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Mar 07 Target Tutorial - Diffuse Nebulae

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#1 Erix

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Posted 01 March 2007 - 09:25 AM

The monthly target tutorial for this month is Diffuse Nebulae. It doesn't matter which diffuse nebula you choose or if it has clusters, etc within or around it.

Please include a complete description of how you've rendered your observation as well any photos of steps you might want to include plus the finished sketch.

#2 Adam S

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Posted 08 April 2007 - 04:44 PM

I'm going to describe my process (right or wrong) in sketching M42. I really wanted to do well by my favorite celestial object and felt that the key would be proper star placement which would make defining the nebulosity easier and more accurate. The sketch took place over several nights-seeing being best on the first night of star plotting.

All sketching is done with an HB pencil, lots of eraser and blending stump.

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#3 Adam S

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Posted 08 April 2007 - 04:48 PM

I then scanned this image and took a copy to the telescope to verify artifacts from scanning and better identify star placement (those crossed out) and magnitudes (my homemade system labels the brightest star as '1' through '6' which is dimmest.

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#4 Adam S

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Posted 08 April 2007 - 04:50 PM

I then modified the original star locations and added nebulosity-this seemed very easy as I'd spent so much time with the background stars.

The stars were plotted with a Televue 11mm plossl (also defined to border of sketch) and 5 and 7.5mm Tak LEs.

I used a 32mm Televue plossl for the nebulosity.

Honestly this is my favorite of the sketches in this sequence.

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#5 Adam S

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Posted 08 April 2007 - 04:52 PM

The next step was to invert the image.

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#6 Adam S

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Posted 08 April 2007 - 05:00 PM

I started to have fun with the computer at this point. I use Adobe Elements 5.0 (a relatively inexpensive software) and used the 'clone' tool to hide misc. graphite marks, page # and binder from sketch pad.

Next was using 'levels' to make the nebulosity appear as I'd remembered and match the original sketch.

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#7 Adam S

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Posted 08 April 2007 - 05:08 PM

This last phase took a long time as my computer skills are a joke. Lots of back and forth-if it were not for the 'undo' feature I'd still be working on it.

I made a mask from the above sketch and used a round brush, white paint and an opacity of 40% and simply altered the size of the brush to cover the given star. Each star was painted over.

I also applied a Guassian Blur to the original-25% seemed just right. It would be very easy to overdo it with the blur.

At some point next season I'll spend more time with M42 and finalize color on the nebulosity. I felt it to be blue, green-maybe a little of both.

For now I'm happy with it-it's very easy to go overboard with the computer; this is a very solid image of what was at the ep.

Any comments are welcome-

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#8 Erix

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Posted 08 April 2007 - 05:41 PM

Wow, Adam, the extra diligence you took with the star placement really speaks for itself!

Did you find it difficult to have the star placement without the bases of the nebula marked on your sketch to begin with? I know it would be the same concept of an open cluster perhaps, but when I sketch nebulae, I have to rub in at least the most obvious portion of the nebula to help out with the star placement.

I really appreciate you taking the time to do this tutorial! Excellent job!

#9 Adam S

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Posted 08 April 2007 - 10:58 PM

I guess I'm backwards. For me the stars need to come first-I observe with several eps (usually an 11mm plossl, 24 Pan and 32mm Plossl) decide which view I want to sketch (later using high power eps for the fainter stars). Then begin plotting a few stars in the center than a few to the outer edges and fill in. That's the beauty, everyone's right!

#10 Erix

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Posted 20 November 2007 - 11:16 AM

My first sketch of M42/M43 was using the 10" LX200. This was back in 2005 and I was inexperienced at observing DSO's. I remember spending what seemed like ages trying to make the nebulosity as accurate as possible to what my eye could see.

Back then, I remember that I used to rub in the structure of the nebula first. Then I would have erased out portions of the nebula if I over sketched. This of course doesn't take in account that I was too heavy handed on sketching in the nebula. That is something I still struggle with.

Next, I would have added in the stars. This, I believe, is another bane of that sketch. Improper placement of stars is apparent and it's because I had to fit them in the nebula instead of drawing the nebula around anchors, or in other words, the stars.

Goodness, I'm almost embarrassed to add this report I made of that night's viewing session. Ahhh, the thrill of the night as seen in this newbie's eyes. :lol:

2005 04 04
First observation with new scope!

Normally my reports consist of lunar observations and I have to admit I’m slightly intimidated to share a DSO report. However, Paul and I have purchased a Meade LX200 10” Classic from AstroJim (Jim M.) so what better time to expand my horizons not only with a new scope, but also in a new section of CN! This is actually the second night of viewing with the 10”, however Paul got first go last night. That meant tonight was my turn to spend some quality time with him!!! (sorry, guys…the scope is a boy and no, I haven’t named him yet)

We put the 26mm SP for a magnification of 96x and set up the ETX70 on the side so that we both could have a scope. The sun was headed over the western horizon very soon and supper still had not been made. Knowing that Orion would not be in the sky long tonight…at least not at our house due to a pesky tree line….I gave up the thought of cooking and jumped in the truck for Wendy’s.

Bringing out a star atlas, sketching pad & kit, and my trusty fleece hat, I propped myself up on a homemade observing chair Paul threw together at the last minute for me….consisting of a milk crate, couch pillow and green plastic porch chair. M42/43 were to be my first subjects with M78 to follow. However, using a red light hanging from a scope instead of my bluish headlamp for lunar observation was proving to be a bit tricky for sketching.

The first view of M42 through the 10” almost caused me to tumble down off the milk carton……simply awestruck to have the nebulosity posing beautifully before my eyes. It looked like an angel standing on a pedestal, or a butterfly on a flower. To my amazement, calmness came over me just as it does when I visit Lady Luna. Just as I dipped my blending stump in charcoal to begin sketching my angel’s wings, a shooting star zipped over her head through the EP! My heart leapt for an instant and my head spun around so fast to tell Paul (who was behind me using the ETX70) that it appeared I was trying for a role on The Exorcist. This was virgin territory for me, you see: a new beautiful scope, my first nebula cloud, and my first shooting star at the eyepiece.

Excited about my M42 & M43 sketch, I headed in the house to scan it in and give Paul a chance for DSI. Only when the image appeared on my screen did I notice that I made a very good sketch of a rooster facing east. What happened to my nebulas?!


And behold, my rooster sketch!
:grin:

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#11 Erix

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Posted 20 November 2007 - 11:42 AM

And here's the same targets a few years later with the same scope. I'm pretty sure that I drew in a few anchor stars first such as the trapezium in M42 and the HD 37061 in M43, and then rubbed in the nebulosity with a blending stump dipped in charcoal.

2007 01 17
M42

After a great day solar observing, I was able to top it off with a little night time observing as well. Paul was going to use the scope after me for imaging, and we both had M42 in our sights as the main target tonight. M42/M43 sketch from tonight

The thin layer of clouds came rolling in on and off during my observation tonight, and the seeing was terrible. So I didn't get to record all the stars that I saw. I did manage getting in the placement stars though.

It was a mad rush to push the nebulosity details as far as I could, and using averted vision really brought the contrast out.

As for the seeing, I'd have to say it was a poor 3 with moments going up to 5 using the Pickering Scale. The stars in the trapezium were twinkling like crazy for a good part of the session.

M43 was very faint in comparison to M42 and resembled the effect condensation has on an eyepiece when looking at stars. The humidity wasn't that bad tonight at 60%, and the EP was clear.

I'm looking forward to another night, hoping to see color, further extension of the nebula, and have the time to record more stars.


Although M42 is hydrogen rich, our eyes aren't as sensitive to this bandwidth. We can generally see a greenish-blue tint visually sometimes in M42 from the ionized oxygen as described by Sue French in her Celestial Sampler book by Sky and Telescope.

If you have that book, she has a detailed observation description of that area that is perhaps the most thorough I've ever read. And on page 16 of that book, I was delighted to see a black and white version of M42 that matches almost perfectly to the views I'm used to in the LX200. She compares that view to what can be captured on film so that we can see what might be expected visually.

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