AIPS HELP file for FIXBX in 31DEC24
As of Thu Apr 18 17:35:28 2024
FIXBX: Task to convert a BOXFILE to another for input to IMAGR
INPUTS
INNAME UV dataset name (name)
INCLASS UV dataset name (class)
INSEQ 0.0 9999.0 UV dataset name (seq. #)
INDISK 0.0 9.0 Disk drive #
SRCNAME Source selected
INFILE previous BOXFILE for IMAGR
containing desired boxes
NMAPS 0.0 4096.0 Old number facets
NGAUSS 0.0 10.0 Old/new number Gaussians
NOISE Old RASHIFT values
PBSIZE Old DECSHIFT values
NBOXES 0.0 50.0 Number of boxes for Clean
NB: field 1 only.
CLBOX -2.0 16384.0 Four coordinates for each box
BOXFILE new BOXFILE for IMAGR to be
given translated boxes
NFIELD 0.0 4096.0 New number facets
RASHIFT New facet RA shift (asec)
DECSHIFT New facet Dec shift (asec)
OBOXFILE new BOXFILE for IMAGR with
translated boxes
CELLSIZE 0.0 new grid spacing in asec
IMSIZE 0.0 16384 new field size
ROTATE new rotation
BPARM (1) Old CELLSIZE(1)
(2) Old CELLSIZE(2)
(3) Old IMSIZE(1)
(4) Old IMSIZE(2)
(5) Old ROTATE
(6) Edge pixels to be avoided
(7) Scale box size factor
HELP SECTION
FIXBX
Type: Task
Use: FIXBX fixes the problem caused by wanting to change the size of
imaging facets or their cell sizes or centers while retaining
the information on Clean boxes generated with the current
faceting.
Two input box files are used. The first (INFILE) defines the
old facet centers and previous Clean boxes. NMAPS and NGAUSS
define the number of facets per Gaussian width and the number
of such widths in the old imaging. INFILE may be supplemented
with values stored in adverbs NBOXES, CLBOX, NOISE, and PBSIZE.
The second input (BOXFILE) defines the new facet centers and
field sizes. Any Clean boxes defined in BOXFILE are ignored.
It may be supplemented by adverbs NFIELD, RASHIFT, and
DECSHIFT. It is wise to specify NMAPS, NGAUSS, and NFIELD in
many cases.
An output box file is written. It will contain any facet
information found in BOXFILE plus the new Clean boxes taken
from INFILE and CLBOX. If an output facet has no Clean box, a
default inscribed circle box will be added.
Input adverbs:
INNAME.....The UV dataset name (name). Standard defaults.
INCLASS....The UV dataset name (class). Standard defaults.
INSEQ......The UV dataset name (seq. #). 0 => highest.
INDISK.....The disk drive #. 0 => any.
SRCNAME....The source to be used from a multi-source file; a single
source name is required to get the central pointing
position from the source table. Ignored for single-source
files.
INFILE.....The box-file previously used with IMAGR containing lines
which specify the fields used for imaging and other
lines giving the Clean boxes used in that imaging.
' ' => all information contained in NBOXES, CLBOX,
NMAPS, NOISE, and PBSIZE.
NMAPS......The old number of fields to map in the antenna beam.
Note that only 64 fields may be described in adverbs, but
4096 are allowed. If NMAPS is zero, then INFILE is used
to define the number of facets and the number of
Gaussians is taken to be 1.
NGAUSS.....Number of Gaussians in the old and new imaging. 0 -> 1.
NOISE......Old 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.
NMAPS values of NOISE will be used as initial values
before INFILE is read - field centers in the file will
override the NOISE values.
PBSIZE.....Old 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.
NMAPS values of PBSIZE will be used as initial values
before BOXFILE is read - field centers in the file will
override the PBSIZE values.
NBOXES.....Number (<=50) of rectangular search boxes to search on the
first field; the Clean windows in all other fields are
given in INFILE. If any boxes for field 1 appear in
INFILE, 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.
BOXFILE....Input text file containing lines which specify the
fields for the multi-field imaging in a changed scheme.
Any Clean boxes in BOXFILE will be discarded. The Clean
boxes from INFILE will be added to OBOXFILE after
translation where possible. No default. ' ' =>
information given by NFIELD, RASHIFT, and DECSHIFT.
NFIELD.....The new number of fields to map in the antenna beam. Up
to 4096 are allowed. If NFIELD=0, the maximum facet
number found in the field and Clean box lines in BOXFILE
will be used. Note that NGAUSS Gaussian widths are also
assumed.
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...New 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.
OBOXFILE...Output text file containing lines copied from BOXFILE
which specify the fields for the multi-field imaging in
a changed scheme. The Clean boxes from INFILE will be
added to OBOXFILE after translation where possible.
This file should then be specified as the new BOXFILE
for IMAGR. No default and the file must not pre-exist.
CELLSIZE...New pixel size for the fields in IMAGR in arc seconds.
No default.
IMSIZE.....New size of each field. No default.
ROTATE.....New rotation to be used (degrees CCW).
BPARM......(1) The value of CELLSIZE(1) used previously.
Default = CELLSIZE(1).
(2) The value of CELLSIZE(2) used previously.
Default = CELLSIZE(2).
(3) The value of IMSIZE(1) used previously.
Default = IMSIZE(1).
(4) The value of IMSIZE(2) used previously.
Default = IMSIZE(2).
(5) The value of ROTATE used previously.
No default
(6) The number of pixels to be omitted from any Clean
box at the edges of fields. 0 -> 3.
(7) Scale the size of the Clean boxes by BPARM(7). 0->1
EXPLAIN SECTION