Thursday, July 30, 2009

What Can I See With My Telescope Books: #2

In my previous article on this subject I recommended The Night Sky Observers Guide, Vol. 1 and 2 as great books to find out what you can see in the sky with any particular telescope.

Now I'd like to recommend the book I use most for figuring out what I can expect to see through my scope, or somebody else's:

This book doesn't have finder charts, like the other one, but it doesn't suffer for it. the descriptions given of the objects and how they appeared in different telescopes are wonderful. They give you a clear idea of what to expect. The descriptions do use astronomer terminology a bit more heavily than the other books. The terminology is pretty simple to learn for anyone with an interest in astronomy, and there's a guide in the book.

All the constellations are here in one volume. The sky is covered from Polaris down to the sky as far south as it can be seen from Flagstaff, Arizona.

The book is definitely geared more toward the "serious amateur" than the Night Sky Observer's Guide. It doesn't have breakouts of particularly interesting objects, nor does it have illustrations of any objects, except a few special cases. However, this also makes is smaller and lighter, and everything is in one volume. It is far more usable at night under the sky.

It covers telescope sizes from 60mm on up, but the focus is definitely on telescopes 8 inches (200mm) and larger. Though there is good coverage for 6" (150mm) scopes.

Tuesday, July 28, 2009

What Can I See With My Telescope Books

About the most common question I hear from new telescope owners, or those looking at buying a specific model, is "What can I see with this telescope?"

There are some books that are designed to answer just that question. First, there's the Night Sky Observer's Guide, Volume 1 and Volume 2 by Kepple and Sanner.

These books are extremely comprehensive. They have an introduction to each constellation that lists the showpiece objects of that constellation. They list them both as the best deep sky objects and the list the best binocular objects, which often make excellent objects in telescopes of any size. They provide an overall orientation chart for each constellation, and several finder charts for each constellation with individual objects marked relative to the nearby stars.

The range of telescopes covered goes from 60mm (2.4 inches) of aperture on up to 18 inches and beyond. Descriptions of the objects give you an idea of what the object should look like, and how well it will appear in your scope. Many of the objects have drawings and photos to give you an idea of what the object will look like, as well.

My only complaints with these books is that they are heavy, and that the finder charts are often confusing. The orientation of the finder charts varies, the orientation is often different from their parent chart. This gets confusing whenno reference for direction is given with the chart--you have to go from chart to chart, often across several different pages, to get an idea of what the orientation of the small chart is compred to the big one. In the dark with a red flashlight this gets to be a pain. It's better to use the books at home before observing, put the likely sounding objects on a list, then use your favorite star charts to locate them out under the stars.

Volume 1 covers the Autumn and Winter constellations. That is, it covers those constellations that cross the zenith at midnight during northern hemisphere autumn and winter. Volume 2 covers the Spring and Summer stars. Specifically:
Volume 1: Autumn and Winter Constellations:
Andromeda, Aquarius, Aries, Auriga, Camelopardis, Cancer, Canis Major, Canis Minor, Cassiopeia, Cepheus, Cetus, Columba, Eridanus, Fornax, Gemini, Lacerta, Lepus, Lynx, Monoceros, Orion, Pegasus, Perseus, Pisces, Piscis Austrinus, Puppis, Pyxis, Sculptor, Taurus, Triangulum

Volume 2: Spring and Summer Constellations:
Antlia, Aquila, Bootes, Canes Venatici, Capricornus, Centaurus, Coma Berenices, Corona Australis, Corona Borealis, Corvus, Crater, Cygnus, Delphinus, Draco, Equuleus, Hercules, Hydra, Leo, Leo Minor, Libra, Lupus, Lyra, Microscopium, Ophiuschus, Sagitta, Sagittarius, Scorpius, Scutum, Serpens Caput, Serpens Cauda, Sextans, Ursa Major, Ursa Minor, Virgo, Vulpecula

Constellations with particularly attractive or interesting stars have those listed at the start of each constellation's chapter.

There's another book I really like for finding out what I can see that I'll cover in my next posting.

Friday, July 3, 2009

Starting Small

A simple pair of binoculars

While a telescope certainly has a "scientific" panache, a good way to start observing is with a pair of binoculars. Very nice binoculars can be bought very inexpensively these days, pairs that used to cost hundreds of dollars are available at sporting goods stores for under a hundred, often less than $50.

A good starter pair should be useful for things other than astronomy. That way you'll get more use out of them. They don't need to be huge, and they shouldn't be too high of a power of magnification.

Numbers on the Binoculars

The numbers used to describe binoculars are usually written something like "7x35" or "15x60". The first number is the magnification of the binoculars. I recommend a magnification of 7x or 8x, certainly 10x or less unless you're expecting to use them on a tripod all the time. Higher magnifications can't be held steady enough to use hand-held. I have a pair of 20x binos that don't really work when hand-held.

The second number is the size of the area that lets light in at the front of the binoculars, the front lens, in millimeters. So a pair of "7x35" binos has front lenses that are 35mm across. A pair of "8x50" binoculars has front lenses that are 50mm, or just over 2 inches, across. The larger the second number, the more light the binoculars collect. So all else being equal, a pair of 50mm binos would be better for astronomy (where we're looking at dim things_ because they collect more light from what you're looking at than a pair of 35mm.

But, if this number gets too big, the binoculars get larger and heavier. That means they're harder to hold steady, and they're less likely to get packed along when you go somewhere. I have pairs that are 35mm and 60mm, and the 35mm pair get used a lot more often than the 60mm pair just because they're more convenient.

So for starting out, I recommend something from 7x35 at the low end to something like 8x55 at the high end.

Avoid binoculars with "ruby" lenses or coatings. These are good for getting rid of glare in the daylight, but we aren't worried about glare and we want to get all the light we can.

Other than that you can get whatever features you are willing to pay for, but remember that you'll be looking upward--so make sure the binos will stay focused when you do that--and you don't want extra features getting in the way of the basic use of the binos.

Light path through porro prism binoculars

What can I see?

Binoculars can see details on the Moon. You can also see the planets, but you won't see them as disks, just as colored points of light. You can see moons of Jupiter and Saturn. Binoculars are good for looking at globular clusters and star clusters, and you can see several bright nebulas, like the Orion Nebula. A few of the brighter galaxies can also be seen as fuzzy patches in the sky.

Even with a telescope, binoculars make a good adjunct. I use mine to help me find new objects in the sky for my telescope. I'll use the binoculars to get my bearing on where the new object is (when it's something I can't see by directly looking at it with my eyes), before I try to get it in the scope.
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