purchasing a telescope for live aboard

[First Mate]

great

thanks again!

[MarkJ]

We really really want one!

But as Slomotion says... how many times are you going to use it?

We love the idea of setting it up on the beach, inviting the other cruisers around for a few beers and star spotting. But the rest of the month is taking up too much space

[Bash]

...might be Nikon Astronomy Astroluxe binoculars IF 10 x 70. They are both fogproof and waterproof, will be much less scary to transport in the dink through the surf zone, and will take up less space aboard the boat. You'll probably want a good tripod to use with them. If you shop around you should be able to find these binos new for $1,000.

[SV Someday Came]

Originally Posted by MarkJ

We really really want one!

But as Slomotion says... how many times are you going to use it?

We love the idea of setting it up on the beach, inviting the other cruisers around for a few beers and star spotting. But the rest of the month is taking up too much space

I do know what you mean Mark, but one view on a pitch black sky towards the gas clouds and star clusters around the Southern Cross would suck the breath right out of your body. And then as you sought to regain your mental balance and your intellect sought its composure at the silent grandeur you just beheld, that one time would be worth a lifetime of months.

[RBEmerson]

A Meade ETX-90 (or 125, if you're lucky - forget the models smaller than the 90) would fit your requirements. They show up on sites like Astromart (Astronomy News Articles, Classifieds and Telescope Reviews) regularly, add a couple of eyepiece for variety and a good sky guide (365 Starry Nights by Chet Raymo or Turn Left At Orion by Consolmagno and Davis, for example), and you're good to go. I beg to differ with MV on finding nebulae (basically glowing gas clouds) - M42 in Orion is easy to spot without a "light bucket" (large telescope). On a really good night, looking at the "sword" hanging from Orion's belt, the middle of the three stars in the sword is actually a nebula and will appear slightly fuzzy to those with good eyesight or even 7x50 binoculars. You can check this out right now, as Orion's still in the sky at night. Next summer, take a look towards Sagittarus to see all the nebulae in the area and visible in the Milky Way.

The rascals that really need a light bucket are most galaxies and small, faint things in general (small moons, for example). Even then, it's possible to find galaxies such as M81 and M82 in Ursa Major (loosely the Big Dipper, although Ursa Major is more than just those seven stars).

Agreed that a telescope on a boat is going to be pretty frustrating, but ashore... sure, why not? The ETX-90 is solidly built and with the same care you'd give an SLR camera, it should be fine on board. Keep in mind a pair of 7x50 binoculars and a sky guide will keep you going for some time, too.

A caution about solar viewing: it can be done easily and there will be more and more to see as the Sun becomes more active over the next few years. That said, viewing the Sun without observing the safety procautions can lead to serious eye damage or outright blindness. Good solar filters (such as the Baaderfilm filters or Thousand Oaks glass filters) properly handled will do an excellent job. Avoid Herschel wedges and "no name" filters made from mylar balloon material - if things go wrong, it's usually irreversable. 'Nuff said.

Finally, advertising hype can be just that: even many large scopes won't give images that look like those seen with Hubble or the large observatories around the world. Nonetheless, there's plenty to see even with a small scope!

[cubicle_zombie]

I would also strongly suggest some decent binoculars.

I have a 10" reflector and a 6" refractor, but hardly get them out anymore. I disappointingly learned that even with a 10" reflector you'll never see hubble telescope type images. Other than occasionally going to high magnification on Saturn or Jupiter almost everything I look at is wide-field (i.e. low magnification).

And since the 10" reflector weighs about 100 pounds (with tripod) I almost never get it out. However, I do go out about 3-4 times a week using binoculars with 100mm objectives.

Try finding satellites right after sunset using this website Heavens-Above Home Page

[Christian Van H]

I have a 16" computer controlled aluminum dobsonian (homebuilt), and even in that nebulae are hard to come by. At the observatory, people would look thru our 16" S/C and be disappointed that it didn't look like Hubble pics. BTW, there are some great books out there on astronomy and telescope usage...are you familiar with Messier? His list would be a great place to start observing. The Messier List of Objects

[SV Someday Came]

Originally Posted by RBEmerson

I beg to differ with MV on finding nebulae (basically glowing gas clouds) - M42 in Orion is easy to spot without a "light bucket" (large telescope). On a really good night, looking at the "sword" hanging from Orion's belt, the middle of the three stars in the sword is actually a nebula and will appear slightly fuzzy to those with good eyesight or even 7x50 binoculars. You can check this out right now, as Orion's still in the sky at night. Next summer, take a look towards Sagittarus to see all the nebulae in the area and visible in the Milky Way.

The rascals that really need a light bucket are most galaxies and small, faint things in general (small moons, for example). Even then, it's possible to find galaxies such as M81 and M82 in Ursa Major (loosely the Big Dipper, although Ursa Major is more than just those seven stars).

Of course M42 -- Orion Nebula -- is easy to spot without a light bucket. Duh!! It is on Messier's list. It can be seen with the naked eye. Charles Messier made that list in the 1700s of naked eye fuzzies so he would not confuse them with comets. Of course you can see the Orion nebulae without a light bucket. if I hinted otherwise, I was an idiot.

I guess I was not clear, What you need a light bucket for is enough light to see the COLOR. To fire the cones in the retina. With a Televue and averted vision and sitting on top of a mesa in the Southwest and sitting in deadly cold air and being in your 20s or early 30s you MIGHT catch a hint o' green in Orion. Mebbe a hint of yellow with M57 in Lyra. A light bucket and a dark sky and a cold night might give you color and it will start to resolve the galactic arms in M31 (Andromeda Galaxy -- our closest spiral galaxy.

And you are spot on about the caveats of solar viewing. But filters and projection plates have come a long way. Coronado Filters - PST. For heaven's sakes we (humans) can actually see the fricking corona of our own sun for a couple of hundred dollars. Don't scare people off without showing options!!

Michael

[RBEmerson]

Tidying up a few loose ends...

About those "M numbers" - Charles Messier, a French Eighteenth Century astronomer, was interested in comet hunting. His search was distracted by object that seemed to be comets (fuzzy blobs in his telescope's eyepiece) but didn't move like comets, didn't act like comets, and, for all I know, didn't quack like comet. So he made a list of "nebulosities" that could be ignored in later searches. Included in his list of 109 object (or 110 - there's some debate about one object) are galaxies, star clusters, and nebulae. For the truly intrepid observer, there are Messier marathons in March when it's possible to locate all 110 items on the list. The Marathon is an all-night affair and takes skill (knowing where to look when) and luck (a full night of good viewing March is asking for a favor from the odd gods of weather). Oh, yeah, and it's Northern Hemisphere event, only (sorry, readers south of the equator).

In addition to M42, the Orion Nebula, M31, the Andromeda Galaxy is also visible, in a clear dark sky, without any optical aid. In the southern sky, two smaller galactic objects are visible, the Large and Small Magellanic Clouds (no M numbers here - Messier was in France, not Tahiti).

Colors in observing... the eye is really a daylight observing system with limited capabilities once the sun goes down. One saying in observing runs "there's no substitute for aperture" (roughly, the size of the front of the telescope) or "Size counts". The more light we can gather, the better the human eye can see colors. The vivid colors seen in astronomical images are often the result of either large apertures and/or extended exposures (another way to gather in more photons). Which isn't to say the sky is colorless, it's just the most eyes aren't quite up to the job of pulling in enough photons to tickle the part of the retinas that handle color. Even stunning M42, close and bright, is mostly pearly grey in even a large telescope. The good news is stars do have color! And there are lots of binaries in differing colors, making striking images in a telescope.

Solar observing has risks, obvious and not, and they're compounded by the fact that eyes don't give any warning of impending damage. It's irresponsible not to point that out. However, properly done, solar observing is easy and worthwhile. The full discussion of solar observing is outside of the scope of this forum. Magazines such as Astronomy and Sky & Telescope have web sites with pages on solar observing and observing in general.

The PST and other filters are specialized "toys" that definitely enhance observing the sun (there's a lot going on, even when it's quiet). The same is true of CCD cameras and so on. Simply put, astronomy has a supporting industry, certainly not as large as the boat world, but certainly every bit as diverse. Again, their discussion is, I think, outside of the scope of this forum. Head back to the magazines and sites mentioned above. And keep a tight grip on your wallet.

[RBEmerson]

One other good site for sights: Astronomy Picture of the Day - Astronomy Picture of the Day

The images, their discussion, and the links included in the discussion will keep you going for a long time!

[SV Someday Came]

Someday observing the sun -- or suns -- so be aware of the solar wind might be as commonplace as downloading a weather map before setting sail on the ocean.

Solar Sail Update, June 23, 2008 - What We Do | The Planetary Society

If you want a good read about sailing that will be a part of our heritage, read The Lady Who Sailed The Soul," by Cordwainer Smith.

Solar Sails in Science Fiction - What We Do | The Planetary Society

Who is to say how far a forum can go afield to be true to its goals?

Michael

[First Mate]

thanks for all your advice folks.

I'll take my time researching this subject before I plop down the dollars. I suspect there may be some personal preference involved.

Some of these telescopes might be too cumbersome and large for a boat. I'll start window shopping now.

[RBEmerson]

The reason for suggesting the Meade EXT-90 or ETX-125 is they're manageable on a boat. The optics is designed so that the longer light path needed by a refractor (basically, the same telescope type going back to Galileo) is folded into a physically shorter tube. Not too surprisingly, there are some costs for this. Bouncing light off the primary mirror at the back and the secondary mirror at the front (behind the small circle in the middle of the correcting lens at the front of the tube) means slight loss of light and possible aberation in the image. Meade does a darn good job of holding that to a minimum. Past that, all you need is a tripod, that folds up into a manageable bundle (no mirrors here ), and a small box for the spare eye pieces. With their excellent Go To mount (part of the telescope, with a built-in computer pointing the telescope to the right place), small size, and impressive optics, this is probably your best fit. (The ETX-90 is, for comparison sake, a 3" telescope and the 125 is a 5" telescope. The size being discussed is the diameter of the lens at the front of the scope, except for reflectors where it's the size of the tube)

Dobsonian scopes are quite simple telescopes and are amazingly effective but not very good on a boat. John Dobson came up with a simple reflector design that is little more than a tube, two mirrors, and a simple mount at the base of the tube - easy to make and easy to use. Aiming, however, is generally "point and shoot". There are some (more expensive) models that can be collapsed down to a moderate-sized box but Dobs' mirrors aren't well protected (nothing is sealed in the tube). In short, not a good choice for a boat.

Refractors come in a variety of sizes and some aren't too big for a boat. However, in many cases you'll need to package them with a tripod and some sort of mount ranging from the simple "point and shoot" (inexpensive but hard to use when looking for "faint fuzzies" in the sky) to complex German mounts with counter-weights (looking like weights from a barbell set) and maybe with or without Go To pointing. Although not the best choice, a refractor shouldn't be counted out. The optics are simple (lens assembly in the front, lens assembly in the back, no mirrors - but good, color-corrected lenses add to the cost, without them bright objects are rimmed with thin bands of red and blue, not awful but it does subtract from viewing pleasure). You can find the worst of these scopes going for peanuts and breathlessly claiming "800X!!!!" on the box. Avoid them - they're about as useful for hitting at a home run derby as acting as a telescope - not very...

There are also a few small Schimdt-Cassegrain telescopes (Celestron has a 5" that might be of interest) that are OK in a larger boat. The optics are closed (correcting plate in the front and sealed elsewhere) and they mount up on a simple tripod and have Go To mounts, too. I wouldn't rule them out, depending on the size of your boat but even when the 5" Celestron is in its folded up position, it's still not that small. BTW, there is a 4" Celestron with a Go To mount but the savings in size isn't all that much and you lose light gathering compared to the 5" version. Meade's LX-90, an 8" Schmidt-Cassegrain, is an excellent telescope with excellent light gathering and a Go To mount but neither the telescope or the tripod can be called small and light. Celestron also makes an 8" Schmidt-Cassegrain with a Go To mount but it's at least as bulky as the LX-90 and, again, neither it or the tripod are light. Nice scopes on shore but not boat scopes, unfortunately.


For a good comprehensive look at telescope options and astronomy in general, try the The Backyard Astronomer's Guide by Dickinson and Dyer.


Schmidt-Cassegrain... this is a telescope design much like that discussed in connection with the ETX series,which uses a Maksutov design. The biggest difference is the piece of glass up front, a concave lens in the Maksutovs and a nearly flat [but not quite!] plate in the Schmidt-Cassegrain design. Otherwise, both have a pair of mirrors with the larger primary at the back sending light forward to a mirror on the back of the lens/plate and back to the eyepiece. BTW, the 4" Celestron is also a Maksutov design.

[First Mate]

Well, I'm definitely going to " The Backyard Astronomer's Guide by Dickinson and Dyer."
Just so I can understand what every one is telling me in this thread ;=>

Can't wait to buy that telescope.

[RBEmerson]

Sounds like a plan!

BTW, sniff around for local astronomy clubs. There's usually some observing with the meetings, a good way to see some gear and get at least a hint of what can be seen with various scopes. Try the Astronomical League web site for some pointers to clubs.