twspeed vel=ccd-velocity den=ccd-density [parameter=value]
twspeed assumes the line of nodes is along the X-axis, the galaxy center and position angle are keywords but not implemented yet?
In the following (x,y) are defined along the major and minor axis
of the galaxy resp., and pspeed will then compute the numerical sums
V(y) = SUM ( vel(x,y) * den(x,y)) / SUM ( den(x,y) ) X(y) = SUM ( x * den(x,y)) / SUM ( den(x,y) )where the summation is along x. This will result in a correlation
V = Omega * SIN(inc) * XThe output will be a table which can be inspected for signal and noise, and fed into a least squared fitter, such as tablsqfit(1NEMO) or tabnllsqfit(1NEMO) .
% mkdisk disk1 10000 harmonic mass=1 % snapscale disk1 disk2 rscale=1,0.5,0 vscale=0 % snapspin disk2 disk3 omega=1 % snaprotate disk3 disk4 30 x % snapgrid disk4 ccd4-den moment=0 % snapgrid disk4 ccd4-vel moment=-1 % twspeed ccd4-vel ccd4-den > ccd4.tab % tabnllsqfit ccd4.tab Fitting a+bx: a= -5.11039e-05 0.000116198 b= -0.499963 0.00931362
17-Aug-87 Original created as pspeed (though never made it into NEMO) PJT 18-nov-03 1.0: documented the new twspeed version PJT 22-apr-04 1.1: changed order of keywords PJT
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