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Another mediocre night

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#1 Astrojensen

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Posted 14 November 2012 - 06:19 AM

Hello!

Yesterday evening did not start out very well. Completely overcast and a bit windy. Well, looks like another evening in the company of Alyx Vance, trying to wrestle the earth from the grip of the Combine*.

Much to my surprise, it had cleared a little bit around midnight, allowing Jupiter to poke through the haze and clouds. Orion, on the other hand, was barely visible. I debated with myself over whether to go out, or to take another round of zombie killing. I work only part time at the moment, so I don't have to get up early.

The stars eventually won and it seemed to have cleared up quite a bit. The stars were twinkling madly, so I decided to forget anything about planetary observing and just hop around with the 12" dob for an hour or so. It's been ages since the last session, so I fumbled around a lot more than usually and wasn't out until 1.00 AM. The wind had picked up and there seemed to be a fairly good sucker hole around the zenith and in the south. North and northeast didn't look good at all.

Naturally, I began with the Orion Nebula. Holy #¤%& it looks GREAT in the 12"! OK, the mirror is freshly cleaned (I couldn't even see the reflection spot of the laser collimator, unless I turned the brightness all the way up!) and Orion looks as if it's in a decent sucker hole right now, but still, it's AMAZING in the 20mm GSO (75x)! But the seeing was horrible. It's the first time I've clearly seen seeing affect a large deep-sky object. In the 20mm, when the seeing was as good as it could get this evening, the whole nebula was as if made of hundreds of filaments, just like the Veil, but the filaments were a bit broader and not as sharply defined. It looked like an old, tighly weaved, dust-filled cobweb. I've never seen it like this before! But when the seeing degraded, the filaments just blurred out and melted together into a broad glow. The four trapezium stars were huge balls of light at those times, almost touching each other, and they were never pinpoint, always flaring or a moving blob. But in the good moments, the nebula was just outright fantastic. I can't imagine how good it must look under good conditions, not to mention excellent ones!

Naturally, I moved the scope around and tried to spot other nebulae in the vicinity. The complex just north of M42/43 was clearly seen, as was the Flame Nebula. I swept the area around M78, but didn't find it. I was probably not far enough north. Never mind. I turned to M1 instead. Very bright and easy to see, but surprisingly identical to what I see in smaller scopes, just much brighter now. A very pretty star field.

I've always wanted to look at NGC 2158 near M35 in a big scope and tonight the chance had finally come! And there it was. Clearly resolved into many stars, well over a dozen, at 75x. The seeing was a bit better at the much higher altitude of M35, than down in the soup near M42. Still, I didn't bother with higher magnifications.

Any galaxies around? Yup, NGC 891 was near the zenith, a little down to the west. Perfect. I soon had the field in the finder (12x60) and when I looked into the 20mm GSO, there it was! And it looked spectacular! The dust band was immediately visible! WOW! I looked up and yes, indeed, the sky around zenith looked really good at the moment. I tried 150x and the view was still spectacular, though the stars got pretty soft. I backed down to 75x and just marveled at the view.

I wanted more galaxies now, but I hadn't brought a map. I wondered if I could pick up some of the galaxies in the Perseus cluster, just by sweeping with the 12", but without success. I then turned to the M81 group, when I saw that region of the sky had cleared a bit, too. I had the field in moments in the finder. M81 was huge and bright, but also fuzzy and ill-defined. I saw no trace of the arms. Hmm. Conditions were obviously not as good as around NGC 891. I moved in the direction of M82 - or so I thought - but ended up with NGC 2976 instead. Woah! It was super large and bright! Is that really NGC 2976? Sure is, according to the field stars. I am still amazed by how much the 12" pulls in. I moved the scope back towards M81 and this time I got NGC 3077... WOW! Now THAT'S what I call a galaxy with high surface brightness! Again, a stunning view, compared to what I am used to. Now, back to M81 for real this time and onto M82. Okay, this one is just super bright! I was amazed by how small it appeared, compared to NCG 2976 and NGC 3077, but I am used to it appearing much larger than those, in my small scopes, and now those had grown so much, the difference was not so drastic any more. M82 has a lot of details, but they are very seeing depending, so they suffered greatly tonight. I tried 150x, but it wasn't good, everything was just soft and fuzzy. Again, I am left wondering what this scope can do on a really good, crisp night...

For some reason, I turned to Rigel. I only expected a blob, so I was stunned to see the double very clearly resolved at 75x! So I turned to Sirius... Aaand - nothing! No companion. None. Zip. Nada. Tried 150x. Nothing. Oh well.

Jupiter showed two fuzzy belts and four moons. That's all. It was clearly evident from the motion visible in the seeing that the reason was not a warm mirror, but very bad turbulence in the atmosphere. It was like looking at a coin at the bottom of a rapidly moving stream of water.

Obviously not a night for planets, I turned to the deep sky again. Wanting another look at NGC 891, I turned to it, but was shocked to find it barely visible. I looked up and sure enough, the sky was starting to get very hazy, also in the zenith. Time to call it a night! I checked my watch and it had only been an hour! It sure wasn't the best seeing or transparency I've seen, not by a long shot, but to a man in a desert, even lukewarm water are welcome news!

I sure drank in those photons tonight like a man in a desert who finally finds an oasis.


Clear skies!
Thomas, Denmark

*)In the exceptional game, Half-life 2

#2 killdabuddha

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Posted 14 November 2012 - 02:16 PM

;) Nice write-up.

#3 uniondrone

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Posted 14 November 2012 - 03:21 PM

I will have to try for NGC 3077 and NGC 2976 next time that I am out observing. I suspect that I may have panned across one of them once when looking for M81 and M82, but wasn't sure what object I saw and didn't pay it much attention.

If you liked the M35/NGC 2158 combo, you should try also for the M38/ NGC 1907 combo as well. NGC 1907 is quite pretty in a larger aperture.

#4 george golitzin

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Posted 19 November 2012 - 10:40 PM

Thanks for the report, Thomas. So was that your first view of M42 in the 12-inch? Kind of nice. I bet you're getting spoiled by all the aperture...

You'll need dark skies to see the arms of M81 well, I think--but I suppose it was also quite low in the sky, compared to some of your other targets. I've not seen them at home (mag 5 or so), but under mag 6 skies they showed pretty well in a 16-inch. Given your (extensive) training with small scopes, I'm sure you'll see them in the 12, provided the sky is dark and the galaxy is up out of the murk.

-geo.

#5 Astrojensen

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Posted 20 November 2012 - 04:21 AM

Hi George

Yes, it was my first view of M42 in the 12" - but it won't be the last! I've already had another one, this time with my 12" and my new Baader 1.7x coma-corrected glasspath corrector for my Maxbright binoviewer. 104x magnification and two 25mm Zeiss eyepieces. Ohmygawd!

I've seen the brightest arm of M81 in my 6" refractor - in a binoviewer! - so I don't have the slightest doubt that it'll be prominently visible in the 12", as soon as I get some really decently clear skies. I've been severely plagued by haze and fog this fall, more than usually.

I've always wondered whether the arms of M81 might be visible in my 63mm from one of those mythical desert sites you guys always talk about.


Clear skies!
Thomas, Denmark

#6 uniondrone

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Posted 20 November 2012 - 10:12 AM

I've already had another one, this time with my 12" and my new Baader 1.7x coma-corrected glasspath corrector for my Maxbright binoviewer.


You're using a binoviewing on a Newt? How is that working out for you? I used a binoviewer for the first time on my club's 12-inch classic Cassegrain observatory scope. The views of Jupiter were better than I have ever seen with a single eye!

I guess that I am a little undereducated when it comes to binoviewers. I had assumed that they weren't for Newtonians.

#7 David Knisely

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Posted 20 November 2012 - 12:48 PM

I've already had another one, this time with my 12" and my new Baader 1.7x coma-corrected glasspath corrector for my Maxbright binoviewer.


You're using a binoviewing on a Newt? How is that working out for you? I used a binoviewer for the first time on my club's 12-inch classic Cassegrain observatory scope. The views of Jupiter were better than I have ever seen with a single eye!

I guess that I am a little undereducated when it comes to binoviewers. I had assumed that they weren't for Newtonians.


The main problem with using binoviewers on Newtonians (and some refractors) is being able to reach focus (that and their weight, especially on some Dobs). Many Newtonians have a focal point location that is low enough to not allow the binoviewer to get focused even with some of the low power focal length extenders. I had to shorten the trusses on my 14 inch f/4.6 Newtonian to get my binoviewers to work, but when I did that and got a night of outstanding seeing, the view of Jupiter in that scope at around 373x just blew me away. I don't often use them on deep-sky objects, but occasionally do on some open and globular clusters. Clear skies to you.

#8 uniondrone

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Posted 20 November 2012 - 02:25 PM

The main problem with using binoviewers on Newtonians (and some refractors) is being able to reach focus (that and their weight, especially on some Dobs). Many Newtonians have a focal point location that is low enough to not allow the binoviewer to get focused even with some of the low power focal length extenders. I had to shorten the trusses on my 14 inch f/4.6 Newtonian to get my binoviewers to work, but when I did that and got a night of outstanding seeing, the view of Jupiter in that scope at around 373x just blew me away. I don't often use them on deep-sky objects, but occasionally do on some open and globular clusters. Clear skies to you.


Hi David,

Thanks for the input! By how much does a typical bioviewer change the focal point? Would changing to a low profile focuser be enough?

#9 Astrojensen

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Posted 20 November 2012 - 02:48 PM

Hi Chuck

A typical binoviewer will need about 4" - 4.5" of back focus, that is, you would need to rack the focuser 4"-4.5" in from the usual position. This is impossible on almost every newtonian. On some, you can change the truss tubes to shorter ones, but if your newtonian is too fast, around f/4 or faster, it will vignette the light path and stop your scope down, even if you can reach focus. The solution to all this is to use a special, dedicated barlow-like lens in front of it. I have a Baader 1.7x glasspath corrector with build-in coma corrector (the 1.7x CC-GPC) for crisp views to the edge of the field, even with long focal length eyepieces, and a Baader 2.6x glasspath corrector that inserts in my Baader 2"/T2 nosepiece for the Maxbright bino. The 1.7x CC-GPC still needs about 20mm of back focus, however. I got this by changing the stock GSO focuser on my Lightbridge to a Baader Steeltrack focuser, which is 20mm shorter. The views are absolutely fantastic. Crisp almost to the very edge with my 25mm Zeiss microscope eyepieces, with a magnification of 104x. I'm just in from observing the Moon with it and the views are stunning!

The main course for binoviewers are of course the Moon and planets, but make no mistake, bright deep-sky objects are fantastic! The view of M42 was nothing short of amazing! You get the same contrast and detail enhancement on bright deep-sky with a binoviewer, as you do on the Moon and planets! Bright nebulae, galaxies and globular clusters are nothing short of startling. Soon you will find that you only use single eyepieces for faint objects, where you really need every photon. I'm still kicking myself for not getting the CC-GPC while M13 was high in the sky... Now I'll have to wait until late March or something, but then I also firmly expect to get my socks knocked off! I did see it with the bino and 2.6x GPC, but the magnification was a little too high for the seeing that night and it has since slipped behind the trees to the west.

If you find all this confusing, a secret little tip is to use a TeleVue 2x PowerMate! It is parfocal with ANYTHING behind it, also a binoviewer! In other words, insert this into the focuser of your newtonian, in with the bino and eyepieces and voilá! Bino goodness in your dob! The 4x PowerMate also works, but is more or less strictly for high-power lunar-planetary.


Clear skies!
Thomas, Denmark

#10 David Knisely

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Posted 20 November 2012 - 02:56 PM

The main problem with using binoviewers on Newtonians (and some refractors) is being able to reach focus (that and their weight, especially on some Dobs). Many Newtonians have a focal point location that is low enough to not allow the binoviewer to get focused even with some of the low power focal length extenders. I had to shorten the trusses on my 14 inch f/4.6 Newtonian to get my binoviewers to work, but when I did that and got a night of outstanding seeing, the view of Jupiter in that scope at around 373x just blew me away. I don't often use them on deep-sky objects, but occasionally do on some open and globular clusters. Clear skies to you.


Hi David,

Thanks for the input! By how much does a typical bioviewer change the focal point? Would changing to a low profile focuser be enough?


The binoviewer itself does not change the focal length of the telescope. However, because the binoviewer places the eyepiece well out from its normal position in a focuser, to reach focus on some systems, binoviewers are often offered with a simple negative doublet "relay lens" systems (focal length extenders) to move the focal point out to where focus can be achieved (they fit in the binoviewer's nosepiece). Such extenders are usually from 1.3x to 2x in power (mine is 1.9x), but even then, unless the focal point of the scope is high enough off the tube, it may still not quite reach focus. In my SCT and my Mak-Cassegrain, I don't have to use my relay lens, as I can move the scope's focal point to whatever location will allow focus to be achieved. With my Newtonians however, I still have to use the 1.9x focal extender. Clear skies to you.

#11 killdabuddha

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Posted 20 November 2012 - 03:53 PM

David,

I've read that some BV users are realizin contrast gain that does more than just return this value by the summation of the split light. Surprised that you don't find the BVer advantageous for yer extended, low surface-brightness galaxies or nebulae.

BTW, noticed our Ultrablocks are different--one bluish and the other purplish. Should be interesting?

#12 David Knisely

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Posted 20 November 2012 - 08:07 PM

David,

I've read that some BV users are realizin contrast gain that does more than just return this value by the summation of the split light. Surprised that you don't find the BVer advantageous for yer extended, low surface-brightness galaxies or nebulae.

BTW, noticed our Ultrablocks are different--one bluish and the other purplish. Should be interesting?


The problem is that with my old Burgess binoviewers, I don't have quite a low enough power and the field of view on the sky (149x, 24 arc minutes maximum true field, slightly vignetted) in my 14 inch Newtonian as I do with some of my other "mono" eyepieces. For large diffuse nebulae, this can be a problem, so I generally do not use my binoviewers in my big Newtonians other than for brighter objects that require more power. I have used them in my 9.25 inch SCT on things like the Ring nebula and a few other higher surface brightness deep sky objects (I love what it does to M11), but I also have seen a somewhat modest but quite detectable loss in light when using them. Again, these smaller objects are fine, but for the larger things like diffuse nebulae or for objects near the limits of my vision and the instrument, the binoviewers just aren't quite what I need. Clear skies to you.

#13 azure1961p

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Posted 21 November 2012 - 06:40 PM

You know, when the aperture gets large and twelve is officially big aperture I wonder if by chance this web or network of details in the nebulosity is something in terms of resolution that typical imagerd can't circumvent - namely the blurring effects of seeing. The eye sees in real-time and so those periods of clarity as you know get saved where as Santa Barbara Instruments gets a smoothed approximation.

Something to think about - at anyrate your enthusiasim is infecticious. Well told - your skills in smaller also no doubt serve here.

Pete

#14 Sarkikos

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Posted 03 December 2012 - 10:53 AM

David,

The problem is that with my old Burgess binoviewers, I don't have quite a low enough power and the field of view on the sky (149x, 24 arc minutes maximum true field, slightly vignetted) in my 14 inch Newtonian as I do with some of my other "mono" eyepieces. For large diffuse nebulae, this can be a problem, so I generally do not use my binoviewers in my big Newtonians other than for brighter objects that require more power. I have used them in my 9.25 inch SCT on things like the Ring nebula and a few other higher surface brightness deep sky objects (I love what it does to M11), but I also have seen a somewhat modest but quite detectable loss in light when using them. Again, these smaller objects are fine, but for the larger things like diffuse nebulae or for objects near the limits of my vision and the instrument, the binoviewers just aren't quite what I need. Clear skies to you.


I have a pair of Burgess Binoviewers also. The clear aperture on these is such that they begin to vignette for eyepieces with field stops greater than about 23mm.

In any case, I only binoview planets and the Moon. Binoviewers will dim the image. They improve the image for planets and the Moon, increasing perceived contrast and making eye floaters less obvious. But those objects have plenty of light. IME & IMO, for dim or large DSO, monoviewing is better. I leave the binoviewers home when I go to my dark site.

This isn't to say that bright DSO won't look great through binoviewers. But for those amateurs - like me - who mostly observe fainter fuzzies, the binoviewers are not so good.

Mike

#15 FirstSight

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Posted 06 December 2012 - 09:43 AM

...The stars were twinkling madly, so I decided to forget anything about planetary observing and just hop around with the 12" dob for an hour or so... It sure wasn't the best seeing or transparency I've seen, not by a long shot...


Thomas, there are sometimes nights of poor seeing everywhere, but you live on an island fifty or sixty kilometers out into the Baltic Sea away from any other land masses such as the principal Danish island of Zealand (Copenhagen) or any of the Scandinavian mainland. Does your location have generally good seeing on clear nights due to the small land-mass surrounded by water, or is this favorable factor more often overcome by prevailing turbulent weather patterns in the region? Even when the atmospheric conditions are otherwise favorable to good seeing, how often is wind a problem in your observing location with holding stable images at more than relatively low powers?

#16 Astrojensen

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Posted 06 December 2012 - 03:05 PM

Hi Chris

My seeing is highly dependent on many separate factors. 1) the temperature delta between the sea and air. 2) the jet stream. 3) local seeing (heat from surrounding buildings, landscape after a warm day, etc) 4) the wind near the surface. All of this becomes tremendously complicated.

I'd say that my seeing, when compared to reports from others and my own very limited experience with observing in other countries, is rarely very good, but on the other hand is also almost never completely terrible, though I'd say that there's a much higher chance of really bad seeing than really good seeing...

The recipe here for good seeing seems to be a late summer or late winter night, when the air and sea temperatures are close to each other. In summer, we can get extremely good seeing. I was stunned when I realized this. I have used my C8 at magnifications over 800x on double stars and the image was just super sharp. On those nights, the air was very warm, it was mid- or late summer and the sea was also warm. Everything was close to equilibrium. In summer we also have very good daytime seeing on many days, allowing exquisite solar views. In spring, when the sea is still cold and the air warms up quickly, the seeing is often horrible, unless we get a cold wind from the north or east or late in the night when the air has cooled sufficiently. Fog is often a huge problem in spring. But the clearest nights in the whole year are often in spring, late March, April or early May, when we get very dry air from the east.

Denmark is a small country, without many natural resources, but there is one thing we have in abundance: Weather! We can have all seasons in one day! And we are often in for complete surprises that can leave the weather forecast almost dumbfounded and red-faced weathermen on TV, trying to explain why there was sudden and violent showers, when they had forecast sunny beach weather the previous evening.

Wind is also a huge factor here. Denmark is a major exporter of wind turbines for a reason... Wind is a huge problem on many nights and the clearest nights are often the windiest. This is one reason I advocate heavy mounts even for small telescopes. Dobsonians seem to have an advantage here. I am often kept at 150x - 200x, even with my dob, on many nights where I could otherwise have gone quite a bit higher. My long refractors often fare even worse. This is unfortunate, since they perform well at very high magnifications on such objects as planetary nebulae, but there just aren't many nights where the seeing is good and there is no wind.

Add heavy humidity and low altitude into the mix, plus three months with no real night (in the season with the most clear nights and the best seeing, to boot), and you can see that observing here can be a bit of a challenge.


Clear skies!
Thomas, Denmark

#17 Feidb

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Posted 06 December 2012 - 03:28 PM

Most viewing nights for me are mediocre at best. However, I'll say that mediocre is better than no night! It's that rare occasion when we get a great or super night. They don't come often.

I'll take what I can get.

#18 Space Dragon

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Posted 24 December 2012 - 01:25 PM

Thomas
I'm in Scotland on a very similar latitude to you and so far this winter conditions have been very bad. Late Summer/Early Autumn was pretty good here, as you describe, some very steady nights.
The UK has been having very bizarre weather for the past 2/3 years, including the driest/wettest/windiest/coldest/warmest periods since records began. Flooding at the moment.
This, coupled with the Jet Stream hovering overhead, means that on the rare occasions we do get a clear, steady night, you really have to make the most of it.
Those good nights, more often than not, seem to coincide with a Full Moon.
Hoping for some great Winter nights like last year, the patience does wear thin on occasions.
I do sometimes wish I lived in Arizona though.






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