mirror of
https://github.com/cds-astro/aladin-lite.git
synced 2026-01-10 20:26:00 -08:00
53 lines
1.9 KiB
JavaScript
53 lines
1.9 KiB
JavaScript
CooConversion = {};
|
|
|
|
CooConversion.GALACTIC_TO_J2000 = [
|
|
-0.0548755604024359, 0.4941094279435681, -0.8676661489811610,
|
|
-0.8734370902479237, -0.4448296299195045, -0.1980763734646737,
|
|
-0.4838350155267381, 0.7469822444763707, 0.4559837762325372 ];
|
|
|
|
CooConversion.J2000_TO_GALACTIC = [
|
|
-0.0548755604024359, -0.873437090247923, -0.4838350155267381,
|
|
0.4941094279435681, -0.4448296299195045, 0.7469822444763707,
|
|
-0.8676661489811610, -0.1980763734646737, 0.4559837762325372 ];
|
|
|
|
// adapted from www.robertmartinayers.org/tools/coordinates.html
|
|
// radec : array of ra, dec in degrees
|
|
// return coo in degrees
|
|
CooConversion.Transform = function( radec, matrix ) // returns a radec array of two elements
|
|
{
|
|
radec[0] = radec[0]*Math.PI/180;
|
|
radec[1] = radec[1]*Math.PI/180;
|
|
var r0 = new Array (
|
|
Math.cos(radec[0]) * Math.cos(radec[1]),
|
|
Math.sin(radec[0]) * Math.cos(radec[1]),
|
|
Math.sin(radec[1]) );
|
|
|
|
var s0 = new Array (
|
|
r0[0]*matrix[0] + r0[1]*matrix[1] + r0[2]*matrix[2],
|
|
r0[0]*matrix[3] + r0[1]*matrix[4] + r0[2]*matrix[5],
|
|
r0[0]*matrix[6] + r0[1]*matrix[7] + r0[2]*matrix[8] );
|
|
|
|
var r = Math.sqrt ( s0[0]*s0[0] + s0[1]*s0[1] + s0[2]*s0[2] );
|
|
|
|
var result = new Array ( 0.0, 0.0 );
|
|
result[1] = Math.asin ( s0[2]/r ); // New dec in range -90.0 -- +90.0
|
|
// or use sin^2 + cos^2 = 1.0
|
|
var cosaa = ( (s0[0]/r) / Math.cos(result[1] ) );
|
|
var sinaa = ( (s0[1]/r) / Math.cos(result[1] ) );
|
|
result[0] = Math.atan2 (sinaa,cosaa);
|
|
if ( result[0] < 0.0 ) result[0] = result[0] + 2*Math.PI;
|
|
|
|
result[0] = result[0]*180/Math.PI;
|
|
result[1] = result[1]*180/Math.PI;
|
|
return result;
|
|
}
|
|
|
|
// coo : array of lon, lat in degrees
|
|
CooConversion.GalacticToJ2000 = function(coo) {
|
|
return CooConversion.Transform(coo, CooConversion.GALACTIC_TO_J2000);
|
|
}
|
|
// coo : array of lon, lat in degrees
|
|
CooConversion.J2000ToGalactic = function(coo) {
|
|
return CooConversion.Transform(coo, CooConversion.J2000_TO_GALACTIC);
|
|
}
|