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ellipse - ellipse (de)projection properties
ellipse de-projects ellipses, and computes the intrinsic properties,
and vice versa. It also computes kinematic properties, assuming flow is
along the ellipses, such as the kinematic minor axis (the major axis cannot
be defined, since the flow-velocity along the ellipse is not defined with
Apart from giving the eccentricity of the ellipse ("bar")
in the disk, and the inclination of the disk, the two angles in this routine
are theta and phi, of which only one needs to be given.
parameters are recognized in any order if the keyword is also given:
Here for a set of apparent position angles w.r.t. line of notes,
and given apparent b/a and inc, the intrinsic b/a, angle between bar and
line of nodes and the (sky plane) kinematic major axis (assumed perpendicular
to the kinematic minor axis) are computed:
- Axis ratio of bar. An array is allowed, in nemoinp(1NEMO)
notation. No default.
- Inclination of disk in which the ellipse ("bar") is located. An array
is allowed. No default.
- Angle between bar and disk in sky plane. An array
is allowed. Either phi or theta (not both) are required. It determines if
projection (theta given) or deprojection (phi given) is done.
between bar and disk in galax plane. Again an array is allowed.
of the bar (currently only projected) bar. If this option is used, the stick
formulae (ba=0) will be applied, and errors can be computed using dphi=.
- Error term in b/a. Useful if you want to compute errors in (de)projected
parameters using nsim=
- Error term in phi.
- Number of monte carlo
to perform to compute an error term. 
- Seed for random number generator.
% ellipse 0.3 45 20:30:2
b/a inc phi b/a’ theta phi_kin
0.3 45 20 0.376558 29.4085 -46.4712
0.3 45 22 0.368488 31.9773 -45.7525
0.3 45 24 0.360246 34.4675 -44.8267
0.3 45 26 0.351921 36.8805 -43.7464
0.3 45 28 0.343591 39.2183 -42.5507
0.3 45 30 0.335325 41.4834 -41.2693
For the stick formulae (a= used) only projection is done.
Skillman et al. A&A 198, 33 (1988), p39.
Arnaboldi et al. 1995AJ....110..199A
fall-1986 V0.0 formulae derived for Skillman et al paper PJT
23-Apr-03 V0.3 added phi_kin PJT
28-aug-03 V0.4 added a= for stick formulae of bars, +errors PJT
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