P/C570 Occultation June 22, 2008
(last updated 2008 05 13)
The shaded area represents where the sun is more than 12 degrees below the horizon. Across the globe pictured above, the three red lines correspond to the northern limit, centerline, and southern limit of Pluto's shadow; the blue lines correspond to the same for Charon's shadow. The northern and southern limits correspond to a radius of 1208 km (the 50% normalized stellar-flux level) for Pluto and a surface radius of 606 km for Charon.
|
| |
Pluto |
Charon |
| Geocentric Mid-time (yyyy month dd hh:mm:ss) |
2008 June 22 19:10:19± 00:00:12 UT |
2008 June 22 19:18:57± 00:00:12 UT |
| Minimum Geocentric Separation |
0.196± 0.016 arcsec |
0.032± 0.016 arcsec |
| Position Angle (Object relative to star; measured N. through E.) |
176.12 degrees |
175.61 degrees |
| Geocentric Velocity |
23.8 km/sec |
23.7 km/sec |
| Prediction Version |
P570-AST-2.0 |
C570-AST-2.0 |
Reference star position:
(UCAC2, at epoch of event) |
RA (h:m:s; J2000) |
Dec (d:m:s; J2000) |
UCAC Mag1 |
| P/C570 Catalog |
17 58 33.0124 |
–17 02 38.374 |
12.26 |
| P/C570 Measured |
17 58 33.0142 |
–17 02 38.351 |
|
1The UCAC bandpass (579-642nm) is between V and R.
|
| Offsets
from Reference Position/Ephemeris3 |
| Body |
RA (arcsec) |
Dec (arcsec) |
Notes |
P/C570 |
+0.0264± 0.0019 |
+0.029± 0.002 |
From 71 strips |
| Pluto/Charon4 |
–0.0589± 0.0123 |
+0.082± 0.015 |
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 positions for Pluto and Charon are those given by JPL Horizon's ephemeris (Pluto source file: PLU017; Earth center source file: DE405). Our residual model is based on the assumption that the same offsets in RA and Dec apply to both Pluto and Charon.
5255 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.
|
Discussion
On June 22nd, 2008, Pluto and Charon will occult P570 and C570 (=2UCAC 25370733; as originally published in McDonald & Elliot 2000a, 2000b; Table). The above map and the following prediction results are from the analysis of 255 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
- The Pluto radius of 1208 ± 9 km for a 50% for a partial occultation by the atmosphere is from Elliot et al. (2007).
- The separation between the center line and each of the limb lines corresponds to Charon's surface radius of 606 ± 2 km is from Person et al. (2006)
- Archive of all PC570
occultation predictions based on alternate sources
of data, including past predictions.
- Independent prediction for this event is given on the website Bruno Sicardy
Site Information
Site |
East Longitude |
Latitude |
Altitude6
(km) |
Pluto Distance7
(km) |
Charon Distance7
(km) |
Pluto Velocity
(km/s) |
Charon Velocity
(km/s) |
Black Springs |
138 53 18 |
–33 53 58 |
0.465 |
1414 N. |
--------- |
23.93 |
--------- |
Hobart |
147 26 24 |
–42 48 18 |
0.043 |
434 N. |
--------- |
23.86 |
--------- |
Mt. John |
170 27 50 |
–43 59 22 |
1.041 |
199 N. |
--------- |
23.73 |
--------- |
Mt. Stromlo |
149 00 35 |
–35 18 57 |
0.813 |
1012 N. |
--------- |
23.86 |
--------- |
Siding Spring |
149 03 44 |
–31 16 17 |
1.205 |
1369 N. |
--------- |
23.87 |
--------- |
Namibia (SW of Windhoek) |
16 30 00 |
–23 16 18 |
1.800 |
--------- |
231 N. |
--------- |
23.98 |
Boyden Observatory |
26 24 17 |
–29 02 20 |
1.395 |
--------- |
695 S. |
--------- |
24.02 |
Geocentric |
---------- |
--------- |
center of Earth |
4523 N. |
736 N. |
23.80 |
23.72 |
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 the object's shadow in the shadow plane. The errors on all closest approach distances are ±343 km (one standard deviation). "S." means the site is South of the center of the object's shadow. "N." means the site is North of the center of the object's shadow.
P/C570 Occultation Predictions for Individual Sites
Site |
Pluto Immersion (UT)8 |
Charon Immersion (UT)8 |
Pluto Mid-Time (UT)8 |
Charon Mid-Time (UT)8 |
Pluto Emersion (UT)8 |
Charon Emersion (UT)8 |
Black Springs |
19:06:53 |
----------- |
19:07:03 (28°) |
----------- |
19:07:12 |
----------- |
Hobart |
19:06:23 |
----------- |
19:07:20 (22°) |
----------- |
19:08:17 |
----------- |
Mt. John |
19:06:22 |
----------- |
19:07:22 (5°) |
----------- |
19:08:22 |
----------- |
Mt. Stromlo |
19:06:13 |
----------- |
19:06:56 (20°) |
----------- |
19:07:38 |
----------- |
Siding Spring |
19:06:27 |
----------- |
19:06:44 (19°) |
----------- |
19:07:02 |
----------- |
Namibia (SW of Windhoek) |
----------- |
19:21:50 |
----------- |
19:22:13 (42°) |
----------- |
19:22:36 |
Boyden Observatory |
----------- |
----------- |
----------- |
19:21:38 (50°) |
----------- |
----------- |
Geocentric |
----------- |
----------- |
19:10:19 (20°) |
19:18:57 (51°) |
----------- |
----------- |
8The errors on all times are ±0:12 (12 seconds; one standard deviation). In parenthesis is the elevation of the body above the celestial horizon in degrees.
** Internal note: A– (20080404) **
Last updated by Carlos A Zuluaga (czuluaga@mit.edu)
2008-05-13 02:26
Please direct all inquiries to Planetary Astronomy Lab (planetary-astronomy@mit.edu)
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