A Question About SOHO LASCO-C3 Images

[michaelmozina]

I have a question for Wayne (or anyone else) about the recent Lasco-C3 images. Specifically I've been looking for a "sign" of a start of the next solar cycle, and I'm noticing something a little "unusual" in the LASCO images.

It could be a processing issue (one of the reasons I'm asking for help), but it "seems' as though the sun is doing some serious "flip-flopping" in the energy (actually light) distribution patterns coming off the sun over the past few days. I went back and looked at this whole month's worth of LASCO images last night, and this full atmosphere "flip flop" seems to occurring at a rate that is significantly "greater than" what I see for the previous month. Is this some sort of processing related light output change, or is there actually some physical solar process that is driving this effect?

 

[MeteorWayne]

As has been explained to you repeatedly, the "baseline" flat field is done once a week. So you would expect there to be a substantial change when that occurs.

The other thing that goes on is that there are time gaps when no observations are made. As a result, there are "jumps" in the images.

Do you have anything specific (wth a UT date and time) that you are referring to so I can look at it?

 

[michaelmozina]

As has been explained to you repeatedly, the "baseline" flat field is done once a week. So you would expect there to be a substantial change when that occurs.

The other thing that goes on is that there are time gaps when no observations are made. As a result, there are "jumps" in the images.

I hear you on both these points, but there seems to be more to it than differences due to gaps in time, or baseline adjustments. I suppose it could be some type of image artifact.

Do you have anything specific (wth a UT date and time) that you are referring to so I can look at it?

Sure. I'm sorry about being vague earlier. I didn't give you much to go on:

If you look at the Lasco-c3 image on 3/22 at 22:18, notice the contrast between that image and the next image in that sequence from 22:48. You might notice that there are two "dark bars" to the left and right of the equator that disappear between these two images. That same pattern continues until about 1:48 of 3/23 where there is a another rapid change and the two dark zones to the left and right of the equator reappear between two image. There is another notable switch in the 3/23 image at 06:18 where the pattern switches again. There is also another change in the 09:18 image on the same date. The next notable change occurs in the 01:18 image on 3/24. At 06:18 of the 24th, there appears to be a glare ring, or some kind of circular wave type pattern that becomes slightly visible in the top half of the image of that specific image. In the next image at 06:42 there is another dramatic "shift" in the output pattern.

I see these sorts of things all the time, and some of them are undoubted related to the issues you mentioned, but this particular sequence of dramatic changes seems "unusual" in the amount of change between images, and the number of changes over a short period of time.

 

[michaelmozina]

Do you have anything specific (wth a UT date and time) that you are referring to so I can look at it?

FYI, I just checked the LASCO-C2 images and these same types of changes are visible in these images as well, at about the same timelines.

 

[michaelmozina]

Do you have anything specific (wth a UT date and time) that you are referring to so I can look at it?

One more thing I'd like you to look at carefully for me Wayne are the three images on 3/24 from 04:42 to 06:18. Look carefully at the upper right corner of the image in about the 11:30 position and go backwards and forwards through these three images. There is some sort of glare effect, or some sort of wave moving though those three image that comes in from the 11:30 position. I think I see some particle movement going on, but it's hard to tell since there are lots of particle artifacts in all these images. In the image that follows the 06:18 image (where the "ring" is most noticeable), there is another dramatic "flip-flop" in the output pattern.

 

[MeteorWayne]

That is interesting. It certaily looks real, not like an artifact. I've never noticed anything like that before; but it goes by so fast I'm not sure I would have seen it if you hadn't pointed it out. It appears to be moving too fast to be near the sun, let me see if I can find anything in between the earth and sun that might have produced it.

 

[michaelmozina]

That is interesting. It certaily looks real, not like an artifact. I've never noticed anything like that before; but it goes by so fast I'm not sure I would have seen it if you hadn't pointed it out. It appears to be moving too fast to be near the sun, let me see if I can find anything in between the earth and sun that might have produced it.

I would have missed it too in MPG movies. The only reason I noticed it is because I used the SOHO Movie Theater to put together a LASC0-C# movie of the whole month. I ran that movie fairly slowly and that's when I first noticed it. It does appear to be "real" in some way, although the ring seems to grow rapidly in size in those three images, as though the source may be close to the spacecraft, like perhaps a boom arm on SOHO?

 

[m230042]

lasco image 2010/01/06-08 ...Solar system entering object stars at about 11 high exits right about 2:30 increase in size.

 

[MeteorWayne]

That's Mercury passing between us and the sun.

See the SOHO Comets/Asteroids/Planets thread on Page 2 toward the bottom (post of 1/4/2010)