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Monstar
29-05-2014, 02:02 PM
..and because I don't seem that good at star hopping,

I've printed and stuck a setting circle for the round part of my SW 130p Dob and will be using a digital spirit level on my phone for degrees alt. To align the base I have marked one of the 3 parts that stick out of the base, but I'm not sure where to align it to. I think I've read on here (maybe another forum) that it's true North as opposed to magnetic north, could someone please confirm if that's correct.

I'm not sure this will be very accurate but it cost nothing and completed in minutes. I'll try it first on Arcturus as that blazes outside from the balcony.

Regulus
29-05-2014, 06:47 PM
Generally south of the equator u use the South Pole - Geographic not Magnetic.
Have a look at Skyeye app. you can blue tack it to a centre line of the scope and type what u want to see and it will provide direction arrows and a circle around the object when your pointing at it. U don't need Polar Alignment to use it, just mark a centre line on your scope.

Monstar
29-05-2014, 08:32 PM
Trevor, I have an iPhone and Skeye is for android. I've tried an app called iPushto but that goes haywire when I bring it near the scope.

I did try a quick go with my setting circles earlier on Jupiter using the alt/az given in Skysafari and although it was aligned very quickly Jupiter was just out of view with 25mm EP. I'll give it a proper go a bit later.

mithrandir
29-05-2014, 09:14 PM
Any device relying on a magnetic compass is not going to work with a steel tube scope. Waving my iPhone around close to the scope to calibrate it doesn't improve things much.

Steffen
30-05-2014, 01:12 AM
No need to use a compass to align the azimuth scale of your Dob. Check your favourite planetarium app for a bright star (or planet) not too high up that crosses the meridian at a convenient time, point the Dob at the object at that particular time and rotate the base to make your azimuth scale show 0 degrees. You can then mark the position of the Dob feet on the ground for future use.

Be sure the planetarium app is set up correctly (location and time zone).

Cheers
Steffen.

Steffen
30-05-2014, 01:28 AM
Or do the opposite: point at Jupiter and make the azimuth scale show the value given by Sky Safari. Apart from the issue that things keep moving while you fiddle with aligning the setting circle (you want to work reasonably fast), this is by definition the most accurate way of setting circle alignment.

Cheers
Steffen.