Polar Allignment in southern hemesphere..

[lloydysun]

Hi,
Please could some let me know how to Polar Align with a Compass in the southern Hemesphere. I was watching one of my friends attempt to polar align with a compass, well he pointed it true south, but then he went 162 EAST of true south (LEFT) for Sutton Forest location, in between Mittagong and Goulburn. Is this the right way or the wrong way?..Thankyou,
Lloydysun.........

[sheeny (Al)]

162 degrees is the magnetic direction of true south if your magnetic declination is -18 degrees. -18 degrees seems a bit big to me. I would've expected -12 degrees (or so) giving a magnetic bearing of true south of 168 degrees.

Magnetic and true south are different obviously, and a compass measures magnetic bearings so you need to know the magnetic declination for your location to convert one to the other.

Al.

[Dennis]

Have a look here and browse the messages.

http://www.iceinspace.com.au/forum/s...ad.php?t=14036

Cheers

Dennis

[hotspur (Chris)]

Ba ha ha ha ha! great names on your piece of kit Dennis,that thread was most interesting and useful and funny!

I hope no one took names seriously,i like the SPAM.but really looks like a most
useful item you have crafted,well done.

If i did'nt have a permanent observatory,-i would make one.

cheers C

[mithrandir (Andrew)]

Originally Posted by sheeny

162 degrees is the magnetic direction of true south if your magnetic declination is -18 degrees. -18 degrees seems a bit big to me. I would've expected -12 degrees (or so) giving a magnetic bearing of true south of 168 degrees.

Magnetic and true south are different obviously, and a compass measures magnetic bearings so you need to know the magnetic declination for your location to convert one to the other.

For reference:

Australian Geomagnetic Reference Field Computation

Sutton Forest (trig station)
Requested: Latitude -34o 36' 00", Longitude 150o 18' 00", Elevation 0 km, Date 2010/03/1
Calculated: Latitude -34.6000o, Longitude +150.3000o, Elevation 0.00 km, Epoch 2010.1616

Magnetic Field Components

D = 12.475 deg

http://www.ga.gov.au/oracle/geomag/agrfform.jsp

[Exfso (Peter)]

Here is my way around it:

http://www.iceinspace.com.au/forum/s...ad.php?t=57919

[marki]

I just use alignmaster - what is a compass anyway .

Mark

[mithrandir (Andrew)]

Originally Posted by Exfso

Here is my way around it:

http://www.iceinspace.com.au/forum/s...ad.php?t=57919

But you still need the local declination. GA have maps for the whole of Oz further down the page on the link I gave. Take one with you on your travels.

[Exfso (Peter)]

Yeah Andrew, that goes without saying. Have looked up SV and for all intents it is 11deg, good enough for me. I have downloaded a chart for Australia which shows this pretty well.

[JimmyH155]

The proper word is variation variation variation:p:p:p:p:p