AIPS HELP file for OOSUB in 31DEC24
As of Thu Apr 25 5:58:52 2024
OOSUB: Task to subtract CLEAN components from a uv data base.
INPUTS
(or, to divide observed visi-
bility by model visibility)
INNAME Input UV file name (name)
INCLASS Input UV file name (class)
INSEQ 0.0 9999.0 Input UV file name (seq. #)
INDISK Input UV file disk unit #
CHANNEL -1.0 9999.0 Spectral channel (0=>all)
Use 0 for continuum
BIF 0.0 9999.0 First IF (0=>1)
EIF 0.0 9999.0 Highest IF (0=>BIF to last)
IN2NAME Cleaned map name (name)
IN2CLASS Cleaned map name (class)
IN2SEQ 0.0 9999.0 Cleaned map name (seq. #)
IN2DISK Cleaned map disk unit #
NMAPS 0.0 4096.0 No. maps to use for model.
INVERS 0.0 46655.0 CC file version #. 0 -> 1
OUTNAME Output UV file name (name)
OUTCLASS Output UV file name (class)
OUTSEQ -1.0 9999.0 Output UV file name (seq. #)
OUTDISK Output UV file disk unit #.
BCOMP First CLEAN comp to sub.
1 per field.
NCOMP Last CLEAN comp to sub.
to use (0 => all)
FLUX Lowest CC component used.
CMETHOD Modeling method:
'DFT','GRID',' '
CMODEL Model type: 'COMP','IMAG'
(see HELP re images)
FACTOR Factor times CLEAN fluxes.
0->1.0 Subtract
-1.0 Add
OPCODE 'DIV ' => divide visibility
observation by model vis.
'MODL' => replace visibility
with model visibility
'MODU' => replace visibility
with model visibility and
unflag all channels
anything else => subtract
SMODEL Source model, 1=flux,2=x,3=y
See HELP SMODEL for models.
BPARM Task enrichment parameters
(1) Antenna diameter (m)
0 -> no correction
(2) Omit CC options
(3) spectral index radius
0 -> no correction
FQTOL Frequency tolerance in kHz
(primary beam & spec index)
IN3NAME Spectral index image name
IN3CLASS Spectral index image class
IN3SEQ Spectral index image sequence
number
IN3DISK Spectral index image disk
IN4NAME Spectral curvature name
IN4CLASS Spectral curvature class
IN4SEQ Spectral curvature sequence
number
IN4DISK Spectral curvature disk
BADDISK Disks to avoid for scratch
HELP SECTION
OOSUB
Task: Subtracts/divides a model from/into a uv data base. The model
may be a specific model, a set of CLEAN components files, or a
set of images. "CLEAN" models may be points, Gaussians or
uniform, optically thin spheres. The task can also replace the
observed visibilities with the model values.
Model images made with both values of IMAGR's DO3DIMAG
option are handled correctly, as are multi-scale images. Set
NMAPS = NFIELD * NGAUSS.
OOSUB works only on single-source files.
OOSUB differs from UVSUB in that it offers the
frequency-dependent primary beam and spectral index options
found in IMAGR.
WARNING: If any part of the IN3NAME group or IN4NAME group of
adverbs is specified, then the images so described will be used
as spectral index and curvature images. Use CLR3NAME and
CLR4NAME if you do not wish to apply such images.
NOTE: this task does NOT apply flagging or calibration tables
to the input UV data. Run SPLIT first if that operation is
desired. The task assumes that the model has been computed or
corrected to apply at the specific frequency in the header,
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NOTE: this task will work on multi-source files (unlike UVSUB)
but the file must contain data for only one source. A single
model will be applied to all data in the file, so a true
multi-source file will be rendered defective.
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If the multi-facet and/or frequency-dependent options are
invoked, OOSUB will attempt to apply all facet models to each
frequency group (set by FQTOL). If the maximum size of the
pseudo-AP (set by verb SETMAXAP) is not large enough, then
OOSUB will use multiple passes through the data applying some
combination of facets and frequencies in each pass. All facets
but only N frequency groups is preferred, but all channels and
some facets will be tried. The fall-back case is one facet and
some channels. The amount of memory required by each facet
model in gridded mode is more than 4 times the number of pixels
in the image (even when Clean components are used). Thus large
model images will produce more acurate gridded modeling but can
use up memory rapidly.
Adverbs:
INNAME.....Input UV file name (name). Standard defaults.
INCLASS....Input UV file name (class). Standard defaults.
INSEQ......Input UV file name (seq. #). 0 => highest.
INDISK.....Disk drive # of input UV file.0 => any.
CHANNEL....Frequency channel, 0 => all (use 0 for continuum)
If > 0, then subtract/divide only this channel but copy
all channels with the others unchanged. NOTE WELL:
EIF will be set to BIF if CHANNEL >= 1.
BIF........First IF to process. 0=>1
EIF........Highest IF to process 0=> do BIF to highest.
Note: not all data sets will have IFs. See note under
CHANNEL directly above too. If the IF axis precedes the
FREQ axis in the header, then all IFs must be done if all
spectral channels are to be done.
IN2NAME....Model map name (name). Standard defaults.
IN2CLASS...Model map name (class). Standard defaults.
IN2SEQ.....Model map name (seq. #). 0 => highest.
IN2DISK....Disk drive # of model map. 0 => any.
NMAPS......Number of image files to use for model. For multi-scale
models, set NMAPS = NFIELD * NGAUSS to include the Clean
components of the extended resolutions. If more than one
file is to be used, the NAME, CLASS, DISK and SEQ of the
subsequent image files will be the same as the first file
except that the LAST 3 or 4 characters of the CLASS will
be an increasing sequence above that in IN2CLASS. Thus,
if INCLASS='ICL005', classes 'ICL005' through 'ICLnnn'
or 'ICnnnn', where nnn = 5 + NMAPS - 1 will be used. Old
names (in which the 4'th character is not a number) are
also supported: the last two characters are '01' through
'E7' for fields 2 through 512. In old names, the highest
field number allowed is 512; in new names it is 4096.
INVERS.....CC file version #. You should specify this. 0 -> 1
OUTNAME....Output UV file name (name). Standard defaults.
OUTCLASS...Output UV file name (class). Standard defaults.
OUTSEQ.....Output UV file name (seq. #). 0 => highest unique.
OUTDISK....Disk drive # of output UV file. 0 => highest with
space
BCOMP......The first clean component to process. One value is
specified for each field used.
NCOMP......Number of Clean components to use for the model, one
value per field. If all values are zero, then all
components in all fields are used. If any value is not
zero, then abs(NCOMP(i)) (or fewer depending on FLUX and
negativity) components are used for field i, even if
NCOMP(i) is zero. If any of the NCOMP is less than 0,
then components are only used in each field i up to
abs(NCOMP(i)), FLUX, or the first negative whichever
comes first. If abs(NCOMP(i)) is greater than the number
of components in field i, the actual number is used. For
example
NCOMP = -1,0
says to use one component from field one unless it is
negative or < FLUX and no components from any other
field. This would usually not be desirable.
NCOMP = -1000000
says to use all components from each field up to the
first negative in that field.
NCOMP = -200 100 23 0 300 5
says to use no more than 200 components from field 1, 100
from field 2, 23 from field 3, 300 from field 5, 5 from
field 6 and none from any other field. Fewer are used if
a negative is encountered or the components go below
FLUX.
FLUX.......Only components > FLUX in absolute value are used in the
model.
CMETHOD....This determines the method used to compute the
model visibility values.
'DFT' uses the direct Fourier transform, this
method is the most accurate.
'GRID' does a gridded-FFT interpolation model
computation.
' ' allows the program to use the fastest
method.
NOTE: data in any sort order may be used by the
'DFT' method but only 'XY' sorted data may be used
by the 'GRID' method.
NOTE: CMETHOD='GRID' does not work correctly for RL
and LR data; DO NOT USE CMETHOD='GRID' for RL, LR!
CMODEL.....This indicates the type of input model; 'COMP' means that
the input model consists of Clean components, 'IMAG'
indicates that the input model consists of images. If
CMODEL is ' ' Clean components will be used if present
and the image if not. Note that Clean images do not make
good models. The Clean components have been convolved with
the Gaussian Clean beam making their Fourier transform be
rather tapered compared to the original uv data.
FACTOR.....This value will be multiplied times the CLEAN component
flux densities before subtraction. The default 0->1.0, so
the clean component model will be subtracted from the UV
data. FACTOR=-1 will add the clean component model to the
UV data. FACTOR will be adjusted by OOSUB for image
models that are in JY/BEAM. FACTOR is used with all
OPCODEs.
OPCODE.....OPCODE='DIV ' => divide observed visibility by model
visibility.
OPCODE='MODL' => replace the visibility with the model
visibility.
OPCODE='MODU' => replace the visibility with the model
visibility, set all weights to 1 undoing any channel
flags
Any other setting of OPCODE causes the task to subtract the
model visibility from the observed visibility (the normal
mode of operation).
SMODEL.....A single component model to be used instead of a CLEAN
components model; if abs (SMODEL) > 0 then use of this
model is requested.
SMODEL(1) = flux density (Jy)
SMODEL(2) = X offset in sky (arcsec)
SMODEL(3) = Y offset in sky (arcsec)
SMODEL(4) = Model type:
0 => point model
1 => elliptical Gaussian and
SMODEL(5) = major axis size (arcsec)
SMODEL(6) = minor axis size (arcsec)
SMODEL(7) = P. A. of major axis (degrees)
2 => uniform sphere and
SMODEL(5) = radius (arcsec)
BPARM......Correction control parameters (SEE EXPLAIN IMAGR):
(1) If > 0 then make frequency dependent primary beam
corrections assuming an antenna diameter of IMAGRPRM(1)
meters. Note that VLA and ATCA arrays (TELESCOPE
header parameter) use the default primary beam
parameters defined elsewhere in AIPS, while other
antennas actually use IMAGRPRM(1) as the diameter of a
"standard" telescope. See FQTOL below also.
(2) If BPARM(1) > 0, you may omit selected CCs from the
operation based on position:
BPARM(2) <= 0 : Include all CCs
= 1 : Omit CCs within the main beam at
all frequencies
= 2 : Omit CCs within the main beam at
some frequncies
= 3 : Omit Ccs outside the main beam at
some frequencies
= 4 : Omit CCs outside the main beam at
all frequencies
(3) 1 => use a spectral-index image represented in
IN3NAME, IN3CLASS, IN3SEQ, IN3DISK below to correct the
Clean component model for each channel. IN4NAME et al
will also be used as a curvature image iff IN3NAME are
specified.
bparm(3)-0.5 is used as a radius in pixels over which
the spectral index image is averaged. When it is small
(0 < BPARM(3) <~ 1), the spectral index is interpolated
rather than averaged. See FQTOL below as well. When
doing spectral index, the primary beam correction
(BPARM(1)) costs very little extra. This parameter is
IMAGRPRM(17) in IMAGR.
FQTOL......Frequency tolerance in kHz. Spectral channels with FQTOL
are handled together (use the same average CC model) when
applying the primary beam and spectral index
corrections. Default is to do each channel separately
which can take a long time.
IN3NAME....Image name of spectral index image; no default.
IN3CLASS...Image class of spectral index image; no default.
IN3SEQ.....Image sequence of spectral index image; 0 -> highest.
IN3DISK....Disk of spectral image image; 0 -> any.
IN4NAME....Image name of spectral index curvature image; no default.
Curvature images should be base 10 rather than base e -
they differ by a factor of 2.3. Also the reference
frequency is 1.0 GHz. These are changes done 2010-07-13.
IN4CLASS...Image class of spectral index curvature image; no
default.
IN4SEQ.....Image sequence of spectral index curvature image;
0 -> highest.
IN4DISK....Disk of spectral curvature image image; 0 -> any.
BADDISK....The disk numbers to avoid for scratch files.
EXPLAIN SECTION