 11–14, 2008, Apple Valley, CA

Copyright information

© Science in China Press and Springer Berlin Heidelberg 2009

Authors and Affiliations

  1. 1.International Center for Relativistic AstrophysicsSapienza University of Rome and ICRARomaItaly
  2. 2.Laboratoire H. Fizeau UMR 6525Université de Nice-Sophia AntipolisNiceFrance
  3. 3.IRSOL, Istituto Ricerche Solari LocarnoLocarno MontiSwitzerland

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