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Daytime Polar Alignment

I would like to use my iPhone with SkySafari Plus to help align my mount in daylight, for the eclipse. However, when I put my phone in position, so that the southern pole is lined up with my Telrad circles, it keeps drifting to the left or right. My mount is not running during these tests, so the position, once on the pole, should not move.

Why does it keep drifting?

Peter Ledlie


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    Bill Tschumy

    How much drift are you seeing?  Is it a degree per second?  one degree per 10 seconds?

    The compass/gyro hardware in mobile phone is notoriously inaccurate.  You can expect the compass to be off by several degrees on average and more at times.

    We have looked at our code many, many times and are convinced that the inaccuracies are due to bad data being reported to us.

    You might try rebooting the iPhone as this sometimes clears up strange compass problems.

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    The drift is sometimes one degree per second, and sometimes faster. Once in a while, it will stay put on target. I have come to the same conclusion, that it's the compass/gyro hardware in my iPhone that's to blame. I think as long as I set my mount up with an accurate latitude, and use a couple different compasses to check for north, I should be close enough for the short duration eclipse photos. 

    Thanks for the info on this, and I'll try rebooting to see if that helps out.



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