Name

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      SUNDISK

Purpose

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      Compute solar disk coordinates as seen from anywhere.

Category

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Calling Sequence

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      sundisk,time, elng, elat, hlng, hlat

Inputs

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      time = UT time (JS or date/time string). in
      elng, elat = Ecliptic long,lat of observer (deg). in

Keyword Parameters

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Outputs

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      hlng, hlat = Heliographic long, lat of out
        solar disk center (deg).

Common Blocks

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Notes

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      Notes: example time in js:
        js0=dt_tm_tojs('2005 aug 18 3:13')
      To test find central disk heliographic coordinates
      as viewed from earth using sunjs, which also gives
      also central heliographic as seen from earth:
        sunjs,js0,app_long=elngs,lat0=hlat0,long0=hlng0
      Earth's longitude is 180 deg from sun's longitude:
        elnge = elngs - 180.
      Using sundisk:
        sundisk,js0,elnge,0.,hlng,hlat
      Compare: help,hlat0,hlat,hlng0,hlng

Modification History

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      R. Sterner, 2001 Jan 18
R. Sterner, 2001 Mar 07 --- Made longitude rel to earth.
  Copyright (C) 2001, Johns Hopkins University/Applied Physics Laboratory
  This software may be used, copied, or redistributed as long as it is not
  sold and this copyright notice is reproduced on each copy made. This
  routine is provided as is without any express or implied warranties
  whatsoever. Other limitations apply as described in the file disclaimer.txt.