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PEterW
professor emeritus


Reged: 01/02/06

Loc: SW London, UK
Re: Single Vs. Double Stack new [Re: George9]
      #5619491 - 01/12/13 05:27 PM

..... So I will now have to start saving for that second filter.... Darn you all! VERY good thread discussion, thanks to everyone!

PEterW


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BYoesle
Post Laureate
*****

Reged: 06/12/04

Loc: Goldendale, Washington USA
Re: Single Vs. Double Stack new [Re: PEterW]
      #5722853 - 03/09/13 07:18 PM Attachment (11 downloads)

Quote:

Question: Bob, have you tried to duplicate Zirin's photo, using a SS filter so that the photosphere is visible and trying to see closer to the base of the spicules by going slightly off-band? That might be a fun experiment. George

... I haven’t tried to image spicules @ 0.7 A with off-band tuning, they would be just as easily imaged with a 0.5 A filter with off-band tuning. When a < 0.5 A filter is used on-band, only the top of a few larger or macrospicules become visible, as in the animation above. The vast “spicule forest” on the limb remains hidden by the general chromosphere when the filter is on-band. Bob




As follow up to the discussion above, and George’s question about capturing the spicule layer off-band; today I could take advantage of better seeing than in December and was able to capture the spicule layer at 0.5 Angstrom FWHM.

The top image shows the on-band performance, with good prominence detail, macro-spicules, and no hint of the “double limb” of the photosphere showing through. The bottom image shows the filter system tilt-tuned off-band, now clearly showing the spicule layer, with the limb of the photosphere now apparent as the filter is blue shifted off the H alpha line ~ 0.5 A.

Note: reprocessed the image to bring out more spicule detail:

Edited by BYoesle (03/10/13 11:49 PM)


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marktownley
Postmaster


Reged: 08/19/08

Loc: West Midlands, UK
Re: Single Vs. Double Stack new [Re: BYoesle]
      #5723362 - 03/10/13 04:36 AM

Excellent demonstration of the effect Bob, thanks

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George9
sage


Reged: 12/11/04

Re: Single Vs. Double Stack new [Re: marktownley]
      #5724722 - 03/10/13 08:39 PM

Wow wow. Great images, Bob.

Is that the same point on the sun at around the same time? I.e., did the prominence disappear almost completely off band? So the prominence is not moving much in our line of sight, but those off-band spicules happen to be pointed towards us, and if you go on band, you are actually seeing different spicules (versus the spicules each having broader emission)?

George


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BYoesle
Post Laureate
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Reged: 06/12/04

Loc: Goldendale, Washington USA
Re: Single Vs. Double Stack new [Re: George9]
      #5724912 - 03/10/13 11:11 PM

Hi George.

Yes it is indeed the same area on the sun's limb, with the top prominence image taken at 23:00 UTC, and the bottom spicule image taken at 22:59 UTC. May not be perfectly lined up - but close.

I'd agree with your interpretation, with the caveat that the large spicules in the prominance image are "macro" spicules projecting above the "spicule layer." I will have to wait for better seeing to get a better resolved pair of images. And as you noted above, tweaking the secondary filters tilt did make the off-band image brighter - confirming your hypothesis - thanks again for your input

BTW - the last image on my March 9, 2013 Sun "polar prominence" images shows the on-band prominence a bit earlier at 22:51 UTC.


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