(last updated 2008 07 28)
The shaded area represents where the sun is more than 12 degrees below the horizon. Across the globe pictured above, the three lines correspond to the northern limit, centerline, and southern limit of Pluto's shadow. The northern and southern limits correspond to a radius of 1208 km (the 50% normalized stellar-flux level) for Pluto.
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| Geocentric Mid-time (yyyy month dd hh:mm:ss) | 2008 August 25 04:38:16± 00:00:50 UT |
| Minimum Geocentric Separation | 0.0099± 0.0190 arcsec |
| Position Angle (Pluto relative to the star; measured north through east) | 148.83 degrees |
| Geocentric Velocity | 8.38 km/sec |
| Prediction Version | P598.2-AST-2.0 |
| Reference star position: (USNO-B1.0, at epoch of event) |
RA (h:m:s; J2000) | Dec (d:m:s; J2000) | R Mag1 |
| P598.2 Catalog2 | 17 53 27.1133 | –17 15 27.340 | 16.1 |
| P598.2 Measured | 17 53 27.0962 | –17 15 27.450 | |
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1From USNO-B Catalog. 2USNO-B, at epoch 1970.3. |
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Offsets from Reference Position/Ephemeris3 |
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| Body | RA (arcsec) | Dec (arcsec) | Notes |
P598.2 |
–0.2550± 0.0057 | –0.110± 0.005 | From 144 Strips |
| Pluto4 |
–0.0013± 0.0184 |
+0.071± 0.018 | See note 5 |
| 3All "offsets" are defined in the ("corrected" – "reference") or ("observed" – "calculated") sense. The offsets should be added to reference positions to get the measured positions, which we use to calculate the prediction. 4The reference position for Pluto is that given by JPL Horizon's ephemeris (Pluto source file: PLU013; Earth center source file: DE405). 5315 strip scans and 89 USNO-61inch Telescope frames were used to develop a model to fit the residuals obtained from our measured positions compared to that of the object's JPL ephemeris.. The model includes the first-order effects of errors in the orbital elements of Pluto: (i) constant offsets in RA and Dec, (ii) linear (in time) offsets in RA and Dec, (iii) sinusoidal terms with the Earth's orbital period, and (iv) sinusoidal terms with the Pluto-Charon mutual orbit. |
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Discussion
On August 25th, 2008, Pluto will occult P598.2 (=USNO-B 0727-0710748; as originally published in McDonald & Elliot 2000a, 2000b; Table). The above map and the following prediction results are from the analysis of 315 strip scans obtained at the Lowell Observatory Astrograph by Rosemary Pike, Amanda Bosh, and Allison Moberger during 2005-2008 (the strip scans from earlier years did not contain Pluto-Charon images) and 89 frames taken on 2005 and 2007 by Steve Levine with the 1.55-m Kaj Strand Astrometric Reflector.
Prediction Notes
Site Information
Site |
East Longitude |
Latitude |
Altitude6 (km) |
Distance7 (km) |
Velocity (km/s) |
Flagstaff |
–111 44 23 |
35 11 02 |
2.31 |
3469 N. |
8.66 |
Las Campanas |
–70 42 00 |
–29 00 30 |
2.28 |
4203 S. |
8.48 |
Lick Obs. |
–121 38 12 |
37 20 36 |
1.29 |
4103 N. |
8.68 |
Magdalena Ridge Obs. |
–107 11 05 |
33 58 36 |
2.21 |
3151 N. |
8.65 |
Mauna Kea (IRTF) |
–155 28 29 |
19 49 46 |
4.18 |
4497 N. |
8.76 |
Mt. Hopkins |
–110 53 04 |
31 41 19 |
2.61 |
3172 N. |
8.67 |
Geocentric |
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--------- |
center of Earth |
227 S. |
8.38 |
6Altitude of each observatory is measured in kilometers above sea level.
7"Distance" refers to the closest approach distance of the "Site" to the center of Pluto's shadow in the shadow plane. The errors on all closest approach distances are ±428 km (one standard deviation). "S." means the site is South of the center of Pluto's shadow. "N." means the site is North of the center of Pluto's shadow.
P598.2 Appulse Predictions for Individual Sites
Site |
Pluto Immersion (UT)9 |
Mid-Time (UT)9 |
Pluto Emersion (UT)9 |
Solar Elevation 10 |
Flagstaff |
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04:30:08 (33°) |
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–28° |
Las Campanas |
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04:31:53 (34°) |
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–71° |
Lick Obs. |
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04:31:25 (34°) |
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–21° |
Magdalena Ridge Obs. |
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04:29:35 (33°) |
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–31° |
Mauna Kea (IRTF) |
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04:38:11 (48°) |
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0° |
Mt. Hopkins |
----------- |
04:30:09 (36°) |
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–31° |
Geocentric |
04:35:31 |
04:38:16 |
04:41:00 |
9The errors on all times are ±0:50 (50 seconds; one standard deviation). In parenthesis is the elevation of the body above the celestial horizon in degrees.
10At the closest approch time for that location.
Last updated by Carlos A Zuluaga (czuluaga@mit.edu) 2008-07-28 3:00
Please direct all inquiries to Planetary Astronomy Lab (planetary-astronomy@mit.edu)
