CCDELLINT(1NEMO) manual page

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Name

ccdellint - integrate map or cube in elliptical (like) rings

Description

ccdellint integrates a Position-Position-Velocity (PPV) cube in elliptical annuli in the first two dimensions, reducing it to a Radius-Velocity (RV) image.

This program also handles 2D images, in which case the output is a table, consisting of 6 columns:

   rad = outer radius of the annulus;
   npix = number of pixels in the annulus;
   int = average in the annulus; (no support for median yet)
   rms = rms in the annulus;
   sum = sum in the annulus;
   cumsum = cumulative sum for all annuli so far.

This is the same order and meaning as the table from ellint(1MIRIAD) .

The particle based program snapshell(1NEMO) does something similar in 3D.

The metric of how the radius is computed can be changed using the metric= keyword. For metric=2 these would be called true rings, for metric=1 a square.

Parameters

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.

in=: input data cube. No default.
radii=: radii of the ring boundaries (Nring+1). See metric= below for different ways to change the metric of computing a radius. No default.
pa=: position angle of disk, astronomical convention. [0]
inc=: inclination angle of disk [0]
center=: rotation center (mapcenter if left blank, 0,0=lower left)
vsys=: systemic velocity. Only needed for cube. [0]
blank=: Value of the blank pixel to be ignored [0.0]
norm=: Normalize values to number of pixels in ring. This only has an effect on the image written, not on the table, which uses both. [t]
out=: RV image, useful for 3D cubes. If not given, no image will be written. Default: not used
tab=: Output table, useful for 2D images. If not give, no table will be written. Default: not used
rscale=: Convenience factor by which radii are multiplied for display in the table. For FITS images this is usually 3600. [1]
iscale=: Convenience factor by which intensities are multiplied for display in the table. For FITS images this is usually 1 / (1.133*(beam/pixel)**2). [1]
metric=N: The exponent of the r^N = x^N + y^N metric to compute a radius. N=2 is the traditional cartesian [2]

Caveats

As with most of these codes, the center of pixel determines to which ring the pixel belongs in it total.

A value of metric=1 can be interesting, though the position angle may need to be adjusted, as the box is mis-aligned by 45 degrees from the major axis. For large values of metric the box is aligned along the major axis.

Examples

Example of generating a gaussian profile from a 2D gauss image

% ccdgen out=- object=gauss spar=1,50 size=256,256 | ccdellint - 0:100:5 tab=-
  5 80 0.997464 0.00145455 79.7971 79.7971
  10 236 0.987487 0.00426892 233.047 312.844
  ...
  95 2924 0.180558 0.0096899 527.951 13127.6
  100 3056 0.149281 0.00837475 456.204 13583.8

For a map in K.km/s that needs to be converted to Jy.km/s, with Jy/K=2.5 and a beam of 12.65 arcsec and 5.5 pixels there are 6 points per beam, therefore the rscale=3600 is needed to view the table in arcsec, and iscale=2.5/6 for viewing in Jy.km/s:

  % fitsccd M100_97520_99703.mom0.fits  - |\
       ccdellint - 0:250/3600:10/3600 pa=150 inc=40 center=45,45 rscale=3600
iscale=1.41/0.65/6.00 tab=-
  10 7 16.3524 0 114.467 114.467
  20 24 11.824 0 283.776 398.243
  ..
  240 290 0.0505762 0 14.6671 3057.86
  250 241 -0.0573514 0 -13.8217 3044.04

Some examples of PPV->RV

  % fitsccd ngc6503.cube.fits - |\
      ccdellint - 0:1000/3600:10/3600 pa=-60 inc=40 center=163,122 out=ngc6503.rv.ccd
norm=f

30-nov-2020    V0.1 drafted    PJT
23-nov-2022    V0.3 confirmed 2D images, added table output    PJT
6-dec-2022    V0.6 use metric= to allow other radius methods    PJT

Table of Contents

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Examples
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