spheres in Sun's corona

[bboyer]

Dealing with lens and imaging dust artifacts is not a trivial problem. Dust at a clean-room manufacturing level is not the issue. One example from the JPL:

AN OPTICAL MODEL FOR IMAGE ARTIFACTS PRODUCED BY DUST PARTICLES ON LENSES

[Doureios]

These anomalies have none of the characteristics of dust particles as presented in the pdf. Dust is a bit obvious when present on a lens. And doesn't appear and disappear every few minutes on a lens in space.

In one site there is an official explanation from NASA (they say it is an answer to an email, don't know if it's true)
It doesn't make too much sence to me but I copy it here for everyone that might understand better.

Answer:
What you’re seeing is the difference between “beacon mode” (near realtime, heavily compressed, binned ) images and normal playback telemetry images (2048 x 2048 native mode, less heavily but still lossily compressed).

Normally, we get most of each day covered by the near realtime, beacon mode data through the help of a variety of ground stations around the world (including some operated by radio amateurs):

[link to stereo-ssc.nascom.nasa.gov] ,

so we have prompt information when space weather events have originated at the Sun. The full-resolution playback telemetry comes from dedicated periods of downlink (“station contacts”) through NASA’s Deep Space Network (DSN). A single playback can last hours, and covers data from a day or more stored on one of the two spacecrafts’ solid state recorders. Those data are then played back over the Internet to the mission operations center and the STEREO science center, and thence to the instrument teams’ home institutions, where they are processed over the course of a day or so. Thus, in normal operations, the full-resolution images will be ~ three days behind real time. Newer images will be the lower-res, more highly compressed beacon mode images, and older images will have been replaced by the full-res, playback data.

On January 18, at ~ 21:47 UT, the “central data recorder” at DSN, that stores all the playback data from all the missions DSN supports, failed. A backup CDR took over, but apparently started working on data from January 10, instead of just the four previous hours, as designed. (The last I heard, the DSN engineers don’t know why, but it certainly sounds like a software issue.) For some reason, DSN is unable to reset a pointer and say, please start processing from this time instead of that time. So we, and all the other missions supported by DSN, are waiting for our playback data from January 18 and all following days. As soon as we get it, and the instrument teams have reformatted the telemetry into scientifically useful formats (that allow, for instance, making SECCHI EUVI data into images), we will post the images and other STEREO browse data in the normal places.

And no, I don’t know why DSN designed such an inflexible CDR system. I suspect they may modify it after this experience.

Best,

(Dr.) Joseph B. Gurman
STEREO Project Scientist

[bboyer]

The reference was intended only as an example of the issue. I would imagine the correctional or compensating software algorithms spoken of in the paper, as well as equipment configuration, would account for the wide differences between the denser dust environment of a lander and that of an orbiter in the ionized "solar wind" and interplanetary medium. I have no idea how, or when, these correctional algorithms are applied in the image sequencing, and whether it's applied on-board, earth-side, or a combination of both. Particularly since we apparently only have access to images 10 minutes apart or whatever it's difficult to see exactly what's happening with the images.

[Doureios]

What troubles me is that suddently all Sun observers appear to have problems.. both US and Russian observers.. more and more images have black areas on them...

I found three nice images, 35 minutes in duration, that can be used for tracking one of the spheres.

http://stereo-ssc.nascom.nasa.gov/brows ... uA_195.jpg

http://stereo-ssc.nascom.nasa.gov/brows ... uA_195.jpg

http://stereo-ssc.nascom.nasa.gov/brows ... uA_195.jpg

Check the sphere at 9, 8, and 7 o'clock respectively.. it looks like an object in orbit.. can anyone do the mechanics of it?

[Siggy_G]

I'm not so convinced that the mentioned dots are spheres, as they appear more like image anomalies. The resolution on the images aren't truly 2048*2048 pixels - they seem more like upscaled blurry images with compression. A bright pixel with compression will often get a dark edge around it, making it appear like a highlighted sphere. So, don't look so much at the low res blurry images.

HOWEVER, on the sharper images, a couple of dark dots seemed at first stationary to me:

But when I backtrack to random previous photos, the dark dot at the top is actually moving slowly horizontally. It is far above the Sun's ecliptic plane, which the inner planets are orbiting within. This seems like the silhouette of an orbiting object, for sure - and not a lens bug. (I had to find dates where the corona is bright enough for the dot to appear):

If you want to compare images, use this URL and replace the date part:
http://stereo-ssc.nascom.nasa.gov/brows ... /195/2048/

[Siggy_G]

I should probably add and underline to my previous post that it seems odd that this dark dot, or a silhuetted object, appears in this area of the Sun. It is also far above where planets would orbit. Perhaps it is possible to dig up images of other wave lengths that enhances the shape of this object. The silhuette in the image above indicates that it is not emitting too much energy and may be a solid object. It may still have an apparent crescent in visible wavelengths.

[Ion01]

I wanted to toss a few things out there on this subject. First, the whole thing about venus having a plasma explosion....as cool and nice as that would be is most definitely a lens effect due to the curvature of the lens. This can be seen in the picture I took with my camera of the orion nebula. http://img705.imageshack.us/img705/681/stacked1.jpg Notice the shape of the stars the closer you get to the edge. With with a bright enough star it will actually complete a circle. Also, notice the extremely "bright" star at the bottom. It appears that bright due to being so close to the edge. (the image is cropped so the top and sides are not actually near the edge of the lens.
Also, notice the archs at the bottom left. This image is actually a stack of 30 images. Due to some shifting in some of the images this lens effect shifted. This is actually a portion of the complete circle that stems from the core of the nebula.
In this image I have made the stars round and removed the archs in the bottom. http://img682.imageshack.us/img682/681/stacked1.jpg
The original stack also contained many other artifact of process, one of which is commonly used by nasa to increase the resolution of the images, that I had to remove. I don't have the original with me now or I would show you.
Here is another reference illustrating the lens effect. http://www.tungstentech.com/Portals/0/a ... 5-FR-2.avi

As for the moving objects. I believe they are dust, but not on the lens itself. First, to assert that not a single speck of dust or lint or whatever could be inside the camera and lens I find hard to believe no matter how clean they attempt to be. On the other side this could easily be dust outside of the lens floating around in space. Its not like there wouldn't be dust outside of the craft floating through space.
This reference from earlier is great http://www-robotics.jpl.nasa.gov/public ... st_2.9.pdf but not all dust artifacts look this large in an image. In the reference they are dealing with a wide angle lens not with multiple lenses of different curvature and mirrors of different curvature where the dust could be on a mirror and not a lens or floating between the two or outside the whole assemble floating a few feet from the assembly. In addition if you stack images to increase the resolution then the dust spots will appear smaller as well.
Typically these artifacts are removed by taking what are called flat frames, however, they cannot be removed if the dust is not stationary and on the same spot in every picture taken during the sequence. This can happen even here by imaging near a dirt road on a dry day. A vehicle drives by and kicks up dirt and as some floats in front of the sheild of the scope you get artifacts that can't be removed by flat frames and moves or varies from image to image as the dust is not stationary and/or setting on the lens or mirrors.

The point is that I am going with these are small particles in front of the lens near the imager.

[Ion01]

I also want to add that I beleive these are particles near the imager as they are only appearing near the edge where the light is faint and not directly infront of the sun. Why is this important? In very bright spots, such as near the core of the nebula in my image, dust artifacts won't show up. Ever wonder why you don't have these dust spots on pictures you take such a portraits of your freinds and other things? When there is enough light present the faint effect of the dust doesn't show up. It only shows up in fainter areas....particularly areas of an image that are stretched to enhance the detail. This is basically what the images looked like before processing/stretching. http://img535.imageshack.us/img535/7002/image1z.jpg
No dust, no artifacts, no archs in the bottom, only a few stars are distorted. Once stretched all these flaws show up. Most nasa telescopes automatically take multiple frames, stack, and process them automatically before sending them to earth. The hubble telescope does this as the amount of data that would have to be sent back to do it here would be massive. In fact, the high resolution images taken by hubble are taken with a imager of lower resolution than the image. My image is almost 1400x1000 but was taken with a CCD chip only 640x480.
Anyways, the point is the particle flaws will only show up in the fainter areas of the image and that is where they are all being found.

[Ion01]

Sorry, one more thing: I am not familiar with the different Modes nasa is talking about causing this "effect" but I would imagine that in the compressed mode the processing that normally takes place to remove such artifacts does not take place or does not work as effective and that would be why their explanation is valid and why these object may not show up in the other mode.

[RayTomes]

...
But when I backtrack to random previous photos, the dark dot at the top is actually moving slowly horizontally. It is far above the Sun's ecliptic plane, which the inner planets are orbiting within. This seems like the silhouette of an orbiting object, for sure - and not a lens bug. (I had to find dates where the corona is bright enough for the dot to appear):

Hi Siggy
In order to do some attempt at orbital calculations it is also necessary to know the orbit of the craft taking the pictures. I haven't been able to find that. Does anyone know that info?
Such slow motion suggests a planet beyond the Sun.
Regards
Ray

[Siggy_G]

Hi Siggy
In order to do some attempt at orbital calculations it is also necessary to know the orbit of the craft taking the pictures. I haven't been able to find that. Does anyone know that info?
Such slow motion suggests a planet beyond the Sun.

Hi,
Since the dot moves sequentially to the right, I believe it would be on the near side of the Sun (unless it moves in opposite direction of other planets). Also, unless the orbital speed of the craft is very fast. As for its orbit:

http://sohowww.nascom.nasa.gov/explore/faq.html Second question there.

[RayTomes]

In order to do some attempt at orbital calculations it is also necessary to know the orbit of the craft taking the pictures. I haven't been able to find that. Does anyone know that info?
Such slow motion suggests a planet beyond the Sun.

Since the dot moves sequentially to the right, I believe it would be on the near side of the Sun (unless it moves in opposite direction of other planets). Also, unless the orbital speed of the craft is very fast. As for its orbit:

http://sohowww.nascom.nasa.gov/explore/faq.html Second question there.

Thanks Siggy

Yes your comment about direction is valid. However in more than 6 months it moves less than 5 minutes of arc. Planets on the same side of the Sun would move far more than that. Mercury would make several orbits and Venus would move many times that much. Even for bodies on the far side of the Sun, they would move much more than that, because the craft itself would complete half an orbit of the Sun in this time.

The only thing that I can see left is based on this:

This orbit is around a mathematical point between the Earth and the Sun known as the Lagrange point or the L1 point. The L1 point is a point of equilibrium between the Earth's and Sun's gravitational field, that is to say that the pull is equal from both the Sun and the Earth. The L1 point is a point of unstable equilibrium (like a bowl round side up with a marble balanced on it).

So maybe the object is actually at the L1 point? But it is an unstable point, so it would need to be another space craft.

[Ion01]

RayTomes-
That would go with exactly what I was saying. That it is a particle or object just beyond the camera closer to the satellite than the sun.