New Horizons: Approach Phase, OpsNav - 25 January 15 to 28 June 15 |
New Horizons: Approach Phase, OpsNav - 25 January 15 to 28 June 15 |
Feb 3 2015, 06:45 PM
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#101
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Member Group: Members Posts: 105 Joined: 27-August 05 Member No.: 479 |
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Feb 4 2015, 09:22 PM
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#102
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Forum Contributor Group: Members Posts: 1372 Joined: 8-February 04 From: North East Florida, USA. Member No.: 11 |
The LORRI image release for today is up at :
http://pluto.jhuapl.edu/News-Center/News-A...p?page=20150204 |
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May 11 2015, 11:10 AM
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#103
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Senior Member Group: Members Posts: 2346 Joined: 7-December 12 Member No.: 6780 |
Starting from manually determined positions of Nix and Hydra
in 17 (until 2015-05-06) of the OpNav Campaign 3, LORRI 4x4, cleaned, stacked and star-background-subtracted image quintuples I've tried to simulate the positions by manually adjusting parameters of assumed circular orbits: This simulation can be extrapolated: After narrowing down the orbital plane I've transformed the processed LORRI images, such that objects orbiting in a circular way around the Pluto/Charon barycenter are mapped to almost constant position; phase angle as x, radius as y-axis: Here an example of the last eight of this image sequence stacked to reduce noise: Versions on less and more processed images: For small radii the method is very sensitive to the barycenter. Nix and Hydra are apparent, Styx and Cerberus not yet evident (to me), despite this excessive processing. |
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May 11 2015, 03:35 PM
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#104
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Newbie Group: Members Posts: 9 Joined: 30-April 05 From: Missouri, USA Member No.: 370 |
I just noticed that the image metadata files have the expected X,Y coordinates of all the objects in each raw image. For example:
http://pluto.jhuapl.edu/soc/Pluto-Encounte...0x633_eng_1.txt lists: PLUTO;X=127;Y=126 CHARON;X=128;Y=137 NIX;X=119;Y=99 HYDRA;X=116;Y=156 KERBEROS;X=152;Y=122 STYX;X=107;Y=126 These seem to have the Y origin at the bottom of the image, and I needed to subtract a pointing offset from all of them equally to get things to line up. But this could help with spotting Styx and Kerberos, perhaps doing a manually shifted stack on the expected XY. Strip the URL back to /info/ for a directory of the files. |
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May 13 2015, 03:57 PM
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#105
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Senior Member Group: Members Posts: 2346 Joined: 7-December 12 Member No.: 6780 |
First congrats to the New Horizons team, and particularly to John Spencer and his image processing team, for accomplishing this milestone!
At least with the published jpegs until 1st of May that's exceedingly difficult. I just noticed that the image metadata files have the expected X,Y coordinates of all the objects in each raw image. ... I needed to subtract a pointing offset from all of them equally to get things to line up. The coordinates seem to be relative to the barycenter of the system. I tried to adjust for this by adding the displacement needed to register stars: But there is an increasing error build-up. I've been pondering for a while for the reason; my best explanation thus far is a changing parallax of the Pluto/Charon barycenter with respect to the starfield background during the OpNav Campaign 3. |
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