Quick Argo Navis question

[Chromed]

What exactly does it do?
Does it just hook up to your 'scope and tell you which way to point to get your target sighting like the tool in the Orion XT's?

[peter_4059]

It has encoders on each axis of the telescope mount that measure rotation. It uses these signals to align itself with known bright stars when you set it up each observing session. It then uses these known positions and an internal database of objects in the sky and their coordinates and gives you a digital countdown readout to help you point the scope in the right direction to find the object. It's a bit like goto - you select the object you are interested in from a list and then you mannually move the mount and it tells you when to stop.

[gary]

Gary Kopff here from Wildcard Innovations.

Firstly, thanks to Peter for the follow-up post.

In a nutshell, 'yes', but it does much more and it does many tasks
better than the legacy Digital Setting Circle systems.

In some more detail, you interface a pair of devices known as optical encoders
to each axis of your scope.

These optical encoders in turn are interfaced to Argo Navis via a cable.

When you rotate the mount around one of its axis, it transmits a series of
electrical pulses to the Argo Navis. In this way, Argo Navis can keep track
of where your scope is.

One then aligns Argo Navis by pointing the scope to any two objects you
know, typically a couple of bright stars.

After that alignment process, when the scope moves, Argo Navis then
'knows' where it is pointing in the sky.

The unit has a display, two buttons and a dial. You can then access an
object from its in-built catalog (30,000 objects and you can add your own)
and Argo Navis will then 'guide' you to it. The display shows two numbers which
are the angles by which you move the mount in each axis in order to acquire the
target. The display updates in real-time so as you move the scope, when both
numbers read zero, you look through the eyepiece and there is the object.

Argo Navis also has detailed information about the objects, including what type
of object it is, its magnitude, for example, in the case of a galaxy, what class of
galaxy it is, in the case of objects such as double stars, the brightness of each
star, their separation and position angle and lots, lots more.
With all this information placed at your finger tips you are then in a better position to
appreciate more what it is you are actually observing.

Argo Navis also works in an 'inverse' mode whereby you point to an object
and can ask it what it thinks it is.

You can even tour objects in various ways.

Its primary purpose is to make your observing time more productive and
as we say, "find more stuff".

Since many of us live in towns and cities where the sky is hampered by
light pollution, Argo Navis can help you 'blind point' to objects that might
be difficult to find otherwise.

It operates with a large variety of mounts including equatorial and
Alt/Az and we have encoders and encoder installation kits
for a large range of mounts plus we can provide custom encoder installation
solutions. See http://www.wildcard-innovations.com.au/mnt_hw_describe.html

It also has some highly advanced modes of operation and this is what differentiates
from older devices known as Digital Setting Circles (DSC's). Instead, Argo Navis
is a new class of device we call a Digital Telescope Computer (DTC).
Unlike a DSC, a DTC can analyze and potentially compensate for many of
the common systematic fabrication errors that exist in all mounts that might
otherwise degrade their pointing performance. For example, if the primary axes
of the mount aren't exactly square, it can analyze and potentially compensate for it.

It has a lot of additional features and I would recommend you browse
a copy of the User Manual which you can find here -
http://www.wildcard-innovations.com.au/documentation.html

It can even interface to some third party motor controller systems and then
provide full motorized slew and track.

The unit is extremely popular with thousands of deployments around the world
on all types of scopes, from small refractors to the the largest of Dobs.
See http://www.wildcard-innovations.com.au/images/barbarella1.gif

The nice thing about the unit is that, like a good eyepiece, if you should
progress from one telescope to another, you can often take the Argo Navis
computer and encoders with you. So it doesn't matter if you are just starting
out or are a veteran observer.

Argo Navis is designed and manufactured in Sydney and the Wildcard Innovations
team are active observers ourselves and have been a sponsor of the
IceInSpace AstroCamps and several other star parties over the years :thumbsup:

By the way, there is also an Argo Navis User's Group at -
http://tech.groups.yahoo.com/group/argo_navis_dtc/
so feel free to join.

Best Regards

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

[erick]

I learn new things every day - I hadn't realised the numbers were the angle to the target :rolleyes:

[gary]

Hi Eric,

That's why you subscribe to IceInSpace! :lol:

The GUIDE display numbers are measured in degrees.

Likewise, the WARP factor is also in degrees.

As a further tip -
If you go to SETUP GUIDE MODE, GUIDE DECIMAL and set it to two
decimal places, when the angle becomes less than 1 degree, it breaks
out into a second decimal place of precision in GUIDE MODE.

Best Regards

Gary Kopff
Wildcard Innovations Pty Ltd.

[mark3d]

how sensitive is the system? does it guide your telescope exactly to the target? or do you still need to then find your target e.g. with a wide angle eyepiece? i just dont think of the dob mount as being a particularly precision mounting :)

[gary]

Hi Mark,

Thanks for the post.

The 10,000 step encoders provide an effective resolution of around 2.16 arc minutes
per step on each axis.

All things being equal, if the mount were 'perfect' you could ideally guide
down to close to the resolution of the encoders.

However, as you mention, various fabrication errors within the mount/OTA
can increase your pointing error residuals. For example, there are typically various
systematic geometric, gravitational flexure and eccentric bearing errors that
contribute to degrading the raw pointing performance of the mount.

The good news is that Argo Navis has a built-in feature called the Telescope
Pointing Analysis System (TPAS). It is a very sophisticated piece of software
that can analyse and potentially compensate for many of these classical
systematic fabrication errors.

What's more, it reports the results to you in real statistical terms. For example,
it will provide you with the Root Mean Square (RMS) pointing performance of
the mount both before and after corrections have been applied.

Anecdotally, on mount such as your LightBridge 10", you might achieve
a corrected pointing performance of typically somewhere between
3 arc minutes to 6 arc minutes RMS, whole sky.

3 arc minutes RMS whole sky would mean that approx. 68% of objects would
fall within a diameter of twice that, namely 6 arc minutes. Nearly all objects
would fall within a radius of three times the RMS, or a diameter of 18 arc minutes.

Your mileage may be different.

Last week, a customer in Europe who has an home-built 12" Dob
was initially experiencing large pointing error residuals. He then used
his Argo Navis to sample some star positions and to perform a TPAS
analysis. He then applied a TPAS model, after which his pointing
performance improved dramatically. He wrote -



Given they are made of wood, what might surprise you is that the raw
pointing performance, that is the pointing performance before any TPAS
corrections are applied, of some Dobs is sometimes actually significantly better
than some of the expensive CNC machined equatorial mounts.

Why would this be so? The reason is that a common weak link is the operator
when they don't mount the OTA squarely on a GEM, either because the OTA
is not 'square' in the rings or because the dovetail has not be attached
'squarely'. Fortunately, such an error, referred to as Collimation in Hour Angle,
or CH for short, is easily identified and corrected by TPAS.

On mounts such as machined equatorials, once TPAS corrections are applied,
it is not uncommon to see RMS pointing performance effectively become
encoder resolution limited.

If a mount has a non-systematic error, such as a sudden mirror flop, then
no system can correct it. Such problems are best cured at the source.

There are a large number of customers using Argo Navis on 8", 10" & 12"
generic Dobs, including the LightBridge range and we have encoder installation
kits available for them.

Thanks again for the question.

Best Regards

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

[Chromed]

With the website saying it takes Synta Sky-Watcher Dosbsonians, I assume that means all the Sky-Watcher Dob models?

[gary]

Hi Greg,

Thanks for the post.

Indeed it does!

As the web site (http://www.wildcard-innovations.com.au/kits/pn-dob-sw-hw_describe.html) mentions, "Fits all Sky-Watcher Dobs including solid tube and
Collapsible 'Flex' truss models."

For a recent instantiation of an Argo Navis on a new Sky-Watcher Flex Dob
see this post by 'Dave47tuc' here -
http://www.iceinspace.com.au/forum/showpost.php?p=404398&postcount=112
and here -
http://www.iceinspace.com.au/forum/showpost.php?p=404959&postcount=120

You can find a copy of the installation instructions for the Az axis here -
http://www.wildcard-innovations.com.au/images/synta_az.pdf
and for the Alt axis here -
http://www.wildcard-innovations.com.au/images/synta_alt.pdf

Thanks again for the question.

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

[mark3d]

thanks for the detailed reply Gary. fascinating that once settled down the dob can be more accurate than an GEM - your explanation makes sense!