Dawn approaches Ceres, From opnav images to first orbit |
Dawn approaches Ceres, From opnav images to first orbit |
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Solar System Cartographer ![]() ![]() ![]() ![]() Group: Members Posts: 10194 Joined: 5-April 05 From: Canada Member No.: 227 ![]() |
On Tuesday (two days from now, for visitors from the future), the first optical navigation image will be taken... hopefully we'll have it in our hands soon after that. So it's time for a new topic. Over the next few months we'll have progressively closer images and full orbit characterization sequences, no doubt including multispectral image sets.
A new world... This is a bit of reprocessing I have been doing with the Hubble images from a few years ago. Phil -------------------- ... because the Solar System ain't gonna map itself.
Also to be found posting similar content on https://mastodon.social/@PhilStooke Maps for download (free PD: https://upload.wikimedia.org/wikipedia/comm...Cartography.pdf NOTE: everything created by me which I post on UMSF is considered to be in the public domain (NOT CC, public domain) |
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![]() Administrator ![]() ![]() ![]() ![]() Group: Admin Posts: 5172 Joined: 4-August 05 From: Pasadena, CA, USA, Earth Member No.: 454 ![]() |
The previously released image was clearly enlarged by a factor of 10, but if the most recent one has been enlarged by an integer factor it's not obvious to me what that integer is. The Dawn Journal says that this observation is supposed to see Ceres 121 pixels across. Top to bottom, the visible disk is about 930 pixels, but that doesn't divide evenly. But if the disk width refers to the equatorial width, I could be convinced that it's been enlarged by a factor of 8.
Edit: Really nice work, Ian. It may be crude but it's pretty ![]() -------------------- My website - My Patreon - @elakdawalla on Twitter - Please support unmannedspaceflight.com by donating here.
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#3
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![]() Senior Member ![]() ![]() ![]() ![]() Group: Members Posts: 4252 Joined: 17-January 05 Member No.: 152 ![]() |
The previously released image was clearly enlarged by a factor of 10, but if the most recent one has been enlarged by an integer factor it's not obvious to me what that integer is. The Dawn Journal says that this observation is supposed to see Ceres 121 pixels across. Top to bottom, the visible disk is about 930 pixels, but that doesn't divide evenly. But if the disk width refers to the equatorial width, I could be convinced that it's been enlarged by a factor of 8. I believe the image here has been enlarged by a factor of exactly 6, as you can see by counting pixels between steps on the jagged left limbs. (Count pixels over as many steps as you can and divide by the number of steps.) This gives a disk size very close to the expected 121 pixels for the original image. The image here appears to be the 6x oversampled image zoomed further by approximately 30% (because bigger is always better ![]() |
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