occultation by charon

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Occultation by Charon 2005 C313.2 Observed by 4 MIT–Williams teams on 5 telescopes: Pico dos Dias (Brazil) – clouded out (Jay Pasachoff and Steven Souza) Cerro Armazones (Chile) (Bryce Babcock and Joseph Gangestad) Las Campanas (Chile) Cerro Pachón (Chile) Movie of C313.2 from Las Campanas- http://occult.mit.edu/research/C313OccMovie.php

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Occultation by Charon. 2005 C313.2. Observed by 4 MIT–Williams teams on 5 telescopes: Pico dos Dias (Brazil) – clouded out (Jay Pasachoff and Steven Souza) Cerro Armazones (Chile) (Bryce Babcock and Joseph Gangestad) Las Campanas (Chile) Cerro Pachón (Chile). - PowerPoint PPT Presentation

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Page 1: Occultation by Charon

Occultation by Charon2005

C313.2

• Observed by 4 MIT–Williams teams on 5 telescopes:

• Pico dos Dias (Brazil) – clouded out (Jay Pasachoff and Steven Souza)

• Cerro Armazones (Chile)(Bryce Babcock and Joseph

Gangestad)• Las Campanas (Chile)• Cerro Pachón (Chile)Movie of C313.2 from Las Campanas-

http://occult.mit.edu/research/C313OccMovie.php

Page 2: Occultation by Charon
Page 3: Occultation by Charon

Cerro Armazones, Chile(L to R) M. J. Person, B. A. Babcock, & J. W. Gangestad

Pico dos Dias, BrazilS. P. Souza (L), J. M. Pasachoff (R)

Page 4: Occultation by Charon

Where we were …

… and the parts of Charon we saw

Page 5: Occultation by Charon

Cerro Armazones Light Curve

Duration: 37 secMid-time: 03:36:36.5 UT

Sharp drop No atmosphere detected

Page 6: Occultation by Charon

Team Light CurvesClay Telescope (6.5 m),Las Campanas

Gemini South (8 m)Cerro Pachón

Cerro Armazones (0;.84 m),Antofagasta, Chile

Du Pont Telescope (2.5 m),Las Campanas

0.85-m

6.5-m 2.5-m

8-m

Page 7: Occultation by Charon

Upper Limits on Charon’s Atmosphere

Gas Molecular Weight (amu) Number density (1013 cm-3)CH4 16.04 2.0H2O 18.02 3.4Ne 20.18 11.9N2 28.01 2.3Ar 39.95 2.0

Clay Telescope data

Gulbis, A.A.S., Elliot, J.L., Person, M.J., Adams, E.R., Babcock, B.A., Emilio, M., Gangestad, J.W., Kern, S.D., Kramer, E.A., Osip, D.J., Pasachoff J.M., Souza, S.P., Tuvikene, T. “Charon’s radius and atmospheric constraints from stellar occultation observations” Nature, in press

Seconds after reference time

Page 8: Occultation by Charon

Radius and Composition Constraints

Radius: 606 ± 8 km

Density: 1.72 ± 0.15 g/cm3

Rock/Ice: 0.63 ± 0.05

This rock/ice fraction is consistent with a collisional formation scenario.

http://ncsdweb.ncsd.k12.wy.us/planetarium/ART/moonimpact.jpg