True North

[Jupiter Martin]

This may sound a stupid question.

Is there away of finding true north when you can't see Polaris.

I would like to set up my goto on my scope but guessing true north actual position is dificult at best. I can roughly Guess it but was wondering if theres another way i could get it spot on.

Any help would be great.

[Whippy]

You could use a compass to get close, but you'd still need to get the latitude right too. You could use drift alignment but for visual observing, it's a long winded way of doing things.

FWIW, you don't have to get it absolutely spot on for the GOTO to work. Close is close enough .

Tony..

[Jupiter Martin]

Thanks Tony yea I have used a compass but that is way out magnetic north is quite some difference. If theres not it won't be a problem I will just have to lean the sky manually instead which is not a bad thing. Just thought there maybe a way around it for my six year old would have like to of done the nights best tour with her than me checking everything to make sure what I am pointing at is right.

[simon84]

I have the same problem as I cant see Polaris because of my roof.

All I did, something I learned in the Scouts, is if you have a watch with an hour hand, during the day point the hour hand towards the sun and then the midway point between the hour hand and the 12 is the north-south line. Then just establish which way the sun rises and sets (rises in the east and sets in the west) and you can now establish true north.

I used this method and was able to track the Pleiades last night for a good hour.

[SteveP]

Martin

For observing purposes and for using your mount's GoTo, polar alignment doesn't have to be precise exactly as Tony says. The GoTo's alignment process should take account of the differences

I can't see Polaris either so what I did was establish magnetic north using a compass and adjusting that for 'true' north which currently in the UK is about 3degrees W of mag north. I borrowed a Wixey angle gauge to establish the correct latitude. In turned out that the Dec gauge on my mount is off by 2-3 degrees and I suspect that is not untypical. I only ever had to set up the correct latitude that once

Later when I started imaging, I established a more precise polar alignment by using drift alignment. At that point I drilled 3 small holes on the patio area which I use for locating the tripod whenever I'm imaging. Now I can do DA in less than 20 mins which is essentially fine tuning of the RA.

Does that help you?

Steve

[Jupiter Martin]

Thanks all I will try all that

[David Galvin]

If you place a stick in the ground, making sure that is truly vertical with a spirit level and then wait until the sun transits the meridian ie due South. The shadow of the stick should point North to South. This could give you a reasonable base line to work to and, besides, its a bit of fun.

[rowan46]

this site has the magnetic declination for your area just follow instructios and add or subtract to your compass settings www.geomag.bgs.ac.uk/uksurvey.html (hope it helps)

[rowan46]

sorry just checked again and it only gives declination form grid north there is a link at the bottom of this page that gives magnetic declination from true north. just google your coordinates from google maps and then enter them to the link at the bottom of this page Geomagnetism - Magnetic declination (Hopefully I have it right this time)