Posts Tagged ‘M13’

Insomnia – I am making some progress on it, but not much, but when I woke up at 1:30 am this morning I at least could see stars. We have had a pretty steady dose of mostly cloudy, hazy, foggy, partly cloud and heavy rains lately – 7 inches one day, five inches more a few days later and about an  inch yesterday  – so clear skies have been unusual and don’t last long.

These clear skies lasted long enough for me to get the 66mm  WO scope out and after a false start – batteries are weak on the Celestron mount I suspect – I got it on the Desert Sky dual mount/Bogen tripod and had a good time with some old friends.

I actually have a little plan in mind – to establish a list of best objects for popular consumption on any given night – or more accurately, any given sidereal/star time – of the year.  My goal would be for these objects to be nice in any scope, so if they’re nice in the 66mm you can be pretty sure they’ll be nice in anything larger.  The 66mm thus establishes a base line. So my observations were made with this in mind.

Yes, I’m pretty sure I could make such a list from memory – but I would trust it more if I check each object with this in mind.

So – up for starters was, of course, Albireo. It did fine at 16X – was really pristine – but I think the newcomer would appreciate it more at 30X. Once they were certain what they were seeing, they could try backing off some.

I have a soft spot for Albireo, but I closed this session wilth Almach and I have to say that although it was pretty low in the east at this time, I still find its colors richer than Albireo. It does take significantly more power. I found it best at 78x, though it could certainly be split with less.

There’s no contest with the Dragon’s Eyes – they are a perfectly matched pair that’s pretty easy to split in binoculars and certainly split easily at 16X, but seem better framed at 30X.

Meanwhile the Dolphin presents more of a challenge. Gamma Delphini is a sort of pale version of Albireo – in fact I would have a sliding scale of intensity for blue and gold stars where I would rank Almach the most intense, then Albireo, and then Gamma Delphini. Needed about 50X to get a decent split and it was better at 79X.

I liked M13 at all powers from 16X to 79X – but it was best at 79X because at that point I could really see individual stars flashing across the main body of this star ball.

M31 was another object that did fine at all powers, though it was easier to pick out M32 at 79X.

As I think – and write – about this experience I basic process for visitors pops into my mind. I want to start them witht he naked eye view. From there, I’ll move them to low power binoculars on amount – just to let them know what they can expect to see with their own binoculars.  Next up would be the 66mm at 16X and on a tracking mount, tobe followed by the 5-inch SCT on tracking mount a with a 24-8 zoom. Finally they could go in the observatory and use the 8-inch SCT,

Last step? Show them a good image  – probably in the observatory and under red light –  of what they’ve been looking at and encourage them to go back and look again.

And in this process define a “glance” as one minute at the scope – a “look” as three minutes or more.


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Actually it was closer to 45 years ago that I began drooling over ads like this one.

And when my first Unitron arrived yesterday it was cloudy and the forecast dismal. But this little dude even knows how to break the new telescope curse. I was about to turn in early when I glanced through the sun room roof and there was the first quarter moon, fighting its way through the high junk. I was so excited I simply grabbed the Unitron – a Model 114 like the one in the picture, only with a few battle scars – and went out on the deck in my stocking feet with no jacket.

Yeah, the moon broke through the  high clouds – so did Mizar, Castor, Algieba and Saturn.


Now I know what the excitement is about. I know there are many observers who are saying – “so what took you so long to learn this? ” Hey – my parents always said my poor performance in school was due to my being a “late bloomer.” I attribute it toa streak of stubbornness where I have to do  everything for myself – the hard way. 😆  But if you’re a doubter and you hear someone saying those old long focal length achros can give modern APOs a run for the money, listen to ’em. I’m a skeptic turned convert and it happened with a single glance through an old .965 Ramsden eyepiece mounted in a “Unihex” that brought my reaction. It’s not a simple one. I know there’s more here than meets the eye – really. We’re talking gestalt! It is a wonderful blend of superb optics, almost quaint technology (like the compression slits that allow you to load six eyepieces into the Unihex and have none of them slip out despite the lack of set screws)  and nostalgia – oh, not to mention utter simplicity, solid build ( the proverbial brick outhouse has nothing on this baby) , light weight – and did I say anything about those optics?

I mean even the old, dirty, .965 stuff using the Unihex which must have degraded some over 30 years or so  – I mean, a 25mm Ramsden! Do you even know what a Ramsden is? If you don’t, I don’t blame you. In the 60s we felt an “achromatic Ramsden” was good – like a good Plossl is today.  You gotta be kidding me – a Ramsden delivering views like this!  And an 18mm Kellner, and a 12.5 Kellner and 9mm Symetrical – that last gives me 100X – more than enough to easily split Castor and Algieba. I couldn’t see the third component of Castor, but geeeeeze, I had mag 2.5- 3 skies! These are not ideal conditions.

And nostalgia. Yeah, it’s there. How about those flip down wooden tripod legs? Or the way the center spreader connects to them – no  chains. And a wooden case! Hell, when the clouds finally drive me in I sit in my library just staring at it, ignoring the book in my hand. It’s tall. When pointed up I can just reach to slide on the lens cap.  But the proportions are all perfect – quintessential telescope. This defines telescope like the Spitfire defines fighter, like the F86 defines jet fighter – or if you are more peacefully inclined – and I usually am – like the Piper Cub defines the fun of flying, or  DC-3 defines air transport.

And that viewfinder? I wasn’t even going to look through it. I mean a 5X23 – could that do anything? I’ve looked through junk like that with cheap modern telescopes and despaired. But this one? It was really one of the biggest surprises of the night.  And it focuses using a slit tube arrangement for compression that really does hold after all these years  – and it’s sharp – and they say the little sucker deliver a 6 degree 22′ field and I believe it. Made finding easy.

Yes, i did try my Televue eyepieces – and yes, on the hybrid .965 to 1.25 diagonal – and yes, there was a lot more through-put of light with them – did I mention the Moon? That was the first target. Honestly, the rugged peaks and valleys of the Apollo 15 landing site – the slash  of the Alpine Valley, of course – everything so darned sharp with such terrific ocntrast – and I cranked the power up to 180X with no sweat – 75X per inch!

Maybe my skies were exceptionally steady because of the high haze – I’m not sure. But I’m already in love.  Yeah, the focusing can be a pain with the old eyepieces because they are not even remotely close to being parfocal – so you have to pull out, or push in the draw tube some times because there just isn’t enough travel in the rack and pinion focus to accommodate the differences. Of course the Naglers are almost parfocal, so no hassle there.

Did I mention the stars. Those wonderfully sharp Airy discs?  That’s what I expect with the APOs – and I get them, of course. Other good achros can deliver them as well. They are a must for my viewing pleasure – though I know it just doesn’t matter to others.

I went to bed quite happy and caught  a break when I woke up at 4 am as well – but I could not split Polaris – too faint – at first I thought I did, but it was only light being thrown into the diffraction ring. BUT – I was able to split the Double Double – the wider component for sure, the other one questionable. (Omicron1 Cygni was lovely with the 25mm Ramsden.)

A friend on the West Coast with a bad case of refractoritis has been my mentor in my little excursion into long focal length achros. He says he uses TV Plossls with his. I’m not sure if that’s for economy, or because he prefers them over the Naglers for these scopes. Anyone have any thoughts on the subject?  I like the gestalt of using the .965 eyepieces and Unihex – but when I’m out at the extremes I’m hauling out the Naglers – with a slightly uneasy feeling, however. Nothing I can put my finger on, but I was thinking a simple Plossl might be a better choice.

Oh – saw the ring Nebula as well – including the central hole. Charming!

And M13 – Messier called it “a nebulae without stars” – now I know why. I would say the 60mm gives us a pretty good idea of the quality of Messier’s scope – I bet when using a good 60mm we are seeing what he saw. ( I know his scope was larger, but I don’t think the optics were this good.)  I felt M13 wanted to resolve – but that was more my past knowledge of it than what was in the eyepiece.

All Unitrons are not created equal. At least that’s the impression I get from reading what much more experienced Unitron users say.  I can’t say what the quality of the lens is that I have – I don’t have anything to compare it to – but it pleases the heck out of me  😆

Oh – and still making it’s way here from Oregon is  the 80mm F15 Towa. And arriving at the same time from Maryland should be a new Explore Scientific 127mm apo-wannabe. (Hey, there’s more to life than nostalgia and while a 4-inch Unitron appeals to me, I am the first to admit that  if you want some extra  photons in a package that won’t strain the typical mount, you need to go apo.

. . . and that’s it folks. I’m only going on AstroMart and the CN classifieds to sell stuff. My cup runneth over. Anyone interested in getting together here in a few weeks for a classics night? Observing with your scopes or mine as long as they are 25 or older? Let me know.

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Clear skies this morning, though I wasn’t prepared. I’m knee deep in planning my class – outlining 12 sessions for the year – but mainly working on this project I’ve devised that is a sort of a cross between and Orrery and a planisphere.

Anyway – that meant I had no plan for this morning and no advanced preparation, so I simply went to the little Observatory, opened the shutter,  and pointed the  8-inch SCT (LX-50) at M5 after scanning around some with binoculars. Transparency was excellent. Seeing wasn’t all that good, though I didn’t put it to the test.

I want to focus on  M13, as I mentioned earlier, but I need to do some comparisons as well and I know many observers feel M5 is  the nicer of the two bright globulars. I hate to pass judgment. M5 is different. It’s great. So is M13.  I’m not sure how I would place a value on the differences.

One thing I did have in mind to do, however, was check on Omicron1 Cygni which is promoted as a nice binocular triple. I couldn’t get three stars out of it the other night with 10X50 binoculars ,however – just two.  So I swung the 8-inch around as dawn was encroaching on M5 and picked up Omicron1 at the lowest power and of course the three are obvious.  I make out the primary as gold, the secondary – the one much closer to it – as blue, and the third, more distant star, as green – wonderful! (I know Bob, they’re all the same color 😉 wonder how others see them?)  This triple certainly deserves its stellar reputation. I can’t begin to imagine why I haven’t looked at it before. Incredible. Cygnus, rich as it is, somehow doesn’t attract me, except Albireo of course. Maybe I get frustrated by all those stars – I certainly get frustrated by the North American nebula. I know where it is. I can “see” it  – sort of, in binoculars. But boy, I can not make out it’s shape. I just see a difference in background color of the sky in that region. I checked on it again this morning – same result as always.

But getting back to Omicron1,  I decided to shut up shop quickly and scoot into the house and bring out the  set-up I devised last night with the 50mm Tasco. I’m using a dovetail bar to mount the Tasco 6TE5 and the 50mm Stellarvue “Little Rascal” side-by-side on a rather flimsy photo tripod.  This is the first time I tried it and it actually works. 😯  I pointed the pair toward Altair and made sure they were seeing the same thing – they are. The Little Rascal is F4.1, so with a 23mm eyepiece it’s delivering about 9X and nice wide field.  It’s good up to about 35X, but after that the image really falls apart. The Tasco can easily take you to 100X.

But this morning I had a .965 26mm Kelner in the Tasco, so that gave me about 26X in the little F12 scope.  So what did I see? The Little Rascal could split it – so my 10X50 binos should – I just need to get them steady. But there was not much joy in the faint images. The Tasco was something else. I enjoyed the view in it more than in the 8-inch. This is a great combination for this triple – a real nice fit. But I really need to fool around a bit with different eyepieces. The Kellner can only be brought to focus if you don’t insert it in the diagonal the whole way. Less than ideal, but a nice power – and yes, even with just 50mm of light  gathering power the colors were still there for me.

Bottom line – in 90-minutes  or so of observing I had more fun with the 5-10 minutes I spent with the Tasco and Omicron Cygni  that with the 8-inch.  I’m really getting hooked on these “classic” refractors – long focus achros. Nearly went crazy this weekend when three attractive scopes hit CN and Amart classified. The first was 60mm Unitron Model 114 on Alt-Az mount with Unihex eyepiece holder and in real nice condition. That’s on it’s way now from Florida and is due here Wednesday.  I’ve been waiting for over 40 years to look through a Unitron, so I guess I can wait a few more days.  😆

The second is a 339 Towa – 80mm F15 OTA.  This one has know nostalgic value for me. I really don’t knbow anything about Towas, except I read ont he web that they’re good.  It was just $120 – seemed reasonable. It now on it’s way from the west coast, so it will be a while.

What I really anguished over was 4-inch Unitron OTA that looked nice, but I was a tad uncomfortable with the seller and his “best offer” approach. Plus this is a guy who has several old Unitrons and right now is breaking them up and selling them piecemeal. If he had had the Alt-az mount ( he sold it a few weeks ago)  for this I think I would have given in and bought it. As it was I had to tie my self to my chair, then roll away from the computer 😉

Come on – I’ve never looked through a Unitron. I know they’re good. But I also am pretty sure that a modern APO is better – certainly has more light throughput with modern coatings. And, of course, is shorter and easier to mount. The guy did have an equatorial mount and clock drive. Ever seen a  Unitron clock drive for one of these large scopes?Looks like something out of a Jules Verne movie -a definite Victorian air to it. But now the price was really getting out of hand.  And I haven’t even looked through a 60mm yet! Gotta slow down.  🙄

Yeah, but running is fun!

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When it came to driving across country, my Dad was always in a hurry. As a result, I’m one of the few people I know who has seen the Grand Canyon – for just five minutes! :lol:

Maybe that’s why I can get fixated on a single subject so long. My Dad isn’t driving me around anymore. Which is perhaps why I was quite comfortable spending another hour or so with M13 for the second morning in a row. Yes, I would really like to make it mean – squeeze some hidden message out of it so the reality finally hits home. I can’t. I know all I can do is look and hope something pops out on its own. It didn’t this morning.

Oh there were some minor details. At one point I got thinking about Pete’s suggestion that the focal reducer is “just extra glass in a visual setup” that could only reduce light throughput. Makes sense. Any extra glass has to have some impact on light throughput, I know – but I can I see it? Not trusting my memory I experimented this morning. This is hardly “hard” science. I didn’t make any measurements, or anything of the sort and there are variables out of my control, including passing clouds during this morning’s session. But I did my best to identify the faintest star I could see with the focal reducer in place, and then using an eyepiece that delivered close to the same magnification, but without focal reducer, I looked to see if I could see the same faint star and if there was anything fainter.

Bottom line – I’m sure there’s a difference, just as Pete says, but I can’t see it. What I do see with the focal reducer is a significantly wider field of view that retains the best qualities of the 24mm Televue Panoptic. That is, I have a wider field and the stars stay sharp to the edges. In a word, nice – very nice. And useful. So the focal reducer stays.

( A clarification: If this sounds a little confusing it’s because Pete and I are talking past one another. Pete is absolutely right when he says the focal reducer doesn’t provide a wider field. And I’m right when I say it does. We’re just talking about two different things and it took me a while to understand that – though I suspect Pete did all along. The focal reducer does not produce a wider field in the way a Nagler or Ethos does – that is a wider field while retaining the same power – which is certainly desirable, but expensive to do well. But the focal reducer does result in a wider field simply because it is effectively reducing the focal length of the telescope and so the same eyepiece delivers a lower power and thus a wider field. That fits my goal which is to get a wider field with the 24mm Panoptic than I generally use on the 8-inch SCT so that it is easier to do star hopping. When you’re aiming the scope with a Telrad you want to start with as low a power and wide a field as you can effectively get.)

It was interesting that in the midst of this casual testing – I hate to even call it “testing” because that implies more rigor than I’m willing to direct to the situation – but in the midst of it I sensed the observatory was getting brighter. I looked up from the scope and saw a huge light dome to my west. What the heck is that? In my sky in the evening the northwest quadrant is my worst one for light pollution, but in the early morning hours the pollution is usually quite diminished. Things dawn on me slowly. In this case it wasn’t light pollution, but clouds, and they were apparently reflecting moonlight from a 24-day-old waning crescent moon that had risen in the southeast. Maybe the light wasn’t coming from the Moon – maybe it was ground lights – but it seemed to be moonlight. A 10-minute wait and the clouds were gone. I put the focal reducer back on and rechecked my earlier observation. Yep – conditions were changing back to what they were and the focal reducer pulled out the same faint star I had seen earlier.

I settled back down to enjoying M13 and this is when I got that distinct impression of driving past the Grand Canyon. But my vehicle wasn’t a 1957 Ford. This time it felt like I was a kid in a space ship making the long journey to M13 and the ship was turning as I pressed my nose to the glass of one port hole and M13 was crystal clear. But the turning ship made it drift out of view, so I ran to the next port hole and got a fresh view. Were we really just 100 light years away? I would guess so. At 241X M13 took up a good deal of the apparent field of view which was 82-degrees – more than my eyes could take in without moving them. It looks ragged – very uneven – at this power and I became more aware of how much brighter it seemed on one side, than the other, I wonder if I can draw it? Others with more patience and skill than I have do, but I know drawing helps me see and I have some new ideas abut how best to approach drawing bright subjects in the dark.

Yes! I can observe M13 reasonably high at some time of night from now until November. Think I will make this the year to really get to know it – with everything from the 50mm to the 15-inch! Of course there are excellent observers with excellent memories who get more out of a minute of observing than I do out of an hour – but I’ve never tried this before – this idea of really focusing on one object. Have you? I don’t mean for an hour – or even the six hours Stephen O”Meara gives many of his subjects. I mean repeated lengthy visits over several months? is there enough there to see? Will there be enough to hold my interest? And most importantly, will this kind of focus get it to mean more to me? Stay tuned! (Or, of course, feel free to go your own merry way – i think I’ll make M13 the Grand Canyon I never go to study ;-)

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The Driftway Clear Sky Clock held great promise, but when I got up around 1:30 am today we were still socked in, so I worked on the May postings for my Web site. By 3 am it was clear – not sparkling, but very nice. I went to the small observatory, where things were still set up from a very brief stint yesterday morning, and used the 8-inch LX50 to check on the Double Double – one of the ways I judge seeing. Not that encouraging. It took 252X to get a really satisfying split – when seeing is good it will split at 140X and when seeing is great, closer to 100 or even a bit less.Of course this could have something to do with the scope, but this is the one Pete so kindly and expertly cleaned for me and it has Bob’s Knobs on it and I have fine-tuned the collimation to the best of my ability and think it’s as good as it gets. However, I’ve never been completely satisfied with the view in any SCT I’ve owned, especially when it comes to doubles. It will be more than interesting to make direct comparisons when the AT6M, a 6-inch Maksutov-Cassegrain arrives in a few days. I’m using a focal reducer on the SCT to get wider views, so it took a 5m Nagler to reach 252X. Meanwhile, I’ve been having a great correspondence with the sellerof the AT6M about dream refractors – geeeeeeesh! I’m waiting for FedEx to deliber my “poor man’s APO” and without even testing it I’m thinking about a big refractor. He sent me a picture of the new 8-inch F0 achro that Astro_Tech is supposed to be introducing at NEAF. I think we both need a session of AstroMarter’s Anonymous :roll:

Enough. I settled in with M3, planning to stay with it most of the morning, but after about 10 minutes it occurred to me that M13 was prime at that time – right near the zenith. The zenith isn’t all that easy to reach in any telescope but as it turns out M13 was really at just 82 degrees – not too, too bad. I have the LX50 on a pier without the wedge, so it is in strict alt-az mode. Pointing it wasn’t that difficult, but I always have trouble judging just how much to rotate the dome to get the observing slit positioned correctly for an object that high. But oh my, it was worth the effort. Especially when I cranked the power up to 180X. That 3D feeling i got the last time I looked at these globulars was still with me – but it had crystalized into something else at this power.

My first thought was crinkled aluminum foil, crunched into a ball rather carelessly. But there was something more. There was still a fairly smooth core and what popped into my head was a Christmas decoration Bren had made nearly half a century ago. She had used a styrofoam ball, then poked sharp, round toothpicks into it so it looked something like a WWII mine, then sprayed it all with “snow.” (OK – some white stuff out of a can.) The result stuck in my mind and was the image that seemed closest to M13 this morning – but there was more. The “snow” of M13 was more like ice crystal and the patterns were not so regular as those jutting toothpicks. My celestial snowball had definetly turned not only 3D, but transparent with all sorts of structure, real or imagined.

And as my imagination played with this I began to think of the possibility of life in such a cluster. I gave up on intelligent life in open clusters long ago – unless they’ve been inhabited from elsewhere. That’s on the assumption, of course, that the 5 billion years it took us to get to this point is par for the course. With no other examples to evaluate, who’s to know? So I ruled out open clusters as ridiculously young. In most of them any solar systems that are forming would still be undergoing the sort of bombardment that the Moon and Earth went through 3.8 billions years ago! (OK – again I’m using the one example we know something about – I admit to other possibilities.

But with the globulars we’re talking really ancient history. It would be pretty accurate to say they’ve had all the time in the world to develop – or rather all the time in the universe – or most of it. Those stars are old. So what’s that mean? Could we be looking at some sort of network of extraterrestrial awareness? The more I stared the more I felt I was looking into a sort of Star Wars type mega-ship.

And while on that subject, I got thinking as we all do, about the incredible distances. Last time I checked M13 was something in the neighborhood of 25,000 light years away. So those were ancient photons I was absorbing – or were they? I’m still mulling over that newish theory from Einstein. I’m a slow learner. But if the patents clerk is right, doesn’t it mean those photons have no time on them at all? They’re good as the day they were “born?” I mean,photons travel at the speed of light and when you move at the speed of light time – and aging – stands still, right? So those photons are only old in terms my time frame. In terms of their time frame they haven’t aged at all?

Please feel free to correct my physics and logic. but this is my way of spending an entirely enjoyable morning at the scope. I can’t get enough of these ;-)

When i posted this on the ASSNE Bulletin Board Pete commented:

Wed Apr 07, 2010 8:25 am

Hi Greg,

Focal reducers are best used to squeeze an image onto a small CCD chip. They’re just extra glass in a visual setup. Actual field of view is strictly a function of the scope’s focal length and the diameter of the eyepiece field stop/field lens/visual back/baffle tube ID – which ever is smallest. See http://www.petersonengineering.com/spreadsheets/Eyepieces_for_8_inch_SCT.htm

If you don’t mind severe vignetting, you can just use an eyepiece with a field stop/field lens larger than your 1.5″ visual back. It’ll give you the same wider actual FOV that you get using the focal reducer with a bit more light throughput.

As for life in a globular cluster, I suspect that the gravitational interaction of those closely packed stars would render planet orbits so unstable as to cast them into a star or into deep outer space. To the point where there are few or no planets in a globular cluster.


That business about focal reducers really through me at first because it sounded like he was going in the face of physics. Turned out we simply weren’t on the same page. Ina ny event, I responded to this, as well as the comment on the possibility of life in a globular cluster. Here’s the hwole exchange:
Re: Snow balls in April!Postby Greg Stone » Wed Apr 07, 2010 10:29 am

petep wrote:Hi Greg,

Focal reducers are best used to squeeze an image onto a small CCD chip. They’re just extra glass in a visual setup. Actual field of view is strictly a function of the scope’s focal length and the diameter of the eyepiece field stop/field lens/visual back/baffle tube ID – which ever is smallest. See http://www.petersonengineering.com/spreadsheets/Eyepieces_for_8_inch_SCT.htm

If you don’t mind severe vignetting, you can just use an eyepiece with a field stop/field lens larger than your 1.5″ visual back. It’ll give you the same wider actual FOV that you get using the focal reducer with a bit more light throughput.

So what you’re saying is it’s a trade off between extra glass reducing light throughput, or putting up with severe vignetting? Since I haven’t noticed the reduction in light throughput – I’m sure it’s there, but I doubt it’s much – my choice would be the focal reducer. (Boy, you had me going there. At first I thought you were saying that they didn’t reduce focal length and thus produce a wider field of view with a given eyepiece? I even went out to the scope to check to see if I had been deluding myself and only imaging the wider field :roll:

The focal reducer is an experiment that I use on just one of the 8-inch scopes. So far I like it. Keep in mind that the basic goal is simply this – to give a wide field of view with my longest focal length eyepiece (24mm Panoptic) to aid in star-hopping – finding the target. You could argue that a good 55mm Televue Plossl might be the best choice. I was tempted to go that way – but it was double the price, so I thought I’d see what the focal reducer does. Besides, the 55mm would result in 5.5mm exit pupil and I’m darned lucky if my old eye makes it to 5mm!

petep wrote:As for life in a globular cluster, I suspect that the gravitational interaction of those closely packed stars would render planet orbits so unstable as to cast them into a star or into deep outer space. To the point where there are few or no planets in a globular cluster.

Absolutely correct, Pete – as far as it goes. Of course I don’t have a clue about this stuff. Most of what I know about globular clusters and planets I got from reading Isaac Asimov’s “Nightfall” a hundred years ago :lol:

But seriously – not all stars in a globular cluster are packed that densely together. I did a quick search on the subject of planets in globular clusters and the first thing I found was the transcript of a discussion panel on the subject at a European observatory from a decade ago. Here’s one of the comments from a panelist who I assume is an astronomer:

In very low-metallicity clusters, probably not; we’d end up with Moon-sized planets at best, after boiling away all the gas; and these little things would not hold on to their atmospheres long enough for life to develop. But in high-metallicity clusters such as many of the ones in the Galactic bulge, big terrestrial planets should be able to form. However, then we need to ask where in the cluster we should look! The central parsec or so, with its frequent star-star interactions, would be a very dangerous environment for planets, which would be removed by tidal encounters. So we’ll have to stay a few parsecs out form the cluster centre, and hope that our star doesn’t have a plunging orbit that would take it through the core every few million years.

Then what would the night sky look like from our hypothetical planet? The core of the cluster would look like a huge nest of multicolored jewels, several degrees across on the sky and almost as bright in total as the full Moon. Inside the core, the main-sequence turnoff stars would be easily visible to the eye as 4th to 5th magnitude – thousands of them sitting on top of the diffuse light of the still fainter stars. But the real spectable would belong to the hundreds of horizontal-branch stars, each as bright as Spica or Altair; and best of all the additional hundreds of yellow and red giants, each shining as brightly as Venus of Jupiter. We should even be able to see the core in the daytime! Scattered more thinly across the sky – but still adding up to thousands of stars visible to the eye – would be the rest of the cluster. And, let’s not forget the Galactic bulge! We are closer to it now, and it is less obscured by dust clouds in the disk, so it would be hanging (somewhere!) in the night sky, again about as bright as the full Moon but much more diffuse. The rest of the Milky Way would stretch across the sky brighter than we see it from Earth.

All in all, a dramatic place to live! The astronomers there must be a happy crowd. And of course, it may be even more fun for us to speculate about how this view of the sky would affect the mythology, religion, and cultural history of any civilisation there.

Call me a romantic. Science may have run me out of the globulars today – I’m not sure. But tomorrow someone will come up with another view. Meanwhile, I’ll dream what doesn’t feel like that unreasonable a dream

Re: Snow balls in April!

Postby petep » Wed Apr 07, 2010 10:53 am

Hi Greg,

The field stop in the Pan 24 is only 27mm. You have an optical path of 38mm. The optimum unvignetted maximum actual FOV would be achieved with a scope such as the Pan 35 with its 38mm field stop. Eyepieces such as the Nagler 31 will give you an even wider actual FOV but will have a bit more than 1 to 1.5 magnitude of vignetting toward the edges.

If used with a properly spaced f/6.3 FR you’re in the ballpark here.


Re: Snow balls in April!

Postby Greg Stone » Wed Apr 07, 2010 11:22 am

Thanks Pete – I always appreciate your suggestions and I know you have a much better understanding of SCTs than I do.

I bought the three SCTs (including the one you cleaned up) primarily for use by my visitors and while I let folks use my best eyepieces and all the scopes, I wasn’t ready to make the investment in a really good eyepieces just to equip each of these SCTs. With the eyepieces you suggest that would cost almost as much as I paid for them on the used market ;-) My generosity knows many bounds. I buy the best equipment first for myself – then I let others use it. But when I’m just trying to equip extra scopes that will be used almost exclusively for visitors, I admit I start looking for cost-effective solutions. I’m trying to get stuff that will fill the instructional task in the best way at the least cost. The LX series is neat this way because the mounts can be either alt-az or equatorial and they have really smooth slow motion controls – and if I decide to invetsi n batteries, they can be put in equatorial mode and made to track. May come in handy some day if I fall of the push-to wagon!

For the 15-inch – also used by visitors – I use the 24mm Panoptic, but ideally I would have a 21mm Ethos, or at least a 22mm Nagler. Those would give me the widest field of view there that my 5mm exit pupil can handle. I still enjoy the 82° AFOV Clearvue 30mm, 2-inch eyepiece I got from Mark several years ago and, of course, it work onthe SCTs, but it already a setady job as the primary eyepiece on the 80mm refractor which gets teamed with the C8 – and because they share the UA DoubleStar mount, there’s no need for the C8 to have a wide field for finding stuff because the 80mm APO becomes a super finder.

Meanwhile, the whole mix may shift soon – depends on the performance of the new Mak-Cass. I want it primarily for planets and double stars – but it, of course, is an F12 and this has a narrow field of view. Still, it may replace the LX10 – I’ll have to see how it does. The main objective with that scope right now is to keep me from going crazy and selling the 15-inch so I can buy a 127mm APO :roll:

Since this exchange I’ve read some more on the subject of M13 and life. Two interesting things:
1. Back in the 1970s the Arecibo radio telescope was used to send a message to alien listeners – they targeted M13 for that message! So obviously folks thent hought life was possible in a gobular cluster and from what I’ve read many contemporary astronomers still do think it is.
2. While very dense, globulars are not nearlyse as they look in our telescopes or pictures.  Burnham presented this model of M13. He scaled each star down to a sand grain that was .03 inches in diameter. This made the whole cluster about 300 miles in diameter – and it meant that there was three miles between sand grains. Debse, perhaps, as space goes – but hardly what it looks like when you’re viewing it from 26,000 light years away 😉 It’s important to keep in mind,a s several author shave pointed out,  that there’s a big difference between average density and what you find in the outlying regions of such a cluster. The whole question of intelligent life elsewhere in the universe is just that – a question. No one has any furm, answers. All we can do at this stage is make reasonable guesses. And when that universe contains so many absolutely huge, unanswered questions – well, the field is open for speculation.

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That was my “eureka” moment this morning as I got reacquainted with M10, M12, M5, M3, M13, and M92 in that order.  I felt real good about it too – until I came in and started rereading Stephen O’Meara’s descriptions in “The Messier Objects” and realized how much I didn’t see 🙂

But in another thread Bob was talking about “getting your mind around what you see” and that’s just about always my main goal and this morning I started by comparing M10 and M12  as they appeared in the C8 at 154X (13mm Nagler). I was noticing some details, such as the small triangle of brighter stars that partially engulfs M12  and how the layer of resolved stars over its core was greater in M10. Suddenly a description I had read popped into my head – one of these globulars was likened to a “gumball machine.” The author was referring to the colors of the resolved stars – only which one was she talking about? At this point I thought it was something Sue French had written, but I couldn’t remember if she was talking about M10 or M12, so I set out to determine which it was that looked more like a gumball machine.

The more I compared the two, the more I appreciated their individuality – but I was darned if I could detect much evidence of color in either.  Still, i decided she must have been talking about M10. And that’s when I had the “aha” moment that lasted and lasted . . .  Suddenly  my mind’s eyes was turning the different layers of stars into one of those snow globes you shake – or maybe more a series of crystal celestial spheres like those woodcuts from the MIddle Ages show. Whatever it was, the gumball metaphor has caused a break through and each globular now looked like what I knew it was – a three dimensional globe of hundreds of thousands of stars. Of course we can’t see 3-D at these distances and with one eye – but the impression was overwhelming and I tried to hold it like you do a dream, knowing if you look too closely it will vanish.

I love to tour the globulars available at this sidereal hour (c. 15h) and so I set out northward for M5. It was a “wow” making  M10 and M12 look pale in comparison. And the 3-D magic was, if anything, enhanced.  I moved on to M3, one I have visited many times in recent months as it was rising on winter mornings. Hmmmm… not as nice as I remembered. I mean cool – but M5 seemed to blow it away. OK, how about the “Great Pumpkin” – the  one everyone knows, M13? it was just about at the zenith and at this point the C8 corrector was collecting a little dew ( probably had something to do with the performance of M3, though I’m not sure.) It was quickly dispersed with  the hair dryer and I warmed up my hands a bit in the process. OK – M13 deserves its rep. I know some observers think M5 is better, but I have to go with M13 – not only because it gets higher in our sky ( which helps) but  because with the same scope and eyepiece you resolve so many more stars and the 3-D impact was overwhelming.  I wanted to look for the galaxy that’s near it, but I couldn’t remember exactly where it was and I didn’t want to break the spell by checking my charts. I was on a roll 😉

So where next? M92, of course, the most under-rated globular in our sky. M92 makes you appreciate that small can be beautiful too.  If M13 is the Great Pumpklin, then M92 is an apple – hard, crisp and bright like a Red Delicious! The 3-D vision held. Hope I can regain it another night!

When I got in I immediately checked Sue’s book to see if the gumball machine was M10 or M12. Ooops – she doesn’t use that metaphor. So i went to Stephen O’Meara. Yep. There it was – and he was talking about M12, not M10 as I thought. But no matter – the remembered phrase triggered that wonderful sensation of a third dimension. And rereading his description I know I have to slow down and spend a lot more time with these old friends over the next few months, for there’s so much more to see in each of them.

I’d started the session, btw, by checking on Porrima and for the first time getting a clean split with the C8 at 286X – but I was disappointed. This pair so bright and the C8 so sloppy ( I probably still don’t have it as well collimated as it should be) that there just was a lot of light in the diffraction rings – far too much. At this point I really missed not having something like a 120 or 127mm apochromatic. The split just isn’t wide enough yet for the 80 to handle – maybe next year.

Oh – and my other revelation of the night? I can’t reheat my tea with the hairdryer! Well, not in 10 seconds, anyway.  Another brilliant idea proven dumb  🙄

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I frequently have to drag myself to the observatory at night – unless someone is coming over, or I have had a solid, two-hour nap during the afternoon. See, I seldom get more than four hours sleep at a time and frequently that’s all I get in 24 – so in the past 24 hours I’ve had two observing sessions and one of them was a flop because I was tired and cranky and even lonely – and the other was totally satisfying because it came shortly after I had had my fours hour of sleep and I felt totally plugged in and at one with the solitude.

The first was around 7:30-8:30 last night and I really didn’t do anything except look at M42 and M35 with the 8-inch LX50. I have it in alt-az mode now. If I put it on the wedge in the observatory it takes up just that much more space so as to become a nuisance with me frequently bumping into the finder, or eyepiece  as I turn to make notes.  So now I’ve set the wedge aside, connected it to the pier which has a flat plate on top, and am using it entirely manually – though the jury is out on whether or not it would be better to use the electronics to move it once I have acquired an object. The manual slow motion controls – really, even just pushing it – works pretty smoothly. In fact, for those coming here to learn this will be a nice inbetween step – a way to get familiar with the controls that is less complicated than also using it in equatorial mode. So they can learn on the LX-50 in alt=az mode, then move to the LX-10 – very similar, but in equatorial mode.

Transparency seemed better than forecast, so I tried to detect the thinner areas of M42, but with little enthusiasm. With M35 I played around more with NGC 2158, its distant companion cluster. As I said, transparency was good. But I still could detect only half a dozen stars or so – the rest were so much powdered sugar.

Then as a closing gesture I decided to look at Mars and was surprised to see it as good as I can remember seeing it.  I was not expecting particularly steady seeing and so had not tried for the  “pup” – I have yet to see this dim, close companion of Sirius – and Sirius was now behind some trees. But Mars! My goodness the north polar cap just jumped right out at you and Syrtis Major with the stuff that spreads out in either direction near its southern base – was all quite clear. Oh, not like what you see on the S&T Mars Profiler (http://www.skyandtelescope.com/observing/objects/javascript/3307831.html) – several individual patches of olive drab blended together in one blob – but quite impressive considering that Mars is only about 13 arc seconds across right now and some 68 million miles away. Needless to say, I am not much of a planetary observer, for had I been I would not have closed up shop and gone in at this point

But when I got up around 3 am it was wonderfully clear and after a little reading I went out to the Observing Deck and played a little with the FirstScope – it’s proving frustrating, but I need to do more testing and I’m trying to get better performance by toying with the collimation. Bottomline – right now an inexpensive 60mm refractor is  blowing it away. More on that another time.  But I soon set it aside and put the 8-inch Celestron SCT in the UA DoubleStar mount along with the Orion 80ED I acquired recently. (There are some real bargains on these little APO wannabees on the used market right now and the one I picked up for $300 included a dual-speed focuser that’s much better than the original. Optically It’s performance is terrific. It gives the SV80S Lomo a run for the money. Though seeing was only average I got a nice clean split of the Double Double at 171X, yet while using similar power on the C8 I was having trouble splitting it. That led me eventually to spend some time in the predawn light recollimating the C8 using Polaris – this scope is another one of my recent bargain purchases.

But before I did any of that I settled down to sip tea and sip in the ancient photons from M13 and its sweet little companion, M92. I’ve been focusing on insight meditation of late and that led me to try to see M13 – not judge it. That is, I find it too easy to think of objects such as this as “beautiful,” or “glorious,” or :charming,” and the words are all worn out and mean little. So what was I really experiencing here? Of course, on one level I am visualizing where I am in the galaxy and where M13 is – and that’s fun. Also visualizing when it is and when I am.  But how can I describe it?  And that’s when the word “crystal” popped into my head, and then “rock candy.” Neither really fit, but they seemed headed in the right direction. The C8 – with a 13mm Nagler (154X) was delivering a wonderful image that showed a core studded with plenty of individual stars  – a snowball with ice shards? Perhaps. It was something like that. I was thinking of that fine ice, though, that comes tinkling down from tree limbs after the kind of icy-snow mix we got from the last storm.

That was the reality for me this morning. That’s what the photons were triggering in my brain after their 25,000 year suicide mission.  (Well, 25,000 years for me, no time for them, right?) In short, it was wonderful for me. The kind of still, star-filled morning I live for – at night I had been alone – lonely even. This morning was different. I was alone, yes – very alone. Most of the lights on the hills across the river were out. The yard was still. The air wasn’t moving. And I can’t hear worth a damn, so there was no sound.  The moon had set. This is being alone – but there is no loneliness, for this is solitude. That’s different. And, of course, not that much had changed from the night before, except that I had had some rest. But that’s why I find each observing session different, even when I’m looking at the same thing from night to night. I don’t think we can begin to exhaust these objects and what we see really depends on what we bring to the telescope.

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