11 replies to this topic

[Karlp295]

I am thinking about testing this out but wondered if anybody has already and what might be a good way to establish when Polar alignment is really dialled in. I guess there is no way like the quality of the stars is there?

 

I ask because I noticed that I left my telescope outside in place and aligned from the night before and yet the second night it said it was only "GOOD" as opposed to "EXCELLENT" the night before and I had to realign it.

 

Is this a can of worms or is there a discussion to be had here about how to test the accuracy of polar alignment in some real way?

[Jim Waters]

This is a 'Can of Worms' discussion.  Pick any PA process with the possible exception of Drift Method and rerun PA you will get different results each time due to many factors...

 

This post is "(No Astrophotography)" so this is this is definitely a Can of Worms.  SharpCap is good enough.  This includes PoleMaster (if you can get the SW to work), iPolar, PHD2, AP ...etc.

Edited by Jim Waters, 22 May 2025 - 01:12 PM.

[MarMax]

Good question but wrong forum. SharpCap is "excellent" for polar alignment, probably the easiest to use method IMO.

[Max Coe]

Why can't a visual astronomer use a camera for polar alignment? I do.

[BrentKnight]

Why can't a visual astronomer use a camera for polar alignment? I do.

Of course you can do that, but it seems a bit excessive.  When I do visual, I basically point the EQ mount north with mark 1 eyeballs - works just fine.

[triplemon]

Why can't a visual astronomer use a camera for polar alignment? I do.

Visual observer are usually a LOT more clever than that. For visual or even goto you won't need any particular accrurate polar alignment, so all that effort of setting up a computer, camera etc, i.e. a full imaging system is way over the top, as mentioned before. And without any further explanation what "good" or "excellent" means in your initial post its hard to tell if you have any real visual issue at all.

 

From my experienc e - its a hallmark of the stereotypical pixel peeper to have a REALLY hard time explaining what he gets or needs or any higher leverl understanding what his numbers or quantities mean. They ask questions completely without context or units like "I get 0.14 - is that enough ?" and your question just sounds very much like that as well. A visual observer would more quantify things like "my goto ends up outside the field of my 7mm ortho".

 

The "good" or "excellent" you are quoting are sharpcap messages that you get while imaging - very unlikely anyone in this forum would ever have even heard of. Try the EAA, beginner deep sky or planetary imaging fori - those folks may use that app and can explain to you with more patience what those messages mean. Its not something you could visually ever tell.

Edited by triplemon, 23 May 2025 - 07:53 PM.

[RetiredDave]

Can one of the mods move this to the EAA or Beginning Astrophotography forums so the OP (who I assume is a beginner) can get some less condescending answers?

[Max Coe]

I can't see polaris from my location because of the trees. But I can do a quick multistar alignment with my camera, which makes me very clever indeed: about ten times more clever than certain other visual observers.

[triplemon]

The very same thing you can also do visually. Visual 2-star alignment is the de-factor standard since DSC or driven alt-az mounts were first made. There are also a number of threads here discussing many other methods do cope with a lack of direct sight of polaris. Some of these work partcilarly fast (or even work in the daytime) for visual only observing when accuracy requirements are low.

 

There is a lot of things one might think are clever until you realize what others do.

Edited by triplemon, 25 May 2025 - 04:50 PM.

[Max Coe]

Yeah. I know about that. Got my first scope in 1962. Not my first rodeo. I was doing Messier marathons before digital imaging chips existed. I now use the the camera because it takes me less than two minutes to get a PA within about 15 arcsec, meaning that my wife, whose vision has degraded over the decades almost to the point of blindness, can look at an object for as long as an hour without having to ask me to recenter it. The same auxiliary scope/camera doubles as a guider when needed. Remember that this is a hobby, and each of us pursues it as we wish. If we do it differently from you, we are not less clever than you. Using a camera as an auxiliary tool is not AP. It's just a tool.

[Buzz999]

I am thinking about testing this out but wondered if anybody has already and what might be a good way to establish when Polar alignment is really dialled in. I guess there is no way like the quality of the stars is there?

 

I ask because I noticed that I left my telescope outside in place and aligned from the night before and yet the second night it said it was only "GOOD" as opposed to "EXCELLENT" the night before and I had to realign it.

 

Is this a can of worms or is there a discussion to be had here about how to test the accuracy of polar alignment in some real way?

You can see how well aligned you are by the accuracy of your guiding. The seeing every night is different and that affects the accuracy of  polar alignment, as does things like expansion contraction, and mount settling. Very good polar alignment can be affected by very small movement. If you have either good or excellent polar alignment and you can guide well you could get away without polar aligning again, but I always redo it when I am using platesolving with sharpcap  or my asi air, because the process is so quick and simple it doesn’t make sense not too. The trick is to accept the vagaries of the seeing that night and get it close enough for the exposure length you are planning  and then  stop.  Focussing on improving the accuracy of an already satisfactory alignment is just cutting into your imaging time.

[triplemon]

If you have a working autoguider, you really don't need to care so much about drift. Even with a full half degree of polar alignment error, worst case drift is 120x less than siderial movement, in the ballpark of what many eq5/6 and similar mounts have in PE. So if your autoguiding can deal with that, polar alignment is good enough.

 

So I second - rather get a few more lights than obsess too long with polar alignment.