44 replies to this topic

[eblanken]

Hi Again,

 

Yes, my "tip-of-the-hat" to Larry and his work noted here !!!

 

Very Best Regards,

 

Ed

 

P.S. I do work at 5-70dBuV/m levels from 30 meters to 1 cm wavelengths and 120kHz FWHM Band Widths or 1 MHz BWs . . . f.y.i.

Edited by eblanken, 27 October 2024 - 11:14 AM.

[Spectrum222]

Ah - I assume 30m... digital modes, ed?!

 

Nice. 

[Spectrum222]

152RFT mini-update with Baader SWAN (directed from my post on 26 Oct/24):

 

Since we have SO much info and good discussions going on here, I have directed my 26 Oct RFT Mg-b posts here too. Just too much fun going on in this thread!

 

27 Oct 2024, 17:20-18:10UT. Very brief - seeing 8/10 (middle 20 minutes), with cloudy periods between endpoints of session. Wind light to calm, temp ~9-10C. 

 

152RFT w/APM wedge, 13mm TS UWAN 82-degree EP (69X), Baader SWAN #1 filter (have marked them to differentiate them):

 

Well... WOW! During the best seeing of this week, I almost got overloaded with details today! Yup - that SWAN filter is a keeper... Rather than drone on about specifics today, I wish to elaborate a bit on the differences I see compared to CFs and Na, and WL board band. More detailed observations will be done next time i have an extended session, because I am certain the changes will be detectable like in the sodium line views. So, here's my better take with good seeing today vs other filtering on the photosphere:

 

• the Mg bands DO show very good granulation, as mentioned previously, similar to sodium WRT granulation looking very fine and dark - i.e.: with VERY fine, mottling all over the surface at powers <80X so far. Similar to sodium for the "salt and pepper" look, but the interior details within mid-disk I find a bit easier to detect and see. Also, I find a bit more granular energy differences ("shading" as I have referred to it), associated with clusters of pores, and very small spot areas. Also shown bordering penumbrae and plage regions.
• Mg bands allow more general-purpose observing equipment - A solar wedge, any type, has plenty of throughput for this filter application, a bit easier to see than the NB Sodium regions, partly due to the fact that ~515-520nm is a bit closer to our photopic maximal eye response is my "guess"; however, both have a very "natural and comfortable" tint to them (Mg/Na). Also usable with full aperture filtering systems, visually and photographically. A wedge or variable intensity solar observing system certainly has additional advantages depending upon magnifications being used, and apertures employed.  
• During use of these filters, as with sodium, there is a definite "sweet spot" for brightness and "just-so" focus that allows details to really POP out. Varies with magnification used, somewhat, but the optimal contrast is immediately obvious in these filters. 
• Plage structures show very well, and extended plage networks show a bit more visible in Mg light. While these structures are also visually detectable in many other photospheric observational configurations, I would say so far the trend is: Mg ~Na > CF > WL, with Mg taking a slight advantage as described above. Inner disk plage shows as bright areas bereft or with reduced granular structure, and looks a bit brighter mid-disk, than other filters, with edge/limb plage VERY easy to make out, similar to Sodium, or a good session with CF filtering. 
• I DO notice a bit more limb darkening with the SWAN/Mg filter than with say, Sodium, and part of this may have to do with Mg-line extinction in deep photosphere paths. Still under investigation...
• Due to the EDGE filtering of these SWAN/Mg filters, eye position does effect to a small, but so far slightly noticeable degree, how DEEP the shading is - I suspect by being near cut off or tight "red" edges of the b-line(s), it may be JUST on the verge of showing deeper contrast images usually seen in line filters, like a Quark, or similar. A lot more to investigate here, but it seems the case, I think, as "tilt" angle will blue-shift the curve a bit (may also be partially or wholly responsible for full-disk view limb edge darkening mentioned, also as a possible contributor. 
• Penumbral filaments are also VERY sharp, and contrasty, as in Sodium. I think more work needed here under near-ideal seeing, but this seems to show well in Mg light also - pores, and very small spots, clusters, and brighter voids in filamentary structures also highly visible as with Sodium. The "dark on yellow" may be advantageous for the sodium details, and might have a slight edge there, but the "dark on green" also shows very well. 
• Umbral bright regions also show well in Mg light, and the light bridges visibly observed so far in various ARs is really prominent, IMO, a bit more so in Mg light and CF 540nm light. WL full spectrum continuum has the advantage of capturing some coloration and tint differences here, and that is the advantage using WL. NB filtering is more of a "monochrome intensity" level variance in lieu.
• Pores, and spots, esp. VERY small ones, also VERY visible and exceedingly well-presented in Mg-light, in some ways at least on par with sodium filtering. Both show this detail VERY well, again, sodium may slightly have the advantage due to a contrast effect with tint. 
•  Pore clusters, and ne small spot clusters, show VERY VERY well in Mg-b. Surrounding these structures and groupings, significant "shading" can be seen surrounding and between these spots/pores rather prominently, at least in the tests done to date. VERY interesting, and this was visible in sodium, but it seems to stand out a bit more in the SWAN/Mg filters. 
• Seeing effects: Here, sodium has the advantage over CF or SWAN/Mg, likely mainly due to wavelength. It can be subtle, but I am finding in the RFT* (more on this below) that Na~Mg>CF>WL. In other scopes I have done (one APO and one ST120 short achromat) Na>Mg~CF>WL. 

*One last point to elaborate: as suspected, in my analysis of this scope's LA (long. chromatic aberration) curves I covered in anther post, which was published on the RFT page by TS Optics, it appeared that another wavelength might be optimal similar to the 588 He d-line. I am finding focal "tolerance" (which also affects seeing effects) at ~515nm very similar to the 589nm sodium line behavior. It was a sort of "educated guess", but made sense from the behavior of the Fraunhofer curves used in the diagram. I add it here again for reference (the modified one with the "b-line" added):

 

 

So a quirk of this non-standard Fraunhofer doublet is that it looks like the region near 500-510nm may be the "other" zero crossing, and that 515nm  is close to this, certainly on par or VERY close to, the 588 line. Weird, but serendipitous in this case of solar use!

 

FYI, I did also find a few options to permit a NB adaptation for these SWAN filters to isolate the Mg-b region even tighter! 

 

My favorite "pre-filter" is the Alluxa 527nm, 22nm (OD6.0 blocked to 1200+nm) Band pass filter:

 

 

With the expected roll-off of the Baader SWAN, this should put the effective FWHM of the pair to ~2.5nm, just allowing all four b-lines.

 

Fused silica, <1/4 wave flatness, but in 25mm OD cell (21mm window width), it is nearly $500USD. That is only just under 1/2 the cost of a Mg-Quark, so I don't know. TBD.

 

Darren

[Spectrum222]

She is VERY tight indeed!!!

 

 

I go this version of the C2 SWAN filter curve picture from Bob Luffel at Alpine Astro. 

 

He mentioned that Baader does not (and will not, he's tried) publish their proprietary filter curve data. Now, Baader MAY still confirm for us (hoping!) whether the cut is around 519.5nm or so, on the outer edge, but what I did in the meantime was to try as best I could (this larger picture was better to work with) to find the cutoff for the peak and "red-side", or longwave edge. IT IS TIGHT! 

 

However, the Mg-b2 line looks to JUST fit into the 95%+ portion of the curve, so this definitely is an edge filter in this application!

 

Just keeping everyone up to date! For fun, I will ask Gerd at Astronomik if he's interested in doing up a 518nm, 6nm FWHM filter. They do these for CCD applications, so a 6nm FWHM centered at 518nm would fit ALL b-lines. No idea whether Gerd and Emil will do this, but worth an ask... If they are, then WIN for us! 

 

Darren

 

[ch-viladrich]

Hi Darren,

 

I don't remember whether you have a Sol'Ex SHG ? If you have, it is quite fun to measure the transmission curve of this kind of filter. You just need a low resolution gratting. (600 line/mm is probably OK).

 

And you can see by yourself the lines of interestd passing (or not) through the tested filters.

[Spectrum222]

Thanks Christian, I was thinking about that the other day when you sent me that PM. 

 

Also, Larry Alvarez' detection of faint, but present, prominences were in Mg-b1 light. I think it might be interesting to look into this down the road too! That is very interesting!

 

Cheers, and thanks for the suggestions, as always! I DO have packed away somewhere a plate 600lpmm glass grating - I might be able to use this for testing my filters. Now I just have to find where I hid it!

 

I do NOT currently have a Sol'Ex yet. 

 

Darren

Edited by Spectrum222, 28 October 2024 - 10:00 AM.

[Spectrum222]

I MAY also eventually have access to my son-in-law's analytical lab's UV/VIS spectrophotometer. Maybe. I know that they are pretty busy in Q4 this year, so we will have to see. They have a pretty busy lab doing soil/water samples for industry in Lloydminster, AB. 

 

If so, I'll have to make a 300km road trip to run a few scans of several filters for evaluation and verification.

 

Darren

[Spectrum222]

Here's a Solar Chat forum post done by Sergio Anlessandrelli in Rome 

 

https://solarchatfor...pic.php?t=42820

 

CF vs C2 SWAN shots using a Rumak 7" f/10 scope. Done ~1 year ago. 

 

IMO, these show something similar insofar as contrast of details, despite PB being almost 2x larger than CF. 

 

Darren

[Spectrum222]

Remember this shot?

 

 

This was from a Hungarian amateur using his So'Ex. He is Pal Varadi Nagy, in Cluj, Romania. 

 

If you look at this shot, HE ALSO caught a Mg-b line prom! Similar location, but this one was earlier in the summer - I think he missed this! 

 

I'll have to ask him whether he tends to tune b2 or b1.

 

Darren

[gstrumol]

More than one, it would appear!

[Spectrum222]

Yes indeed!

 

Darren

[spicerack0]

Remember this shot?

 

VNG_Mg_b1_Solar_Jul2024.jpg

 

This was from a Hungarian amateur using his So'Ex. He is Pal Varadi Nagy, in Cluj, Romania. 

 

If you look at this shot, HE ALSO caught a Mg-b line prom! Similar location, but this one was earlier in the summer - I think he missed this! 

 

I'll have to ask him whether he tends to tune b2 or b1.

 

Darren

is that guy on cloudy nights or another forum, interested in a link to his other images

[Spectrum222]

He has his own blog page in Romania, but I'll post the links to some fantastic He-D line and Mg images:

 

"Hi Darren!

 

I usually try both D1 and D2, and b1 and b2, for Na and Mg respectively. It's (or it was) a bucket list for me,

to have flares and proms and filaments, and on-disk details in as many lines as possible.

So I also caught a prom in the He I line at 447.15nm, an exotic, almost never imaged He line

 

https://www.asztrofo...mage/1719258176

https://www.asztrofo...mage/1723760150

 

He I D3 line info contrasted with a nearby continuum,

https://www.asztrofo...mage/1730057954

 

Only the He I D3 line info,

https://www.asztrofo...mage/1730051130

 

Mg b1 line:

https://www.asztrofo...mage/1729454658

Na D2:

https://www.asztrofo...mage/1728766441

Na D2:

https://www.asztrofo...mage/1727514614

Mg b1:

https://www.asztrofo...mage/1723973474

Na D2:

https://www.asztrofo...mage/1723928157

 

Na D2:

https://www.asztrofo...mage/1723011806

 

clear skies,
P"

 

VERY impressive stuff he's getting!

 

Darren

Edited by Spectrum222, 29 October 2024 - 02:00 PM.

[spicerack0]

that first helium shot is spectacular, never realized it was so "inky" at that wavelength on the surface. 

 

What slit are you using?  I inherited a 27mm diameter x 25mm slit length x 10 micron from a decommissioned optics lab that I plan on using in my first shg build,  but i recently found some on ebay for sale;  this 13mm long 7 micron  https://www.ebay.com/itm/176102005810 more difficult to mount a rectangle. The one i have just fits nicely inside of a standard 1.25" telescope optic mount, but obviously a 7micron has tighter resolving capability so I may check it out.  Similar to what "thesmiths" was selling on other forums.

[ch-viladrich]

that first helium shot is spectacular, never realized it was so "inky" at that wavelength on the surface. 

 

What slit are you using?  I inherited a 27mm diameter x 25mm slit length x 10 micron from a decommissioned optics lab that I plan on using in my first shg build,  but i recently found some on ebay for sale;  this 13mm long 7 micron  https://www.ebay.com/itm/176102005810 more difficult to mount a rectangle. The one i have just fits nicely inside of a standard 1.25" telescope optic mount, but obviously a 7micron has tighter resolving capability so I may check it out.  Similar to what "thesmiths" was selling on other forums.

In fact the first one is a combination of Na and He D3. This is why it is called a "Nap, He I D3 koncept" by his author.

 

An actual He I D3 is more like this (image by Didier Favre with Sol'ex) :

http://www.astrosurf...llee-948-1.webp

 

Sunspots are much more fuzy.

[Spectrum222]

Pal does use the Sol'Ex as well, with standard slit I think. 

 

Darren

[Spectrum222]

UPDATE on C2-SWAN, visual at 82X in 152mm RFT, 29 Oct, 2024 between 1715-1820UT:

 

11nm NT6 (TV Nagler) for 82X (81.8X) in the scope. Seeing held pretty well with a couple of "OMG!!!" moments in between!

 

I don't even know where to begin...

 

 

Well, let's start with AR 13872 and 13873 areas:

 

Whoa! What a fun region to play in today on the sun with this filter!! Seeing was Pickering 8/10 average, with periods of 9+/10. Temp ~3C. A light breeze <10km/h for the majority of the session, was crisp but tolerable. That region --- well first off, during the session, pores and small spots dotted all over the place - between the two larger groups, and off to the eastern side of AR13873, trailing - associated with most of these "collections" or clusters of small spots was that "shading" I refer to - really obvious during the session - inter-dispersed with some plage structure in between some of them. More on Plage in general later. The penumbral region by AR13872's big spot had a gap - which started as two bright voids, bordered on the upper (N) side by at least 3-4 pores. Over the session, this dual void merged and expanded, and two of the 4 main pores merged (or approached towards each other such that my resolving at that power could not fully separate them anymore), with another smaller pore off to the outer edge of this region. A range of penumbral filamentary changes were also visible here: they "parted" a bit proximal to this merging penumbral void, and an extension mid-way off the N central edge formed. Inside the main Umbra, some hot/bright spots showed well for about 1/2 the session when checked over the ~1h period. Became general hotter near the rim by the "penumbral void" area, and was developing into a full light bridge/cleft between the umbrae. Very cool stuff to follow in REAL time! 

 

Okay - there was more, but you get the idea; now for AR 13875: 

 

That was IMO one of the two big treats today! That central AR has mostly smaller spots and dotted with a couple of small and larger pores from near disk centre towards the NW mid disk. During better to the best seeing, this region -well- exploded with subtle and not-so subtle structure - mostly fine plage networks and granulation... temperature/brightness differences in some small, compact areas surrounding the main insolated larger spots - micropores were coming and going in a 25 minute timeframe. Not totally disappearing but subtle changes in appearance and contrast. Awesome. Some of this may have been "seeing effects" too, but in general, repeated checks DID show subtle changes at the scale of view. There appeared to be some additional dark regions surrounding the main larger spots of this AR (13875)... 

 

AR 13874's two larger spot umbrae touted some brighter central areas, the trailing one was a sort of "V" shape, following the shape of the border a bit; the other spot ahead of the bigger one, had most of the umbral area looking a bit brighter, changed intensity over the hour session during "spot" (punny!) checks. The frontal large spot of this group also had a tenuous bright region, which I say because for some reason, this spot was the toughest to follow finer detail - sometimes seeing effects really plagued this one. However, during the best seeing, this was resolvable, as a "stripe" following the umbral cleft on the N side. Subtle facular Plage between the areas and small pores and spots dotted between the two larger regions, with a shaded thin "trail" of darker granulation coming off the front spot for ~2/3 the separation distance or so. Very novel, and not as well seen in Na light, though I did not run Na today - it likely would have shown too. (?)

 

AR 13868's big lone spot had very nicely developed penumbral fans - very symmetrical and following the shape of the spot umbra. A nice two pore or small spots could be made out during best seeing - one larger one for sure, and the other smaller one was pretty much in contact with the umbra, so may have been an extension. hard to tell there at 82X. Still neat...

 

LOVELY Plage network along the leading western side through the departing 13863's twin small spots. DEEP bright areas, and one lone bright round, isolated section approx 1/3 way from the limb to AR 13874's leading spot. subtle plage network structure, showing as a less intense bright, and blanker (lack of regular granulation), followed from there through into between mid disk, where the small spot/pores were seen mid-way from AR 13875 and 13876. Best seeing had this structure showing in an almost-overwhelming way today. (!!)

 

AR 13877's small spot group had lovely "shading" showing also esp. towards the west side, below the frontal spots, towards AR 13873 - sort of obliquely diagonal on the west side before the "border" (?) with the '73 group's trailing spot. Some pores above this as well came and went with seeing, 

 

Finally, AR 13878 and AR 13879 (new big spot - assuming it is to be 79); AWESOME plage structure throughout both regions - connecting by tendrils of plage (!!!) - the other big treat of the day... Showed really well, including the new big spot's umbral extension to the eastern limb - Penumbral structure and plage to JUST near the limb edge with best seeing - really one of the best limb views I've had in some time. Just awesome!!! 

 

So, those are the main highlights. As always, for brevity  , I'll stop there, except to say that these C2-SWAN filters are certainly not at all a disappointment. VERY impressed as visual filters, and suspect a few shooters may get some surprises in the future. 

 

Final note: I am communicating currently with two major well-known filter suppliers to offer an "enhanced photosphere" filter set. Obviously with Na/Mg in the mix. One so far has shown significant interest, TBD.

 

I am not/will not be getting anything ($$) for these, as compensation, so I can mention that this currently interested supplier is Player One.

 

If anyone is interested in "nudging" them along, please feel free to ask if a set like this could be a possibility. Remember, Na CAN also be used for Mercury atmospheric studies, Io flux-studies in bigger scopes, Comet Na tail viewing and shooting, and so on, and NO ONE currently offers a Na filter!!! Since LED lighting I cannot believe the non-Na line trend still. HPS/LPS lighting is all but gone in 90% of the civilized world.

 

The added plus here is a dedicated NB (~5-6nm wide) Mg filter to pass all three bands. Big help for Larry! LOL! The more queries, the more likely they are to offer these. Hopefully we may have a set in the not too distant future, but for now, it's the C2-SWAN for this band... and these are doing pretty darned well, at least in my visual system, so far! More to do, but awesome... Ultrafine filaments are a BIT easier so far to see in Na, but Mg light is also VERY good in this regard! Likely a color-contrast thing. Both are fun though! 

 

Cheers, clear skies, and good solar!

 

Darren

Edited by Spectrum222, 29 October 2024 - 11:27 PM.

[Spectrum222]

HOT OFF THE PRESSES!

 

Larry Alvarez kindly shared his spectrum of the Sol'Ex that he uses for those superb images he's getting!

 

This is the spectrum of the C2-SWAN, and I added the green band which is a 515-520nm spectrum off another site for the sun:

 

 

As you can see, THIS filter of Larry's passes well past 520nm, so totally usable for the Mg-b lines - visual, photo, or isolation for a SHG instrument.

 

Many thanks Larry for this test and info. Please share your Mg shots if you feel like it. His H_a, H_b, and Ca-K shots are amazing in that SHG!!!

 

Darren

[Spectrum222]

I am hoping to get out again soon withe either my 120mm or 152mm this weekend, but we will see - it has been either cloudy or VERY windy this past week. Hence the lack of reporting on my end. 

 

Well done, Larry! I LOVE that 120mm scope setup you have configured. Amazing... 

 

Darren

[Spectrum222]

Early Winter Weather hath curtailed my SOLAR fun...  

 

So, until our skies warm and clear, I guess I'll keep vicariously living through all of you fine folks! 

 

Keep those shots a-coming, and Happy Thanksgiving to our American Friends here!

 

Been about 15 degrees below seasonal here with lots of "oxidane dust" (aka: snow!) and overcast skies... I am missing out on some dandy spot stuff lately - I hope it stays busy when our skies clear later after the weekend...

 

CS, and good solar

Darren