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I am reading Roobert Hooke's paper An attempt to prove the motion of the earth from observations (1674, faksimile). Hooke writes

The principal dayes of doing which will be about the 4 of April, when our Zenith passeth by the said Star at midnight

The said star is Gamma Draconis, and the observations are made in London. As far as I see it, the star is closest to the Zenit at 6 in the morning in London at April 4th.

So, why does Hooke say at midnight? Is this an expression of the 17th century?

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    $\begingroup$ That would be April 4th on the Julian Calendar, should be about the 15th April Gregorian. But Gamma Draconis is at the zenith at midnight around 21st June in London. $\endgroup$ Jan 19 '15 at 9:50
  • $\begingroup$ Isn't it eta Ursa Majoris? $\endgroup$ Feb 12 '15 at 16:24
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I read this as "Benenaim" (another name for Alkaid) too (not Etamin, which is another name for Gamma Draconis), and that star does indeed transit the meridian near midnight on April 4th (12:44am to be more precise). Note that the hour angle is 0 in the Stellarium screenshot below, and the star is only 35 minutes from the zenith position:

enter image description here

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One of us has misread the paper because I think he says he plans to use "Benanaim" which seems to be an alternative name for Alkaid, $\eta$ Ursae Majoris and very much "ultima cauda ursae majoris" and which would, indeed, transit the meridian at around 9pm on that date.

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  • $\begingroup$ Did you mean to say midnight? $\endgroup$
    – user21
    Sep 23 '15 at 1:31

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