My Account

New to Astromart?

Register an account...

Need Help?

If you have any questions or experiencing an issue please report to

Go-to or Not To Go-To, That is the question

Posted by Ed Moreno   01/22/2005 12:00AM

Go-to or Not To Go-To, That is the question
The answer? Go-To.

Now a lot of purists will say that people should learn the sky first, or that they are expensive frills, but I disagree completely that Go-To is either expensive, or a frill.

Actually, I get along quite well without Go-To on one of my main mounts, and yet I am a strong advocate of the Go-To mount as the way to go when factoring your telescope purchase.

Here are my justifications for my belief.

First, I am a BIG believer in using at the minimum, an equatorial mount with a Right Ascension (RA) drive. I find that looking at an object for a few minutes unveils more and more fine or faint detail. If I have to manually move a telescope, it disrupts the observation process. At really high powers such as those used in lunar or planetary observing, I find this especially true. It is VERY hard for me to do really good observing with less than a driven mount. That isn’t to say that this is true for everyone, but it is for me. The main reason is that when you move a mount manually, your eye looses focus on the object under observation. It takes a few moments for the eye to re-establish its “Lock-On”. Having this happen repeatedly makes much of the observing time lost to me. Hence, I think it is better to have a telescope that tracks. ALL Go-To telescopes have tracking.

Now once you have used a telescope on a GEM mount with a RA drive, the next thing you might find yourself wanting is a DECLINATION drive. This is particularly nice when you are just exploring an area of sky as a tourist, or trying to hunt out a difficult to locate object such as a double-star. Over my 30 years in astronomy, when I could afford it, after getting a RA motor drive, the NEXT thing I would put on a mount was the DEC drive. Well, guess what – ALL Go-To scopes come with a DEC motor.

Now realize that dual-axis motors for many budget mounts start at between $100 and $200, and for premium mounts like the Japanese mounts, $200 is the STARTING price for motors. Mid-range mounts typically come with RA and DEC drives, though…

Now once you have motors, you start wanting to move around the sky a bit faster than Sidereal speeds. Most GEM mount systems allow for 2x, maybe 4x, and MAYBE 8x the Sidereal rate. Most Go-To scopes have 9 different rates, and move at far higher speeds than the standard GEM mounts. With standard GEM mount RA/DEC motors, you can de-clutch for large jumbs, but when moving maybe from M37 to M38 it is an annoyance.

Now your are cruising with your GEM mount with 8x Sidereal speed in both axis’s. You decide that you really like being able to cruise aimlessly, but because the manual setting circles only work when your scope is exactly polar aligned, you decide to be lazy and add Digital Setting Circles (DSCs) so you don’t have to accurately polar align every time you use your scope. This will allow you find faint objects in your moderately light polluted sky (your charts aren’t helping as much as you would like because you can’t find jump-off stars to hop from) without having to exactly polar align. Tracking will still be close enough, and even if the object drifts from center a bit this will take several minutes and you can use your DEC and RA motors to re-center without ever loosing visual lock on the target. Now several things happen when you add DSCs.. First, the cost goes up REALLY high. You have to add brackets, encoders, and a computer. Figure anywhere from $400 to $1000, depending on the kind of mount, accuracy of the encoders, and the computer.

Of course the advantage to DSCs ISN"T that it makes it possible to locate objects. Good charts and patience make it possible to locate difficult objects even when using a Dob. The REAL advantage of DSCs is that it makes it QUICK to locate objects. Using DSCs, you can hunt down many more objects in a session, and spend more time observing them than you can with charts and patience… THAT to me, is VERY important. I don’t get as much time to observing as I would like, and until the advent of DSCs, my observing sessions were never all that productive. I would spend a lot of time trying to locate objects. Since having my first DSCs 15 years ago, I have always gotten the MAXIMUM out of my sessions. This innovation alone to me ranks as the most important innovation in amateur astronomy in the last 50 years. I could never be without DSCs again. Now it is true that over the years, you will get to know the sky well enough that you will be able to just manually point to them using a zero-power finder on your scope. But there are THOUSANDS of targets out there, and frankly, at my age, I just can’t remember where they all are!!!! I can bring out a list of objects and use the Digital Setting Circles to quickly and efficiently burn through a list of 10 objects in an hour, spending MOST of that time observing those objects, rather than spending 1//3 of that time navigating to them. Hard-core Amateurs say that you will never learn the sky with Go-To, but you sure will spend a lot of time OBSERVING the sky with it… And if you LOVE astronomy, of course you will learn VERY well over your life-time, I promise…

Another issue it the ugly tangle of cables and mechanical un-tidiness that you introduce to the GEM mount. My fully equipped GEM mounts are a jumble of gears, brackets, and cables. My Go-To GEM mount looks sleek by comparison.

Hmmm. Go-To scopes already have digital setting circles and a computer, all in a tidy, integrated package.

Here is my MAIN argument for a Go-To mount – They are CHEAP!!! Today, you can buy a really good Go-To mount for as little as about $700. For that money, you get RA and DEC motors, a variety of slew speeds, DSCs AND the computer, all in a sleek, integrated package!

In fact, unless you are going to be doing really heavy-duty astrophotography, the new computerized GEM mounts look like an absolutely INCREDIBLE VALUE.

Now frankly, I am not necessarily a fan of the Go-To feature itself. With my really big GEM scope, I can manually slew across the sky in a fraction of the time that I can get across the sky with either my Go-To GEM or my big Alt-Az Go-To SCT. But the down sides to that mount are that it is cluttered with cables (my encoders are not gear driven, so at least that part looks clean) and has a very slow electronic slew, and it cost quite a bit to put all the components together. But the DSC and catalogs make it possible to get around the sky faster than with the Go-To scope or by trying to navigate using charts, so the fact that the Go-To basically just adds automatic movement isn’t really all that big a deal to me… It is actually the fact that you get all these other things as part of the deal!

Now what about the difference between an Alt-Az fork mounted SCT and GEM mounted SCT (in many other cases, there isn’t a choice in similar design packages). Well as much as I like my large fork-mounted Go-To SCT, in the smaller ranges (below 10”, I would opt for the GEM. The reasons are that the GEM mount is more flexible and it breaks down into more manageable pieces. You can use it for a wide-field refractor or good APO as well as the SCT. Above 10” and the decision becomes more difficult. The largest SCTs in the fork mounting aren’t really portable, so I suspect that these are being mounted in observatories… But the large GEM mounts are a real handful to handle.

Now again, I am totally a fan of driven mounts and DSCs, so much so that this actually plays a prominent role in my telescope selection. The reason that I own a large Go-To SCT is that it is the most aperture I can manage and transport without buying a truck or SUV, and still enjoy tracking, motor-driven slow-motion and high speed movement, and Digital Setting Circles!!!. So you see, to me, The Go-To is just something that happens to be there based on my REAL needs.

Consider these issues. If you are in the market for telescope, and have decided that you want a scope with a driven mount, then maybe the decision to maybe save up a bit more money and go with a Go-To scope might be easier to make….

For what its worth, I consider the 8" GEM mounted Go-TO SCT to be perhaps the greatest all-around telecope package on the market today. It is hard to find a more versatile and capable combimation in such an exceptionally managable and transporatble package, and even if price is NO factor, I still consider this to be the setup to beat. I own one. Meade and Celestron both make this combination, and the prices are absolutly incredible. Out of all the telescopes I have ever owned (PLENTY)It is my SECOND favorite telescope to use behind my 11" SCT.

As always, I send warm greetings to my Marine Corps Brothers and Sisters in the sands, and to all other military (and contractor personnel)in harm's way in the Mid-East. I can't bring you home, but I can hope for your safety. I HAVE written to my Congressional Representative about your armor though....

My regards
Ed Moreno

Click here for more information about goto mounts. -Ed.