The Voyager observations of Phoebe appear in Table 10 (click here) in the form of the pixel and line locations in the Voyager camera frame. The table also gives the inertial camera pointing angles which were derived from the background star images. As a simplification, the effects of uncertainty in the pointing have been incorporated into the location accuracies quoted in the table. The observations have not been corrected for stellar aberration; they provide measures of the apparent position of Phoebe as seen from the spacecraft.
| Picture ID | Observation time (UTC) | Camera pointing angles (deg) | Pixel | Line | ||||
| Rt. Ascen. | Dec. | Twist | Value | Acc. | Value | Acc. | ||
| 41901B+37 | 17 Jun. 1981 00:11:52.12 | 203.323974 | -7.744627 | -129.273157 | 465.80 | 0.71 | 589.34 | 0.61 |
| 42182B+27 | 26 Jun. 1981 08:51:52.12 | 205.345157 | -8.780149 | -127.860860 | 492.73 | 0.60 | 402.65 | 0.58 |
| 42351B+55 | 02 Jul. 1981 00:26:11.21 | 206.845295 | -9.510055 | -127.253253 | 571.33 | 0.67 | 319.07 | 0.65 |
| 42800B+50 | 16 Jul. 1981 23:34:11.21 | 212.089857 | -11.710938 | -123.628497 | 372.56 | 0.58 | 381.50 | 0.58 |
| 43300B+39 | 02 Aug. 1981 15:25:32.81 | 222.738376 | -15.963989 | -118.780588 | 422.66 | 0.70 | 140.20 | 0.58 |
| 43461B+08 | 07 Aug. 1981 23:48:44.81 | 228.634792 | -17.725684 | -115.402728 | 339.80 | 0.70 | 547.97 | 0.62 |
| 43491B+27 | 09 Aug. 1981 00:03:56.81 | 230.085968 | -18.288527 | -115.301906 | 642.37 | 0.57 | 388.94 | 0.58 |
| 43696B+50 | 15 Aug. 1981 20:22:19.85 | 241.941386 | -21.485373 | -110.265804 | 323.33 | 0.66 | 399.83 | 0.66 |
|
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To process the observations, first compute the apparent position of Phoebe:
where t is the observation time (ET), 
is the light travel time from
the Phoebe to the spacecraft, 
is Phoebe's position vector, 
is the spacecraft position vector, and 
is the Saturnian system
barycenter position vector; the former two positions are relative to the
Saturnian system barycenter, and the latter is relative to the Solar System
barycenter. The vectors 
and 
are the respective
velocities of the spacecraft and Saturnian system barycenter. This computation
implicitly involves an iterative procedure to determine from the true
relative distance between Phoebe and the spacecraft.
Next rotate the apparent position into camera body coordinates:
where 
, 
, 
are the right ascension, declination, and
twist camera pointing angles from Table 10 (click here), and 
is
the standard
rotation matrix about the 
axis.
Then project the camera body coordinates into the focal plane via the gnomonic
projection:
where f is the focal length of the camera and Pi is the
component of the vector 
.
The focal plane coordinates must be corrected for electromagnetic and
optical distortion:
where r2=x2+y2 and the ei are the distortion coefficients.
Lastly convert from the focal plane coordinates into pixel and line:
where 
is the camera transformation matrix and p0,l0 are
the pixel and line location of the optical axis.
For the Voyager 2 narrow angle camera the focal length is 1503.49 mm,
the optical axis is located at (398.07, 401.95),
the elements of the conversion matrix are:
and the distortion coefficients are:
| Picture ID | Position (km) and Velocity (km/s) | ||
| x | y | z | |
| 41901B+37 | 63212533.0 | 19188537.5 | 4918608.4 |
| -10.271438 | -3.060466 | -0.771611 | |
| 42182B+27 | 54904032.8 | 16712535.5 | 4294300.1 |
| -10.274296 | -3.062307 | -0.772204 | |
| 42351B+55 | 49888808.0 | 15217592.1 | 3917311.5 |
| -10.277604 | -3.063816 | -0.772655 | |
| 42800B+50 | 36591667.8 | 11252598.7 | 2917747.4 |
| -10.295356 | -3.070303 | -0.774463 | |
| 43300B+39 | 21738982.8 | 6823497.4 | 1799317.7 |
| -10.350959 | -3.087303 | -0.779872 | |
| 43461B+08 | 16946391.4 | 5393865.6 | 1438146.6 |
| -10.390964 | -3.100103 | -0.783285 | |
| 43491B+27 | 16038694.3 | 5123047.7 | 1369718.5 |
| -10.401263 | -3.103412 | -0.784171 | |
| 43696B+50 | 9856547.4 | 3277698.5 | 903262.8 |
| -10.521137 | -3.142626 | -0.794836 | |
|
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Table 11 (click here) contains the Voyager position, , and velocity,
, vector components at the observation times.