noob questions

bungaro79

hi
i'm thinking about getting a goto telescope but am a bit confused about a couple of things. is goto a mount or is it built into the telescope. if it is just a mount does that mean you've to buy a telescope to put on top of it?! and are they easy to use? can you get co-ordinates online someplace and then just program them in? and last question is for the scope, is aperture the biggest thing i need to consider when buying??
thanks!

ps200306

GOTO is the mount. A complete setup may involve three things -- a tripod/stand, a mount, and a telescope or "optical tube assembly" (OTA). If something is advertised as a GOTO telescope, it will probably include all three, but make sure you check. In a smaller scope, the parts may not be really separable, e.g. this Meade ETX 70. If the mount is an equatorial type, you will generally also need counterweights to balance the OTA.

Generally a GOTO scope will have a built-in database of objects already. You can usually augment this with your own user settings, but since the database may have tens of thousands of objects, there may not be any need to. Aperture is certainly important, but by no means the only consideration. The sturdiness/steadiness of the mount is important for a clear view, especially if doing astrophotography.

Also, the mount type is important. Only an equatorial mount can track the stars properly for long exposure photography. That's because it moves the OTA in polar coordinates -- celestial latitude and longitude (more properly called declination and right ascension). Once the OTA is pointed at your target, the mount only tracks in RA, matching the movement of the stars across the sky. Contrast this with an altazimuth mount (like the aforementioned Meade ETX). This moves the OTA in altitude and azimuth, that is, height above the horizon and angle around the horizon. Because it tracks parallel to the horizon, the field of view will appear to rotate. If you take longer exposures this will cause streaking.



A fork mount is a common type of altazimuth mount. It's less cumbersome and will generally give a less awkward eyepiece position than an EQ. It can be adapted to work as an EQ using a "wedge", which tips it over so that one axis is aligned with the pole, just like an EQ. However, on a big scope this unbalances a lot of weight, and allegedly may cause instability, floppiness or backlash in the mount's worm gears. I have to say, I've used a big 12" Meade LX200 SCT on a fork mount with equatorial wedge for taking and stacking lots of multi-minute exposures, with no apparent problem.

You can Google all these topics for more info.

bungaro79

thanks ps, great info there although a lot of it went over my head!