Argo Navis DSC's

[Dave47tuc]

Hi All :D
Today i installed the Argo Navis DSC's on my scope :thumbsup:

After a few small problems all turned out very well :thumbsup:

A few photo's of the set up. But its cloudy and I can't use the scope :doh:

Mind you one has to be very keen as the AN DSC'c cost more than the scope :scared:

[iceman]

Excellent Dave! The AN is one fine piece of kit.. one day i'll upgrade my SkyCommander to a ArgoNavis. It doesn't need anything else upgraded (on my scope), works with existing encoders so just plug it in!

[asimov]

..;)

[ausastronomer]

Dave,

Give it a month and you will think AN is the best 1,000 bucks you ever spent.

CS John B

[elusiver]

it's not fair.. :(

top purchase dave.. the AN is on the wish list on i think almost every dob owner here.. we're all green with envy..

el :)

[Starkler]

Does the altitude encoder release easily for transport?
On my Kendrick supplied kit the alt encoder is held by a thumb/grubscrew and the bracket is held to the base by a magnetic strip

[Starkler]

The price of an argo + dob is still very cheap compared to goto alternatives in this aperture class.

[Dave47tuc]

Hi Geoff,
Yes it does. A small wing nut and bolt used here. Easy to undo for easy transport. :thumbsup:

As for cost yes its a push to scope for around 2k, Meade LX200 10" over 5k :poke:

[p medcraft]

I was one of the first purchasers of the AN a few years ago (and recently sold it to Wavelandscott along with 12" of glass). They are remarkably easy to use once you learn the basics and I found mine to be stunningly accurate. Several other ASV members bought the Argo on the strength of seeing mine perform in the field. Hats off to Gary and his wife at Wildcard.
Read the instructions carefully so that you can take full advantage of the ability to adjust for mount errors, the accuracy climbs even further when you do. Most Dobs including those proffessionally made have minor errors simply because you need to leave some clearance on the bearings, this allows the tube to move laterally during use etc etc.

Paul Medcraft

[Daemon]

THis is going to seem a stupid question guys, but I thought the Argo Navis was a goto computer for hooking up to stepper driven, but non-goto mounts (ie making a tracking mount into a goto mount). What use is it on a Dob? Obviously I'm missing something here :doh:


Daemon

[Starkler]

It turns a dob into a push-to, rather than a goto . The screen tells you which direction and how far to push the dob to find the object one seeks. Almost as good as a goto except you do the pushing :D

[ballaratdragons]

Just like a GPS in a car Daemon. It tells you where to go and when you are there, but you do the driving! :thumbsup:

(Unless they have invented the GoTo car and I wasn't looking lol)

[Daemon]

THanks for that, makes sense to me now. Good idea.


My wife has a goto car, it has a Daemon installed in the driver's seat. Even comes with an added wallet driven auto fuel filler and repair system.

Daemon

[gary]

Hi Daemon,

Gary here from Wildcard Innovations.

This background might be helpful.

Argo Navis can be used both as a "PUSH-TO" system (using what John
Dobson would refer to as 'yoghurt power') or combined with a servo
motor controller such as the ServoCAT.
See http://www.servocat.biz
The two interface together via one of Argo Navis's dual serial ports.

In a PUSH-TO configuration, you simply need to add a pair of optical
encoders to each axes of the scope.

There are Argo Navis installations on everything from small Alt/Az
mounts such as those from Tele Vue and small equatorial mounts
such as EQ-3's, 4's and 5's right up to being installed on some of the
largest Dobs on the planet.

For the GOTO controllers, Argo Navis performs all the object offset
and tracking rate calculations. For an Alt/Az mount like a Dob, which
is tracking in both axes simultaneously, it needs to update the tracking
rate multiple times every second. The nice thing about servo controllers
such as the ServoCAT is that you can still push the scope around manually
if you wish and the Argo Navis will keep tracking of its position via the
encoders.

By the way, servo motors have a lot of advantages over steppers in many telescope
control applications, but that's another topic.

What is impressive is seeing a big Dob, like a 20 or 25" Obsession, being
driven in GOTO mode! A lot of people do a double-take when they see for
the first time a scope that big start moving on its own! :)

Best Regards

Gary Kopff
Wildcard Innovations

[Dave47tuc]

Hi :D

This is the scope ready for a run. :thumbsup:

My first run last night was a non event as I had some settings wrong :doh:

So if the weather is clear tonight I hope to get it right. :prey:

[iceman]

Very nice Dave, you're lucky to be able to put your scope on a levelled concrete paver like that, will definitely help your pointing accuracy with the DSC's.

Unfortunately in my backyard, I need to move to different spots to access different parts of the sky.

[ausastronomer]

Mike,

Argo doesn't need the scope level to work properly. You can have the scope at any angle you like and pointing accuracy is unaffected. One of its many advantages over cheaper systems.

CS-John B

[Starkler]

What John says is right. The alignment process calculates the position of the base in relation to the sky. It doesnt matter what tilt your base is at, the alignment process calculates it and it will remain accurate as long as the base doesnt move. This is where the paver comes in handy.
Away from home in a grassy field, the base can move and rock if the footing isnt solid and give pointing errors.



John, which cheaper systems are affected by this? PalmDSC isnt and I cant imagine any taki algorithm based DSC having a problem here.

[Dave47tuc]

Well after a non event the first night, last night was fantastic. The Argo Navis (AN) DSC’s worked perfectly. :thumbsup:
I spent around 4 hours observing from home. Once I did my initial alignment I had what’s called a warp of 0.1. This is supposed to be very good.

My first object I went to was Jupiter, and there it was in my 12 mm Nagler. Also the same with Venus. One more check to be satisfied, onto M4 spot on!

The biggest reason I purchased the AN system was because I liked the TOUR feature.
So for the next few hours I spent touring around the night sky.
I did a Globular Tour all objects fell in the field of my 12 mm. I put my 31mm
Nagler in and did an Open Cluster tour. This was great. Someone just asked about Naglers. I have the 12 mm & 31 mm these EP’s are just unreal.
I find it to hard to explain to say seeing is believing.

So the AN system was a complete success. I don’t miss my LX200 as much anymore. :P

[ausastronomer]

Dave,

Now that you have it working properly there is a feature called "Auto Adjust On". Check your user manual and see how to enable this feature, it will further refine your pointing accuracy. You can't enable this feature until you have the "Alt Ref Angle" correct but obviously that is now fine as your pointing accuracy is good, so you should now enable it.

Any problems post back here or email Gary Kopff, but I know Gary is going to be away for a few days at Astrofest.

CS-John B

[ving]

:D
sweet

[Dave47tuc]

Thanks John, :thumbsup:
Gary and I have spoken on this and its my next thing to do.
Cheers.

[Daemon]

Gary from Wildcard,


Thanks for the further info, definitely helpful.

Daemon

[Orion]

I sometimes find that I have to realign a couple of hours after the fist alignment depending on how soft the ground is and how heavy the scope is. Re-aligning is no big deal and as said before, a unleveled ground has no affect to the argonavis accuracy.
The servocat and argonavis work perfectly together there's nothing more satisfying than to press a button and watch the scope go to it's target.

[Stu]

How much is the servocat?

I have about 3 grand to spend. I was thinking about a GSO 12" + Argo + servo, is it possible?
If not I'll just have to get the serial communication details off Gary and build the electronis and motors drives myself (I'm an electronic engineer). Probably would be more fun that way but would take up valuable time.

[ausastronomer]

Stu,

The 12" premium dob is going to cost you about $1100/1200 and its worth the extra over the basic model. Argo Navis with all the encoders and mounting hardware about $1,000 and the servocat junior which should be fine for a 12" dob about $1,600, so not quite within your budget but close.

CS-John B

[Stu]

Thanks for the details. I think the servocat is a bit much so I'll have a go myself first and see what happens. Either that or I'll completely change my mind and buy something different, but at this stage the only thing stopping me getting a dob is getting good shed to roll it into when it's not being used.

[Dave47tuc]

Hi :D
Just a question for anyone who has the AN system maybe John or orion.

I find different alignment stars give me different warp errors :confused:

Stars far apart give bigger warp errors :shrug:

Why is this :help:

Thanks for any information. :D

Mind you once i get a 0.3 warp or similar the AN works super :thumbsup:

[ausastronomer]

Dave,

When you select your alignment stars you need to follow some simple rules, merely selecting stars that are widely spaced isn't necessarily a good option.

The 2 alignment stars need to be:-

1) Make the scope move more than 30 degrees in BOTH axis. Selecting stars that are both at an elevation 60 degrees above the horizon and 180 degrees apart isn't much good.

2) Don't select stars too close to the zenith. Max 80 degrees elevation is good.

3) Don't select stars too close to the horizon. The effects of atmospheric refraction will cause you to get incorrect altitude readings and hence greater pointing inaccuracies.

I have "Auto Adjust On" enabled hence I don't get "warp errors" when I do an alignment, but when I disable Auto Adjust I invariably get warp errors of less than .1.

CS-John B

[Dave47tuc]

Thanks John :thumbsup: that has helped a lot.
I used Arcturus and Hadar and yuk! 1.7 warp.
On what you have said the above was wrong. :doh:
I got a better result with Spica and Rigil Kentaurus.
I will learn what Stars are best and take on your advice. :thumbsup:


I tried the "Auto Adjust on" Not so good, not even close to targets.
I have a bit to learn here :rolleyes:

[ausastronomer]

Dave,

Something doesn't sound quite right to me. Make sure all your grub screws are tight on the encoders. Do you have the encoder mounting kit with the plastic sleeve on the azimuth encoder shaft ? Do a daytime test on a fixed target some distance away. Switch to "mode encoder" and make sure your encoders come back to zero when you re align on the target. There is info in the manual on this. The other thing that you may need to tweak is the "alt ref angle" what do you have this set at ? On my 10" GS dob it needs to be 92.75 deg I would assume your scope would need to be set at a similar angle.You actually calculate this by trial and error, there is also info in the manual on this.

CS-John B

[Dave47tuc]

Thanks again John,
All hardware is fine. I will work on getting it right.
Cheers. :thumbsup:

[gary]

Hi Dave,

Thanks for the post and I hope you have been well.

Firstly, thanks to John B. for the excellent follow-up. Very much
appreciated.

Next, don't forget you can email us at any time for support at anytime
sales@wildcard-innovations.com.au
You can phone us 09:00 - 17:00 Australian Eastern Standard Time
on 02-9457-9049
There is also an Argo Navis User's Group hosted on Yahoo at -
http://groups.yahoo.com/group/argo_navis_dtc/

The reported WARP value is expressed in units of degrees.
It is the difference between the angular separation of the two alignment
stars (as a function of time because of the apparent motion of the sky)
and the angular distance the encoders appeared to move based on your
ALT REF setting.

As John suggests, the first thing to check is always the mechanical
aspects of the setup along with the cabling.

The angular separation of Hadar & Arcturus is about 79 degrees.
The angular separation of Rigel Kent & Spica is about 55 degrees.

When the reported WARP value was larger on the former pair,
it could simply be whatever problem you are experiencing is a function
of angular separation. In other words, the further the two stars are apart,
the more likely the difference between their real separations and what
your scope measures by way of the encoders is a larger numerical value.

You might ask, what type of problems could result in a large WARP value?
As John has noted, mechanical slipping is always the first thing to check.
This is where a daytime encoder test is indispensible.

If the daytime encoder test gives satisfactory results, the next thing
to try is AUTO ADJUST ON (I note you have tried this).
What AUTO ADJUST ON does is assumes that the only error is the setting
of the ALT REF point. It then adjusts this point to give you a non-zero
WARP factor. For mounts largely free of fabrication errors or slippages,
this is exactly what you want to do. However if your mount has some other
problem, then the ALT REF point might become incorrectly adjusted
and will only deteriorate the pointing more.

Therefore next is to consider whether the mount has one or more geometric
fabrication errors or flexures. A quick check of your sets of alignment stars and
a guess that you were performing an alignment not long after sunset
reveals nothing obvious to me. Both pair look as if they have about roughly equal
zenith distance separations from your Victorian location at the early
post-sunset time (this is significant in terms of some mount errors which
I won't go into here in this brief response).

Do you know whether your pointing error worsens as you approach the zenith?
(Please don't use the GUIDE numbers as a estimate of pointing error, since these
have been decomposed into two axes of rotation. Instead it is better to estimate
the pointing error in terms of eypiece FOV's). Rather than reply here, it is always
better to email me at sales@wildcard-innovations.com.au as I will tend to
spot a direct email faster than we can monitor all the forums.

Finally, one further piece of advice is that in the face of most types
of systematic errors, the pointing error will tend to be smallest in the
neighborhood of the two alignment stars. Keep in mind that you can
re-align at anytime. With this in mind, you should select one of the stars
to be in the neighborhood of the region you are about to observe in.
When you move to a new part of the sky, then simply align again.

Hope this is helpful.

Best Regards

Gary Kopff
Managing Director
Wildcard Innovations Pty. Ltd.
20 Kilmory Place, Mount Kuring-Gai
NSW. 2080. Australia
Phone +61-2-9457-9049
Fax +61-2-9457-9593
sales@wildcard-innovations.com.au
http://www.wildcard-innovations.com.au

[Dave47tuc]

Thanks very much Gary for the information.
Reason for asking here and not emailing you as others on this group mite find it interesting, as many people here may buy your product. Which is very good.
Cheers.

[Orion]

All very good advice to be sure.

Dave have you tried aligning it with more than two stars?

From my personal experience using the Argonavis now for some time with my 18inch dob is that I have to remember two things.
The first thing is that I know I have some slight mount errors in my telescope (one being that the Alt bearing is slightly higher than the other) I have fixed the problem mechanically as best I can but it is one thing that I am aware of. I find that aligning with more than two stars works best for me.I set the Align Pick for 2 of 2 stars.

The second is that I need to re-align throughout the night as the telescope settles into the ground.
doing these two thing I find the accuracy quite good.

Sorry for the late response.

[Dave47tuc]

Thanks Ed,
I'm looking into all of the above. Its going to rain soon and for the next few days. I hope to have a good look at it all over next weekend.

Again many thanks to Gary, John and Ed.

[Dave47tuc]

Hi Guy's :D
Last night I got 2 hours observing in before cloud got me. In this time I was able to sort out the "Auto Adjust On"

I set Alt ref angle at +090.000. Then put Auto adjust on. I did the alignments and checked a few objects which were very good I mite say. Then went to mode encoder checked the angle it read, +090.640. I did this four times with readings of +090.640 which I got twice and one at +090.650. and one at +090.820. Reason for this reading was I aligned to Vega and Altair.

So with that I re set Alt Ref Angle to +090.650. Re aligned, with "Auto Adjust On" and all went perfect until cloud got me. :cloudy:

All objects fell into the field of my new super 15.5 Ep :P

Oh reason it showed so close to +090.000. Is when I got the AN system I levelled the scope with a level at 90Deg. I then put a hard stop on the mount so the scope stopped in this position. This is just something I did. I was pretty close at the angle getting the above readings I think!!

So all sorted and I keep smiling with my Argo Navis. :D

I will keep in mind the advice re alignment Stars :thumbsup:

Thanks again Guy's. :clap:

[ausastronomer]

Sounds like you have it sorted out Dave, Great news.

CS-John B