Poor polar alignment + 3 star calibration + time

[Garbz (Chris)]

With all these cloudy skies about all I can do at the moment is think about using my telescope which has led me to an interesting thought and quite possibly a realisation that I may have been doing things wrong and making matters worse rather than better....

My polar alignment isn't spot on, it's good, but not spot on. Definitely good enough to get a decent guided session going without visible field rotation over a few minutes, so I'm not really having a problem imaging (except for the aforementioned crappy clouds).

What I was thinking is if you do the following:

1. Setup telescope
2. Don't 100% accurately polar align
3. Do a 3 star alignment.
4. Go to dinner, read a manual, try find something interesting in a star atlas, etc. Something that takes more than just a minute.
5. Slew to somewhere else, and .... you can't find your star.
6. Find your star and add it as another alignment star in EQMOD.

Now. Is the model of my sky distorted? I ask because I've had this issue recently which resulted in me not being able to accurately slew to any of the objects I was looking for even if they were part of the original 3 star alignment.



Does this make sense? If my polar alignment isn't spot on I should basically leave no time between doing a 3-star alignment and slewing to my target if I hope to find it right? Obviously the correct answer is to do a proper drift alignment before I do anything fancy, but my train of thought is correct isn't it?

[ZeroID (Brent)]

I would have thought that doing an alignment then leaving the mount 'tracking' at sidereal rate ( pointed at nothing in particular ) should maintain the sky model. Theoretically it would be left pointing at the last star in the alignment process and as long as you completed it it should still be there, minor drift and misalignment excepted of course.

[Garbz (Chris)]

Yes that is what I'm talking about. Not having 100% accurate drift alignment.

So you do your alignment, but your sky model drifts away a bit. Then you come back later and add another alignment star and all of a sudden what happens to your sky model?