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2008 Jan 25 solar limb and surface detail

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#1 Erix

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Posted 25 January 2008 - 04:34 PM

2008 01 25, 1205ST –1330ST (1705UT – 1830UT)
Solar H-alpha
PCW Memorial Observatory, Zanesville, Ohio, USA, Lat: 40.01 / Long: -81.56
Erika Rix

Temp: 16.0 °F / -8.9 °C
Winds: SSW at 4.6 mph
Humidity: 71%
Seeing: 5/6
Transparency: 2/6
Alt: 30.5 Az: 170.9

Equipment:
Internally double stacked Maxscope 60mm, LXD75, 40mm ProOptic Plossl, 21-7mm Zhumell, ETX70-AT with 8mm TV Plossl for white light observation.

Sketch Media:
Black Strathmore Artagain paper, white Conte’ and Prang pencils, white vinyl eraser.
Added –25 brightness, +5 contrast after scanning in color at 300 dpi. I then turned the image into monochrome. I scanned initially in color to eliminate cross hashes that the scanner creates in grayscale. Tilting Sun program used for digital Sun insert.

The NE and the SE limbs are still at it. Snows and overcast prevented me from viewing yesterday, but on the 23rd of January, two proms on the NE limb were spread out a little further from each other and the one that was around 55 degrees PA had two very bright upright legs to it with a faint line of connection in between them. Today, there is a very tall fainter prominence around 45-50 deg PA that looks like two hands pressing against each other with a small prominence just north of it by about 2-3 degrees. Then around 55-60 degrees PA (maybe even a little more distance than that) was a brighter prominence defined by a very bright tall slender arm on the northern side of it with a few shorter slender arms jetting out to the southern portion. The base of the main southern portion was about twice as thick as the northern arm.

To the SE around 135 degrees was a very bright cone shaped prominence about half as tall as the two proms on the NE limb. The inside of the cone appeared hollow. Bumping up magnification, and adjusting the T-max, I noticed a small, round, faint cloud just to the south of it, reaching up above by about half its height. I lowered magnification again for better contrast and it didn’t take long for me to notice a few other portions of it. Playing with the zoom eyepiece, I soon found a happy medium in magnification to tease out as much detail as I could, bringing out this prominence to fuller glory. It was huge and very similar in shape, only much fainter, to the prominence in this same area two days ago.

I was hoping to see some sort of evidence from the pore that the Hinode captured. Of course, it most likely is too small yet for me to see and even so, with the poor transparency today, I imagine it would have been difficult even it were visible for my scopes. After my H-alpha session, I pulled out the ETX70 for a white light view and couldn’t see any evidence with pore nor facula. Something I did see, however, was a claw like marking just inside the limb about 25 degrees in the NNE quadrant. I’ve included a close up view of what it looked like. There were dark areas resembling a filament that had dissipated.

All in all, I observed 7 different areas of prominences around the limb. The NW section of limb appeared rough and turbulent with the long section of short prominence weaving up and down off the limb.

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#2 smc89

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Posted 25 January 2008 - 04:40 PM

Outstanding Erika!!!! :bow:

#3 darkstar528

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Posted 25 January 2008 - 05:06 PM

Another awesome presentation!...I did go back outside, after some gentle prodding, in search of the pore, I too couldn't find it and strained to see details on the surface giving it away...I did see some thickening cloud-like filaments off the NNE limb that I didn't see before...

#4 stets

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Posted 25 January 2008 - 09:36 PM

... yes, Stephen to those filaments that looked cloudlike near the NNE limb ... beautiful sketched, Erika

#5 cocobolo

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Posted 25 January 2008 - 09:37 PM

Erika, your sketches are simply out of this world!! Fantastic!! Keith

#6 Special Ed

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Posted 25 January 2008 - 10:33 PM

Erika,

Excellent observation. You've done an outstanding job of rendering the appearance of these prominences--and that is not easy. :waytogo: I know because I tried it again.

I got set up about 12:30 PM EST (it had warmed up to 24°F from an overnight low of 1°F by then) and observed for about an hour and a half before I started sketching. Those two big proms stretching way out into space on the NE limb were changing rapidly. They were dynamic and fascinating--parts would brighten up and then fade in minutes and the magnetic fields shifted constantly. I couldn't stop watching them long enough to start a sketch--not to mention they seemed to change every five minutes. The smaller teepee shaped prom on the SW limb did not appear to change much during my session. There were also a couple of very small proms on the NW limb (~PA 285°).

I almost gave up before I started sketching, but I figure I'll never learn if I don't try.

The first set is the prom closest to north--the second set is closer to east. The position angles (PA) are approximate and don't coincide exactly with Erika's but we're close.

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#7 Special Ed

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Posted 25 January 2008 - 10:42 PM

Here is the other prom. This one appeared very twisty at the beginning of my observing session but by the time of my sketch, it had morphed into this faint leaf shape with a solid bright component. I changed from watercolor pencils to charcoal pencil for these drawings.

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#8 darkstar528

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Posted 25 January 2008 - 10:47 PM

Awesome sketches!...

#9 Erix

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Posted 26 January 2008 - 01:17 AM

Thanks guys!

Michael, superb report and sketches. Thanks for adding them.

It's good to experiment with different media, trying to find good ways to render the views. As much fun as colored pencils are, I love the simplicity of black and white. As you know, the view changes so rapidly that a person doesn't have time to spare when drawing them. I don't spend more than a few minutes with each prominence sketch, because if I do, the view has changed and you find yourself constantly playing catchup if the view no longer matches your sketch while you're in the middle of it.

That being said, as much as I like your colored pencil sketch, I really love your charcoal one. The dramatic contrast captures what it's like while viewing.

I find it helps to draw the brightest areas first to anchor the sketch and then quickly fill in the fainter areas.

As for my position angles, I always try to state that it's approximate because I find it difficult to get a really accurate orientation within 5-10 degrees increments. I'm pretty sure I had my drift arrow that I drew correct, but still, if I record it even slightly leaning one way or the other, it throws off the orientation by quite a bit. I really need to work on it and at the moment, it's the bane of my sessions. :shakecane: :lol:

#10 Special Ed

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Posted 26 January 2008 - 09:11 AM

Thanks, folks.

Erika, I agree totally that keeping it simple is the best route to take (do you know this acronym? KISS ). I'm looking forward to trying with white (or color) on black paper as soon as that order we talked about gets here. That will make it even simpler--I like the charcoal pencil but it still forces me to invert the view in my mind (think negatively? ;)) and that adds a step when I'm trying to reduce steps. I know your experiments led you to black paper--remember, imitation is the most sincere form of flattery. :grin:

I too am finding the position angles hard to figure exactly, especially on a featureless disk--a couple of big sunspots would help. An eyepiece with crosshairs or some kind of astrometric eyepiece would probably be useful. Maybe someone knows a source?

Your drift is correct and your PA's are close (maybe even right on the money--there's no guarantee that mine are exact). We are within 20° of each other and we both put those big proms in the NE quadrant, so we're on the right track. :)

Best,

#11 Erix

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Posted 26 January 2008 - 11:18 AM

I've got a Celestron crosshair that I could try when recording drift. That's a good idea. We used to have an illuminated reticle eyepiece that Paul used for drift alignment for the LX200. We gave it away to an imaging friend and to be honest, the crosshair would probably work just as well or better for what I'd need it for.

I would like to look into getting an eyepiece that has some sort of measuring tool inside it. This would be very handy in more ways than one. Just think of how much more accurate we could get with placements of features and also measure prominences, etc. My birthday is coming up, but I've already asked for a chain saw so I wouldn't have to borrow my step father's anymore. :lol:

I hope you find the black paper useful. I think one of the best advantages of it is that with the black background, there's not as much glare from the Sun that momentarily blinds you when you put your eye back to the eyepiece. When I used to do charcoal sketches on white paper, it took longer for my eyes to adapt back to the darker view in h-alpha. It wasted valuable time for sketching the changing prominences.

#12 Special Ed

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Posted 26 January 2008 - 05:50 PM

Do you remember what size that Celestron crosshair ep was? It would be good to have one that yielded fairly high mags. I'll look around on the net and see what's available when I get a few spare moments.

BTW, I forgot to mention that I compared my 8mm Burgess/TMB planetary ep to my other 8mm ep, a Celestron Nexstar Plossl. I liked the BO/TMB much better, mainly because it had such great eye relief--it was a pleasure to look through. The views are sharp and there is not much orange glow. I got the Nexstar on sale--it's not a high end ep to begin with but it's OK. Just a little hard to look through--it's not well suited for solar observing.

I've read that, like you, many people prefer to use a zoom ep to more easily cope with seeing conditions--makes sense to me and I'll probably get one before too long to use with the PST.

#13 Erix

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Posted 26 January 2008 - 07:25 PM

My crosshair is 20mm. I haven't used it in ages, but used to find it helpful when beginning a lunar sketch. I'll dig it out the next clear day I have for solar and give it a whirl. I could stick a barlow with it if necessary.

Thanks for the feedback on the Burgess planetary. Sol uses those Burgess/TMB planetary's if I remember right. I have yet to try one out but have been meaning to pick one up from Burgess. I still very much enjoy my 8mm TV Plossls, but because of the versatility of the zoom eyepiece, I rarely use it with my Maxscope anymore unless I have the binoviewers on the scope. And even then, I usually go with my Burgess 12mm set to help brighten things up a bit.

I do notice an orange glow sometimes with my TV Plossls but assumed it was due to transparency and the amount of aperture. So it's the glass then?

Could I ask what the dimensions are on your new black cloth? Do you know what the weights are made of? I had to wrestle mine down the other day....it was a battle of wills between us, but I was the victor in the end. :sumo: :lol:

#14 Special Ed

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Posted 27 January 2008 - 01:18 PM

Erika,

I'm no eyepiece expert, but I think the orange glow is related to the ep design and quality. For instance, designs with four or more lenses (e.g., Orthos or Plossls) have less internal glow and better quality ep's have better internal blackening which reduces reflections. The Sun is such a bright object that I doubt that the glow can be eliminated entirely, even with a quality ep like your TV Plossl, but it can be minimized.

I found this unilluminated single crosshair 25mm ep that is relatively inexpensive. Like you say, it could be barlowed. It's a Kellner design and might have more internal reflections and glow when looking at the Sun--this design has a reputation for internal reflections.

I was thinking though (always dangerous). Why not spend the $ on a more versatile ep--one that can be used for solar and nighttime observations of comets, double stars, planets, and Luna?

I found this Celestron astrometric ep on the Astronomics website. It is an Orthoscopic (4 lens) design. Also this Meade astrometric ep. They both have an adjustable illuminator and they both are good ep's, but the Meade is a Kellner type design.

Veteran observers (like Carlos Hernandez) say try to buy the best quality eyepieces you can afford. And Astronomics is giving CN members a discount.

The head cloth that my daughter-in-law made me is 30 inches by 38 inches. If you're making one, it could be a little bigger, say 36 inches by 42 inches, but I'm not complaining, bless her heart. :)

#15 Erix

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Posted 27 January 2008 - 06:42 PM

The Meade one is pretty much what we had before. I had thought at the time that it was strictly for imaging so it was used by Paul. That Celestron one is tempting.

I'll be seeing the friend that we gave the Meade one to in the near future. We get together several times a year, so I can test it out for solar viewing and see how I get on with it. If it's as helpful as I'm hoping for visual, then I'll certainly consider getting another. 12mm would be a very useful size too.

Think what it could do for plotting stars!

Thanks for the measurements. I've managed to get a few projects done today around the house plumbing wise. I've got a coupon for the fabric shop and can pick up some good materials there for the next project. Sewing is always funner than fixing pipes. :p

#16 cocobolo

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Posted 27 January 2008 - 08:02 PM

So not only are you an incredible astro artist, but a plumber to boot!! Amazing!! Keith

#17 Special Ed

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Posted 28 January 2008 - 08:25 PM

The Meade one is pretty much what we had before. I had thought at the time that it was strictly for imaging so it was used by Paul. That Celestron one is tempting.

I'll be seeing the friend that we gave the Meade one to in the near future. We get together several times a year, so I can test it out for solar viewing and see how I get on with it. If it's as helpful as I'm hoping for visual, then I'll certainly consider getting another. 12mm would be a very useful size too.


I'm considering getting one also, but I discovered something that affects how it works with solar telescopes. I read in Phil Harrington's Starware that both the Celestron and Meade astrometric ep's are calibrated to use with a scope that has a focal length of 80 inches (2000mm).

The description of the Celestron Micro Guide on the Astronomics website says that it can be used with virtually any telescope and also says that it can be used to measure binary star position angles to one degree accuracy with a 2000mm fl scope.

I called Astronomics today and asked about accuracy gauging the PA's of proms on the solar limb using it with a PST of 400mm fl. The rep I talked to said it would probably be accurate to five degrees. What's the focal length of your SM 60?

Right now, by eyeballing I'm probably accurate to 15-20 degrees, so five degrees would be an improvement but I could probably be that accurate using the $50 crosshair ep. On the other hand, the Celestron ep could also be used after dark as designed with my 20cm/2000mm focal length CAT. You have a scope like that too, don't you?

What do you think?

#18 Erix

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Posted 28 January 2008 - 08:47 PM

Hmmm. Thanks for that information, Michael.

My scopes are as follows:

LX200: 2500mm fl.
ED80: 600mm fl.
ETX70: 350mm fl.
60mm Maxscope: 400mm fl.
12" homemade truss: haven't measured it after I got it and have been making some adjustments on it anyway so it would have changed regardless.

My main purpose of wanting this eyepiece would be for solar, although I would also like to use it for nighttime viewing.

I'm selling the Thousand Oaks white light filter I have for the LX200. I have Baader for the ED80 and a glass filter for the ETX and am hoping to use this for sunspots as well.

I reckon eyeballing PA's, I'm about 15-20 degrees accurate as well give or take. If I could find enough use for this eyepiece for measurements and placements, then it would be worth it to narrow that down to 5 degrees. I really would love to find a way to measure the size of prominences and other features on the Sun. Do you know of a way I can do this without that type of an eyepiece, strictly visual work?

I use the LX200 mainly for lunar and haven't been getting very good views lately for planetary with it. Most of my DSO stuff is done with the 12" truss or the ED80. In fact the ED is my most used night scope now...at least until I'm done making the mods on the truss.

My Celestron cross hair eyepiece is great for bright night time objects like the Moon. I need to mention that I have only used it for initial anchor markings because the crosshairs would soon get in my way for viewing, similar to stray hair falling down in front of my eyes. It can get very irritating.

#19 Erix

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Posted 28 January 2008 - 08:57 PM

So not only are you an incredible astro artist, but a plumber to boot!! Amazing!! Keith


Not really. :lol: I had to learn muck in along side the guys, fixing machinery and trucks, fences, building, etc. My fingernails were always dirty from soil, grease, livestock grunge. You can save a lot of money and learn a lot as well from fixing things yourself. Thank goodness I have an older brother I can call if I've made things worse, though. :grin:

#20 Special Ed

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Posted 29 January 2008 - 09:55 PM

Hmmm. Thanks for that information, Michael.

My main purpose of wanting this eyepiece would be for solar, although I would also like to use it for nighttime viewing.

I'm selling the Thousand Oaks white light filter I have for the LX200. I have Baader for the ED80 and a glass filter for the ETX and am hoping to use this for sunspots as well.


I would think that this eyepiece would be useful for measuring the size of active regions in white light or H alpha with shorter focal length scopes than for which it was designed, once the error was calculated and allowed for. Get the size of a current active region from SOHO or NOAA, measure it oneself using the ep, calculate the diameter using the ep instruction manual, and the difference should enable one to calculate the percentage of error for that focal length. Did I forget anything?

I reckon eyeballing PA's, I'm about 15-20 degrees accurate as well give or take. If I could find enough use for this eyepiece for measurements and placements, then it would be worth it to narrow that down to 5 degrees. I really would love to find a way to measure the size of prominences and other features on the Sun. Do you know of a way I can do this without that type of an eyepiece, strictly visual work?


Just memory and comparison. For instance, the recent Two Towers extended into space a distance of 4 Earth diameters (according to Greg Piepol's post, iirc). If you remember what they looked like, that gives you a benchmark for the next prom. SOHO, NOAA, and/or SW usually describe the size of active regions in fractions of degrees or compare them to planetary diameters. There's another benchmark. I'm able to roughly estimate the size of AR's in white light on my projection sketches by converting the 4 inch diameter template into millimeters (4 x 25.4 = 101.6mm), then divide the solar diameter (let's say it's 865,000 miles) by the template diameter (865,000mi. / 101.6mm = 8514mi) to give me the scale of the image in miles per mm. Then I measure the size of the active region in mm and convert to miles (and km). This method works best when AR's are near the central meridian and solar equator to minimize the effect of foreshortening.

My Celestron cross hair eyepiece is great for bright night time objects like the Moon. I need to mention that I have only used it for initial anchor markings because the crosshairs would soon get in my way for viewing, similar to stray hair falling down in front of my eyes. It can get very irritating.


Probably would be less of an irritant in daytime and since it would only be used briefly.

I'm really leaning towards getting the Celestron ep. I'm thinking that Jeremy Perez got an astrometric eyepiece not too long ago--maybe we should ask him about his. I don't think he frequents the Solar forum.

#21 Erix

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Posted 29 January 2008 - 11:01 PM

Very helpful information, Michael. Thank you! I usually measure detail by approximate degrees. But I want to take it a step further and start working out the approximate sizes like you suggest with miles or kilometers. The only thing is that I am not sure I could eyeball prominences for a semi-accurate height or width. That's a good point about foreshortening affects as you get nearer to the limb.

You know, I think you're right about Jeremy. If you haven't already, I'll post a query about it in the sketching forum.

#22 Jeremy Perez

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Posted 30 January 2008 - 11:40 AM

Heheh, that was the right place to post that question. =)

I picked up the Meade Astrometric eyepiece about 9 months ago and have been using it to measure double star separations and position angles. I can't say I've even come close to mastering it yet, because I only recently calibrated it and started using it. I've used it to measure 6 doubles, and make 10 measurements on comet 17P/Holmes. After checking my double star measurements against the Washington Double Star database, and Brian Workman's Double Star Calculator, my double star measurements have been within ± 5 degrees for position angle, and within ± .8 arc seconds for separation. I think I just need to get more practice and a stronger barlow (3X) to whittle down the PA and separation error.

It's really a great tool. Once I worked out the process for calibrating it, and taking the measurements, I could really see the potential for using it in a lot of areas (like the comet measuring). I'm sure it would be a great resource for Solar observing. Calibrating the separation rules to your telescope would be the interesting part. (PA should be a breeze, assuming you use drift to determine that.) Ideally, calibrating the separation marks to some stable double stars would be the best method; however, that Ha filter would be a real killer for doing that =) Michael's suggestion of using a SOHO image to calibrate the size of an active region sounds like it might be a good way to do it. Something I would wonder about is how much the sun's angular size changes between Earth's perihelion and aphelion. Would that make a noticeable difference if you calibrated during the winter and then found out your summer measurements were off because the sun is three million miles or so more distant? If it did turn out to be a noticeable difference, you'd probably need to put together a table with weekly or monthly factors to adjust your measurement scale.

I've almost finished an illustrated tutorial I put together on how I've been using the astrometric eyepiece--I just need to put some finishing touches on it. This might be the motivation I need to actually finish it. I think I'll try to put it up tonight or tomorrow night and post a link.

Let me know any questions I can answer apart from the ramblings I threw together just now...

#23 Erix

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Posted 30 January 2008 - 11:53 AM

Jeremy, thank you so much for that information.

"you'd probably need to put together a table with weekly or monthly factors to adjust your measurement scale."

That's a great point and something that I could do fairly easily, I believe, once I got the initial calibrations done.

I'd probably have to calibrate it by sunspots instead of active regions and do it in white light since the visual views can vary so much in h-alpha. And like Michael suggests, while a sunspot is in the center of the disk.

I most certainly can calibrate the ETX70 for night time and then use it for white light observations of the Sun.


I'll look forward to your tutorial Jeremy!

#24 Jeremy Perez

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Posted 31 January 2008 - 02:00 AM

I just finished the tutorial. It can be found here:

Measuring Double Stars

Hopefully, what I'm trying to do with doubles there will translate to working on solar measurements. I'm actually going to be requesting input from the fine folks in the double star forum to see if any parts of my process are off-kilter.

#25 Special Ed

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Posted 31 January 2008 - 06:10 AM

Jeremy,

Nice to see you in the sunny Solar Forum and thanks for sharing your experiences with your astrometric eyepiece. Being able to use it for comets as well as solar (and all the other applications) is a real bonus.

I'm looking forward to reading your new tutorial--they are always excellent.

Best,






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