Pluto Occultation20/21 August 2002

Occultation Sequence

Pluto

CharonP131.1

5:33 UT 6:26 UT 7:03 UT 7:31 UT

Occultations by PlutoOccultations by Pluto

2002P131.1

Pluto + Star

Pluto only

Williams’s light curve from August 2002, taken at University of Hawaii 2.2-m telescope

Pasachoff, Jay M., Steven P. Souza, Bryce A. Babcock, David R. Ticehurst (Williams College); James L. Elliot, M. J. Person, and Kelly B. Clancy (MIT); Lewis C. Roberts, Jr., and Doyle T. Hall (Boeing Co., Maui); and David J. Tholen (U. Hawaii) 2005, "The Structure of Pluto's Atmosphere from the 2002 August 21 Stellar Occultation," Astron. J., 129, 1718-1723.

Occultation by PlutoOccultation by Pluto

2002P131.1

Pluto + Star

Pluto only

Williams’s light curve from August 2002, taken at University of Hawaii 2.2-m telescope

Pasachoff, Jay M., Steven P. Souza, Bryce A. Babcock, David R. Ticehurst (Williams College); James L. Elliot, M. J. Person, and Kelly B. Clancy (MIT); Lewis C. Roberts, Jr., and Doyle T. Hall (Boeing Co., Maui); and David J. Tholen (U. Hawaii) 2005, "The Structure of Pluto's Atmosphere from the 2002 August 21 Stellar Occultation," Astron. J., 129, 1718-1723.

Pluto + Star

Pluto only

Time (seconds after 8/21 06:40:00 UT)

Nor

mal

ized

Flu

x

0.8

1.0

0.6

0.4

0.0

0.2

450 500 600 650550 800700 750

UH 2.2-m/Williams CCD Light Curve

UH 2.2-m/Williams CCD Light Curve

0.75

0.8

0.85

0.9

0.95

1

1.05

300 400 500 600 700 800 900 1000

Nor

mal

ized

Flu

x

Time (seconds after 8/21 06:40:00 UT)

Half-light immersion time:2002 08 21: 06 47 59.3038 UT

Half-light emersion time:2002 08 21: 06 53 08.4001 UT

Duration: 5.15 minutes

Observations: Mauna Kea, 20 August 2002

Telescope: University of Hawaii 2.2 m f/10.14CCD: Princeton Instruments (Roper Scientific)

TE/CCD-576EFT frame-transfer CCDFrame Capture Rate = 2 Hz

Resolution: 0.2 arc sec pixelsunbinned for astrometric imagesbinned 5x5 for 20-min occultation run

Seeing: 0.4 arc sec

Support: Research Corporation

Technical Details

0.78

0.8

0.82

0.84

0.86

0.88

0.9

0.92

700 720 740 760 780 800

Nor

mal

ized

Flu

x

Time (seconds after 8/21 06:40:00 UT)

Zoom in of UH 2.2-m/Williams CCD Light Curve

Spikes, ingress and egress (flipped)

-0.2

0

0.2

0.4

0.6

0.8

1

1.2

100 110 120 130 140 150

UH_2.2BothWays.kg

Normalized Flux

Seconds after 2002 08 21 06 30 00

Haleakala data, I-bandAEOS Telescope/Boeing LTS

Comparison of Light Curves

Distance from Shadow Center (in units of half-light radius)

No

rma

lize

d S

tella

r F

lux

0.0

0.6

0.4

0.2

1.0

0.8

0.0–0.5–1.0 1.51.00.5–1.5

Changes in Pluto’s Atmospheric Pressure

Emersion (2002)Emersion

(1988)

2.0 6.0 8.04.0

1275

1255

1235

1215

Pressure (bar)

Rad

ius

(km

)

Papers published

"High-Time-Resolution White-Light Observations of Pluto's Occultation of P131.1 in

2002 August”

Elliot et al.

"The recent expansion of Pluto's atmosphere," Nature 424, 165-168, July 10, 2003.

Pasachoff et al.

Astronomical Journal paper on our data.

Person et al.

Meeting paper on the shape of Pluto’s atmosphere.