View Full Version here: : Polar aligning
21-01-2006, 02:33 AM
I'm new to polar aligning as I've just purchased an equatorial wedge for my LX90.
My question is: is it possible to align if Sigma Octans (or whichever star is closest to the pole) is not visible? Or, is it always visible? I tried aligning last night; I set my scope up with one leg of the tripod (behind me) facing north. I set the scope in the "home" position; declination of 90 degrees and RA pointing south. Everything looked to be in good order. However, when I tried aligning using AutoStar's Two Star method, the alignment stars were way off. I slewed in both axes to centre them (Sirius and Canopus). After I thought they were aligned, I got an alignment unsuccessful message. I'm positive this is because I had to slew in both axes a considerable amount.
Also, how do I read the latitude scale? Should my adjustment knobs be smack bang on 33 degrees? If that is not how it is done, then how is the angle to be measured? Do I draw an imaginary horizontal line from the top of the wedge, and then measure an angle of 33 degrees with the plate to the horizontal line?
It's cleared up and I'd dearly love to go out and set up the scope, but it takes too long. I might just do some binocular observing from my balcony.
Hopefully, if Kurnula gets the go ahead tonight, someone may be able to demonstrate to me how to set up my wedge properly and even align!
21-01-2006, 05:13 AM
I had a look in Starry Night Pro.
Of course it's always visible.
I'm such a noob.
But, still need help with the other questions!
21-01-2006, 06:13 AM
OK, after having sat in front of the wedge and looked at the latitude scale (the gradient from 0 to 60 - duh!), and the fact that Sigma Octans is always visible, everything clicks now.
My latitude is 33 degrees 43 minutes south. This is the same angle from a horizontal plane to the south celestial pole. It all makes sense.
I've also taken magnetic declination into account as well.
I think I'm ready to mount equatorially and also align correctly as well.
21-01-2006, 07:02 AM
Good to see that you are mastering the art of polar alignment - well done for persevering! Let us know how you get on because the footprints you leave will no doubt be useful to others faced with the same challenges.
PS - With my German Equatorial Mount (GEM) and its built-in Polar Alignment Scope (PAS) with illuminated reticle, all I do is use a compass (with magnetic offset) to find South, set the altitude scale to 27 deg 30 sec for Brisbane and when I look through the PAS, lo and behold – there is Sigma Octans. Then, it’s a simple case of tweaking the Altitude and Azimuth fine adjustment knobs to centre Sigma Octans in the illuminated reticle.
21-01-2006, 08:47 AM
Humayan, if you haven't already done so, you have tell the LX that it's polar mounted. There's a good explanation of polar aligning and the LX90 at Petes Astronomy site. http://www.users.bigpond.com/lansma/art_sh_polar_alignment.htm
21-01-2006, 10:50 AM
Hi Humayan. Check out a couple of the links at the bottom of the page. There is some useful info in some of them.
Don't trust your alt readings of the wedge, they will only be able to get you in the ball park and it's likely it will be a degree or two out.
Have you managed to find sig Oct with a pair of binocs yet? Maybe go along to a local astronomy night and get someone to show you a couple of short cuts for finding the SCP.
Being an ex-lx200 owner I can understand some of the issues you are having trying to set up with a wedge. As a suggestion, to make life a lot easier when adjusting your Azimuth setting see if you can cut yourself a couple of discs of thin acrylic sheet, or a teflon disc, or some other stiff product that has low friction. The disc/s are to go between the wedge base and the top of the tripod surface as a friction rducing bush. I found it a nightmare at times trying to get the wedge to move smoothly when adjusting the az adjustment.
If you want to get really accurate polar alignment for imaging then drift aligning is going to get you much much closer to polar alignment than by trying to do it visually.
Hope thats been a help
btw I've tried the iteration method of polar aligning with the LX200 and gave up in frustration. But if your interested in looking at other methods its an option. Try googling "polar aligning using iteration" (for a short cut this was the first search result "LX200 Polar Alignment Procedure Iterative Method" http://www.astrocruise.com/polarold.htm )
21-01-2006, 12:00 PM
Thanks for that!
I'll be sure to update the thread when I get a chance to go out for a night of observing again.
Hopefully this cloud cover will go away.
21-01-2006, 12:04 PM
Yes, I've set the mount to polar in AutoStar.
I just think I was going about the whole thing in the wrong fashion. I should have taken the time to understand it and read a little bit of the theory behind it, rather than try to be smart and get it working whilst playing with it! Observing with telescopes isn't like playing with a mobile phone or a DVD player or other hardware. In most cases, you can just play with the item and you'll figure it out. Aligning is one of those things that isn't intuitive at first. But, once you look at a few diagrams, read a little theory and then try to apply it to your application, it starts making sense.
21-01-2006, 12:13 PM
OK, I'll keep that in mind and adjust the altitude to get Sigma Octans somewhere in the middle and then fine tune.
I've never looked that way before, I don't think. I did go out last night with an old pair of Hanimax binoculars, but I didn't look for Sigma Octans. Most definitely tonight, if I can get out, I'll search for it with the binoculars first.
I haven't had that problem with the LX90; it appears to move about quite smoothly. I'll bear that in mind, though. Cheers.
Hopefully, if Kurnula goes ahead tonight, someone can show me how to drift align. I think I understand the method, however.
I read the iterative method on Pete's Astronomy Page. It seems rather long-winded, but it works for him!
21-01-2006, 05:43 PM
fwiw, see atached.. hth. :D L.
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