What makes a good goto?

What do you value in a goto system? How do you want it to work? What
should it do and how should it do it?


Tim
--
I was not a helicopter.

On Fri, 11 Mar 2005 01:06:32 +0000, Tim Auton
wrote:

What do you value in a goto system? How do you want it to work? What
should it do and how should it do it?


Tim

The ability with minimal effort to put the target in the field of
view, consistently. IMO, if when properly set-up it can't put
an object in a 0.5 deg field, it's not a good goto scope.
-Rich

Tim Auton:
What do you value in a goto system? How do you want it to work? What
should it do and how should it do it?

What is your purpose in asking this question? How do you think that
people will answer it? What do *you* think a goto should do?

Davoud

Since the OTA is just a passenger (unless it's really long or heavy) in
most systems, I'll assume your question relates to the performance
characteristics of the goto mount. My experience with goto includes two
extremes -- a Celestron GT80 mount for portable use with a small APO
refractor, and a Paramount ME on a permanent pier. I also frequently use
a Tak EM-10 GEM without any goto capability because it's portable enough
to take in the field and can handle heavy OTAs at higher magnifications.
That said, IMO there is no ideal or perfect goto system, and each has
strengths and weaknesses. Here's my list of characteristics in order of
importance:

1) Reliability, over temperature extremes, loads, voltages, etc.
2) System stability, no run aways, lock ups, unexpected weirdness
3) Pointing accuracy - what's the use of a goto if it can't "go to"?
4) Mechanical stability and load rating
5) Easy interface to PCs and autoguiders
6) Service and repair parts, are they available?
7) Working PEC for longer and/or unguided imaging
8) Retains alignment between sessions (permanent pier only)
9) Slew rates over 5 deg/sec are nice to have
10) Provisions for cables and 3rd-party accessories

I'm sure others will see different priorities, especially in portable
systems.



Tim Auton wrote:

What do you value in a goto system? How do you want it to work? What
should it do and how should it do it?


Tim

Tim Auton wrote:
What do you value in a goto system? How do you want it to work? What
should it do and how should it do it?

Here are some commonly listed criteria:

1. It should point accurately. (Duh.)
2. It should be reasonably quiet.
3. It should be reasonably fast.
4. It should not exhibit significant backlash.
5. In slewing from point to point, it shouldn't tangle the cords.
6. Selecting an object to GOTO should be straightforward.

Brian Tung
The Astronomy Corner at http://astro.isi.edu/
Unofficial C5+ Home Page at http://astro.isi.edu/c5plus/
The PleiadAtlas Home Page at http://astro.isi.edu/pleiadatlas/
My Own Personal FAQ (SAA) at http://astro.isi.edu/reference/faq.txt

It should break early and often, forcing you to "GOTO" your star
charts, learn how to use a finder and get familiar with the sky.

Mark


Tim Auton wrote:
What do you value in a goto system? How do you want it to work? What
should it do and how should it do it?


Tim
--
I was not a helicopter.

Tim Auton wrote:
What do you value in a goto system? How do you want it to work? What
should it do and how should it do it?


Tim
--
I was not a helicopter.

Hi Folks:

I may be wrong, but this sounds suspiciously like some of the weird
semi-on-topic spam/trolls that seem to floating around Usenet lately.

If this is a genuine inquiry, my apologize to the poster.

Peace,
Rod Mollise
Author of:_Choosing and Using a Schmidt Cassegrain Telescope_
http://members.aol.com/RMOLLISE/index.html

It should go to.

--

-----

"Tim Auton" wrote in message
...
What do you value in a goto system? How do you want it to work? What
should it do and how should it do it?


Tim
--
I was not a helicopter.

Davoud wrote:
Tim Auton:
What do you value in a goto system? How do you want it to work? What
should it do and how should it do it?

What is your purpose in asking this question? How do you think that
people will answer it? What do *you* think a goto should do?

I'm going to make one. I was hoping an open question might give me
some insight into what people like.

Judging by the responses, everybody just seems to want something which
works, rather than something which works a particular way.


Tim
--
I was not a helicopter.

Tim Auton wrote:

What is your purpose in asking this question? How do you think that
people will answer it? What do *you* think a goto should do?

I'm going to make one. I was hoping an open question might give me
some insight into what people like.


As you develop the 'scope-control code, be aware that the customary
two-star alignment algorithm (for instance, the method described in
"A New Concept in Computer-Aided Telescopes," by Toshimi Taki, from
_S&T_, February 1989, pp. 194-196, and in more detail on his website:
http://www.asahi-net.or.jp/~zs3t-tk/aim/aim.htm) works well, though it
can be modified to allow even better pointing accuracy by invoking a
straightforward mathematical tactic. (The specific idea will be
submitted next month for publication in the _Journal of the British
Astronomical Association_.)

It is conceivable that some commercial manufacturers of Go To 'scopes
or digital setting circles have already implemented the very same
trick. If so, they've kept it a trade secret until now. (Since I'm
not privy to their source code, I honestly don't know if any existing
products take advantage of the idea.) However, if it turns out the
concept hasn't yet been realized, then the good news is, once the
manufacturers become cognizant of it, their existing products can be
made to achieve better pointing accuracy with just a firmware update.
In other words, the improved accuracy results without having to expend
additional effort at calibration time, nor must one upgrade to
higher-precision encoders.

--
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Mark Gingrich San Leandro, California