ACGRG5 Meeting Christchurch New Zealand 18 XII 2009 Measuring solar diameter with Baily beads: from Watts to Kaguya's lunar profiles Costantino Sigismondi, Mitsuru Soma, Dave Herald sigismondi @ icra.it ACGRG5 Meeting Christchurch New Zealand 18 XII 2009

Solar astronomy in Rome

to Sapienza University Capitol Observatory (until 1937) Leo XII in 1823 to Sapienza University Roma turrita, di Emma Amadei. Fratelli Palombi Editori, 1943, pag. 145.

Ertel Meridian Circle (1853) for DRIFT-SCAN METHOD

Dotted line: Capitol; continuous line data from Greenwich Seeing influence From P.J.D. Gething, 1955 Greenwich observations of the horizontal and vertical diameters of the Sun MNRAS 115, 558.

Annular eclipse of 1567 in Rome relinquebatur in Sole circulus quidam exilis undique totam lunam ambiens (Annular) Clavius, Commentarium in Sphaeram, Roma 1581

Contribution from D. Herald, Australia Occult 4 Baily’s Beads

Contribution from M. Soma, Japan: Kaguya lunar probe Analysis of old and new data

Method of Eclipses

Lunar and Earth’s Orbital motions are precisely known e. g Lunar and Earth’s Orbital motions are precisely known e.g. LLR, tropical year

Lunar Limb: profiles accuracy Chester Watts (1962) published the atlas of lunar limbs at all libration phases

Digitized Watts Atlas

Kaguya completed its mission this year: the crash looking for water

Kaguya LALT Accuracy ± 1m, sampling each 1.5 to 10 km

Observational strategy: Grazing Eclipse

Geographical location Referred to permanent landscape features GPS / Satellite image

UTC timing Has to be precise (0.01 s) Has to be portable (2 temperature calibrated quartz watches)

Imaging the eclipse Naked eye (1567-1715-1925) Video + high density filters Video + projection

Signal to Noise ratio To determine the faintest bead or its limiting magnitude

Sky background If the projection is not made in a camera obscura there are different background levels, ranging over more than 1000 in intensity Total eclipse, Egypt Zawyet al Mahtallah march 29, 2006 Southern Limit

Sunset /Sunrise Ostia (Rome) September 5: horizon extinction

High Clouds Roma, October 18

Atmosphere extinction Deviation starts at ~2° above horizon

Solar Limb Darkening Function From Rogerson, 1959

+ + + Our equipment White Projection Screen Camcorder and 2 quartz calibrated watches

Our Measurements Spain, 2005 (clouded) Data from IOTA (2005-on)

Egypt, 2006 published in Solar Phys 257, 237

Corona at the shadow limit Before totality (± 4 minutes of visibility at naked eye) Video dr. Fady Morcos Zawayet al Mahtallah 29.3.06

At maximum eclipse At naked eye the irregular structure of the corona was well visible. Does exists a Circular Inner Corona?

French Guyana, Sept. 2006 Eclipse at sunrise, high extinction and seeing 16 beads identified Preliminary ΔR= 0.04±0.04 arcsec

And planetary transits? Venus 1769: Discovery of Black Drop effect by Captain James Cook at Tahiti

Explanation of Black drop due to instrumental optical distortions

Transit of Venus 2004, also Mercury 1999, 2003 and 2006 Chord method

Solar Diameter measurement at Venus’ Transit in Hα 50 images (A. Ayomamitis, Athens, Greece) Internal contacts: 2nd @ 7 am ± 8 s (low Sun, high atmospheric turbulence) 3rd @ 1 pm ± 1 s D. Herald’s Occult4 software: ΔR=+0.34±0.38 arcseconds (in agreement with Neckel, So Phys 153, 91 1994)

publications Solar Physics 257, 237 (2009) Kilcik, Sigismondi, Rozelot and Guhl Analysis with Watts profile of 2006 total eclipse Synopsis of eclipse data historical and recent Diameter vs solar activity

Real lunar limb vs Watts profile

δR=-0.41” on 29 march 2006

Solar Physics 258, 191 Sigismondi et al. Atlas of Baily Beads 2005-2008 Observational data from 25 observing stations; 600 beads Standard of blocking filters Limovie video analysis

standard filter’s transmittance

Video analysis with Limovie (Japan)

Works in progress: at Locarno Observatory Switzerland

DRIFT-SCAN Method: transits on fixed hourly circles Transit timing is proportional to solar diameter Atmospheric seeing affects measurements Space data (eclipses and PICARD satellite) for calibration

Diameter and seeing monitor Time [1 frame] Quicktime 7.0 Window video setup

The solar image drifts on the screen along this direction

ρ”=15”·σ·cos(δ) Seeing formula Without seeing the time intervals tn+1-tn are all equal. The standard deviation σ of time intervals is related to the seeing ρ by the formula ρ”=15”·σ·cos(δ) where δ is the solar declination

Eclipses and PICARD (launch 15.2.2010) for absolute calibrations

Perspectives Eclipses observations: international coordinated IOTA champaigns, collaboration with PICARD satellite Drift-scan with Seeing monitor at IRSOL Application of Kaguya profiles to old and new eclipses