AIPS HELP file for CCEDT in 31DEC24
As of Thu Apr 18 16:45:24 2024
CCEDT: Select CC components in BOXes and above minimum flux.
INPUTS
INNAME Input file (name).
INCLASS Input file (class).
INSEQ 0.0 9999.0 Input file (seq. #).
0 => high
INDISK 0.0 9.0 Disk unit #. 0 => any
INVERS Input file version no.
OUTVERS Output file version.
BCOUNT 0.0 Beginning row to copy
ECOUNT 0.0 Last row to copy: 0 => end
CUTOFF Minimum merged flux. Use
large negative for no edits.
0.0 cuts off at zero.
BOXFILE
Text file with Clean boxes
NBOXES Number of boxes in CLBOX
CLBOX Clean windows to apply
NCCBOX -10.0 10.0 Number of boxes
< 0 -> write multiple CCs
CCBOX Four coordinate values for
each box in arcsec.
CPARM (1,2) = half size of rectang.
in X,Y(arcsec) in which
to get total flux for
CUTOFF.
(1) < 0 => (2) is radius of
circular aperture in CUTOFF
Automatic model splitting:
3 = Max number of output
tables. >0 => automatic
model splitting enabled.
4 = Min fractional flux in
the output models. 0=>0.95.
HELP SECTION
CCEDT
Type: Task
Use: CCEDT allows the user to filter Clean components and only keep
those within a region defined by boxes. These are given in
BOXFILE (if not blank), else in NBOXES boxes in CLBOX (if
NBOXES > 0), else in NCCBOX boxes defined by CCBOX. It also
combines all components at the same position (like CCMRG)
and then allows the components below CUTOFF to be rejected.
Under some circumstances, such filtering of Clean components
before self-calibration can be a more effective way of obtaining
convergence of hybrid mapping (mostly for VLBI) than restricting
Clean windows.
*****************************************************************
NOTE: IMAGR now offers the option of filtering the Clean
components as you Clean and at the end of the Clean. The methods
used by IMAGR are considerably more efficient than those used by
CCEDT.
*****************************************************************
CCEDT has two modes of operation: either it writes all the
filtered components into one CC table OR it writes a new table
for the components inside each individual input box. This is
controlled by the sign of NCCBOX. The latter mode of operation
is useful when splitting a Clean model for use by LPCAL. In this
mode, warnings of overlapping windows will be given, although a
single Clean component is never placed into more than one output
table.
The task will handle as many components as your computer's
(virtual) memory will support. The task supports CC files in
which the components are Gaussians, but only if the Gaussians
all have the same widths and position angles.
The boxes can be set using TVBOX and converted to arcseconds
using the procedure BOX2CC. (RUN BOX2CC ; BOX2CC). The
presence of NBOXES and CLBOX as adverbs to CCEDT make this step
of little use.
Adverbs:
INNAME......Main file name (name). Standard defaults.
INCLASS.....Main file name (class). Standard defaults.
INSEQ.......Main file name (seq. #). 0 => highest
INDISK......Disk drive # of image. 0 => any
INVERS......Input extension file version #.
OUTVERS.....Output extension file version #. 0=>make new
BCOUNT......Beginning row number to be included .
ECOUNT......Last row number included. 0 = highest.
CUTOFF......The minimum acceptable flux. 0 means zero - a common
desired value. Use large negative to avoid this
filter.
BOXFILE.....A text file specifying field Clean boxes. See IMAGR
help for details. This is used if it is not blank and
the field number is determined from the INCLASS.
NBOXES......Number of boxes in CLBOX used if > 0 and BOXFILE=' '.
CLBOX.......NBOXES Clean windows in pixels.
Circular boxes are allowed: -1, R, Xc, Yc where R is the
radius, (Xc,Yc) the center in pixels.
NCCBOX......The number of regions within which to keep components.
Used only if BOXFILE=' ' and NBOXES <= 0.
IN ALL CASES, however, if NCCBOX is negative, multiple
output tables are written, one for each region.
CCBOX.......The lower left and upper right coordinates of the
rectangular regions within which to keep Clean components
in arcseconds relative to the reference position. Up to
10 boxes are allowed. Recall that objects to the left on
an image have positive RA offsets. Use a contour plot
with LTYPE=4 to get the values or use TVBOX and proceedure
BOX2CC to convert to NCCBOX and CCBOX.
Circular boxes are allowed: -32000, R, Xc, Yc where R is
the radius, (Xc,Yc) the center in arc seconds.
CPARM.......For each component, all components within +-CPARM(1) in X
and +-CPARM(2) in Y (in arcseconds) are summed. The flux
density test (CUTOFF) is then applied to the summed flux
density. If CPARM(1) < 0, then a circular aperture of
radius CPARM(2) arc sec is used. CPARM(1) = 0 -> 5 X
cells, CPARM(2) <= 0 -> 5 Y cells.
Controls automatic model splitting option useful in feed
polarization calibration by LPCAL.
CPARM(3) is the maximum number of sub-models produced.
If >0, the automatic splitting is enabled and NCCBOX,
CCBOX. NBOXES, CLBOX, and BOXFILE are ignored.
CPARM(4) is the required minimum ratio of the combined
flux in the output sub-models to the total flux in the
input Clean model. 0 => 0.95.
EXPLAIN SECTION