Declination

[poider]

Ok, I am bamboozled as usual, when doing polar alignment I live in Southern Adelaide my declination is 7.93 degrees. does this mean when pointing my polar alignment finder and holding the i Phone against the side of the mount, I use the basic I phone compass, do I adjust the mount until the compass reads 172.7 degrees or do I point it to 187.93 degrees or does the I phone compass automatically allow for declination?
I have my pavers set out and get pretty close pretty ease but I am going to Uluru in a few months and want to be able to set up quickly in a new place
Please help.

[astro744]

A magnetic declination of +8 deg (east) means that 8 deg is added to true north to get magnetic north. Therefore true north is 8 deg west of magnetic north. When facing to the north, true will be 8 deg to the left of magnetic. Same at the south, true S will be 8 deg to the left of magnetic S.

(I always struggle to remember which is which but I believe I am correct unless what I just read online is not).

At Ayers Rock Airport (YAYE) the magnetic declination is 3.87 deg, about half of that at Adelaide). YAYE is approx. 6km from Uluru.

There are many free compass apps that also give you true bearings. I would rather trust a good oil filled orienteering compass but whichever compass you use keep it away from your mount when taking a bearing to avoid any influence from the mount.

[Startrek]

Central Australia is full of iron ore and your compass not matter how well designed will always be affected by magnetic flux. As soon as you take a compass measurement take the compass away and then redo that measurement again I guarantee the two will be different
The only sure way to align your tripod as close as possible to true south is to use solar noon and a shadow stick.Then set the altitude on your mount to local latitude using a digital inclinometer (eg: Accumaster )
I use it at various locations and get to within a few degrees of the pole, then polar aligning is fairly quick after that.
The sun never fails you , no matter where you are
Initially tried compasses of all types many years ago and gave up ( sold them ) ended up to far away from true south

[astro744]

The Sun method is of course more accurate and preferred but not very useful if traveling and you get to each new location after solar noon or you want to find N/S in the evening.

You can of course use a similar method as for the Sun but using stars. No shadow of course but all you need to know is when a particular star (preferably one low in the north) will be on the central meridian, i.e. culminating at greatest altitude. When a given star is on the CM simply drop a vertical to the horizon and that is the direction of true north. South is then 180 deg. behind you.

A lower star makes it easier to drop a plumb line to the horizon. You can of course do the same in the south and perhaps pick the stars of the southern cross. Note when above the SCP the stars will be culminating and this info is easily obtainable from apps like Stellarium or Sky Safari. (There is a free Sky Safari version).

Plan ahead by setting your new location into an app and seeing what stars are up in the evening. Stellarium is also available free on PC but when travelling you'll likely want an app on a mobile device.

[Merlin66]

I use the Suncalc app:
https://www.suncalc.org/#/-38.1873,144.7089,16/2020.12.04/11:04/1/3
Just enter your position and it give the Sun's position throughout the day.
Check your meridian at noon, is the easiest and best.

[Sunfish]

Probably repeating myself here but a GPS system which uses 3 satellites will give precise cardinal orientation. Any lesser device is a waste of time.

My camera works that way and provides star tracking ( by turning the ccd) as well a very accurate compass based in GPS. Calibration each time you turn it on and waiting for the satellite lock takes a little while but it always delivers octans in scope.

[Renato1]

If you live in Adelaide - latitude 34 deg 55m 44sec south - the declination set on a telescope cannot be 7.93 degrees.
Unless you are all talking about something else here.
Regards,
Renato

[kon1966]

For android users, download solar polar align.
Line up the centre thick line with the circle on the end with a vertical shadow, eg tube or even a can of softdrink on flat level ground. The circle on the end of the line is pointing towards the sun.

The top and bottom of phone is 90 degrees to true south so you can put a beam down and rest 2 of your tripod legs against them. The 2 long sides point to true south.

The thick line with circle is updated every 2 minutes.

Have attached photo as well and can be used antime in the day.

All you need to do now is your elevation.

Regards
Kon