Last updated: 20 February 2004

Polar home position

Date: 2/17/04, 17:35
From: Rick Hudson (
I looked through all of the documentation on your site which pertained
to scope alignment, and while it was tremendously informative and
useful, it still did not answer my fundamental question, shown on the
image attached.

Since I happen to be a graphic designer, I put the ol skills to use and
made this ETX diagram in should be VERY clear, and if
you could please just tell me which of the three (I think its STATE 1)
is the correct Home position for an ETX-125, I would greatly appreciate

Polar HOME position
Image courtesy Rick Hudson,
Thanks in advance. It IS state 1, right? And which align do I use on Autostar? Two-star? Is there a way to TELL Autostar that "My scope is POLAR Aligned" ? That is not in any documentation either Thanks! </RICK>
Mike here: Well, since the Polar Home Position has the telescope "pointed at Polaris" (in the Northern Hemisphere), State 1 is obviously not going to work. And since the eyepiece and finderscope are not too useful in State 2, if you guess that State 3 is the one to use you would be correct. As to the Autostar, set the mounting mode to Polar and then use the alignment mode you are comfortable with.


Indeed, you see, your response assumes that I *already KNOW* what the
"Polar Home Position" IS. But NOWHERE, in ANY documentation, does it
actually *tell* you what the Polar Home Position is. Yes, it says to
"Point the Telescope" toward Polaris, but does that refer to the BASE or
the OTA, or both? That's what I mean. To the novice, the documentation
is insufficient.

So State 3 is the correct Polar Home State, then? And thus it is the
position from which you initialize and align Autostar, then? And I can't
use "Easy Align," since that apparently is only available in Alt.Az
mode. Or at least, I don't know HOW to get to the Polar align mode, and
the docs sure as heck don't help any. Once again, I apologise for my
lack of basic knowledge, but hey. We all gotta start somewhere!
Mike here: When putting the telescope into the Polar home position, don't forget to do the rotation to the RA hardstop and back about 120 degrees, just like when in Alt/Az mode. As to aligning, just follow the prompts on the Autostar; it knows what to do.

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