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List:       kstars-devel
Subject:    [Kstars-devel] KDE/kdeedu/kstars/kstars/skyobjects
From:       Alexey Khudyakov <alexey.skladnoy () gmail ! com>
Date:       2010-07-01 16:38:43
Message-ID: 20100701163843.2A57CAC8E2 () svn ! kde ! org
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SVN commit 1145064 by khudyakov:

Use proper formula for calculation of star's proper motion.
Formula below was used which correct for plane

 sqrt(ra^2 + dec^2)

On the sphere another one should be used

 sqrt( (cod(dec)*ra)^2 + dec^2 )

CCMAIL: kstars-devel@kde.org

 M  +2 -1      starobject.cpp  


--- trunk/KDE/kdeedu/kstars/kstars/skyobjects/starobject.cpp #1145063:1145064
@@ -422,7 +422,8 @@
 
 double StarObject::pmMagnitude()
 {
-    return sqrt( pmRA() * pmRA() + pmDec() * pmDec() );
+    double cosDec = dec().cos();
+    return sqrt( cosDec * cosDec * pmRA() * pmRA() + pmDec() * pmDec() );
 }
 
 void StarObject::JITupdate( KStarsData* data )
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