GOTO - what is & isn't possible?

[muttley]

Hello,

I have a SW 200p dob, which I am thrilled with. The one thing I find though, as a beginner, is that it really doesn't 'share well' - by which I mean it is difficult to enthuse my family. Sure, Jupiter & Saturn are fantastic, but as soon as I find an interesting DSO (which can take me some time), it is certainly lost again by the time I go inside to bring my wife out to see it. Strangely enough, she finds standing around in the cold, waiting for me to locate a grey smudge again rather less exciting that I do.

What I think I need (OK, so 'need' is probably a bit strong!) is a GOTO system, so that the faint DSO is still in view by the time she has got her coat on. I know this must be a common question, but what exactly can a GOTO mount do? Ideally I would like the following:

1. Quick setup. No point asking a beginner like me to identify 4 or 5 stars in order to correctly orient the system. Do any systems have auto-setup?

2. The ability to manually slew the OTA round to roughly the right area to save time (I am not renowned for my patience)

3. The ability to use the scope manually when I want to hunt for things myself

I would love to hear from anyone with a GOTO system, as I don't want to spend the money only to find that it takes me an age to setup each time, or just doesn't pinpoint DSOs well enough. I am guessing that it would be possible to retrofit a GOTO system to my dob mount, as Skywatcher offer ready made GOTO dobs.

Any advice very gratefully received. I am starting to realise that this could be a very expensive hobby!

Thanks,

Simon

[breezy]

Not got a dob mate but I do have an auto tracking mount and it works quite well if a few mins are spent making sure it's level etc and it will point where you want it to just by pushing the direction button

[ronin]

In general a goto will do 2 and 3.

The Meade LS6 and LS8 will do 1 but cost is high.

You have to do 1, no real choice, otherwise the scope has no idea where it is so has no idea where to go to. Worst case is set it up pointing South, do align and just say Yes to anything so it thinks the alignment star is centred then it is no use asking it to goto anything in the sky.

Is the intention a complete new scope or a mount to glue the 200P to ?

[Astro_Baby]

Well number 1 isnt that hard. Usually Synscan for instance picks the stars, I actually have no idea which star it wants but its usually the brightest in the sky in the general area where the mount is pointing in its alignment phase......ie the mount is pointing west and its named Capella as the first alignment star, lookng generally west , if you dont know where west is the scope will be pointing more or less that direction after its first slew to its first alignment star ....this is just by way of example. Its alignment star could be anywhere on a real alignment process........anyway where its pointing there is probably only one bright star visible. i have never known Synscan to not pick the brightest one to the eye as its alignment stars Sooooooo its not that hard BUT a Gem type mount is a steep learning curve and judgimg by posts on here some people just arent able to hack it.

The slew speed is pretty fast on something like an HEq5 or EQ6 so it only takes it a minute or so to find an object....2 minutes at maxI reckon...its certainly not long. If you dont have that much patience your probably in the wrong hobby to be honest.

The alternate approach would be a Nexstar which only requires you to line up three bright objects but I always foundnd the Necstar slew speed very slow and quite painful durring the alignment phase. With that said its one of the easier GoTOs yo manage.

Any GoTo though is not a quock fix, they all require you to invest some time leanng to get the best from them. This is especially true of any EQ based system. goTo is not the same as plug and play, it aint like a TV or a DVD player which just works at the press of a buton. Once mastered its the bong though, I can configure an EQ GoTo like my HEQ5 in about 10 minutes inlcuding polar alignment, star alignment takes maybe another 5-10 minutes tops and then I can press a button and dind my targets real quick. The tracking is a boon with two people using a scope and its also a boon not having to worry about keep the target in the EP with contsant bumping the scope.

[muttley]

thanks very much for the quick replies.

I don't mind investing a bit of time in GOTO, if I can spend more time seeing and less time looking! Sometimes finding is the fun part, but not finding really isn't much fun. It would be great to track objects once they are found, and it does sound like a GOTO does do what I I hoped it would. I would want to keep my OTA if possible, as that is plenty good enough for my level. Thanks again.

[RikM]

The Skyliner Flex tube GoTo Dobs http://www.firstlightoptics.com/dobsonians/skywatcher-skyliner-200p-flextube-goto.html do pretty much what you want. You will have to align it, but as Astro_Baby says, it's not that hard. The nice thing about the GoTo Dobs is the dual encoder, which means you can swing it about to more-or-less the right place and then let the motors take over and finish it off for you.

[Astro_Baby]

Good point rik, i tend to think fo GoTo as an EQ based system , or at east

An alt/az system for SCT tpe scopes a la Nextstar but of course yoU can have GoTo Dobs as well or even push to. Never used a push to system so cant comment on that. Maybe a GoTo Dob is the answer which would cut out the learnin curve of an EQ but still give you the advantage of GoTo. Penaps a GoTo Dob user could chime in.

I do understand the GoTo need, the thrill of the hunt is one thing but when you get so few good nights it seems a shame to waste them looking at nothing much. I found GoTo a huge help and it made i serving so much more relaxed.

[muttley]

The Flextube goto looks perfect. I'd better start saving up! Thank you.

[Eastridge]

In the meantime, until you saved up for that: I have been known to take my mobile into the garden with me & tell hubby I will phone 3 rings ( his moby is always with him, but could be on landline) as a "I've found something come and look" signal. That way I don't have to leave the scope and risk loosing the object.

[ollypenrice]

I often show "astronomers' partners" round the sky while the the astronomers look after themselves. (It isn't always the wives and girlfriends who are the non astronomers, either, by the way.) My word of warning would just be this; don't expect faint fuzzies to get wild reactions.... The moon, Saturn, Jupiter, M31, Albireo, M42 and the Pleiades, and then the warmth of the sitting room seems to beckon!

Olly

[stem1989]

In general a goto will do 2 and 3.

The Meade LS6 and LS8 will do 1 but cost is high.

You have to do 1, no real choice, otherwise the scope has no idea where it is so has no idea where to go to. Worst case is set it up pointing South, do align and just say Yes to anything so it thinks the alignment star is centred then it is no use asking it to goto anything in the sky.

Is the intention a complete new scope or a mount to glue the 200P to ?

Couldnt of said it any better... good luck whatever you decide to do.

[CSM]

as I don't want to spend the money only to find that it takes me an age to setup each time, or just doesn't pinpoint DSOs well enough

With GOTO systems such as the NexStar once you have aligned it you can use the Hibernate feature when you finish. This will ensure that when you next start up all you need enter is the time and date. Also, you can do a simple one star align which can sometimes be surprisingly accurate when slewing to new objects, though I think a decent finderscope is really essential - and a knowledge of what you are actually looking for - use Stellarium or something like that.

[JamesM]

Hi Simon, thought I would chip in with my thoughts too. First off, the 'Synscan' system offered on Skywatcher EQ mounts can also be useful in helping you to identify an object as well as provide a guided tour which can be great when the family comes round to be impressed by the resident 'expert'. I think one of the most underrated aspect of Goto is observing when there is some occasional cloud about. Providing there are enough gaps to fulfill the alignment procedure at the start, having Goto can make the difference between actually doing some observing or packing up and going back inside and given our recent weather - I'll take whatever window of opportunity there is! Though not exclusive to Goto systems, I personally find that tracking is something that really is worth having, especially if you're are sharing the view or if you are starting out and have to spend a little longer finding the star formations from which to 'hop' to order to find your chosen object or even when using higher magnifications on planets for example. For anyone with a potential interest in imaging then a Goto is a must, not just for finding objects that can be invisible to the eye but because the electronics open up a whole host of possibilities that can provide better tracking accuracy (autoguiding) and can even help facilitate taking a number of overlapping images that will go towards constructing for example a mosaic of the moon. Lastly some Goto designs provide the electronics to connect with a planetarium program thus providing a more visual interface from which to locate new targets.

Like many things there is a final point to consider. A Goto system has the ability to locate an object for you but the ability to see it, will depend on the scope that you use. Many manufacturers will list in their specifications that their Goto catalogue has thousands of listed objects which of course will be true, but your observing location (light pollution) and aperture of the scope (resolution) will most definitely help reduce that number of objects available quite considerably. What I am trying to say, is that if you can afford Goto and plenty of aperture then it will be a successful marriage but if Goto has to be paid for out of the scope's aperture budget, then I would certainly give it some serious consideration.

James

[sgazer]

The setup I sometimes use with the kids is a Samsung integrating colour CCTV camera, with a zoom lens on an SLT mount, hooked up to a monitor. The camera integrates over 10 seconds and with a fast lens, most larger DSOs are easily and instandly visible on the monitor. Definately beats staring at faint grey smudges for the family and is very easy and quick to setup, particularly hooked up to a laptop, alignment takes just a few minutes.

[Eastridge]

With GOTO systems such as the NexStar once you have aligned it you can use the Hibernate feature when you finish. This will ensure that when you next start up all you need enter is the time and date. Also, you can do a simple one star align which can sometimes be surprisingly accurate when slewing to new objects, though I think a decent finderscope is really essential - and a knowledge of what you are actually looking for - use Stellarium or something like that.

Probably a silly question - To be able to use the Hibernate to remember the settings do you have to place the scope in the same position the next / each time? If not how far away can you be - elsewhere in the same back garden? front of the house? a nearby dark sky site etc.

[muttley]

What I am trying to say, is that if you can afford Goto and plenty of aperture then it will be a successful marriage but if Goto has to be paid for out of the scope's aperture budget, then I would certainly give it some serious consideration.

James

Thanks very much for all the very helpful advice, it is good to hear some well reasoned feedback about GOTO. As a beginner, it seemed as if GOTO was something which was rather sniffed at by the experts, as if it is a shortcut to the 'real astronomy' of star hopping. However, I can see that GOTO certainly does have its place, even for seasoned astronomers. I will aim to replace my 200p dob with the 200p flextube GOTO, so I don't plan to trade aperture for GOTO. Bigger is always better it seems, but for me anything larger than the 200p would just be too big to easily take to the local dark sky site (my garden is cursed by a fringe of rather tall trees, so hopeless for astronomy unless you just want to look straight up). Let's hope I can find a power lead which plugs into the cigarette lighter - that would be very handy.

For me, there are probably no more than a hundred or so sights that are really worth seeing (and possibly far fewer) - the real five star gems. I don't want to just tick off the really faint fuzzies, I would rather keep re-visiting the sights that I find most excitiing. Maybe that will change as I gain more experience, as this does seem to be a hobby that grows & grows (both in terms of time & budget committed). Thanks again.

Simon

[EntropyStar]

Hi,

So dare I say....I'm going to be a voice of dissent here and recommend you don't get a GOTO and instead invest your money on optics (ie aperture or upgrade your EP's). A little over a year ago I was in a similar position to yourself, new into it and unable to decide whether I wanted to invest in a GOTO system or go for decent optics for my first 'proper' scope and I'm so glad I went for optics over the 'initial' convienance of a GOTO system. Judging by what you've said in that you're only really interested in locating approx 100 of the brightest 'big hitter' style objects then I feel it's a little foolhardy to plow the better part of £475 into a 200p Flextube GOTO to get exactly the same view as your current scope. That money would be far better spent (imo) on upgrading your EP's, buying a telrad, and getting yourself well acquainted with star hopping. GOTO's are all very well until you can't get them aligned or you run out of power. Also your knowledge won't come on as quickly if you're reliant on something else doing it for you. You seem quite concious in impressing others, how's that going to look when someone asks you 'what's that?' and you have to go off consulting a book/PC etc??

I went for a 250px when I choose a scope and I haven't looked back once, it keeps getting better and with every upgrade in equipment and my knowledge. I borrowed a friends Celestron 4SE a few months back which is a similar price (approx £400) and quite frankly I found it a frustrating and unrewarding experience. I found the views through it were not a patch on my 10" Dob. Plus my 'slew' time to objects is in seconds that you can count on one hand!

Star hopping is easy and isn't the 'old fogey' method that some people think it is. I use the telrad to centre a target star, I then use a widefield EP (ie my 38mm Panaview) and then bring up on Stellarium the view as it is through my Ep and walk my way down a chain of stars until I get to my object. It's dead easy and takes mins once you've got the hang of it. A lot of the objects I've observed I can slew the telescope in their general direction and aim in the rough area with the telrad, 9/10 looking through a widefield EP I can immediately pick out my target.

You make a few points in your OP that i'd like to expand on maybe a say a few things to help you decide what you want

Alignment stars - It's really not the much of stretch to learn at least a couple of bright star's names, if you're unwilling to do that then it doesn't bode well for the rest of your exploration of astronomy!! You say it takes too long for your wife/friends to come out and see what you're viewing, the sky doesn't move that much in 5 mins!! If you loose site of your object and can't get it by nudging the scope on a little then drop down to a lowered power EP until you find it again. You'll soon get a feel for how much the sky moves in a few mins. Also you're the one with the stargazing bug, not your wife/friends etc....it's unrealistic to expect them to be impressed and have the same impetus to see objects like you do. You're fighting an uphill battle with that, don't waste your time!!

If I was in your shoes and I was considering spending £475 to improve my experience I'd buy:

Telrad : £35

70-100 degree widefield 32mm - 38mm EP (these will also help you locate objects) £100-£200

70 -100 degree high magnification EP's 4mm - 9mm £100-£200 each

2x Barlow £50-£100

I wish you all the best in whatever you decide.

[muttley]

You raise an interesting point about alternative upgrades, but in fact I do have some William Optics EPs and a telrad already. It is not that I am unable or unwilling to starhop, simply that there are times when I think GOTO/tracking would be handy. Also, with the dob if I run out of power or can't align it, then I can still use it manually - giving me the best of both worlds.

You will have to excuse my extreme ignorance, but I am not sure of the advantages of a larger aperture. I can see that the larger light-gathering potential would allow you to see fainter objects, but would the view of M42 or the planets through a 10" dob be improved in any way over my 8" dob? I can't see why this would be the case.

Now, if someone could find a way to give me much greater magnification without the need to move to a remote mountainous area with far better seeing, that would be most helpful!!

[EntropyStar]

There are defo advantages to GOTO but I'm a little wary of relying on it, as your knowledge will increase and it becomes second nature to finding your way round better. In the interim period before you potentially take the plunge and splash out on a GOTO mount upgrade for your scope I'd give star hopping another try with your telrad and lowest power EP (what EP's do you have?). Do you use programs such as Stellarium to help navigate around? Do use the telrad plugin? If need help on how to input your telescope specs and EP's into it just shout and I'll happily write you a post how to configure them correctly. The reason I advocate at least getting used to star hopping is that some objects (such as asteroids) don't seem to feature in many beginner spec GOTO system software and you would have to manually search for those types of objects anyway, so you'll be kinda forced into star hopping. Ideally you should be adept at either technique as they're both useful and complimentary to each other.

I think I was in a similar position in regards to finding things myself that you're currently in. Once I got past finding the big easy targets from my annoying light polluted garden I kinda felt a little cheesed off. It's all very well having 1000's of objects to choose from but no good if you can't even find their general area due to a lack of reference stars. I put the scope down for a couple of weeks and found myself scanning through adverts for second hand GOTO mounts, luckily the cost of them delayed me purchasing one and I threw myself into star hopping, a year on from that and I'm glad I held back. I will one day get a GOTO mount such as HEQ-6 but at the mo I have to save for other things. I'll get the mount primarily for tracking purposes and astrophotography, and not for finding objects.

In regards to increased aperture, in your case going from say 8" to 10" won't be a huge difference in comparison to other scopes, but the 10" does offer 55% more light gathering capability over the 8"...is it double the viewing pleasure? Doubtful.....but it does mean that fainter objects are more visible and general resolution of existing objects is better. I did a comparison with my friends 4SE (4" mirror) to my 250px (10") on the star cluster M37. I counted 36 resolved stars in the 4SE and gave up counting at 80 stars via the 250px. Okay so it's a larger increase in aperture than what we're discussing but it's worth considering. The view of say M42 would be better through a 10" Dob over an 8" Dob but it wouldn't be as big jump as the above comparison I did. It's not just the fainter objects becoming more visible, it's also the resolution increases when you magnify the object. I'm not experienced enough to give a direct comparsion of an 8" to a 10" but I'm sure someone will be along soon who could expand on that better. There's no doubt that the 'maths' indicate a better view but if the upgrade from an 8" to10" is worth it then that'll be a subjective opinion based on the cost.

[RikM]

8" to 10" is an improvement but not a huge one. To get an immediately noticeable improvement, you would generally want to go up by at least 4", so 8" to 12" would be the 'normal' route.