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Description: 
 This attribute
specifies the geodetic altitude of the observer, in metres, relative to the IAU 1976
reference ellipsoid. The basic 
Frame class makes no use of this attribute, but
specialised subclasses of Frame may use it. For instance, the 
SpecFrame, 
SkyFrame and
TimeFrame classes use it. The default value is zero.  
Type: 
Floating point.Applicability 
  Frame  
 All Frames have this attribute.  
  SpecFrame  
 Together with
the 
ObsLon, 
Epoch, 
RefRA and 
RefDec attributes, it defines the Doppler shift introduced
by the observers diurnal motion around the earths axis, which is needed when
converting to or from the topocentric standard of rest. The maximum velocity error
which can be caused by an incorrect value is 0.5 km/s. The default value for
the attribute is zero.  
 TimeFrame  
 Together with the ObsLon attribute, it
is used when converting between certain time scales (TDB, TCB, LMST, LAST)  
  Copyright (C) 2021 East Asian Observatory
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 A Library for Handling
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