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

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)