On Tue, 24 Jan 2012 11:04:08 +0000 "Poul-Henning Kamp" <[email protected]> wrote:
> In message <[email protected]>, Attila Kinali > w > rites: > > >All this talk about telling the time using stars or the sun made me wonder > >how did people tell what position their telescopes had back in the days > >before GPS? > > Back then the stars were the coordinate system and the position of > the telescope the unknown, so you did it by observing stars with > documented coordinates with your new telescope and then you set > your clock and calculated your lattitude accordingly. > > Remember: back then longitude and time were as single convolved coordinate. That's what i'm aiming at. Yes, the lattitude can be calculated using angle measurements relative to a known horizontal plane (mercury mirror) or a vertical line (plumb bob). Still not easy to get below an arc minute, but doable. But how do you untangle longitude and time? How do you know that you are looking exactly south (or north)? Attila Kinali -- The trouble with you, Shev, is you don't say anything until you've saved up a whole truckload of damned heavy brick arguments and then you dump them all out and never look at the bleeding body mangled beneath the heap -- Tirin, The Dispossessed, U. Le Guin _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
