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A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: Pointer star question
From: Richard B. Langley
Date: 2013 Feb 03, 00:46 -0400
From: Richard B. Langley
Date: 2013 Feb 03, 00:46 -0400
PyEphem, the Python equivalent of XEphem, gave the result as 34:04:12.3. As viewed from Fredericton at 22:00 UTC using a standard atmosphere, PyEphem computed the separation as affected by refraction as 34:02:43.0 with the refraction on Polaris' altitude of 46:37:17.5 being 0:00:53.9 and that on Marek's altitude of 20:47:34.9 being 0:02:30.0. Wolfram Alpha can compute the separation between celestial bodies too: http://www.wolframalpha.com and enter "angular separation between polaris and merak on 2 February 2013 at 22:00 UTC" But the result was a bit off: 34 degrees 4 arc minutes 12.89 arc seconds Differences here (and with USNO-computed values) can be due to different precisions of the J2000 coordinates for the stars and the differences in precision and accuracy of the various algorithms for updating the coordinates to the equator and equinox of date. -- Richard Langley Quoting "Richard B. Langley": > According to the program XEphem, at the moment, the separation is 34°04'12" > -- Richard Langley > > Quoting Mark : > >> Hello all! I've been a lurker for several years now but I've been >> unable to find an exact answer the angular separation between >> polaris and merak, does anyone know what it is? Thanks, Mark. >> ---------------------------------------------------------------- >> NavList message boards and member settings: www.fer3.com/NavList >> Members may optionally receive posts by email. >> To cancel email delivery, send a message to NoMail[at]fer3.com >> ---------------------------------------------------------------- >> >> >> >> >> : http://fer3.com/arc/m2.aspx?i=122230 > > > > ----------------------------------------------------------------------------- > | Richard B. Langley E-mail: lang---ca | > | Geodetic Research Laboratory Web: http://www.unb.ca/GGE/ | > | Dept. of Geodesy and Geomatics Engineering Phone: +1 506 453-5142 | > | University of New Brunswick Fax: +1 506 453-4943 | > | Fredericton, N.B., Canada E3B 5A3 | > | Fredericton? Where's that? See: http://www.fredericton.ca/ | > ----------------------------------------------------------------------------- > > > > > > : http://fer3.com/arc/m2.aspx?i=122237 ----------------------------------------------------------------------------- | Richard B. Langley E-mail: lang@unb.ca | | Geodetic Research Laboratory Web: http://www.unb.ca/GGE/ | | Dept. of Geodesy and Geomatics Engineering Phone: +1 506 453-5142 | | University of New Brunswick Fax: +1 506 453-4943 | | Fredericton, N.B., Canada E3B 5A3 | | Fredericton? Where's that? See: http://www.fredericton.ca/ | -----------------------------------------------------------------------------