1. 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
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ACGRG5 Meeting Christchurch New Zealand 18 XII 2009

2. Solar astronomy in Rome

3. 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.

4. Ertel Meridian Circle (1853) for DRIFT-SCAN METHOD

5. 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.

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

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

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

9. Method of Eclipses

10. 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

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

12. Digitized Watts Atlas

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

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

15. Observational strategy: Grazing Eclipse

16. Geographical location
Referred to permanent landscape features
GPS / Satellite image

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

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

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

20. 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

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

22. High Clouds
Roma, October 18

23. Atmosphere extinction
Deviation starts at ~2° above horizon

24. Solar Limb Darkening Function
From Rogerson, 1959

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

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

27. Egypt, 2006 published in Solar Phys 257, 237

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

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

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

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

35. Explanation of Black drop
due to instrumental optical distortions

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

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

38. 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

39. Real lunar limb vs Watts profile

40. δR=-0.41” on 29 march 2006

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

45. standard filter’s transmittance

46. Video analysis with Limovie (Japan)

47. Works in progress: at Locarno Observatory Switzerland

48. 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

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

50. The solar image drifts on the screen along this direction

51. 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

52. Eclipses and PICARD (launch 15.2.2010) for absolute calibrations

53. 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