SDO, (Solar Dynamics Observatory) |
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SDO, (Solar Dynamics Observatory) |
 Apr 23 2010, 05:45 AM
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#76
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 The Poet Dude  Group: Moderator Posts: 5551 Joined: 15-March 04 From: Kendal, Cumbria, UK Member No.: 60  |
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Apr 23 2010, 09:38 PM
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#77
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Junior Member Group: Members Posts: 89 Joined: 27-August 05 From: Eccentric Mars orbit Member No.: 477 |
QUOTE (elakdawalla @ Apr 22 2010, 10:17 PM)  What exactly was said about that? It surprised me when I heard it but I was busy writing down other things so I didn't get what the P.I. said. It seemed weird to me that an image of the Sun showing up so beautifully on a detector would be a "mistake." From the report on Spaceflightnow.com: http://spaceflightnow.com/news/n1004/21sdoimages/ QUOTE "Our first image from EVE doesn't look anything like it should," Pesnell said. I may have misinterpreted this, but I remember thinking at the time that it sounded like he said this was a mistake. |
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Apr 23 2010, 10:09 PM
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#78
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 Senior Member Group: Members Posts: 1419 Joined: 26-July 08 Member No.: 4270 |
Yeah, the way it was worded made me think it was a problem too.
-------------------- -- Hungry4info (Sirius_Alpha)
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Apr 24 2010, 12:00 AM
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#79
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Senior Member Group: Members Posts: 1582 Joined: 14-October 05 From: Vermont Member No.: 530 |
QUOTE (kwan3217 @ Apr 23 2010, 05:38 PM) I may have misinterpreted this, but I remember thinking at the time that it sounded like he said this was a mistake. But, is it? Is there worry that at solar max the pinhole image will obscure the spectrum? (Or some such thing?) It's "unexpected," but is it okay? |
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Apr 24 2010, 04:09 AM
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#80
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Junior Member Group: Members Posts: 89 Joined: 27-August 05 From: Eccentric Mars orbit Member No.: 477 |
QUOTE (stevesliva @ Apr 23 2010, 06:00 PM) But, is it? Is there worry that at solar max the pinhole image will obscure the spectrum? (Or some such thing?) It's "unexpected," but is it okay? We don't expect the SAM image to cause a problem, even at solar max. There is plenty of space on the CCD between the solar image and the spectrum. If it does somehow cause a problem, we can turn the SAM filter wheel to 'dark' and effectively turn SAM off. SAM is a lower priority measurement -- EVE is primarily a spectrometer, and there are five other cameras on SDO, all higher-resolution than SAM. SAM isn't even really an imager - we plan on using it to get a spectrum as well. The main EVE measurement is a spectrum from about 7nm, right on the edge between ultraviolet and x-rays, out to about 120nm, at the Lyman Alpha line. We use SAM to fill in the spectrum from 7nm down to almost zero, in the soft x-ray band. It's really hard to build a diffraction grating that works for x-rays. The smaller the wavelength is, the smaller the lines on the grating have to be. It's hard enough to get a grating that works well in extreme ultraviolet. Also, x-rays being x-rays, they have a tendency to pass through the grating rather than be diffracted by it. So, SAM doesn't use a grating at all. We collect the image of the sun, and then analyze that image pixel-by-pixel. SAM is designed with a small-enough pinhole and short-enough exposure that we expect only one x-ray photon to hit any one pixel. When a pixel does get hit, its brightness is directly proportional to the energy of the photon that hit it. Then we can use Planck's constant to get the wavelength of each photon, then count and bin the photons to get a spectrum. It's a really neat concept, and one that hasn't to my knowledge been tried in space. The theory is good, but in theory, theory and practice are identical, while in practice, they are not. We are treating it as an engineering experiment. We have a long way to go before we see this work, but initial signs are good. |
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Apr 25 2010, 06:55 AM
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#81
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 Senior Member Group: Members Posts: 2492 Joined: 15-January 05 From: center Italy Member No.: 150 |
Perhaps I missed the information within thread... do we have any indication of public, regular, real-time images release in the next future???
-------------------- I always think before posting! - Marco -
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| Guest_Sunspot_* |
Apr 27 2010, 08:48 PM
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#82
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Guests |
SDO Day 76: Getting Ready for Science Data
Mon, 26 Apr SDO is moving toward becoming an operational science mission. The data will be available from several sites in a variety of formats. SDO scientists and engineers are working to set up those access points, but we won't be ready for regular data releases until mid-May. Next step is the EVE calibration rocket, scheduled to fly on May 3, 2010 from the White Sands Missile Range. |
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Apr 27 2010, 11:25 PM
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#83
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Senior Member Group: Members Posts: 1582 Joined: 14-October 05 From: Vermont Member No.: 530 |
More prominence vids:
http://science.nasa.gov/science-news/scien...r10_plasmarain/ |
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Apr 28 2010, 03:21 AM
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#84
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Junior Member Group: Members Posts: 37 Joined: 20-November 05 Member No.: 561 |
Now that we have "real-time" images of the sun, I've been wondering about the issue of light-time delay:
In these images, do the scientists need to take into account the light-time travel distance between different parts of the sun? For most planets, even Jupiter, it doesn't make much of a difference. But the sun is several light-seconds wide. (Ah, "about 4.643" in diameter from a quick Wikipedia lookup.) The sun is a globe, so if dead center of the image is "now", the edge of the images would presumably show events that happened a few seconds "before" the center's events--in other words, no picture of the sun shows it all "at the same time"! Would this effect distort the shape of prominences? (I mean really big ones.) Should we "correct" images for it? (Leave the center alone, but shove the part at the edge back closer to the sun so "the is the shape it really was at that moment"?) Maybe we should mentally overlay an archers-target of concentric rings over sun images: label bulls-eye as "now", the next ring as "x sec. ago", etc. Can we fix this? Merge pictures taken a few seconds apart: keep the center and merge the outer part from a few seconds before it... Oh darn. It only takes pictures every 10 seconds. Missed the window! But you know what I'm going for. What is the way solar scientists handle this issue? |
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Apr 28 2010, 03:40 AM
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#85
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Senior Member Group: Members Posts: 1419 Joined: 26-July 08 Member No.: 4270 |
I would imagine that since not a lot of things occur in a 4-second duration on the sun, compared to what all is being observed, it's forgivable.
But I'm not a solar physicist so that's just my uneducated guess. -------------------- -- Hungry4info (Sirius_Alpha)
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Apr 28 2010, 03:55 AM
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#86
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 Merciless Robot Group: Admin Posts: 8783 Joined: 8-December 05 From: Los Angeles Member No.: 602 |
The scale of observations should be considered. Phenomena of interest such as prominences, etc. are fairly localized, so the speed of light isn't really much of a factor. In any case, events that might effect the entire Sun (i.e., long-period 'seismic' oscillations) obviously propagate at far less than the speed of light, so again SOL lag isn't really a consideration for observation or interpretation.
-------------------- 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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| Guest_Sunspot_* |
Apr 28 2010, 06:47 AM
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#87
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Guests |
There are smaller version available on youtube if you don't fancy the 25MB version http://www.youtube.com/watch?v=3C9L90uAOXs
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| Guest_Oersted_* |
Apr 28 2010, 09:49 AM
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#88
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Guests |
ouch, a hair on the lens?!
Spectacular images! - I really look forward to a hi-def 1080p hour-long movie for my flat-screen tv! |
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Apr 29 2010, 06:58 PM
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#89
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Junior Member Group: Members Posts: 94 Joined: 15-October 09 Member No.: 4979 |
QUOTE (Oersted @ Apr 28 2010, 04:49 AM) ouch, a hair on the lens? Looks like it's directly on the detector, or it was a CR hit on the flat field calibration frame. |
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