AIPS HELP file for CHKFC in 31DEC24
As of Sat Oct 5 16:41:03 2024
CHKFC: Makes images showing the fields and boxes in BOXFILE
INPUTS
OUTNAME Output Image name (name)
OUTSEQ 0.0 9999.0 Output Image name (seq. #)
OUTDISK 0.0 9.0 Disk drive #
BOXFILE disk file to read field locs
and Clean boxes
COORDINA Center RA, Dec
CELLSIZE 0.0 (X,Y) size of grid in asec
IMSIZE 0.0 16384 field size
NFIELD 0.0 4096. Number facets
RASHIFT New facet RA shift (asec)
DECSHIFT New facet Dec shift (asec)
NBOXES 0.0 50.0 Number Clean boxes
CLBOX -2.0 Clean boxes: facet #1
DOBLANK -1.0 1.0 > 0 Use blanks for unCleaned
DOWEDGE -2.0 2.0 > 0 Add field number in boxes
HELP SECTION
CHKFC
Type: Task
Use: CHKFC reads an input BOXFILE which defines the fields for
IMAGR. It makes a set of images with 1's in the Clean windows
and blanks or 0's outside the Clean windows. It can take its
inputs from adverbs instead of or in addition to the BOXFILE.
Adverbs:
OUTNAME.....The output image name (name). Standard defaults.
OUTSEQ......The output image name (seq. #). 0 => highest.
OUTDISK.....The output disk drive #. 0 => any.
BOXFILE.....Input text file containing lines which specify the fields
for the multi-field imaging. This file should then be
specified as the BOXFILE for IMAGR.
' ' => take all inputs from adverbs.
Leading and trailing blanks from all lines in the text
file are discarded, so "column 1" below means the first
non-blank column in the card.
This option is used to specify field parameters for
fields 1 through NFIELD which are then copied to the
fields used for additional resolutions (if any). To
specify a field's parameters, put the letter F or f in
column 1 followed by the field number, the X and Y FLDSIZE
values, the RASHIFT amd the DECSHIFT for the field
(separated by blanks). Any field specified in this way
overrides the corresponding parameters given in the
adverbs. Thus,
F 2 450 450 -25.5 6.7
specifies that field 2 is to have a FLDSIZE of 450x450 with
an RASHIFT of -25.6 and a DECSHIFT of 6.7 arcsec. If this
is the only F card in the file, then fields 1 and 3 through
NFIELD are set by the adverb values. As an alternative, a
field may also be specified with a "coordinates" card
having a C or c in column one. After the C, give the field
number, the X and Y FLDSIZE values and the center Right
Ascension (HH MM SS.S) and Declination (signDD MM SS.S)
separated by blanks. Thus
C 2 450 450 11 34 45.67 -00 14 23.1
specifies that field 2 is to have a FLDSIZE of 450x450 with
a center RA of 173.6902917 degrees and a center Declination
of -0.23975 degrees. All 9 numbers must be given; the sign
is optional for positive declinations and is given only on
the degrees term.
To set Clean boxes, specify one box per line, as field
blc-x blc-y trc-x trc-y (5 integers) e.g.
1 200 205 220 222
1 230 232 240 241
2 100 100 130 121
...
or circular "boxes" as
field -1 radius center-x center-y (5 ints) e.g.
001 -1 10 210 214
001 -1 5 235 237
....
Column 1 must contain a numeric character (part of the
field number); otherwise the line is treated as a some
other sort of line. Fields with no boxes specified
default to the size specified by IMSIZE and FLDSIZE (see
above and including FLDSIZEs read from this file).
COORDINA....Center RA and Dec as HH, MM, SS.S, DD, MM, SS.S. This
is used only if the BOXFILE contains F cards which
define fields by a shift from the reference COORDINA.
There is no default in this case. BOXFILEs that use C
cards which define fields by their center coordinate do
not use the value of this adverb.
CELLSIZE....Pixel size for the fields in IMAGR in arc seconds.
IMSIZE......Size of each field.
If CELLSIZE and/or IMSIZE are zero, the data are read to
find the maximum baseline and maximum W in order to
estimate these parameters.
NFIELD......The number of fields to map in the antenna beam. Up
to 4096 are allowed. Number used will be the max of
NFIELD and the max field number in BOXFILE.
RASHIFT.....New RA shift of the phase center of each field from the
tangent point of the uv data in asec. Map center =
tangent point + shift. If X>0 shifts map center to east.
NOTE: RASHIFT is a shift in RA scaled by cos (Dec_0) as
Ra_new(i) = RA_0 + RASHIFT(i) / cos (Dec_0)
where _0 => the tangent point in the uv data. This is a
change for 15OCT99 from shifts in -SIN projection (which
do not work for -NCP data and large angles). If the UV
data have been rotated then RASHIFT and DECSHIFT refer
to X and Y in the new coordinate system.
NFIELD values of RASHIFT will be used as initial values
before BOXFILE is read - field centers in the file will
override the RASHIFT values.
DECSHIFT....Declination shift of map center from tangent point of
each field in asec. Map center = tangent point + shift.
If Y>0 shifts map center to north.
NFIELD values of DECSHIFT will be used as initial values
before BOXFILE is read - field centers in the file will
override the DECSHIFT values.
NBOXES......Number (<=50) of rectangular or circular search boxes to
search on the first field; the Clean windows in all
other fields are given in BOXFILE. If any boxes for
field 1 appear in BOXFILE, NBOXES and CLBOX are ignored.
CLBOX.......A 4x50 array with the parameters of each box.
0 => use window specified in FLDSIZE.
CLBOX(1,i)=-1 indicates a circle of radius CLBOX(2,i)
pixels centered on (CLBOX(3,i), CLBOX(4,i)).
CLBOX(1,i) >= 0 indicates a rectangular box.
DOBLANK.....True (> 0) => pixels outside Clean boxes are represented
with magic-value blanks; otherwise 0's are used. When
FLATN is run, 0's are interpolated and averaged causing
interesting but sometimes odd effects. Blanks are
usually better.
DOWEDGE.....True (> 0) => insert the field number in all Clean
windows that are large enough. Image intensity 2 is
used for window boundaries, 1 for Clean windows outside
the numbers and 3 times this for numbers. DOWEDGE 2
telss the task to make the numbers rather larger (for
TVLODs with TXINC and TYINC > 1). Again FLATN's
interpolation can do some odd things.
DOWEDGE < -1 says to use intensity 1 for the edges of
the boxes rather than 2.
EXPLAIN SECTION