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Re: Polaris SHA
From: Paul Hirose
Date: 2008 Sep 20, 19:24 -0700
From: Paul Hirose
Date: 2008 Sep 20, 19:24 -0700
Here is a table of the SHA of Polaris on the first day of each month in 2008. The values are for 0 hours Terrestrial Time (= Terrestrial Dynamical Time = Ephemeris Time). This time scale is ahead of UT1 by a value called delta T, currently about 65 seconds. The left column is the month. The first SHA column includes precession and nutation but not aberration. There's a continuous decrease amounting to 22' during the year. The center SHA column includes aberration but not precession and nutation. It shows a periodic variation through a range of 53'. The last column includes all effects. The total variation is more than one degree during the year. Polaris coordinates for 2008 01 319°46.3' 319°31.5' 319°31.5' 02 319°44.5' 319°45.5' 319°43.7' 03 319°43.4' 319°58.7' 319°55.8' 04 319°42.0' 320°09.0' 320°04.8' 05 319°40.2' 320°12.7' 320°06.7' 06 319°37.7' 320°09.5' 320°01.0' 07 319°35.1' 320°00.5' 319°49.5' 08 319°33.3' 319°47.7' 319°34.8' 09 319°32.4' 319°34.3' 319°20.4' 10 319°31.2' 319°24.1' 319°09.0' 11 319°29.0' 319°19.4' 319°02.0' 12 319°26.3' 319°22.1' 319°01.9' 01 319°23.9' 319°31.8' 319°09.2' What about parallax and proper motion? They're included in all columns but don't have their own column because at .1' resolution the monthly SHA values are identical. Basis of the tabulation: star coordinates, parallax, and proper motion from the Hipparcos catalog. Transformation to apparent coordinates of date via The Astronomical Almanac rigorous method. IAU 2006 precession, IAU 2000A nutation. -- I block messages that contain attachments or HTML. --~--~---------~--~----~------------~-------~--~----~ Navigation List archive: www.fer3.com/arc To post, email NavList@fer3.com To , email NavList-@fer3.com -~----------~----~----~----~------~----~------~--~---