Archive for August, 2010

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Blingitty bling bling bling

August 28, 2010

Back in May I logged my final Messier object, thus completing the requirements for the Hononary Messier certificate from the Astronomical League (you can get the regular Messier certificate for observing 70 of 110 Messier objects). Although you can submit your observations to the AL yourself, it is recommended to have the AL representative of your club look at your logbook and send a letter to the AL to the effect that your observations are satisfactory. The PVAA doesn’t have a regular AL liaison but the then president, Ron Hoekwater, was willing to vet my logbook. He also suggested that I hang on to the certificate so that he could present it to me at the next meeting.

The problem was, I didn’t attend the next meeting, because in June I was crazy busy with teaching. And I didn’t attend the meeting after that, because in July I was in Uruguay. So tonight’s meeting was the first that I’d attended in three months.

And in those three months I went to Uruguay and finished the observations for the Southern Sky Binocular Club…

…and the Southern Sky Telescopic Club.

And when I got back, I logged the final object for the Deep Sky Binocular Club, which I’d been working on since January.

So the certificates and pins have been slowly piling up. In fact, the bling for the Southern Sky Telescopic club arrived in the mail just this afternoon. At tonight’s meeting Ron presented all four to me, and asked me to say a few words to the members about the AL observing clubs and about observing the southern skies from Uruguay.

In other PVAA-related horn-tooting, after missing the month of July my series counting down the world’s largest telescopes resumed in this month’s Nightwatch. This link should be good for the next three months, after which it will be available at the archive site.

Last night I actually got  out for an hour and bagged three targets for the Urban Club, so that club has 66 down and either 34 or 44 to go. Anyway, it was an enjoyable hour of stargazing.

Back on January 1 I resolved to finish the Messier Club, the Galileo Club, and the Lunar II Club this year. The Messiers are done, but I haven’t worked on either Galileo or Lunar II since January. The fact is, I’ve been having too much fun with other observing projects. And I’m okay with that. The real goal of making that resolution was to finish three clubs this year; I just figured that Galileo and Lunar II would be the easiest since I had already started Galileo and had just come off Lunar I successfully. In the actual event, I sort of fell in love with deep sky observing, especially with binoculars, and that’s been the direction of my observing this year. In fact, I think it is now probably impossible for me to finish the Galileo Club this  year, because I won’t be able to track Venus through enough of its cycle before the end of the year, and I also think I missed something for Jupiter. But on the other hand, I’ve finished five observing clubs this year (in order: Binocular Messier, Messier, Southern Sky Bino, Southern Sky Telescopic, Deep Sky Bino) and I’m on track to finish Urban at least by the end of the year, so I’m going to declare the spirit of the resolution fulfilled even if the letter is not. That’s usually how people rationalize this stuff, right? Just move the goalposts and declare that whatever you did instead was the actual goal. 🙂

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So close and yet so far

August 24, 2010

Some of the folks on Cloudy Nights have really cool quotes in their sig files. Last night I came across this one, which crystallizes the elusive feeling that I catch on some nights and pursue on all the rest:

There is a moment after you move your eye away
when you forget where you are
because you’ve been living, it seems,
somewhere else, in the silence of the night sky.

I figured this had to be part of a poem, so I Googled it, and found the original source here. It’s a poem entitled “Telescope” by Louise Gluck, and it originally ran in New Yorker on January 17, 2005. Since it’s already out there on the intarwebz, I don’t feel bad about reproducing it with attribution.

Telescope

by Louise Gluck

There is a moment after you move your eye away
when you forget where you are
because you’ve been living, it seems,
somewhere else, in the silence of the night sky.

You’ve been stopped being here in the world
You’re in a different place
a place where human life has no meaning.

You’re not a creature in a body.
You exist as the stars exist,
participating in their stillness, their immensity.

Then you’re in the world again.
An night, on a cold hill,
taking the telescope apart.

You realize afterward
not that the image is false
but the relation is false.

You see again how far away
each thing is from every other thing.

I think it’s a smashing poem and I wholly agree with the sentiments expressed, right up until the last two stanzas. Then, as far as I’m concerned, it all goes straight to heck.

– – – – – – – – – –

M8 photographed by Rob Gendler

One of the things I like best about observing is that with very modest equipment, one can see most of the stages of the life cycles of stars. Turn to M8, the Lagoon Nebula, or M42, the Great Nebula in Orion, and you can see stellar nurseries. The nebulae are great clouds of gas and dust that are only visible because they are illuminated from within by the terrifying light and heat of newly formed stars.

This process cannot last forever. Even as the last few protostars of a nebula straggle into ignition, their older siblings are blowing away the nebular cocoon by the force of their stellar winds. Eventually the nebula will be entirely dissipated, and all that will remain is a cluster of young stars, all of similar ages and chemical compositions. These are open clusters–as opposed to the vast and ancient globular clusters that haunt the galaxy’s halo–and they include some of the sky’s most brilliant jewels, such as the Pleiades and Hyades, the Beehive, the Double Cluster, and thousands more, of many sizes, ages, and distances.

The Double Cluster photographed by Rob Gendler

Even the stars of open clusters are not destined to remain together forever. They may remain together for tens or hundreds of millions of years, but the lives of stars are measured in billions of years. As open clusters orbit the core of the galaxy, repeatedly passing through the galactic plane, being overtaken and left behind by successive spiral arms, their constituent stars are stripped away from their weak mutual gravitation embrace. Eventually the cluster is entirely dispersed, its constituents becoming the un-clustered field stars that make up most of the galactic disc. Almost all of the stars  that you can see with the naked eye are field stars, each pursuing its own course around the galactic core, forever sundered from their siblings. Lurking out there in the Milky Way are the long-lost sister stars of our own Sun, which we might identify now only by their chemical fingerprints.

Even stars do not last forever. Near the end of their lifespans, with most of the hydrogen fuel in their cores converted to helium, main sequence stars start fusing hydrogen in the shell around the helium core. The star’s interior heats up still further, and the outer layers expand into a vast tenuous envelope. The surface area of this envelope is much larger, in relation to the total energy passing through it, than the star’s old surface. Hence it is cooler, and the light emitted at the star’s surface is shifted toward the red. The star has become a red giant. Arcturus in the constellation Bootes and Aldebaran in Taurus are familiar examples, respectively the third and thirteenth brightest stars in the night sky.

Still larger stars start to fuse helium to carbon and eventually carbon into still heavier elements. These stars may become red hypergiants, so large that they could swallow the entire inner solar system. Betelgeuse in Orion and Antares, the glaring red eye of Scorpio, are red hypergiants, and respectively the eighth and sixteenth brightest stars as seen from Earth.

M27 photographed by Rob Gendler

Now we come to a fork in the road. In small and mid-sized stars, such as the sun, the process of helium fusion proceeds in fits and starts, alternatively heating and cooling the star’s outer envelope. As it expands and contracts, the gas in the outer envelope picks up enough kinetic energy to escape the star’s gravity and expand into space. This process repeats, and star comes to be surrounded by concentric shells of blown-off gas. The gas is still energized by the star’s radiation, and glows as a nebula. This type of nebula is called a planetary nebula, not because it has anything to do with planets (the planets of such a star will have been scorched to cinders or completely eroded by star’s late-stage pulsations), but because they are often round and looked something like planets in the small telescopes of early astronomers. M57, the Ring Nebula, and M27, the Dumbbell Nebula, are two of the best and brightest planetary nebulae. Even tiny NGC 7662, the tiny round glow Brian and I star-hopped to last week, could not be mistaken for anything else. After blowing off most of their mass, the cores of the former giants persist as white dwarfs, which glow not because they sustain fusion but because their matter is heated to fantastic temperatures by gravitational contraction. Even after their planetary nebulae dissipate, white dwarfs may shine feebly for tens of billions of years.

Stars over a certain size, just a few times larger than the sun, have a different destiny. Bigger, hotter, they sustain more rapid fusion, exhaust their hydrogen and other light elements in rapid succession, and then blow themselves apart as supernovae. The cores of the exploded stars persist as neutron stars and black holes. Although supernovae are frequently spotted in other galaxies, there hasn’t been a naked-eye supernova in the Milky Way in centuries. There are some fine supernova remnants, however, diffuse halos of material still expanding outward from the explosions that created them. M1, the Crab Nebula, is one, and the much older and larger Veil Nebula in Cygnus is another.

M1 photographed by Rob Gendler

The matter blown off by dying stars, slowly and gently in planetary nebulae or all at once and violently in supernovae, rejoins the vast, diffuse molecular clouds that clot the galactic disc. Eventually the clouds will be sufficiently compressed, by the pressure waves that form the spiral arms, or by the shockwaves of nearby supernovae, for knots of material to start to accumulate. As the gravitational force of these concentrations pulls in more and more material, they will pass a critical threshold: fusion reactions will start in their cores and they will become new stars, lighting the encircling nebula from which they were born. The circle is then complete.

– – – – – – – – –

It is often noted that we are made of stardust. This is true, but it has become such a cliche that I fear it has lost its visceral impact. Consider: every breeze that has ever cooled you, every bite you’ve ever savored, every caress you’ve ever felt, the blood in your veins, the brain that you think with, the pillow under your head at night, the plastic and metal on which you’re reading this–every atom you’ve ever perceived with any of your senses, and all of others in the universe that you have not perceived, were born in the hearts of stars (except for the hydrogen and some of the helium atoms, which formed in the cooling fires of the Big Bang itself). So, yes, you are made of stardust. And so is everyone and every material thing you know.

And we will be stardust again. In five billion years the expanding sun will envelope the Earth. Our atoms, having been through the planetary cycles dozens  or hundreds of times, and incarnated in countless organisms of which we are but a snapshot, will be blown off with the rest of the crust and outer mantle. For a while we will shine as part of the sun’s planetary nebula, before being dispersed into the interstellar medium. But our constituents will know still greater fires when they are taken up into new stars, and new life when they are incorporated into other worlds.

Ashes to ashes, dust to dust, light to light.

– – – – – – – – – –

That is why I disagree with the estimable Louise Gluck, former Poet Laureate of the United States. When I am packing up the telescope, I don’t see how far each thing is from every other thing. I am still charged by what I have seen, and by the knowledge that I have been a nebula and an open cluster, a red giant and a supernova remnant. Any stage of stellar evolution that I can see in the sky, my atoms have gone through–and will go through again. There is no distance separating me from the stars. There is only time.

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Sigh…another impact on Jupiter

August 23, 2010

Well, it’s happened again. Something hit Jupiter while Earthlings were watching. Why is this newsworthy? It’s only the fourth time it’s happened in recorded history, but the third time it’s happened in the last 13 months. It seems increasingly likely that Jupiter is getting creamed by rocks that would dwarf the dinosaur-killer (seriously, the fireballs we’ve been seeing on Jupiter are the size of continents) all the time, but we’re just now catching on because finally enough amateur astronomers are watching (and digitally recording) the planet to provide something approaching continuous monitoring.

That’s right: amateur astronomers. All three of the recent impacts were found by amateurs. This latest was independently detected by two Japanese amateurs, one using a 6″ scope and one a 9.25″ scope.

More info and a link to a video of the impact at both Sky & Tel and Space Weather.

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Observing report: Mount Baldy by moon and telescope

August 18, 2010

After having a lot of fun with binoculars on Mount Baldy last week, Brian and I resolved to get back out with scopes before the moon got too bright to observe anything else. We went up last night with both my 6″ and 10″ scopes.

Normally I don’t let houseguests escape without a look at the top 2 or 3 things in the sky, whether they’re in from across the country or just across town, so Brian has looked through both of my big scopes before. But that’s from town, when I was driving the scope, and we’d never been out for a proper telescope observing run before last night.

We got both scopes set up in a nice spot just a little after 9:00 PM. At his request, Brian was driving the XT6 and I was manning the XT10. We started out on the first quarter moon, which looked pretty darned good. We were still getting solid images at 200x, which means the seeing was very good by urban SoCal standards (even though we were on the mountain, to view the moon we were looking south over the Inland Empire). Brian got an MS in geology before switching to biology for his PhD, and he immediately recognized the Alpine Valley (the laser-straight valley near the bottom center in the  image below) as a fault.

After that we cruised through the best and brightest between Scorpio and Aquila–M7, M6, M25, M22, and so on up to M11, the Wild Duck Cluster. This was familiar territory for us both since we’d just been over it with binoculars less than a week before. This time we had a lot of additional aperture and magnification on our side, but we were also fighting the moon, which was swamping out a lot of the fainter stars and nebulosity on deep sky objects to the south.

To fight the moonlight we turned west to take in the globular clusters M13 and M5. From a dark site I think the smaller but more compact M5 gives M13 strong competition, but by the time we got there M5 was pretty low in the sky, and about twice as close to the moon as M13, so it wasn’t even close. M5 still looked acceptable, but M13 looked great.

We had a look at M57, the Ring Nebula, which was a big glowing doughnut at 200x in the 10″. We also got a clean split on Epsilon Lyrae, the Double Double star, which is always cool. Both scopes have the horsepower to do that split pretty easily, if the atmosphere cooperates. From town it often doesn’t, and I have to settle for a pair of 8s instead of four cleanly separated stars.

We finished up in the north, starting with the galaxy trio of M31, M32, and M110. M31, the Andromeda galaxy, has always been a favorite of mine, but the satellite galaxies M32 and M110 have often bedeviled me. After unambiguously identifying them several times in recent weeks–at Big Bear Lake, and now twice on Mount Baldy–I’m getting a lot more confident about recognizing them. And my appreciation of them is growing as I learn more about them. I’m reading The Perfect Machine, by Ronald Florence, about the building of the 200-inch Hale telescope on Palomar Mountain, and I just learned that M32 was the first external galaxy resolved (split into its constituent stars) all the way to its core by astronomers. That was done by Walter Baade using the 100-inch telescope at Mount Wilson, during World War II. In my 10″ scope M32 is nothing more than a bright glow, and having been to Mount Wilson a couple of times I can certainly appreciate the achievement in resolving it completely using one of the great iron and plate glass leviathans of the early 20th century.

I lent Brian a planisphere and a mag 7 star atlas (this one, which is free) and he rocked along with aid or supervision for the most part. In fact, I’ve never seen anyone pick up the use of a telescope and atlas so quickly. By the end of the run he was really feeling his oats. After the Andromeda galaxy trio he picked out a nearby planetary nebula, NGC 7662, more or less at random and suggested we try that next. We even had a little friendly competition to see who would be the first to star-hop to the nebula starting from M31. Brian got to the location of the nebula first, but he couldn’t see it clearly in the 6″ scope. And no wonder–even in the 10″ it was a very compact round glow, like a fat star, at low power, and a slightly bigger but no more detailed glow even at 200x. Not one of the sky’s more breathtaking sights, but we had a fun time getting there. And even when all you can see is a bright dot, there is something arresting about watching the death throes of so great a thing as a star.

We finished the observing session on the Double Cluster, going back and forth between the two scopes and trying out a variety of eyepieces to see which would yield the most pleasing view. And after packing up and driving down the mountain, we finished the evening at In-N-Out Burger with some earthbound but equally delicious Double Doubles. Some fine gastronomy to put a cap on an evening of fine astronomy. I worry that might be getting spoiled.

Photos taken with a Nikon Coolpix 4500 digital camera, shooting handheld through an Orion XT10 Dobsonian telescope with Orion Stratus eyepieces.

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Observing report: Binoculars on Mount Baldy

August 14, 2010

Thursday night my buddy Brian and I drove up Mount Baldy to do some casual observing. Brian probably wouldn’t describe himself as an amateur astronomer (yet), but I’m working on him. We’ve been talking for months about going out with binoculars and a planisphere and just spending some time learning the sky. When I got back from Uruguay I realized that Brian had been in town for a year and we hadn’t been out observing yet, so I started bugging him regularly. Thursday night, we went.

It was just by chance that Thursday night was the peak of the Perseid meteor shower; we were going out anyway and the meteor shower didn’t affect our decision one way or another. But it was a nice perk, and we both saw some excellent meteors up on the mountain. Not as many as we might have if we had gone for that purpose, because the best meteor watching is done with both eyes wide open, laying on the ground or on the hood or trunk of the car. Even binoculars cut out so much sky that you’re more likely to miss meteors than to see them if you’re scanning the sky with binos. That said, Brian did catch at least one through binoculars. Brian had along his 10x50s and I had my 10x50s, 15x70s, and SV50. We looked at just about every good target with all three instruments. Usually we’d find things with the 10x50s, kick things up a notch with the 15x70s, and go to the SV50 for a steady fixed view and sometimes for more power. It was a useful, easy-to-use set of instruments that I thought complemented one another well; my only regret was not bringing the eyepiece rack for the telescope mount, because I spent more time than I wanted fiddling with end caps when I was switching eyepieces on the telescope.

We started out facing south, down the mountain, toward Scorpio and Sagittarius. Those are two of the most recognizable constellations, Scorpio because it actually looks like a scorpion and Sagittarius because of the striking ‘teapot’ asterism. They’re also prime territory for deep-sky observing, with binoculars or telescopes of any size. Our first target was M7, just above the “stinger” of Scorpio. M7 is a BIG, bright cluster, and it looked pretty darned good even though Scorpio was down in the light dome over LA. M6 is right next to M7 and looks like its smaller sibling. From there we went up into Sagittarius, to M8, M22, and M24. M8 is the Lagoon Nebula, and M22 is the brightest globular cluster in Sagittarius. M24 is “not a ‘true’ deep sky object, but a huge star cloud in the Milky Way, a pseudo-cluster of stars spread thousands of light years along the line of sight, perceived through a chance tunnel in the interstellar dust”, according to its SEDS page.

At that point I was doing something else–switching eyepieces on the telescope, as likely as not–and Brian was just cruising with the 10x50s when he ran across another bright cluster. We identified it, and several other “discoveries” of the evening, by the following process: one person would find something in binoculars, and then hold the binos with one hand while getting a green laser pointer on target with the other hand. Then the other person would follow the line of the green laser to the target using his binoculars. That first time, the target was M11, the Wild Duck Cluster, one of the true gems of the summer sky. Other “discoveries” sent me scrambling for the star atlas.

By that point we had been facing south for more than half an hour and we needed a stretch and a change of pace. We hit M13, Epsilon Lyrae (the Double Double star), and M15 in the mid sky before settling down to face north. Our  first northern target was M31, the Andromeda galaxy. It was grand. We also spotted its two satellite galaxies, M32 and M110, without much trouble. By that time the Double Cluster had cleared the treeline to the north so we spent a few pleasant minutes contemplating that celestial showpiece. Then we just panned around Cassiopeia taking in all the good stuff. Even with binoculars, you can spot clusters in Cassiopeia faster than you can identify them, unless you already have them committed to memory, and we saw a lot more than we logged. Specific objects that we noted or looked up included the open clusters Stock 2, M34, and NGC 457. Our last two objects were M33, the Triangulum galaxy, and the Engagement Ring of stars around Polaris.

We wrapped up about 12:30 AM after a solid hour and a half of unhurried observing, during which time we had seen several asterisms, one nebula (M8), one identified double star (Epsilon Lyrae) and at least one unidentified by us, seven identified open clusters (M7, M6, M11, the Double Cluster, Stock 2, M34, and NGC 457) plus several more unidentified, three globular clusters (M22, M13, and M15), five galaxies (M31, M32, M110, M33, and our own Milky Way arcing high overhead), and a galactic star cloud (M24). So we had seen at least one of just about every class of deep sky object except for planetary nebulae and dark nebulae. If I’d been more target-oriented I would have remember M27, the Dumbbell Nebula, and then we’d have gotten a planetary as well.

But I wasn’t target-oriented. I was just there to have fun surfing the sky with a friend. I had a heck of a good time, and I think Brian did too. I’m already looking forward to the next time out.

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Telescope tradeoff: aperture vs portability

August 14, 2010

In a comment on the last post, Jon Lindberg brought up some good points about the aperture/portability tradeoff with telescopes. It’s fertile ground for discussion, because there is always a tradeoff.

The big up-front ground rule for this discussion is that when it comes to portability, your mileage may vary. Some people consider 8″ or even 10″ scopes to be “grab-n-go”. For me, scopes break roughly into two categories: those that require one hand and one trip–my definition of grab-n-go–and those that require some more setup, either two hands or multiple trips or other fiddling. And at any given time, there is only one scope in each category that I’m using heavily.

Right now my big gun is a 10″ Orion dob. It weighs about 55 lbs assembled, which is about half in the tube and half in the base. I can move it while it’s assembled, but usually not without having a few twinges in my back the next day. So I usually carry the base to where it’s going to be set up, then put the tube on, then set up  some kind of  chair next to the eyepiece. Including a trip for my eyepiece case and some charts, it’s usually about four trips. But that’s okay, because I only tend to set it up when I’ve got some serious observing to do, or when I want to impress houseguests.

My old “big gun” was my first telescope, a 6″ Orion dob. It weighs about 33 lbs assembled, and I always carry it out in one piece. But it lives out in the garage with the 10″ and also requires a chair, so I’m still making two or three trips to get it set up. If I’m going to go to that much effort, I might as well get out the 10″ and get the benefit of nearly three times the light-gathering ability and almost twice the angular resolution. So I’ve barely used the 6″ at all since I got the 10″.

The 6″ is also facing competition from the other end, from my 5″ Skywatcher reflector on a homemade Dob mount. That one weighs just under 20 pounds and is short enough that I can use it sitting on the ground, so it’s more grab-n-go-able and still delivers most of the performance of the 6″ scope.

One of the lessons of all of this might be that I have too many telescopes. The more broadly applicable point is that the goodness or badness of a telescope for any particular application depends on what else you’ve got in the stable. When I only had one telescope, it was of necessity both my big gun and my grab-n-go scope. But my enthusiasm for hauling out a 30 lb scope on short notice declined markedly when I had something under 10 lbs to use for quick peeks.

But let’s get on to the meat of Jon’s question, which I am going to interpret as, at what point as you go down in aperture do you start noticing the compromises?

Again, the answer will be different for different observers. Some people think that anything smaller than 8″ is a waste of time. Obviously I disagree. I think that the vast majority of observers would say that a 3.5″-4″ telescope is probably at a threshold between noticeable compromise and being to see most familiar targets–moon, planets, Messier objects, the occasional comet–with rewarding vibrancy and detail. I base that in part on the massive commercial success of 90mm Maksutovs and 4″ refractors, especially apochromats. Also, some of the best deep-sky observers in the world like Stephen O’Meara and Sue French use 4″ refractors as their primary scopes.

That’s not to say that smaller telescopes aren’t popular as well. Refractors in the range of 60-80mm have always sold well and probably always will, especially short focal length, widefield scopes like Orion’s ShortTube 80 (pictured above). And you can have a lot fun pushing these little scopes to their limits, as Jay Reynolds Freeman did when he completed the Herchel 400 with a 55mm scope. But achievements like that get noticed because nobody expects to be doing serious deep-sky work with a tiny telescope. Sub-3″ scopes are almost always intended to be either introductory-level instruments or purpose-built grab-n-go and travel scopes.

So what’s the real word? My little SV50 is well into the realm of trading away performance for portability. So far it has shown every Messier object I’ve tried for, but all but the biggest and brightest have been faint fuzzies at the eyepiece, without a great deal of detail. And a scope that small absolutely requires dark skies to do any meaningful deep-sky work. Here in town it just doesn’t have the horsepower to cut through the light pollution. But that’s okay, because I didn’t get it to use here in town. I got it mainly for airline travel, and if I’m flying, it’s usually to someplace darker than the LA area, so it fills its very specialized niche admirably.

One thing that the little scope excels at is putting a truckload of stars in my eyes. Bigger scopes with longer focal lengths have smaller fields of view, that’s just an inescapable fact of optics. I’ve noticed that when I’m using bigger scopes I’m usually hunting for particular targets. With the SV50 I have a lot of fun just panning around the sky. It is the only scope that I have used that delivers the same super-wide field of binoculars, but with the advantages of being solidly and comfortably mounted (image crouching behind a pair of  mounted binoculars when they’re pointed at a target more than 45 degrees above the horizon) and having variable magnification.

For a little more than double the weight and volume, the C90 is still very portable and delivers a LOT more light and a LOT more detail. But for me it has two distinct disadvantages compared to the SV50. First, it’s just big and heavy enough to require a bigger tripod, so the whole kit-and-kaboodle won’t fit into a tiny bag that I can stuff into the bottom third of my backpack. So if I’m traveling with it, it becomes one of the focuses of my packing, instead of something I just shove in the bag and forget about until I reach my destination. Also, the folded light path gives the C90 a very long focal length for its size–900 mm–which makes reaching high powers a breeze. That makes it easy to power up on planets and specific deep-sky targets, but it also means that the scope has a fairly narrow field of view. So my mindset when I’m using it is more along the lines of, “what individual small thing am I going to look at next”, and not, “let me pan around the sky and see what I stumble across”. If you want the latter experience in a more capable scope than the SV50 that still only weighs about 5 lbs and is eminently airline portable, consider a Short Tube 80.

If you’ve got a little more space and don’t mind a little more weight, a 4″ Mak or a 5″-6″ Schmidt-Cassegrain will put a lot of aperture into a decently small space. Something like a Celestron C5 is about the size of a big coffee can but gives you enough light grasp and resolution to go after just about anything you want, especially if you have dark skies. The caveat I’ll add from my own bitter experience is that at this size of scope you have to put as much or more thought into the mount. When I got my first Mak, a 4″, I put it on a cheapo camera tripod from Wal-Mart. That was a disaster–the mount was so shaky that using the scope was an exercise in almost terminal frustration. Moving down to a 90mm scope didn’t really help, and my little scopes didn’t get much use until I got a decent tripod. And by “decent” I mean “costing as much or more than the telescope itself”.

I brought up the Short Tube 80 and all of the catadioptric scopes (Maksutov-Cassegrains and Schmidt-Cassegrains) first because they’re probably the most airline-portable of the bigger scopes. If portability is important but you don’t plan on flying with the scope, at least not regularly, the Orion StarBlast 4.5 and Edmund Astroscan both put some serious aperture into a one-hand telescope. Both are bulkier than a 5″-6″ SCT, but in both cases the bulk includes a base so you don’t have to worry about buying a separate mount and tripod (although you may want something, even a picnic table, to get them up off the ground). The StarBlast has better optics and a better focuser, but the Astroscan is almost indestrucible. As with any optics purchase, read around to find out the good and bad about them both before you make any decisions. The links to telescope reviews on the sidebar are good places to start.

Most telescopes are made in China and Taiwan these days, and the same models that are sold by Orion and Celestron in the US are usually available from SkyWatcher or Konus in the rest of the world. Happily, just about all of the scopes I’ve discussed can be had for $200-300 or even less if you’re willing to shop used (for example, at the Cloudy Nights Classifieds, where I’ve bought and sold just about all of my astro gear). If you have any questions, feel free to ask in the comments. I’m always happy to talk about telescopes.

UPDATE March 11, 2013: Here’s Doug Rennie’s StarBlast 6 hanging out amongst the flora–see comments for explanation!

Doug's SB6

 

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Small telescope quest complete

August 10, 2010

When I caught the astronomy bug in the fall of 2007, my first priority was to get a decent scope. I spent about a month doing research in print and online and just about everyone said the same thing: get a cheap 6″-8″ Dob and some serviceable binoculars and start learning the sky.

This I did. My first scope was an Orion XT6 that I named “Shaft”. For two and a half years, Shaft was my workhorse scope.

But Shaft was still getting broken in when I decided that I needed something more portable. An XT6 is about 4 feet tall and weighs 33 lbs. It’s easy enough to  take the tube off the base and stow them both in the car for camping or a trip to the mountains, but I wanted a scope small enough to fly with. My parents live in rural Oklahoma under very dark skies and I knew all too well what I was missing here in the light-polluted swamp of California.

So began my quest for a grab-n-go scope. Not just any grab-n-go scope–some people consider a 6″ Dob to be grab-n-go. What I was really looking for was my “no excuses telescope”: a scope that would be so triflingly small and light, and yet so capable and easy to use, that I would never have an excuse not to have it along, whether I was driving up the mountain for a quick peek or flying to another hemisphere.

I’ve always had a thing for Maksutov-Cassegrains so my first venture was a little Mak, an Orion Starmax 102, that I picked up used. And it was a great scope. But I realized that a StarMax 90 would deliver most of the performance of the 102 but it would be a couple of inches shorter and a couple of pounds lighter (3.5 vs 5.5, if I remember correctly). So I got a Starmax 90, found it delightful, and sold the 102 (that’s my ad photo above).

The Starmax 90 was my small scope for a long time; it’s the scope I waxed lyrical about in this post. But I also thought that the old orange-tube Celestron Cassegrains looked pretty sweet, and I was entranced by the tank-like build and simple operation of the C90. Same aperture as the Starmax 90, but it was another couple of inches shorter. So I found a used one on Cloudy Nights and sold the Starmax 90.

The C90 has been a very fun little scope. It is even more rugged and versatile than I expected, and it fits in an insulated plastic-lined six-pack cooler, to boot. Nothing like getting an armored scope case for $5.99 at Wal-Mart (the black thing laying over the tube in the photo above is the finder, wrapped in one of the soft cloth bags that come over my wife’s favorite shoes).

But on some level I’ve known for a long time that the C90 would be at best a temporary stop on my quest for the smallest reasonably capable telescope. Because a couple  of years ago when I was surfing Cloudy Nights I discovered the Stellarvue SV50.

As I understand it, the SV50 started life as a high-end finder for larger telescopes, and one version is still sold that way today. I fully support that; one of my first upgrades for Shaft was a 9×50 finder that made star-hopping a lot easier. But people started using the SV50 as a telescope in its own right and it developed quite a following. It is now sold as “The Little Rascal”, a stand-alone spotting scope with a clamshell mounting ring, eyepiece, and in the latest guise, a carrying case.

My SV50 was a present to myself for finishing my summer teaching. I bought it from Oceanside Photo & Telescope on the last possible day that I could have done so and still have had the telescope delivered before I left for Uruguay. I was on the phone for maybe 5 minutes tops and in that time the sales guy (whose name I’ve unfortunately forgotten) answered all of my questions instantly and authoritatively, processed my order with admirable efficiency, and even managed to find me a discount I hadn’t known about. If that’s not good customer service, I don’t know what is.

This is a tiny, tiny scope. The aperture is 50mm, the focal length is 205mm, the magnification with the included 23mm eyepiece is 9x. So you could think of it as one half of a pair of 9×50 binoculars. Except that it’s not.

For one thing, it accepts any eyepiece in the standard 1.25″ barrel size, so you can vary the magnification. And it is really, really well made, as one would expect from StellarVue. There are binoculars out there that are made to equal or better specifications, and there are binos that have interchangeable eyepieces, but they’re out of my price range so they don’t come in to this story. And you can put it on a tripod and look at things directly overhead without breaking your neck.

Also, having had the opportunity to compare the performance of the SV50 with that of my admittedly low-end 50mm binoculars, the image in the SV50 seems brighter.  Possibly because it has fewer internal reflections to steal light from the path, possibly because it’s just a better made instrument, possibly because my binoculars are cheap. Whatever. I’m deliriously happy with the SV50.

The SV50 is 9.5″ long and weighs 1.5 lbs. By comparison, the C90 weighs 3.9 lbs fully loaded (i.e., with diagonal, eyepiece, and finder), and the Starmax 90 weighed 4.6 (the less said about the positively Brobdingnagian Starmax 102, the better). Crucially, this means the scope is light enough to ride comfortably on my little Manfrotto 785 tripod, which only weighs a couple of pounds itself.

And that’s good because the folded tripod is the same length as the scope, so it fits into a roughly equal space. I found a little travel shaving kit at Target that holds the scope, doubly wrapped in bubble wrap; the tripod; three eyepieces; the handle for the alt-az head that goes atop the tripod; my mini red flashlight (a mini Maglite painted over with red nail polish); and a small notebook and pen for recording observations. The only thing that doesn’t fit in the bag is the alt-az head itself, a DwarfStar from Universal Astronomics. Close enough, says me.

By comparison, the ~4 lb C90 and StarMax 90 require the beefier Manfrotto 190CXPRO4, which weighs 3 pounds and folds down to 21″. Which, okay, means you can still get away with scope, accessories, DwarfStar, and tripod for just under 9 lbs. But why settle for 9 when you can have 4.5? More importantly, I have not had the courage to put the bigger (and much more expensive) tripod in my carry-on luggage. For the love of Pete, I use a netbook as my primary computer because I hate carrying heavy stuff through airports. Anything that gives me adequate functionality at half the volume and mass, I will be on in a heartbeat.

For eyepieces I’ve been using the included 23mm eyepiece, yielding 9x; a 10mm Orion Plossl giving 20.5x; and a 6mm Orion Expanse giving 34x. At 9x the SV50 functions as its own finder and requires no other. At 20.5x the scope just gets out of the way and lets me observe. It is honestly one of the most hassle-free setups I’ve ever used. At 34x the optical train is starting to pant a bit. A focal ratio of f/4.1 is hard on eyepieces, especially widefields. The view is still acceptable but focus gets to be very touchy. Fortunately the built-in helical focuser is super-smooth, with no backlash, and is a real joy to use. At the end of the day the three eyepieces get rolled up in a Ziploc bag to fit into the small empty space between the scope and tripod.


So far my SV50 has only seen serious use away from home. In Uruguay I used it to do all of the observations for the Southern Sky Telescopic Club, and this weekend in Big Bear Lake I spent a pleasant hour chasing some Messiers. In fact, I’ve decided to re-observe all of the Messier objects with this scope. I don’t know how long it will take because it will absolutely require dark skies, which I don’t get to as often as I’d like, but I’ll just chip away at it as opportunities present themselves. In any case, I think my quest for the “no excuses telescope” has finally come to a happy end.

I don’t know what I’ll obsess about next, but if you stick around you’ll probably find out. Clear skies!