#1  
Old 09-03-2020, 02:48 PM
Aces High (Mark)
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compass help needed

My yard and surroundings have created a problem for my new Goto HE5Pro mount.

I have two old fashion compass's and a digital compass app on my phone.
My problem is I'm having trouble finding "true South".

The yard where I use my scope is surround by a steel fence, power cables over head etc.

I can move any of the compass around and get ten different readings.
The digital app is set to True south and still it gives different readings.

I'm told there is stick, shadow, midday sun method but not sure where to find a updated link to exactly how to do this. Plus at the moment it is overcast with a threat of rain. LOL

Any help appreciated. I'm in Bankstown, Sydney.
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  #2  
Old 09-03-2020, 03:49 PM
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anj026
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Print the solar noon calendar for your location and then use the stick shadow midday sun to show a line North/South.

http://www.solar-noon.com/
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Old 09-03-2020, 05:06 PM
Malcolm
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If you have an iPhone look for PolarAlignPro, there is a meridian tool that you can use to align the mount. Unfortunately there's nothing like it available for Android, which sucks.
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Old 09-03-2020, 06:30 PM
Startrek (Martin)
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Mark,
Guaranteed method to find true south (accurate to less than a few arc minutes )
Procedure below -

Finding Celestial True South using Solar Noon Meridian method

Items needed
1 metre length of 12mm diameter timber dowel with a 2mm deep 90 deg cross cut into one end using a hacksaw
2 x 3 metre pieces of 1mm string cotton type
4 x weights like a brick or paver etc...
1 x straight edge, alum angle or ruler 500mm long would be good
1 x fine point black permanent marker
1 x 300mm long Stanley or quality boat type builders bubble level
1 x PC with a planetarium software program. Stellarium is a good choice as its free and easy to use
1 x Smartphone like an iPhone

Location
Your observing location ( approximately 1.5 sqm ) or where you will set up your telescope mount should be a reasonably flat and level area with a good view of the sun at around midday ( a paved , tiled or concrete area is preferable) At a remote site you will need to clear the ground and make it reasonably flat or level

Procedure

(Setting up for your Shadow)
Erect timber dowel vertically below your preferred observing tripod position and use the 2 strings to anchors the dowel like tent guy ropes at N,S,E and W using weights to hold it in position. Use your bubble level to ensure dowel is exactly vertical at 90 deg in all directions ( very important ) The hacksaw cuts at the top of the dowel make it easy to adjust the dowel N,S,E or W

Finding Solar Noon Time

(Using your Planetarium like Stellarium )
Start your PC mid morning and open Stellarium. Rotate your cardinal point to the North position and raise view up until you see the Sun
Click on the Sun and then click on the clock , move the time forward or backward to the point where the Suns Alt/Az degrees goes from 359 deg to 0 deg or exactly bisecting the North South meridian line ( refer to top left hand data on screen for Az/ Alt deg )
Record this exact time which is Solar Noon ( hypothetical eg 12.35pm )

(Finding Solar Noon on a Website)
Most meteorological websites show Solar Noon times at or near your observing location

Marking your Celestial True South Line

Go to your observing location 10 minutes before Solar noon with your smartphone , ruler and permanent marker. The dowel should be casting a 12mm wide +500mm long shadow on the surface towards the south
At exactly Solar Noon time mark a thin line on the surface or ground from the central base of the dowel outwards along the exact centre of the shadow for at least 500mm ( be as precise as you can )

This line is marks the Celestial Meridian (True North / South )

Use this line to align your tripod front leg Nto True South and then set up your mount
I found this method far more accurate than any app or compass with magnetic declination

Glad to be of help to you !!

Regards
Martin
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Old 15-04-2020, 10:49 PM
SA_Dolphin_22 (Tony)
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Evening, If you are using a digital camera then a great process is D.A.R.V. or Digital Alignment by Robert Vice. A helpful youtube tutorial is available by Forrest Tanaka. Once you get you head around converting to Southern Hemisphere speak (wasn't that hard at all, just watch the tutorial a couple of times and listen as he tells which way to go for us Southerners) then it is really easy to use and you only have to be approximately pointed to Sth. The alignment process will assist to adjust the mount accordingly. Once done another basic star alignment and you are off and running. Hope it helps , Cheers Tony
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Old 16-04-2020, 02:26 AM
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turbo_pascale (Rob)
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I made a video on this. It's effectively the "stick in the ground" method.

https://youtu.be/LbZkCKXBAx8


Or you can look at the deviation from a magnetic compass here to double check yourself:

https://www.magnetic-declination.com...EY/118140.html

You clicked here:
Latitude: 33 54' 53.5" S
Longitude: 151 1' 13.3" E
BANKSTOWN
Magnetic Declination: +12 36'
Declination is POSITIVE (EAST)
Inclination: 64 24'
Magnetic field strength: 57113.9 nT
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Old 16-04-2020, 01:31 PM
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AstroJunk (Jonathan)
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I had to do this myself a couple of weeks ago whilst building an observatory.

Here's a photo of my approach. I used a camera tripod with a makeshift plumb bob to ensure it was dead center of where the pier is destined to go, I ballanced a tube wrench on top to make it a little more 'pointy' and waited for solar noon (11:52 on that day).

Mark the position, draw a line, simple as that.

A week later I installed the scope and aligned it to the chalk mark on the floor. When I went to do a polar alignment at night I found that I was already within 20 arc second of true
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Old 16-04-2020, 02:28 PM
Startrek (Martin)
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Yep
Solar noon method never fails , simple and reliable
The more care you take doing it , the closer you get to the SCP
When I first started I was advised to use a compass, so I bought an expensive Silva Bush walking compass with magnetic declination and ended up so far off from the SCP compared to the good old solar noon method ( gave the compass away to a friend )
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Old 24-05-2020, 10:53 AM
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Swagman105 (Geoff)
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It is essential to find true south using the solar noon shadow method. Working out true solar noon is however a complex problem involving variations in the earths orbital speed amongst other things. Fortunately there is a website www solar-noon.com that will calculate a full years printable table of solar noon times for your geographical location. To do this you will need to find out your exact geographical coordinates first from a gps or smartphone app.
I used this table to, on three days (not consecutive due to cloudy weather), mark the true south shadow line which I then scribed permanently into my concrete driveway.
If you are able to leave your tripod legs spread and fixed between uses, it is just a matter of placing the front leg precisely on the scribe line and using a straight edge across the back legs and a carpenters square to precisely set the back legs at right angles to the scribe line.
Works every time although I now use a polemaster to refine my precise alignment.
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Old 28-05-2020, 11:00 AM
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jayconnor (Jay)
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i used Martins "startreks" method with the string and stick and got true south easy as!
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