Explaining the Geocentric Celestial Reference System

[Matter_Matters]

Hi there guys,

I was wondering does anyone have a layman's explanation of the GCRS as defined in the title. I am confused as to whether this is an inertial or non inertial system. In text modern reference books such as this (chapter 10, section 10.3.2) they define rotating/non rotating geocentric frames which is a contributing factor to my confusion with the GCRS.

Secondly, terminology such as kinematically/dynamically non-rotating with respect to an appropriate barycentre have further led to my confusion about this seemingly trivial to understand reference system.

The equations of motion (defined in the GCRS) as recommended by the IERS technical note 36 (chapter 10) when combined with the Newtonian acceleration due to gravity allow one to derive conserved quantities such as energy and angular momentum. Of course, this would not be possible in a non-inertial frame. However, the modern terminology has me utterly confused.

Any references or explanations are greatly appreciated.

 

[sweet springs]

I am sure your GCRS exists and daily used. We describe the Sun, the Moon, and other natural and artificial celestial bodies are traveling on celestial sphere above us such and such position and speed to much extent of precision we like. Astronomers will give you a right answer. I do not think at all that there is a simple equation of motion like Newton's to describe in GCRS. Newtonian, both inertial and under gravitation, motion in IFR and rotating system both spinning and going around the Sun might consist of GCRS. Thus synthesized system cannot be inertial one. Many technical calculations used to be by hand and now by computer should be carried out.