Channel Maps

Another thing one can do is use channel-maps to make sequence of maps of the integrated or average emission in successive velocity slices. Figure  shows the result I got from the following:

>> chann
Velo range? (km/s  ) [-160.0000,-140.0000] -144.5 -136.5
Integrated intensity? (rather than average) (Y/N) [Y]
R.A. offset scaled from   36.000 to  -36.000
Dec. offset scaled from   24.000 to  -36.000
Channel width? (km/s  ) [     1.000]
Generating maps from cube - please be patient!
Maps now generated, going to contour them...
How many maps across page? (0=auto) [ 0] 4
Plotting on hardcopy device
 -- scale_bar --
    greyscale limits:   0.0000000E+00   6.000000
    plot limits:         25.00000       259.9995       40.00000
  137.9164
    device size:         264.9995       197.7896
    nx and ny:                   4           2
Setting colour table 1: linear grey scale
..

The number of maps across the page can be chosen by you, but the auto option often does a very presentable job. In this case I wanted eight maps, four to a row.

Figure: Output of the channel-maps command

Most of these map facilities are touchy and few people get the picture they want the first time. Experiment with them though, it's a good way to pass the time at the summit.