DSCOVR |
DSCOVR |
Jan 6 2006, 08:55 PM
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#101
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Senior Member Group: Members Posts: 2454 Joined: 8-July 05 From: NGC 5907 Member No.: 430 |
ADMIN NOTE: Please note that this topic was unavoidably poltical before the 'No Politics' rule. Please restrict future comments to the mission/spacecraft/news updates etc.
WHAT'S NEW Robert L. Park Friday, 6 Jan 06 Washington, DC DEEP SPACE CLIMATE OBSERVATORY KILLED. http://bobpark.physics.umd.edu/index.html -------------------- "After having some business dealings with men, I am occasionally chagrined,
and feel as if I had done some wrong, and it is hard to forget the ugly circumstance. I see that such intercourse long continued would make one thoroughly prosaic, hard, and coarse. But the longest intercourse with Nature, though in her rudest moods, does not thus harden and make coarse. A hard, sensible man whom we liken to a rock is indeed much harder than a rock. From hard, coarse, insensible men with whom I have no sympathy, I go to commune with the rocks, whose hearts are comparatively soft." - Henry David Thoreau, November 15, 1853 |
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Oct 13 2016, 06:10 PM
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#102
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Senior Member Group: Members Posts: 1669 Joined: 5-March 05 From: Boulder, CO Member No.: 184 |
Thought I'd mention that I'm attempting to resolve a discrepancy in the geometry contained in the metadata. For a case that I'm simulating, the image at 18:04 UTC on September 20 states that the SEV angle is 9.2 degrees (on the website). If I use the subpoint (centroid) of the spacecraft from the json file (4.3N and 102.6W) though I come up with a solar elevation angle consistent with an SEV angle of about 10.4 degrees. My simulated image also shows a bit more limb shading than the actual image. Judging from my simulated image the sub-point looks OK since the continents line up pretty well. Thus I wonder if the stated time of the image could be off by a few minutes and is actually about 18:08?
-------------------- Steve [ my home page and planetary maps page ]
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Oct 31 2016, 04:36 PM
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#103
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Newbie Group: Members Posts: 11 Joined: 29-August 16 From: Israel Member No.: 8032 |
Thought I'd mention that I'm attempting to resolve a discrepancy in the geometry contained in the metadata. For a case that I'm simulating, the image at 18:04 UTC on September 20 states that the SEV angle is 9.2 degrees (on the website). If I use the subpoint (centroid) of the spacecraft from the json file (4.3N and 102.6W) though I come up with a solar elevation angle consistent with an SEV angle of about 10.4 degrees. My simulated image also shows a bit more limb shading than the actual image. Judging from my simulated image the sub-point looks OK since the continents line up pretty well. Thus I wonder if the stated time of the image could be off by a few minutes and is actually about 18:08? Hi Steve, I also have a weird discrepancy when confronting the ephemeris data provided on the EPIC website against the images themselves. See this video I generated from my Blueturn app, of the last July 5th Moon photobombing, when I also represent a virtual Moon model at the location provided in the ephemeris. I just don't understand the difference. I double checked and couldn't find any error in my perspective projection matrix. It looks like either the Moon position is wrong, or the DSCOVR position (all in J2000), or the time stamp itself. Or, maybe this is because my rendering engine is OpenGL-based and is in floating precision. What do you think ? I saw your nice simulation of the future eclipse across the US, so maybe you could also re-simulate the July 5th, 2016 Moon crossing, and tell me if you see the same difference as I do... See the video, or a direct deep link to my WebGL app (the virtual ephemerid-based Moon is right-most) : https://vimeo.com/189285144/6916063e34 http://blueturn.earth/app/EarthPlayer/?dat...0&cameraY=0 (Press 'm' to show the virtual Moon) |
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