as2r = !pi / 180.0 / 3600.0
y_ang=fltarr(2,6)
z_ang=fltarr(2,6)
sig_s = 0.07

;       ODB_ACISI_FIDS = 1,5,6,  3,5,6   1,3,5,  1,3,6,  1,4,5,
;       ODB_ACISI_FIDS = 2,4,5,  3,4,5,  1,4,5,  1,5,6,  2,4,6,          !Final Value: Source: Tom Aldcroft CXC
;       ODB_ACISS_FIDS = 2,4,5,  3,4,5,  1,4,5,  1,5,6, 2,4,6,           !Final Value: Source: Tom Aldcroft CXC
;                        3,5,6,  4,5,6,  2,3,4,    
n_set = 12
n_fid = 3

fid_set = [[1,5,6],$
           [3,5,6],$
           [1,3,5],$
           [1,3,6],$
           [1,4,5],$
           [2,4,5],$
           [3,4,5],$
           [2,4,6],$
           [3,5,6],$
           [4,5,6],$
           [2,3,4],$
           [1,2,3]]

y_ang[0,*] = [    940.34,   -755.44,     57.77,   2157.92,  -1808.47,    406.35]
y_ang[1,*] = [    937.58,   -756.64,     54.95,   2157.72,  -1810.42,    403.57]

z_ang[0,*] = [  -1722.91,  -1727.05,  -1856.11,    181.57,    175.11,    818.69]
z_ang[1,*] = [   -829.23,   -835.30,   -962.29,   1070.60,   1068.74,   1712.75]

y_ang = y_ang * as2r
z_ang = z_ang * as2r

det_name = ['ACIS-S', 'ACIS-I']

for i_det = 0,1 do begin
    for i_set = 0, n_set-1 do begin
        xi = y_ang[i_det, fid_set[*,i_set]-1]
        eta = z_ang[i_det, fid_set[*,i_set]-1]
        
        gamma2 = total(xi^2 + eta^2)
        eps2 = (mean(eta))^2 + (mean(xi))^2

        sig_x = sig_s * sqrt(1./n_fid + 0.5 / (gamma2/eps2 - n_fid))
        sig_th= sig_s * sqrt(0.5 / (gamma2 - n_fid*eps2))

        print, det_name[i_det], fid_set[0,i_set], fid_set[1,i_set], fid_set[2,i_set], sig_x, sig_th
    end
end
        
end