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sophiecentaur

Scale on reticle of ioptron polariscope.

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Polaris appears to follow a circular path round the celestial pole once a day (24 h ours). Finding a 12 hour 'clock' face, marked on the reticle has left me confused. Whilst I have no problem with mimicking the picture on my iPhone app (apart from the lousy visibility that the red led provides) I cannot see how there are 12 'hours' marked on it and not 24 hours.

HAs anyone else been confused by this or is there a simple explanation?

Edited by sophiecentaur

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almcl    200

Not sure I can express this simply although the explanation is simple but here goes.

The use of a clock face to express the relative position of Polaris is merely a convenient scale, it has nothing to do with the rate of rotation about the pole and could as easily be calibrated in degrees.  The use of a clock face with 60 divisions could be replaced by one with 120 (they might be a bit small in the average polarscope) or even one calibrated in mils, the sole function is to indicate a relative position.

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wxsatuser    3,635

I would go along with that unless anyone knows better.

The clock is 24hours anyway, just double each hour, 1 o'clock then becomes two o'clock and each increment becomes 20minutes instead of 10minutes.

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I can't think what's wrong with degrees as an angular measure. Still, there's probably a history to this and there's no point in changing things that aren't actually wrong. :happy7:

Thanks for the replies.

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GeoC    17

I think it is 12 main divisions because we are used to seeing 12 hour clock faces. I look at the ioptron app to see where Polaris is and easily see this as a 'time' eg 6:30.

That is then used to orientate the polarscope.

The reticle is hard enough to see as it is - if it was in 24 divisions those of us with aging eyes would be in trouble.

 

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