Pluto occultation 2006 June 12 from Australia

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Pluto occultation 2006 June 12from Australia
New Zealand

• Leslie Young, Eliot Young, Catherine Ruhland,
  Catherine Olkin (SwRI)
• Richard French (Wellesley College)Marc Buie
  (Lowell Observatory)Jeff Regester (Greensboro
  Day School, NC)Kevin Shoemaker (Shoemaker Labs,
  Longmont CO)Martin George (Launceston
  Planetarium, Tasmania)John Broughton (Reedy
  Creek, Australia)Grant Christie,Tim Natusch
  (Auckland Observatory)Ross Dickie, Peter
  Jaquiery, Graham Blow (RASNZ)Dave Gault
  (Hawkesbury Heights, Australia)Blair Lade
  (Stockport Observatory, Australia)

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Occultation Overview
Temperature Pressure Extinction
Flux Position in shadow
Bending angle
gt
gt
Refractivity
gt
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OccultationReconstructed Shadow Path
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Reedy Creek 0.51 m (20")John Broughton
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Anglo-Australian Telescope 4-m (163 ")Dick
French, Kevin Shoemaker
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Hawkesbury Heights 0.25 m (10")Dave Gault
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Stockport Observatory 0.51 m (20")Blair Lade
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Longford Farm 0.36 m (14")Eliot Young, Jeff
Register
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Auckland Observatory 0.36 m (14")Grant Christie,
Tim Natusch
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Carter Observatory 0.41 m (16")Marc Buie, Trina
Ruhland
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Farm near Wanaka, 0.36 m (14")Leslie Young,
Cathy Olkin, Peter Jaquirey, Ross Dickie
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Geometric Solution
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Geometric Solution
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Change in Shadow Radius 1988 to 2002 2.74
1.36 km/yr (increase) 2002 to 2006 1.17 4.31
km/yr (consistent with no change)
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Frame Rate 10 Hz SNR per point 62 SNR per 60
km 331 GPS-based absolute timing accuracy better
than 100 µsecond. Spikes are resolved, differ in
detail between ingress/egress
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T0
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Lower Atmosphere Inversion(Ref Elliot, Person
and Qu 2003)

• Small Planet Case
• No Ray Crossing
• Geometric Optics
• Clear Atmosphere

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Immersion
R (km) v. dT/dr (K/km)
R (km) v. T (K)
dry adiabat
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Emersion
R (km) v. T (K)
R (km) v. dT/dr (K/km)
dry adiabat
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Monte Carlo-Based Error Estimates
R (km) v. T (K) - Nominal Case - 1-sigma env.

• Monte Carlo errors based on 100 simulated
  lightcurves with appropriate noise.
• The Temperature Inversions Similar overall
  shape, similar wiggles, but largest errors (up to
  18 K) above the temperature inversion at 1240 km.

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Effects of an example haze layer
Consider the effects of sudden haze onset at 1263
km with a scale height of 15 km.
R (km) v. T (K)

• Haze dramatically changes the lower temperature
  profile.
• Brings dT/dr closer to a dry adiabat.

dry adiabat
R (km) v. dT/dr (K/km)
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Conclusions

• Pluto's bulk atmosphere (geometry)
• 1988 to 2006, pressure has increased by 0.98
  0.09 µbar, a factor of 2.170.21
• For N2 surface vapor pressure equilibrium, this
  implies an increase in surface temperature of
  1.2-1.7 K.
• Pressures consistant between 2002 and 2006
• Plutos upper atmosphere (model fit)
• Non-isothermal. dT/dr -0.1270.028 K/km
• Average (103.93.2 K) same as 2002 (1042 K,
  isothermal fit), and 1988 (104.07.3 K).
• 99.43.1 K (ingress, 30.0 S, summer), 105.53.5 K
  (egress, 53.2 N, winter) dispite 1500 less
  insolation averaged over the winter latitude, so
  not tied to insolation (in a straightforward way)
• Plutos lower atm, clear assumption (inversion)
• As in 1988 2002, not isothermal.
• Temperature inversion around 1210 - 1220 km.
• Ingress Egress are qualitatively similar, but
  the density perturbations differ in detail.
• Plutos lower atm, haze assumption (inversion,
  removing haze from model fit)
• Top of haze poorly constrained.
• Temperature purturbations qualitatively similar
  to those seen on Earth, Jupiter, Titan