Re: New member: AP GTO on Parallax mount

Charles Sinsofsky <strfire@...>

OK, hello,
to answer your questions regarding the safe zone, and also I will place
this into the group area so that others may also use the information if they
find it usefull

1) Orion below the horizon, when it really was not.. Well that really
depends on how you set up the internal clock and date and your location
information. Remember the mount will calculate the altitude of an object
based on this information. if an object is relativly close to the horizon,
but visualy it is not, if your internal clock and position information is
not correct then it may very well indicate it is below the horizon.

2) the safe zone, what it refers to is the number of defrees in a giant
circle from the zenith (stright above your head) outword. so a 20 degree
safe zone would mean the scope would refuse to slew into any object at
altitude 90 - 20 (or nothing greater then 70 degrees up). we designed it
this way as not to have a large refractor bump an expensive camera or
eyepiece or ccd into the tripod or pier rob or base for that matter. in
most cases you will not have to set the safe zone. or rightly explained or
refered to as 'exclusion zone' the scope will not enter that area.

One last note, inside the mount itself is more code, above and beyound
that what is in the hand controller, sometimes it is possible depending on
your code base, I do not know what code would be in a paralex 'bought the
a/p goto system' e-prom code base, the hand controller first decides if it
is safe to move to an object, the code there will say 'fine' and send the
mount the ra/dec cords though it is possible that the mount itself will
refuse. this is a safety feature built into the code base in the mount
because not everyone uses the mount with a hand controller. remember the a/p
goto system can be used directly from a p.c. if the given computer program
being used did not check for horizon it could technically inform the mount
to move the scope into the pier...we placed in additional checks for horizon
to compensate for just that type of case. this code has over time been even
more refined, so because of this, I am not sure what level of code would be
in your given gto system, as opposed to the latest and greatest one in a
given a/p gto mount right now.

But I would not worry about it...really..

- Charles Sinsofsky
Author: DigitalSky Voice, and contributor to the A/P mount GTO system.

----- Original Message -----
From: Mike Mah <>
To: <>
Sent: Sunday, March 26, 2000 9:58 AM
Subject: [ap-gto] New member: AP GTO on Parallax mount

Hello everybody,

I've just joined and I find these postings useful and informative. I
hope I can find help for some questions:

I have an AP155 EDFS with piggybacked Tak FSQ106 on a pier mounted
Parallax Series 125 with AP GTO v2.6. I have acquired these recently
and have only used this setup a few times, so that I have more
equipment than experience. I am waiting for an AP1200 mount, to which I
will move the AP155.

With mount level and after proper polar alignment using the Polaris
routine, I have noticed that occasionally objects are indicated as
below the horizon when they are not. For example, last night at about
9:30 pm the Orion Nebula was indicated to be below the horizon when it
was not, and I could goto Betelgeuse. Did I miss something in the
manual on the GTO keypad controller about the horizon?

When I tried to goto M81, I had to stop the slewing as the scope was
going to hit the pier. What angle does the safety zone number (0-20)
refer to? Degrees from the polar axis so that the safety zone is a cone
(or circle on the sky)? Is this then a blind spot that the scope can't


Mike Mah

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