FUNCTION chisqr_par, p

; Description: This function is called by the module "plot_light_motion_curve.pro".
;
; Author: Dan Bramich (dan.bramich@hotmail.co.uk)
;
; Dependencies: (i) DanIDL v2.0 (www.danidl.co.uk)
;
; History:
;
;   21/05/2013 - Module created (dmb).


;Declare common data
common data

;Calculate some constants
L = rev2rad((d_ast_hjd/365.25D) + 0.75D, stat, /NO_PAR_CHECK)
p0_use = deg2rad(p[0], stat, /NO_PAR_CHECK)
p1_use = deg2rad(p[1], stat, /NO_PAR_CHECK)
epsilon = deg2rad(23.439281D, stat, /NO_PAR_CHECK)

;Calculate model values
ra_par_fac = ((cos(epsilon)*cos(p0_use)*sin(L)) - (sin(p0_use)*cos(L)))/cos(p1_use)
ra_model = p[0] + ((p[2]/cos(p1_use))*d_ra_dec_hjd) + (p[4]*ra_par_fac)
dec_par_fac = (sin(epsilon)*cos(p1_use)*sin(L)) - (sin(p1_use)*cos(p0_use)*cos(L)) - (cos(epsilon)*sin(p1_use)*sin(p0_use)*sin(L))
dec_model = p[1] + (p[3]*d_ra_dec_hjd) + (p[4]*dec_par_fac)

;Return the chi squared
return, total((((d_ra - ra_model)/d_ra_dec_err)^2) + (((d_dec - dec_model)/d_ra_dec_err)^2), /DOUBLE)

END