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velcube - create a data cube from a velocity field
velcube
[parameter=value]
velcube creates a theoretical position-position-velocity
data cube with signal derived from a velocity field (required) surface
density and velocity dispersion map (both optional).
The following
parameters are recognized in order; they may be given in any order if the
keyword is also given. Use --help to confirm this man page is up to date.
- out=
- Output file name (a cube) in image(5NEMO)
format. The X,Y coordinates
will be inherited from the input velocity field, the Z coordinates set
via nz= and zrange= (see below). No default.
- invel=
- Input velocity field.
No default. This map
- inden=
- Input surface density (optional). Should be
0 or positive Negative densities are skipped and reported.
- insig=
- Input
velocity dispersion map (optional). Should be 0 or positive Negative dispersions
are skipped and reported. Zero dispersion amounts to only 1 slice to be
populated.
- zrange=low:high
- Range in (Z) velocity. The lower value must really
be lower than the higher value. [-2:2].
- nz=
- Number of gridding pixels in
Z [64]
- sigdefault=
- Default (constant) velocity dispersion in case no
dispersion map is given. [0].
A model velocity field can be easily
made with ccdvel(1NEM0)
, and using the amp=t keyword density and dispersion
(sigma) maps can also be created. Another way to create a smooth velocity
field is using rotcurshape(1NEMO)
using a 0 input map and fixing all fittable
parameters. The resulting output residual map then contains -1 times the
desired velocity field.
nemoinp 0:100:1 > map1.radt
tabmath map1.radt - "%1/sqrt(40+%1*%1)" all > map1.velt
ccdvel out=map1.vel radii=@map1.radt vrot=@map1.velt pa=30 inc=60 size=256
Here is an example of creating a (0/1) mask cube based on where you expect
emission from a rotating disk given the geometry
ccdvel out=$tmp.d radii=0,$r0,$r1 vrot=1,1,1 inc=$inc pa=$pa size=$nx
cell=$cell amp=t
ccdvel out=$tmp.v radii=0,$r0,$r1 vrot=0,$v1,$v1 inc=$inc pa=$pa size=$nx
cell=$cell amp=f vsys=$vsys
ccdvel out=$tmp.s radii=0,$r0,$r1 vrot=100,100,50 inc=$inc pa=$pa size=$nx
cell=$cell amp=t
velcube - $tmp.v $tmp.d zrange=${vsys}-5*${nz}:${vsys}+5*${nz} nz=$nz sigdefault=$sig
|\
ccdmath - - ’ifgt(%1,0,1,0)’ |\
ccdfits - $mask refmap=$refmap refaxis=1,2,3 crpix=$nx/2,$nx/2,$nz/2 cdelt=-$cell/3600,$cell/3600,$chan
where a $refmap was used to inherit the WCS from.
ccdvel(1NEMO)
, ccdmath(1NEMO)
, rotcurshape(1NEMO)
src/image/rotcur/velcube.c
Peter Teuben
29-May-04 V1.0 Created PJT
6-may-2021 Add full example PJT
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