2011/12/26 by Costantino Sigismondi, Sigismondi, Costantino
Physics and Astronomy · #FOS: Physical sciences #Instrumentation and Methods for Astrophysics (astro-ph.IM) #Solar and Stellar Astrophysics (astro-ph.SR) #astro-ph.IM #astro-ph.SR
paper · pdf · doi:10.48550/arxiv.1112.5878
PhD thesis of University of Nice-Sophia Antipolis, Sapienza University of Rome and French-Italian University; 119 pages with 96 color and b/w figures, tables and schemes. Discussed at the Sapienza University of Rome on 12 December 2011. Revision 23 November 2012
arxiv created 2012/11/23 · arxiv updated 2012/11/26
The measurement of the solar diameter is introduced in the wider framework of solar variability and of the influences of the Sun upon the Earth's climate. Ancient eclipses and planetary transits would permit to extend the knowledge of the solar irradiance back to three centuries, through the parameter W=dLogR/dLogL. The method of Baily's beads timing during eclipses is discussed, and a significant improvement with respect to the last 40 years has been obtained by reconstructing the Limb Darkening Function's inflexion point from their light curve and the corresponding lunar valleys' profiles. The case of the Jan 15, 2010 annular eclipse has been studied in detail, as well as the last two transits of Venus. The atlas of Baily's beads, realized with worldwide contributions by IOTA members is presented along with the solar diameter during the eclipse of 2006. The transition between the photographic atlas of the lunar limb (Watts, 1963) and the laser-altimeter map made by the Kaguya lunar probe in 2009 has been followed. The other method for the accurate measurement of the solar diameter alternative to the PICARD / PICARD-sol mission is the drift-scan method used either by the solar astrolabes either by larger telescopes. The observatories of Locarno and Paris have started an observational program of the Sun with this method with encouraging results. For the first time an image motion of the whole Sun has been detected at frequencies of 1/100 Hz. This may start explain the puzzling results of the observational campaigns made in Greenwich and Rome from 1850 to 1955. The meridian line of Santa Maria degli Angeli in Rome is a giant pinhole telescope and it permits to introduce didactically almost all the arguments of classical astrometry here presented. The support to the PICARD mission continues with the analyses of the transit of Venus and the total eclipse of 2012.