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Old 13-05-2014, 07:33 PM
Ouija (Tony)
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Question about POLAR ALIGNMENT.

Hi all.
you will have to bare with me on this as i am a n00b to all this.

No1: I heard that if you find the true SOUTH point in the sky ( i did tonight with the help of STELLARIUM ).
this is not the point you set your mount to, you have to go another 11 deg from that point & set your scope to that ?.

No2: The first night i set it up, i did not have south aligned, it was just in the general direction. then i went through the 3
star alignment & all went well with that. ( i did have to adjust scope to all 3 objects ) So to me that means ( i am probly wrong )
to me that if you have your 3 star alignment done
, it should not matter if you are perfectly pointing at the south pole or not , ?. But,
i found when i was tracking a few objects, the tracking would deviate after abit of time, so now im thinking the south pole
( + the 11 degrees ) has to be spot on to have the tracking work correctly. anyway, i will leave the answers to you guys/gals as
i am totally nieve when it comes to this machine lol.

thank you very much. .

PS: i have a HEQ5 pro.
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Old 13-05-2014, 08:49 PM
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Geoff45 (Geoff)
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The mount has to point true south, which is about 11 degrees from magnetic south in Sydney. Magnetic south is not true south.

Last edited by Geoff45; 14-05-2014 at 11:59 AM.
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Old 13-05-2014, 09:04 PM
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alocky (Andrew lockwood)
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The difference between true south and magnetic south depends on where you are on the planet. Here in WA it's only 0.5 a degree. You need to look up the magnetic declination for the IGRF - google it and enter your lat and long.
Cheers,
Andrew.
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Old 13-05-2014, 10:10 PM
glend (Glen)
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And make sure your latitude is set up correctly, the Skywatcher gauges are not very accurate so try to use an inclinometer to set the angle. If you have the scope pointed to true south and at your latitude angle you should be very close to the South Celest pole. I don't know if the HEQ has the two adjustment screws for true south alignment on the base like the NEQ does but its a handy way of doing small movements.
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Old 13-05-2014, 10:47 PM
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mithrandir (Andrew)
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You can get your official magnetic variation from Geoscience Australia.

For Geelong it is about 11.384 deg
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Old 14-05-2014, 11:53 AM
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Octane (Humayun)
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There is an iOS app called Declination which will also tell you what it is.

Or, you can switch your iOS Compass app's settings to give you magnetic or true pole.

H
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Old 14-05-2014, 03:01 PM
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mithrandir (Andrew)
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Quote:
Originally Posted by Octane View Post
There is an iOS app called Declination which will also tell you what it is.

Or, you can switch your iOS Compass app's settings to give you magnetic or true pole.
Question is, where do these apps get the values and how often are they updated? Magnetic variation is a continually moving target.
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Old 14-05-2014, 03:05 PM
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Octane (Humayun)
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That's very true, Andrew.

I figure the residual difference could be easily taken care of with careful drift alignment.

H
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Old 14-05-2014, 07:42 PM
gb44 (Glenn)
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Yeah, good polar alignment is worthwhile. Have a look at StarTarg by Andys Shotglass. Its a useful and cheap system I use. With a ccd camera and barlow the process isnt too bad.
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Old 14-05-2014, 08:24 PM
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Geoff45 (Geoff)
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Quote:
Originally Posted by mithrandir View Post
Question is, where do these apps get the values and how often are they updated? Magnetic variation is a continually moving target.
Let's be realistic here. The errors made with the compass reading and setting the mount according to the magnetic variation are going to far exceed the variation in magnetic declination over a year or two.
This is certainly a case of going with "near enough is good enough" and letting drift alignment take care of any errors.
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Old 15-05-2014, 10:19 AM
julianh72 (Julian)
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How to use your smartphone to do a pretty good "quick and dirty" polar alignment on a GEM:

http://www.iceinspace.com.au/forum/s...9&postcount=19
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Old 15-05-2014, 11:05 AM
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^ that's pretty much what I do, as well.

Handy little things!

H
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Old 15-05-2014, 06:29 PM
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When I had an HEQ5 I liked the technique of finding South by looking at the shadow cast by the sun at solar noon (sun crossing the meridian). I put a big line with masking tape on my deck and could set up fairly quickly from night to night. Once the altitude was set properly my tracking was good enough.

Peter
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