Sample Cleaning MAPPING session

A basic Cleaning session with MAPPING is the following

CLEAN\READ DIRTY  file.lmv       ! 1
CLEAN\READ BEAM   file.beam      ! 2
SIC\LET NITER 200                ! 3
SIC\LET ARES  0.10               ! 4
SIC\LET FRES  0                  ! 5
SIC\LET GAIN 0.2                 ! 6
GTVL\DEVICE IMAGE                ! 7
FOR I 1 TO Nplane                ! 8
SHOW DIRTY I                     ! 9
CLEAN\SUPPORT/CURSOR             ! 10
CLEAN\HOGBOM                     ! 11
CLEAN\CLARK/PLOT                 ! 12
SHOW CLEAN                       ! 13
...                              ! 14
GREG2\WRITE POL file-'i'.pol     ! 15
NEXT                             ! 16
CLEAN\WRITE CLEAN file.lmv-sky   ! 17

1.

Read the dirty image from file ``file.lmv''

2.

Read the associated dirty beam. Note that point 1 and 2 are not necessary if you have produced your dirty image within MAPPING .

3.

Specify the number of clean components

4.

Specify the absolute residual level

5.

Specify the fractional residual (0 means use absolute level)

6.

Specify the loop gain

7.

Connect to an X-Window terminal for colour display

8.

Start a loop over all channels

9.

Show a bitmap of plane I of the dirty image. SHOW is a symbol defined to execute a command procedure which plots the image.

10.

Define where clean components must be searched for for this plane, using the cursor to create a polygonal area.

11.

Now make a simple HOGBOM clean.

12.

or a faster CLARK-like one. Adjustment of the loop gain is possible after each major cycle. Note that HOGBOM and CLARK operate on the first plane defined in command SHOW

13.

Show a bitmap of the corresponding plane of the clean image, to check if the result is satisfactory.

14.

Iterate points 10, 11 or 12 and 13 until you are satisfied with the result.

15.

optionally save the polygon which defined the support of the clean components in this plane.

16.

Loop over all image planes

17.

And once all planes have been cleaned, write the clean image on a file.

That's it. MAPPING should be used whenever the standard ``CLEAN box'' is not sufficient to specify where is located the true emission. The additional flexibility of modifying the loop gain in the CLARK method allows much better deconvolutions than using the standard techniques.