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• Introduction• Experimental setup• Summations measurements of Baily’s bead width during contacts• Inflexion points and contacts• Measurements of intensities continuum of the last C2 and first C3 Baily’s

bead during contacts• Fitting of the Baily’s beads spectra with the lunar profile• Solar edge analysis at the 3rd contact : F and emission lines• Conclusion

Flash spectra and contact timing at high frame rate, during the July 11th 2010 total solar eclipse

observed from the atoll of Hao, French Polynesia

Cyril Bazin, Serge Koutchmy, Jean Mouette, Patrick Rocher and François Sevre

Institut d’Astrophysique de Paris- IAP/CNRS-UPMC & IMCCE-Obs de Paris

IAP Eclipse meeting30th Sept 2010

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Introduction• Contacts timing to evaluate the solar diameter thanks to

solar eclipses in the context of the Picard experiment• True continuum between solar edge emission lines with

flash spectra : no parasitic/scattered light from the disc• The eclipse phenomenon occurs in space : no seeing

effects due to the Earth turbulence• Precise contact measurements (millisecond range)• Spatial resolution (~ 20 km) on the Sun much better than

the scale height (~100 km) due to the differential angular motion of the Moon and Sun : approx 1’’/2 second

• The lunar profile should be taken into account

Motivation

• What is the influence of emission lines superposed to F-line when defining the limb of the Sun ?

• How the solar limb is defined when measuring the solar diameter ?

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I) Flash spectra experimental setup :high dynamic CCD Lumenera Camera of 12 bit, 15 frames/s

The slit less eclipse experiment put on its equatorial mount using manual pointingDay of the 11th July total eclipseAtoll of Hao, in front of the ocean(Photo by Meleana Adams)

Views of the grating 50 mm objective and removable filters

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Diagram of the flash spectra eclipse setup

Spectral resolution : 0,012 nm/pixelSpectral range : 470,0 +/- 5,0 nmSpatial resolution (effective achieved) : 1,5’’/pixelTime effective exposure : 55,1 ms

Software used : Lucam Recorder

USB-2

CCD Lumenera camera12 bit – 15 frames/sPixel size 4,6 µ

PC computer for spectra acquisition

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II) Summation profile of the Baily’s bead width in arcseconds2nd contact of the 11th July 2010 total eclipse in Hao

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Intensity levels In log scale

II-1) Enlargement Baily’s bead width summation profile in arcseconds2nd contact of the 11th July 2010 total eclipse in Hao

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Intensity levels In log scale

II-2) Enlargement Baily’s bead width Summation profile in arcseconds3rd contact of the 11th July 2010 total eclipse in Hao

- C3

He I 471,3 nmHe II 468,6 nm

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Thicker clouds

Intensity levels from 0 to 4095 aduIn linear scale

II-3) Summation profile of the Baily’s bead width in arcseconds3rd contact of the 11th July 2010 total eclipse in Hao

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Missing points :Images lost : -saturation of the caméra-low frame speed

III) Last Baily’s bead intensity profile during the 2nd contact – C2of the 11th July 2010 total eclipse

Last Baily’s bead

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III-1) Last Baily’s bead intensity profile during the 3rd contact – C3of the 11th July 2010 total eclipse

Missing points : realignement

Last Baily’s bead

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III-2) Results of contact timing measurementsusing the Baily’s beads « width » measurements

• 1st inflexion point 2nd contact : 18h 41 min 26, 9 +/- 0,1 s (TU, GPS time)• 2nd inflexion point 2nd contact : 18h 41 min 32,2 +/- 0,1 s (TU, GPS time)• 1st inflexion point 3rd contact : 18h 45 min 04,5 +/- 1,0 s (TU, GPS time)• 2nd inflexion point 3rd contact : 18h 45 min 08,0 +/- 0,7 s (TU, GPS time)

Bad precision at 3rd contact C3 : thicker clouds

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IV) Fitting of the spectra and the lunar limb profile at the 2nd contact – C2

Lunar profiles fromPatrick Rocher, IMCCE

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Lunar profiles fromPatrick Rocher, IMCCE

IV-1) Fitting of the spectra and the lunar limb profile at the 3rd contact – C3

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IV-2) Solar edge analysis of F and emission lines at 3rd contact – C3Height evaluation of their transition : region of the He I line 471,3 nm

108 ’’

32’ <=> 180° (azimuts)

Intensitiesin Log scale

1pixel = 1,5 ‘’=0,012 nm 1125 km/pixel1’’ = 750 km

Transition 3’’

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IV-3)Levels adjustements to show the F and emission linessummation of 5 pictures near the 3rd contact – C3

He II 468,6 nm

He I 471,3 nm

N° 5168 at 18h 45 and 6,2 s

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• Solar contacts evaluations using inflexion points• Eclipse duration evaluated• True continuum between lines well estimated• Intensity continuum profiles of the last and the first Baily’s

Bead during contacts : to be evaluated• New Solar edge definition : F-lines and emission lines seen

simultaneously ?• Perspectives : solar diameter measurements : model of the upper layers of

the solar atmosphere

V) Conclusion

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Bibliographic References

• A great total solar eclipse on July 22 2009, by S. Koutchmy, J. Mouette and C. Bazin Observations et Travaux, Société Astronomique de France, December 2008 , Vol 71, p 2-12

. Poster at the Leuven (Be), solar physics conference : « Helium shell, formation and Origin », C. Bazin and S Koutchmy, April 2009

. «Results from 2008 solar eclipse », C. Bazin, and S. Koutchmy, Suzhou China Conference, 25/07/2009,

• « The chromospheric spectrum at the 1962 eclipse, Dunn », Evans and Jefferies, ApJ Supplement, 15, 275, 1968

• « The He+ 4686 A line in the low chromosphere », SP Worden, JM Beckers, T. Hirayama,, Solar Physics, Volume 28, Issue 1, pp 27-34 01/1973

• « Theoritical line intensities, Excitation of chromospheric He II and hydrogen », R.G. Athay, High Altitude Observatory, ApJ, Vol 142, p 755 08/1965

• « A model of the chromosphere from the helium and continuum emission », R.G. Athay and D. Menzel,ApJ, vol 123, p 285 03/1956

• « Observation of prominences in He II with a new 25 cm Coronograph », T. Hirayama, Y Nakagomi, Tokyo Astronomical Observatory, Astronomical Society of Japan, vol 26, p 53 1974

. « Model atmosphere, VAL » , Vernazza, Avrett, Loeser ApJ Suppl. Series, Vol 45, p 635 – 725 04/1981

. « Continuum of the extreme limb and chromosphere at the 1970 eclipse », H. Kurokawa, Solar Physics, Vol 36, Issue 1, pp 69 – 70 05/1974

. « Baily’s bead Atlas in 2005-2008 Eclipses » Sigismondi, C et Al Solar Physics, Vol 258, Issue 2 P 191-202

. Solar database, Bass 2000 : http://bass2000.obspm.fr/present_fr.html (visited 8th July 2009)

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. IMCCE Ephemerides, Eclipses solaires, Rocher P.http://www.imcce.fr/fr/ephemerides/phenomenes/eclipses/soleil/index.php

. « guidelines for measuring solar radius with Baily’s bead analysis » Sigismondi, C. November 2009, Science in China Series G: Physics, Mechanics and Astronomy, Volume 52, Issue 11, pp.1773 -

1777 .Koutchmy, S., Vial, J-C. (1973) «Angular Dependence of the Optical Properties of a Narrow Band Interference Filter», Astronomy & Astrophysics, 25 p 145.Françon, M. (1984) «Séparation des radiations par les filtres optiques», Masson EditionSafety while using Coronado filters and manual user guides: http://www.coronadofilters.com/pdf/Coronado_Manual_06.pdfvoir également la présentation en français par J-M. Malherbe et N. Mein sur le site http://solaire.obspm.fr/pages/obs_amateur/coronado.htmlBray, R.J., Loughhead, R.E. (1974) «The solar chromosphere», Chapman and Hall edition, Londonp 16-68.Zirin, H. (1987) «Astrophysics of the Sun», Cambridge University Press 433 p. Athay, G. (1961) «Physics of the solar chromosphere», Interscience publishers, 384 p.Vilinga, J. (2006) «Analysis of the variations of the Solar Chromospheric Shell and its Prolateness», PhD, Pierre et Marie Curie University, ParisVI, 7th December 2006http://www2.iap.fr/users/leboutei/JDT/Vilinga_fichiers/frame.htm.Vilinga, J., Filippov, B., and Koutchmy, S. (2007) “On the dynamic nature of the prolate solar chromosphere: jet formation” Astronomy and Astrophysics, 464, Issue 3, p 1119-1125

Bibliographic References

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Additional slides

I) PC computer time calibration with US Navy web site :

http://tycho.usno.navy.mil/simpletime.html

9h50 TU the 27th June 201020h 50 TU the 7th July 2010 The PC advances + 3 s on 10 days and 11 hours (903600 s)

The computer was calibrated the 8th July evening 3 days before eclipse by substarcting 1 second in order to try to be at the exact time at the eclipse day

Next checking of the drift of the computer after eclipse :The 27 of September at 19h 30 TU advance of + 30 s confirmed81 days (6998400 s) so 1 second for 2,7 days

Depend on the calibration of the US Navy timeDrift also linked with temperature

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II) Methods of measurements of the time difference GPS - PC

-The screen of the GPS was recorded by the same Lumenera camera used for flash spectra :-camera removed and insertion of a small focusing lens -Transition between 18h 51 min 29 s and 30 staken as reference.

- Using DS9 : fits headers of the image of GPS gives PC time

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III) time difference calibration : PC – GPS

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IV) Trying explanations of the factor 2 or 2,5 for the scale

True width

Measured width on flash spectra

Alpha ~ 26 ° and sin (alpha) ~ 2

Image : J. Mouette2nd contact - C2

Frame n° 2780