(last updated 2011 06 21)
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Across the globe pictured above, the six solid lines correspond to the northern limit, centerline, and southern limit of Pluto's (Black) and Charon's (Red) shadow. The northern and southern limits of Pluto correspond to a radius of 1400 km (605km for Charon). The upper and lower dashed lines indicate 3-sigma errors. The shaded area represents where the sun is more than 12 degrees below the horizon.
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Table 1: Prediction Details |
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| Pluto Geocentric Mid-time (yyyy month dd hh:mm:ss) | 2011 June 23 11:25:07± 00:00:231 UT |
| Pluto Minimum Geocentric Separation | 0.113± 0.0181 arcsec |
| Charon Geocentric Mid-time (yyyy month dd hh:mm:ss) | 2011 June 23 11:14:31± 00:00:231 UT |
| Charon Minimum Geocentric Separation | 0.173± 0.0171arcsec |
| Position Angle (Pluto relative to the star; measured north through east) | -6.13 degrees |
| Geocentric Velocity | 23.85 km/sec |
| Occultation Star UCAC2 magnitude | 14.432 |
| 2-MASS Catalog IR Magnitudes | 10.957 (J), 10.054 (H), 9.743 (K) |
| NOMAD Catalog BVR Magnitudes | 15.7 (B), 14.4 (V), 13.6 (R) |
1One standard deviation of random error.
2The UCAC bandpass (579-642nm) is between V and R.
Table 2: Reference Star Position |
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| Reference star position: (UCAC2, at epoch of event) |
RA (h:m:s; J2000) | Dec (d:m:s; J2000) | Notes |
| PC20110623 Catalog | 18 25 55.4890± 0.1650 | –18 48 07.047± 0.063 | |
| PC20110623 Measured3 | 18 25 55.4731± 0.0073 | –18 48 06.990± 0.011 | From 75 USNO 61-inchTelescope frames. See note 4. |
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Table 3: Projected KBO Offsets from Reference Ephemeris at the Time of the Event |
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| Body | RA (arcsec) | Dec (arcsec) | |
| Pluto |
–0.109± 0.024 |
+0.198± 0.014 | See Notes 5 and 6 |
| 3Measured position corresponds to RA offset of -0.2387'' and Dec. offset of +0.056''. 4All "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. 4Data analyzed using UCAC2 reference network. A weighted average of the data from the two telescopes was used to calculate the RA and DEC. The errors given are 1 standard deviation. 5The 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. 6Data from the Lowell 42-inch, SMARTS, du Pont, USNO 61-inch, and Lowell Astrograph telescopes over the span of 6 years were reduced with respect to stars in the UCAC2 catalog. A model was developed to fit the residuals obtained from our measured positions compared to that of the object's JPL ephemeris. All residuals obtained from the different telescopes were consistent with the model. 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. The model was propagated to obtain the predicted position and error of the Pluto at the time of the occultation. The errors listed for the Pluto are the RMS of the models fitted. |
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Table 4: Site Information
Site |
East Longitude |
Latitude |
Site Altitude6 (km) |
Pluto Distance7 (km) |
Charon Distance7 (km) |
Velocity (km/s) |
Breit Ideas Observatory |
–121 42 10 |
37 06 47 |
0.28 |
1850 N. |
605 N. |
24.06 |
Cairns, AUS |
+145 46 28 |
–16 55 25 |
0. |
2499 S. |
3934 S. |
24.14 |
CSUSB |
–117 19 19 |
34 10 54 |
0. |
1510 N. |
274 N. |
24.04 |
Grove Creek Observatory |
+149 21 59 |
–33 49 46 |
0.9 |
4272 S. |
5690 S. |
24.11 |
IRTF |
–155 28 29 |
19 49 46 |
4.18 |
1243 N. |
52 S. |
24.23 |
Leeward |
–157 59 04 |
21 23 28 |
0.02 |
1414 N. |
113 N. |
24.24 |
Mt. Stromlo Observatory |
+149 00 31 |
–35 19 09 |
0.77 |
4433 S. |
5851 S. |
24.11 |
Table Mountain |
–117 40 54 |
34 22 54 |
2.29 |
1537 N. |
301 N. |
24.05 |
Sonoma, CA |
–122 27 28 |
38 17 31 |
0. |
1954 N. |
706 N. |
24.06 |
USNO-FS |
–111 44 24 |
35 11 00 |
2.31 |
1430 N. |
199 N. |
24.01 |
Windward |
–157 48 55 |
21 24 36 |
0.09 |
1414 N. |
113 N. |
24.24 |
Geocenter |
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center of Earth |
2561 S. |
3907 S. |
23.86 |
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 ±408 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.
Table 5: PC20110623 Occultation Predictions for Individual Sites
Site |
Charon Immersion (UT)9 |
Charon Mid-Time (UT) |
Charon |
Pluto Immersion (UT)9 |
Pluto Mid-Time (UT) |
Pluto |
Pluto Altitude |
Solar Altitude9 |
Breit Ideas Observatory |
11:11:52 |
11:11:53 |
11:11:54 |
----------- |
11:22:19 |
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21 |
–14 |
Cairns, AUS |
----------- |
11:17:49 |
----------- |
----------- |
11:28:17 |
----------- |
44 |
----------- |
CSUSB |
11:11:14 |
11:11:37 |
11:11:59 |
----------- |
11:22:03 |
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20 |
–14 |
Grove Creek Observatory |
----------- |
11:17:22 |
----------- |
----------- |
11:27:50 |
----------- |
48 |
----------- |
IRTF |
11:13:17 |
11:13:42 |
11:14:07 |
11:23:38 |
11:24:05 |
11:24:32 |
50 |
----------- |
Leeward |
11:13:28 |
11:13:53 |
11:14:17 |
----------- |
11:24:15 |
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49 |
----------- |
Mt. Stromlo Obs. |
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11:17:21 |
----------- |
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11:27:49 |
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48 |
----------- |
Table Mountain |
11:11:16 |
11:11:38 |
11:12:00 |
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11:22:05 |
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20 |
–14 |
Sonoma, CA |
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11:11:57 |
----------- |
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11:22:23 |
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20 |
–14 |
USNO-FS |
11:11:01 |
11:11:25 |
11:11:48 |
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11:21:52 |
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16 |
–10 |
Windward |
11:13:27 |
11:13:52 |
11:14:16 |
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11:24:15 |
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49 |
----------- |
Geocenter |
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11:14:31 |
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11:25:07 |
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9The errors on all times are ±0:20 (20 seconds; one standard deviation). The solar altitude is given for locations where it is relevant (solar altitude greater than -18°). No entry in the immersion and emersion columns indicates that the occultation is not predicted to be visible at that site.
Last updated by Carlos Zuluaga (czuluaga@mit.edu) 2011-06-21 20:50
Please direct all inquiries to PAL (planetary-astronomy@mit.edu)