AIPS NRAO AIPS HELP file for SPMOD in 31DEC18



As of Mon Jun 18 14:47:34 2018


SPMOD: Task which inserts a spectral-line model into uv data

INPUTS

INNAME                             Input UV file name (name)
INCLASS                            Input UV file name (class)
INSEQ             0.0     9999.0   Input UV file name (seq. #)
INDISK            0.0        9.0   Input UV file disk unit #
SOURCES                            Source name
QUAL            -10.0              Calibrator qualifier -1=>all
CALCODE                            Calibrator code '    '=>all
STOKES                             Stokes of output
TIMERANG                           Time range to use
SELBAND                            Bandwidth to select (kHz)
SELFREQ                            Frequency to select (MHz)
FREQID                             Freq. ID to select.
SUBARRAY          0.0     1000.0   Sub-array, 0=>all
BIF                                Low IF number to do
EIF                                Highest IF number to do
BCHAN             0.0              First channel included
ECHAN             0.0              last channel included
DOCALIB          -1.0      101.0   > 0 calibrate data & weights
                                   > 99 do NOT calibrate weights
GAINUSE                            CL (or SN) table to apply
DOPOL            -1.0       10.0   If >0.5 correct polarization.
PDVER                              PD table to apply (DOPOL>0)
BLVER                              BL table to apply.
FLAGVER                            Flag table version
DOBAND           -1.0       10.0   If >0.5 apply bandpass cal.
                                   Method used depends on value
                                   of DOBAND (see HELP file).
BPVER                              Bandpass table version
SMOOTH                             Smoothing function. See
                                   HELP SMOOTH for details.
DOACOR                             Include autocorrelations?
OUTNAME                            Output UV file name (name)
OUTCLASS                           Output UV file name (class)
OUTSEQ           -1.0     9999.0   Output UV file name (seq. #)
OUTDISK           0.0        9.0   Output UV file disk unit #
INLIST                             List of sources up to 9999
FLUX                               Noise level in Jy/Weight.
FACTOR                             Multiplication factor.
QUAL                               If >0 then weights are
                                   reset to a value of 1.
DOHIST                             > 0 => list sources in
                                   history file
BADDISK                            Disks to avoid for scratch

HELP SECTION

SPMOD
Type: Task
Use: Modification of existing UV data by the addition of spectral-line
     models.  UVMOD does continuum models including polarization and
     spectral index, SPMOD adds objects as spectral-line features.
Adverbs:
  INNAME.....Input image name (name).       Standard defaults.
  INCLASS....Input image name (class).      Standard defaults.
  INSEQ......Input image name (seq. #).     0 => highest.
  INDISK.....Disk drive # of input image.   0 => any.
  SOURCES....Source to be copied.   '  '=> all; if any starts with a
             '-' then all except ANY source named.
  QUAL.......Qualifier of source to be copied. -1 => all.
  CALCODE....Calibrator code of sources to copy. ' '=> all.
  STOKES.....Specifies which STOKES parameters are written in the
             output data set:  in this case, no cross-polarization is
             allowed so the output is really only 'HALF', 'I', or 'IV'.
  TIMERANG...Time range of the data to be copied. In order: Start day,
             hour, min. sec, end day, hour, min. sec. Days relative to
             ref. date.
  SELBAND....Bandwidth of data to be selected. If more than one IF is
             present SELBAND is the width of the first IF required.
             Units = kHz. For data which contain multiple
             bandwidths/frequencies the task will insist that some form
             of selection be made by frequency or bandwidth.
  SELFREQ....Frequency of data to be selected. If more than one IF is
             present SELFREQ is the frequency of the first IF required.
             Units = MHz.
  FREQID.....Frequency identifier to select (you may determine which is
             applicable from the OPTYPE='SCAN' listing produced by
             LISTR). If either SELBAND or SELFREQ are set, their values
             override that of FREQID.  However, setting SELBAND and
             SELFREQ may result in an ambiguity.  In that case, the task
             will request that you use FREQID.
  SUBARRAY...Sub-array number to copy. 0=>all.
  BIF........First IF to include.  0 -> 1.
  EIF........Last IF to include.   0 -> max.
  BCHAN......First channel to copy. 0=>all.
  ECHAN......Highest channel to copy. 0=>all higher than BCHAN
  DOCALIB....If true (>0), calibrate the data using information in the
             specified Cal (CL) table for multi-source or SN table for
             single-source data.  Also calibrate the weights unless
             DOCALIB > 99 (use this for old non-physical weights).
  GAINUSE....version number of the CL table to apply to multi-source
             files or the SN table for single source files.
             0 => highest.
  DOPOL......If > 0 then correct data for instrumental polarization as
             represented in the AN or PD table.  This correction is
             only useful if PCAL has been run or feed polarization
             parameters have been otherwise obtained.  See HELP DOPOL
             for available correction modes: 1 is normal, 2 and 3 are
             for VLBI.  1-3 use a PD table if available; 6, 7, 8 are
             the same but use the AN (continuum solution) even if a PD
             table is present.
  PDVER......PD table to apply if PCAL was run with SPECTRAL true and
             0 < DOPOL < 6.  <= 0 => highest.
  BLVER......Version number of the baseline based calibration (BL) table
             to apply. <0 => apply no BL table, 0 => highest.
  FLAGVER....specifies the version of the flagging table to be applied.
              0 => highest numbered table.
             <0 => no flagging to be applied.
  DOBAND.....If true (>0) then correct the data for the shape of the
             antenna bandpasses using the BP table specified by BPVER.
             The correction has five modes:
             (a) if DOBAND=1 all entries for an antenna in the table
             are averaged together before correcting the data.
             (b) if DOBAND=2 the entry nearest in time (including
             solution weights) is used to correct the data.
             (c) if DOBAND=3 the table entries are interpolated in
             time (using solution weights) and the data are then
             corrected.
             (d) if DOBAND=4 the entry nearest in time (ignoring
             solution weights) is used to correct the data.
             (e) if DOBAND=5 the table entries are interpolated in
             time (ignoring solution weights) and the data are then
             corrected.
             IMAGR uses DOBAND as the nearest integer; 0.1 is therefore
             "false".
  BPVER......Specifies the version of the BP table to be applied
                0 => highest numbered table.
               <0 => no bandpass correction to be applied.
  SMOOTH.....Specifies the type of spectral smoothing to be applied to
             a uv database . The default is not to apply any smoothing.
             The elements of SMOOTH are as follows:
             SMOOTH(1) = type of smoothing to apply: 0 => no smoothing
               To smooth before applying bandpass calibration
                 1 => Hanning, 2 => Gaussian, 3 => Boxcar, 4 => Sinc
               To smooth after applying bandpass calibration
                 5 => Hanning, 6 => Gaussian, 7 => Boxcar, 8 => Sinc
             SMOOTH(2) = the "diameter" of the function, i.e. width
               between first nulls of Hanning triangle and sinc
               function, FWHM of Gaussian, width of Boxcar. Defaults
               (if < 0.1) are 4, 2, 2 and 3 channels for SMOOTH(1) =
               1 - 4 and 5 - 8, resp.
             SMOOTH(3) = the diameter over which the convolving
               function has value - in channels.  Defaults: 1,3,1,4
               times SMOOTH(2) used when input SMOOTH(3) < net
               SMOOTH(2).
  DOACOR.....> 0 => include autocorrelations as well as cross
             correlation data.
  OUTNAME....Output image name (name).      Standard defaults.
  OUTCLASS...Output image name (class).     Standard defaults.
  OUTSEQ.....Output image name (seq. #).    0 => highest unique
  OUTDISK....Disk drive number of output image.  0 =>
             highest number with sufficient space.

  INLIST.....Text file containing one line per source, giving

             RR, DX, DY, Maj, Min, PA, type, line center, width, LL

             blank separated free format and trailing zeros may be
             omitted.  The resulting NGAUS will be #lines in INLIST.
             Limit 9999.
             RR is the right-right flux, LL is the left-left flux
             and an omitted LL is set equal to RR (but you can enter 0
             for LL to have the line solely in RR or vice versa).
             Note too that RR and or LL may be negative or positive.

             DX, DY, Maj and Min are in arcseconds, PA in degrees,
             line center and width (FWHM) are in channels
             Channels are counted from BCHAN through ECHAN as 1 - N in
             IF BIF, N+1 - 2N in IF BIF+1, etc.

             Blank lines and lines beginning with # or ; (semi-colon)
             are taken as comments
  FLUX.......Noise level to be added (in Jy. per Weight).
  FACTOR.....Factor by which original data are multiplied before they
             are added to the model.  If FACTOR = 0 then only the model
             will be left.
  QUAL.......If QUAL > 0 then all Weights will be set to a
             value of 1 in the output file.
  DOHIST.....List sources in history file if NGAUS <= 4 and/or DOHIST
             > 0.
  BADDISK....The disk numbers to avoid for scratch files (sorting
             tables mostly).

EXPLAIN SECTION

SPMOD: Task which modifies UVDATA by scaling the existing data,
       and adding a specified model (See also IMMOD).
RELATED PROGRAMS: UVMOD, MODIM, IMMOD

                  PURPOSE

     SPMOD modifies an already existing UV data file by the addition of
one of several model types as spectral-line features.  The original
data may be scaled by a multiplicative factor, including negative
values and zero, before they are added to the model.  Random noise may
also be added to the UV data.  The program could be useful in
investigating the affects of CLEAN on a specific geometry, or for
removing models from data, i.e. planetary disks.

     The flux options allow you to model Zeman splitting by have two
components, one in RR and a different one in LL.  You may also add
absorption features with RR and or LL negative.

     The six available models to choose from are 0) point source, 1)
Gaussian, 2) solid disk  3) solid rectangle, 4) optically thin sphere,
and 5) exponential.  These models are first Fourier transformed and
then added to the UV data.  The resulting functions are:

          0) Point -> A constant visibility amplitude is added to the
                      data.  The GWIDTH adverbs have no affect on this
                      model.  Used with CTYPE <= 0 or > 5.

          1) Gaussian -> The function EXP(-3.559707*R**2) is added to
                      the UV data.  The function R is given by:
                         R = Sqrt(UU**2 + VV**2) where
                         UU = BMAJ*(V*COS(BPA)+U*SIN(BPA))
                         VV = BMIN*(U*COS(BPA)-V*SIN(BPA))

          2) Disk ->  The function J1(R)/R is added to the UV data,
                      where J1 is the Bessel function of order 1 and R
                      is the same as above.

          3) Rectangle -> The function SINC(UU)*SINC(VV) is added to
                      the UV data, where SINC(X) = SIN(X)/X.  UU and
                      VV are defined as above for the Gaussian.

          4) Sphere -> The function (SIN(A)/A - COS(A)) / (A*A) is
                      added to the UV data where
                         A = BMAJ * Sqrt (U*U + V*V)
                         A = max (A, 2 pi / 100)
                      The GWIDTH adverbs have no affect on this model.

          5) Exponential -> The function
                           2 Pi / (1 + a * a * R * R) ** 3/2
                      is added to the UV data where R is defined in 2
                      above and a is Pi/ln(2).

Note that all functions are scaled by the total flux and a complex
vector representing the phase of the model before being added to the
scaled input visibility data.

MAJ, MIN, PA :

The dimensions of the resulting functions are determined by MAJ, MIN
and PA (position angle).  For the Gaussian the first two values are
the FWHM of the two axis.  For the Disk and the Rectangle, the first
two values are the absolute dimensions of the two available axis.  If
MAJ and MIN are both zero then all the models reduce to the point model.

FACTOR :

     The FACTOR term allows one to add a scaled version of the
original data to the model.  FACTOR is simply multiplied by the
original data which is then added to the model.  If FACTOR = 0, then
only the model will remain in the final UV data base.

Coordinate considerations:

     FPOS is translated to an RA, Dec following the formula (assuming
no rotations):
          Dec = Dec0 + FPOS(2)
          RA  = RA0 + FPOS(1) / cos (Dec0)
These are then turned into l,m,n for phase = ul + vm + wn as (for -SIN
geometry):
          l = cos (Dec) * sin (Ra-Ra0)
          m = sin (Dec) * cos (Dec0) -
              cos (Dec) * sin (Dec0) * cos (Ra-Ra0)
          n = sin (Dec) * sin (Dec0) +
              cos (Dec) * cos (Dec0) * cos (Ra-Ra0)
Suitable formulae are used for -NCP geometry as well.


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