16.09.2020 An odd dark patch.

[Rusted]

Hi,

In the absence of much to look at I patrolled the disk and found this dark patch.
Image borrowed from my blog. The original is on the laptop.
An extended filament? It was only visible using the PST BF.
Nothing obvious there using the Lunt B1200. NOT a dust bunny!

16.09.20 09 copy 3.jpg (70.89 KiB) Viewed 548 times

[Montana]

That's a very interesting dark patch, did you see it on GONG as well? It looks like an odd pattern of darkened mottles

Alexandra

[DeepSolar64]

I had too bad of observing conditions yesterday to notice it if I could have seen it visually. Check out yesterday’s GONG image I posted. What part of the disc was it on? Northeast? Eric Roel posted some good pics from yesterday too.

[marktownley]

Nice shot!

[Rusted]

Thanks.

North east. A larger area of more subtle darkening lies to the SW of the main "blob."
I wouldn't have seen it without the PST BF. I use this BF to image proms.
Because it needs much less gain than the Lunt B1200. Which means much less noise.

Both BFs show completely different appearances on surface detail.
I don't believe this is just a tuning issue. The B1200 usually wins on surface detail.

Sorry, I don't remember whether Gong showed anything in this area.
Gong-Ha has been absent on many of the observatories recently. Bad weather?

[rsfoto]

Hi Chris,

Interesting shot. Check you camera window for dust ... Maybe it is dirty.

[EGRAY_OBSERVATORY]

As it seems somewhat circular, suggesting a speck of something on the optics.

Terry

[Rusted]

With the greatest respect, the spot remained fixed on the sun. Not in the field of view.
I could use the drives to move completely away from the darker region and return to it as fixed point on the sun.
In fact I was using the drives as usual to centre "the blob." Which would be impossible with a dust bunny.

I am very familiar with dust bunnies and they always remain fixed in the frame.
Nevertheless I shall investigate further and check all the videos I captured that day.
It may be possible to isolate the region in the B1200 videos but I cannot remember if I captured any of that region while using it.
The blob was absent on the next day using both BFs. I'd hoped to relocate it further westward to check for any changes.

[EGRAY_OBSERVATORY]

Hello again Chris,
With the testing that you've done, then perhaps there is a possibility that the region of interested suffered some sort of temperature-change causing the artefact to show-up.

Certainly quite unusual and if it requires a name for that type of artefact, I'd name it as a "A Rusted Patch"

Best Wishes
Terry

[Rusted]

Hello again Chris,
With the testing that you've done, then perhaps there is a possibility that the region of interested suffered some sort of temperature-change causing the artefact to show-up.

Certainly quite unusual and if it requires a name for that type of artefact, I'd name it as a "A Rusted Patch"

Best Wishes
Terry

Fame at last!

There's a similar dark patch on the north western quadrant now.
I haven't been following the path of surface features so can't confirm this is the same feature.

18.09.20 11.08 pst bf x2.6 gpc bw.jpg (33.37 KiB) Viewed 465 times

18.09.20 11.08 pst bf x2.6 gpc col.jpg (35.73 KiB) Viewed 465 times

[Montana]

That is most definitely a filament great shot

Alexandra

[Highbury Mark]

Interesting. I don’t remember seeing a dark patch yesterday through 70mm filters with excellent surface contrast. But didn’t observe for very long.

[DeepSolar64]

I occasionally see filaments or darker mottle patches that GONG doesn’t show which always leave me puzzled. I first eliminate the chances of them being dirt on the optics and make sure I can see them cleanly. In a few cases, especially with Rainer’s images If I can’t see them on GONG they will show up on someone else’s images and verify my find.

[rsfoto]

With the greatest respect, the spot remained fixed on the sun. Not in the field of view.
I could use the drives to move completely away from the darker region and return to it as fixed point on the sun.
In fact I was using the drives as usual to centre "the blob." Which would be impossible with a dust bunny.

I am very familiar with dust bunnies and they always remain fixed in the frame.
Nevertheless I shall investigate further and check all the videos I captured that day.
It may be possible to isolate the region in the B1200 videos but I cannot remember if I captured any of that region while using it.
The blob was absent on the next day using both BFs. I'd hoped to relocate it further westward to check for any changes.

Hi Chris,

No offense meant but you did the correct research and so we can put a checkmark on " It is not a dust bunny "

[EGRAY_OBSERVATORY]

Chris, I've attached one of the SDO images of this evening 18th, which along with most of their other light-images show darker patches all over the disk, so maybe there is a connection to what you imaged ??

Just a thought...

Terry

[Rusted]

We can all relax. I have just confirmed a dark patch in H-a in the correct position on the Learmouth archives for the 16th.
It may appear on other archives too had I the time to search. I ought to correct for CET but it is far too "time consuming."
Particularly given that these solar observatories are scattered across the globe and coincidence of capture time is very unlikely. [Local day/night.]

My memory is far too poor to be certain that the Gong image had me searching for this darker patch.
Though it is quite likely. During this deep minimum I usually have a quick look on Gong.
Just to see if I am wasting my time or have some juicy targets to locate and capture.

This was just one image chosen at random from that day's archives at Learmouth.

http://halpha.nso.edu/keep/hav/202009/2 ... 630Lh.jpg

Note how the "patch" changes in shape over time: It is even absent in some images!

http://halpha.nso.edu/keep/hav/202009/20200916/

I just wish my image was better but my PST BF has some limitations on displaying surface features.
Oddly, the Lunt B1200 showed nothing obvious there. Tuning?
I always have to adjust both focus and etalon tuning when changing back and forth between blocking filters.