Table of Contents

**snapifu in=**snapshot **out=**image [parameter=value]

The output image is
written in standard *image(5NEMO)*
format, where the X coordinates enumerates
the grid points, the Y axis is dummy, and the Z axis the spectrum.

**in=***in-file*- input file, must be in
*snapshot(5NEMO)*format. Multiple snapshots can be stacked uses the**times=**keyword: see**stack=**below. [no default]. **out=***out-file*- output file, will be in
*image(5NEMO)*format [no default]. **times=***t1:t2,t3,..*- Selection of the times of snapshots to be
selected for gridding. For
**stack=t**all snapshots will be co-added into one image, however selecting**stack=f**or selecting multiple**evar**’s one can request multiple output images. [Default:**all**]. **xgrid=***x-positions*- A set of X (see
**xvar=**) positions where spectra are taken. Use*tabcols(1NEMO)*if the grid points are hidden in a columns in a table. Default: 0.

**ygrid=***y-positions*- A set of Y (see
**yvar=**) positions where spectra are taken. Default: 0. **size=**- Size of the grid point. The shape of the point is circular,
and the size is the diameter of this point. For square/recangular shapes,
use
*snapgrid(1NEMO)*. **xvar=***x-expression*- The value of
*x-expression*is gridded along the X axis. [default:**x**]. **yvar=***y-expression*- The value of
*y-expression*is gridded along the Y axis. [default:**y**]. **zvar=***z-expression*- The value of
*z-expression*is gridded along the Z axis (**nz**>1), or moments taken off (**nz=1**). [default:**-vz**]. **evar=***emissivity*- Variable to denote emissivity per particle.
You can select more than 1 expression, in which case different images will
be written out (only in
**stack=f**mode) [default:**m**]. **tvar=***tau*- Variable to denote the optical depth of a particle. [Default: 0]
**dvar=***depth*- Variable to denote the line of sight. [Default: z]
**zrange=***xb:xe*- Range in
**zvar**to bin, or take moments of [default:**-infinity:infinity**]. **nz=***z-pixels*- Number
of pixels along the Z axis of the cube. If one pixel is choosen, moments
can be taken (see below), else a simple gridding is used. [default:
**1**]. **moment=***number*- Order of the Z-gridding. Most commonly choosen are:
**0**(total intensity),**1**(velocity zvar weighted intensity) and**2**(velocity square weighted intensity), where ’intensity’ should really be read as surface density per square unit length. Special values of**-1**and**-2**can be used to directly compute the mean and the dispersion from the mean. [default:**0**]. **mean=t|f**- Should the
*emission*in a cell be averaged? This also controls the units of the gridding. For**mean=f**(the default) a*surface-density*is computed (emission per area), whereas for**mean=t**the average per

pixel is computed of the units of emission. [Default:**f**]. **stack=t|f**- Should
all snapshots from the input file be stacked, or write one image per selected
(see
**times=**) time? [default:**f**].

When channel maps are produced (**moment=0**), the data
are not normalized w.r.t. the convolving velocity beam. For a rectangular beam
(**vrange=vmin:vmax**) the data should formally be divided by **(vmax-vmin)**, for
a gaussian beam (**vrange=vmean,vsig**) by **vsig*sqrt(2*pi)**. Also remember that
a gaussian beam has **FWHM = 2.355*sigma**.

mkplummer p10 10 seed=123 snapprint p10 x,y > p10.tab set x=(‘tabcols p10.tab 1‘) set y=(‘tabcols p10.tab 2‘) snapifu p10 p10.ccd xgrid="$x" ygrid="$y"

Currently the spectra are written to a CCD image where the 2nd axis is
a dummy axis. There are least two ways to view these data. With *ccdfits(1NEMO)*
you can write a *fits(5NEMO)*
file and ignore the dummy axis, and then display
it in your favorite display program

snapifu p10 p10.ccd xgrid="$x" ygrid="$y" zrange=-2:2 nz=32 ccdfits p10.ccd p10.fits dummy=f nds9 p10.fitsor use

ccdsub p10.ccd p10a.ccd dummy=f ccdplot p10a.ccd ccdprint p10a.ccd x= y=

src/nbody/imagesnapifu.c

8-apr-09V1.0: CreatedPJT