Juno at Jupiter, mission events as they unfold |
Juno at Jupiter, mission events as they unfold |
Jul 5 2016, 07:53 PM
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Merciless Robot Group: Admin Posts: 8785 Joined: 8-December 05 From: Los Angeles Member No.: 602 |
This topic will consist of discussion of Juno operations post-JOI until end of mission, currently anticipated in Feb 2018.
-------------------- A few will take this knowledge and use this power of a dream realized as a force for change, an impetus for further discovery to make less ancient dreams real.
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Aug 8 2016, 11:18 PM
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#2
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Senior Member Group: Members Posts: 2346 Joined: 7-December 12 Member No.: 6780 |
Based on images JNCE_2016164_00C196 to JNCE_2016164_00C220, and assuming 80.943 JunoCam frames per Juno rotation,
Brownian K1=-0.00000003839251, K2=2.6E-015, I found an x/z pinhole scale factor of 1477.939165 +/- 0.275290, an x-position of the optical axis of 835.665952 +/- 3.204528, a y-position of the optical axis of 601.001077 +/- 1.892324, the CCD rotated around the z-axis by 0.002747 +/- 0.000225 radians, (0.157 degrees), with 1-sigma error bars over the considered data set, or 5-sigma error bars of the means by a sample size of 25, and normal distribution presumed. The parameters have been optimized for each image individually. The above parameters and errors are mean and standard deviation over the individual images (not the standard deviation of the mean). The maximum misalignment of the red and green centroid along either x or y relative to the green centroid was -0.032618/120 degree (about 0.01 raw pixels). The applied model is a spinning pinhole model distorted by a purely radial Brownian model with coefficients K1 and K2, slightly rotated around the optical axis. Most of the values look credible, but I doubt, that the x-position of the optical axis can be made consistent with EFB images and SPICE trajectory data. Therefore I think, that some assumption is wrong. For completeness, I'm intending to modify the three constant parameters, i.e. number of frames per rotation, K1, and K2, as an approach to register the color channels. But I'm skeptical (based on preliminary data), that the misalignments will turn out to be sufficiently sensitive with respect to these parameters to be able to allow for a good value for the x-position of the optical axis, and to stay consistent with EFB images and with laboratory data. Hence I expect considering a small chromatic aberration as the most promising approach to resolve the misalignments in an overall consistent way. Parameters for each of the considered images: JNCE_C196_C220_RGBAlignCSV.txt ( 7.24K ) Number of downloads: 229 An aligned example images (C197) : |
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