Procedure: rbsp_gse2mgse Purpose: Transforms from GSE to MGSE (modified GSE coord..defined below) If W gse is the spin axis unit vector in GSE coordinates, then (1) Ymgse = -(Wgse x Zgse) So Ymgse is now in the spin plane and in the ecliptic plane and duskward. (nearly same as Ygse) (2) Zmgse = (Wgse x Ymgse) So Z mgse points in the spin plane nearly along the positive normal to the ecliptic (3) Xmgse= Ymgse x Zmgse This actually the spin axis of the spacecraft X mgse= W gse One of the properties of this coordinate system is that if the spin axis points towards the sun, then the MGSE system is exactly the same as the GSE system. This is a real advantage when thinking about the data and comparing to other instruments. Second, since on RBSP the spin axis has a large angle relative to the z GSE axis the cross product in equation 1 is well defined. None of the cross products involve nearly parallel vectors- nothing is ever close to degenerate. Input : tname = the tplot variable with data in GSE coord [n,3] wgse = the w-antenna direction in GSE coord. This can either be a [3] element array or an [n,3] element array. newname = name for output tplot variable. If not set then new name is old name + '_mgse' Example: rbsp_gse2mgse,'mag_gse',[1,0,0],/nochange Written by Aaron Breneman, Oct 31, 2012 2013-10-02 -> added a check to make sure the WGSE array is the correct size. Returns if it isn't.