Fixing a Star with the use of mounts

No it wasn’t broken… but it would be nice to be able to see it for more than a few seconds… Imagine this conversation:

“Oh wow, man, you have to see this. I found a red star right next to a blue one!”

“Oh let me see! Let me see! … I don’t see anything!”

“Did you touch the telescope?”

“No, man I just looked in the view-thing.”

“Get out of the way… let me see.”


Drifting Away…

Newbies have this problem all the time. If you look due north and find the star at the end of the Little Dipper’s handle, that’s Polaris. The two stars in the pot-end of the Big Dipper point right to it. Since our planet spins in space, all the stars in the sky seem to rotate around Polaris in the Northern Hemisphere in a counter-clockwise direction (clockwise if you happen to be looking south).

Near the celestial North Pole you hardly notice as Polaris describes a little circle every night. If you look at something high in the South through a telescope, you’ll notice it rocketing by at breakneck speed. It has to traverse half the sky, from one horizon to the other in just 12 hours (You do understand that we’re moving beneath it, and it is relatively still, correct?). At the opposite end of our planet it’s a small constellation called Octans that is very difficult to see, and mirroring Polaris’ role in the southern sky is the dim 5th-magnitude sigma Octanis, which lies within a degree of the pole.

Mounts

If you use a mount it can significantly steady your view. We’re not Sea Captains studying far horizons looking for land, so handheld telescopes are fairly useless here. They can be very simple sturdy Altazimuth mounts that just support the mass of your telescope or they can be complex pieces of computerized technology. Most telescopes can accommodate photographic mounts and camera mounts. Let’s look at the differences.

Altazimuth

Figure 1 Altazimuth or Alt-Azimuth Mount or Fork mount

Figure 1 Altazimuth or Alt-Azimuth Mount or Fork mount

Figure 2 Homemade Dobsonian

Figure 2 Homemade Dobsonian

This mount supports your ‘scope and allows it to move it two directions that are at right angles to each other. It can point up and down (the Altitude) or round and round (the Azimuth), hence Alt-Azimuth name. This is fine for low magnification of, say, the Moon, and can actually be an advantage. You can set it on one edge of the lunar disk and let it pass right through your entire view over the course of a minute or two. It’s less convenient if you happen to find that really neat small crater with the eight micro-craters in it that looks like someone drew Charlie Brown’s head a bit lopsided (no I’m not telling you where it is –go look!) At the magnification necessary, you have to constantly adjust to keep it in the view finder. The Altazimuth is basically a point-and-look arrangement. Typically a variation of this is found on most Dobsonian telescopes.

Equatorial (motor drive)

Figure 4 North Latitude type

Figure 4 North Latitude type

Figure 3 World Latitude type

Figure 3 World Latitude type

This mount is a bit more complex. You know the Earth spins and consequently the object you’re looking at is going to move out of your vision constantly. The EQ mount is designed to make the tracking match the star’s apparent motion.

Latitude

Locate the latitude adjustment on your mount which can look like either of the images in Figure 3 or 4. Loosen the lock and tip the mount until the pointer matches your local latitude within a degree or two. Lock it.

Using a bubble level, or a weight on a string make sure the tripod is level by adjusting the leg-lengths of the tripod.

Loosen the clamps securing the telescope tube and slide it back and forth until it is balanced in the clamps. If you add a Barlow or heavy eyepiece the balance will change so you may have to alter this over the course of viewing as things change. Tighten the clamps but leave them loose enough that you can still move the tube when needed.

Figure 5 Scope Weight

Figure 5 Scope Weight

Turn the tube horizontal. Loosen the counterweight for the telescope tube and sliding it back and forth, achieve a balance as in Figure 5. This is basically precautionary for your telescope. The last thing you need is an expensive accident because you overlooked something as simple as making sure it was stable. Lock it in place.

Turn the scope to starting position, tube directly over the mount, weight directly below aligned with both the declination axis (up and down axis) and the right ascension axis (the one with the telescope on one end and the counterweight on the other). Turn the tripod until the rearmost leg points directly south. You’re done. Now when you turn the motor-drive on the telescope will continue to point at the same point in the sky – you won’t have to make any adjustments (except possibly speed on your motor drive if it’s analogue).

GoTo

This is the simplest. You type in the position you want, or in some cases, the actual name of the star, such as 40 Eridani, and the scope finds it all by itself. These guys align themselves with pointer stars and are as close to fully automatic as you can get. In truth I wouldn’t advise it. Heck, I wouldn’t even advise getting a telescope until you’d spent some time with binoculars getting to know the sky. But if you use a GoTo mount and it says “Here’s your star!” how are you going to know if it is right, or out of adjustment? If it’s pointed east claiming to have located Polaris you won’t know unless you learn at least a little bit about where things are…

Tripods

They’re not all created equal, but here’s your best clue. The bigger and more substantial they are, the happier you’re going to be. If you’re going to move a lot, get a slimmer one with less weight (square tube with leg-extender locks). Generally I stay away from round legs with twisty friction-locks. Those are for cameras, not big, heavy valuable telescopes.

Get something you can transport relatively easily unless you’re mounting it permanently in a fixed location. In that case, pour a concrete pad and build a slide-top shed (where the roof can roll away on rails) or an actual dome.

Conclusion

Thinking about getting a telescope? Do it. There’s a whole universe out there waiting to be discovered. And the cool part is, if you find something no one has ever seen before, you get to put your name on it, officially. Who wouldn’t want that?

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