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 # SRCNAME 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 # NGAUSS 0.0 9999.0 Number of sources CTYPE 0.0 5.0 Component type: 0 point, 1 Gaussian, others see help FMAX Peak I value of sources FPOS (X,Y) position in asec FWIDTH (Major,Minor,PA) in asec,asec,deg INLIST List of sources up to 9999 ZEROSP Zero spacing flux for (1) ignored, (2) Q, (3) U, and (4) V in Jy. FLUX Noise level in Jy/Weight or Jy if FACTOR=0. DPARM Spectral indices to use FACTOR Multiplication factor. WTUV If >0 then weights are reset to a value of 1. DOHIST > 0 => list sources in history file FQCENTER >= 0 -> center frequency axis BADDISK Disks to avoid for scratch

UVMOD Type: Task Use: Modification of existing UV data by the addition of models. 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. SRCNAME....Source name to be modified. Must specify if input is a multi-source data set, otherwise all sources are included. 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: ' ' => 'FULL' 'I','Q','U','V', 'IV', 'IQU', 'IQUV' 'RR','LL', 'RL', 'LR', 'RRLL', 'RLLR', 'RLRL' 'VV','HH', 'VH', 'HV', 'VVHH', 'VHHV', 'VHVH' 'HALF', 'CROS', and 'FULL' have sensible interpretations depending on the Stokes present in the data. The last in each of the 3 rows above == 'FULL'. Note that many combinations of polarizations in the input and values above are not supported. 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. NGAUSS.....Number of sources 1 - 4 use CTYPE, FMAX, FPOS, and FWIDTH; > 4, use INLIST file. Limit 9999. Note, if INLIST not blank and NGAUSS > 1, the INLIST file will be used BUT the value of NGAUSS will limit how many components are read from INLIST. Set it large when you use INLIST if you want the full contents of INLIST. CTYPE......Type of each source: 1 Gaussian, 2 solid disk, 3 solid rectangle, 4 optically thin sphere, 5 exponential otherwise point. FMAX.......I polarization max of each source FPOS.......Offset value of the X,Y centroid of the sources in arcsec. Positive values mean increasing R.A. and DEC. These are offsets in the coordinates with R.A. scaled by cos(DEC) and are applied with the W term taken into account (as of 1997-04-16). See Explain at the end. FWIDTH.....Model major and minor axis in arcsec and PA in degrees. Full width or full width to half maximum (GAUS). INLIST.....Set this blank unless you want an input components list. Text file containing one line per source, giving I, DX, DY, Maj, Min, PA, type, spix, Dspix, Q, U, V blank separated free format and trailing zeros may be omitted. Used if NGAUSS > 1 and INLIST not blanks. The resulting NGAUS will be min (NGAUSS, #lines in INLIST). Limit 9999. Note that I, Q, U, V and the spectral indexes are assumed to apply at the header (reference) frequency. Any line in INLIST beginning with a $ or a # is taken as a comment and ignored. Negative values for I are allowed, but I=0 lines are ignored. ZEROSP.....Zero spacing flux of (2) Q, (3) U and (4) V in Jy used with the first source only and only if INLIST blank or NGAUSS=1. For more polarization in models, use the INLIST option. Be sure to put in the zeros (or other values) for the parameters that precede the Q,U,V values on each line in INLIST. FLUX.......Noise level to be added (in Jy. per Weight or Jy if FACTOR=0). This means, when FACTOR is not zero, that the noise added is FLUX/sqrt(weight) so that FLUX scales the data rms, assumed to be 1/sqrt(weight). DPARM......(1-5) Spectral index to use for components 1,2,3,4,noise (6-10) Spectral index curvature for comp 1,2,3,4,noise A non-blank INLIST gives these if NGAUS > 1. DPARM(5) and (10) still used for noise. See explain at the end. Curvature numbers are based on base 10 logarithms with a reference frequency of the *** header frequency ***. 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. WTUV.......If WTUV > 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. FQCENTER...> 0 => Change frequency axis reference pixel to Nchan / 2 + 1 else => do not change reference pixel BADDISK....The disk numbers to avoid for scratch files (sorting tables mostly).

UVMOD: Task which modifies UVDATA by scaling the existing data, and adding a specified model (See also IMMOD). DOCUMENTATION: Eric R. Nelson NRAO/VLA/UNM DATE OF DOCUMENTATION: 14 JUNE 1983 RELATED PROGRAMS: IMMOD, UVMAP, APCLN, COMB PURPOSE UVMOD modifies an already existing UV data file by the addition of one of several model types. 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 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. The spectral index is applied to make the peak flux log(F/F0) = spix * log(nu/nu0) + Dspix * log^2 (nu/nu0) where F0 is the model peak flux at the header reference frequency nu0 (BEFORE any application of FQCENTER). log functions are base 10. BMAJ, BMIN, BPA : In this discussion, BMAJ = GWIDTH(1,i) for the i'th component, BMIN = GWIDTH(2,i) for the i'th component, and BPA = GWIDTH(3,i) for the i'th component, The dimensions of the resulting functions are determined by BMAJ, BMIN and BPA (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 BMAJ and BMIN are both zero then all the models reduce to the point model. ZEROSP: This adverb, array indices 2-4, allows you to add polarization to the first model component only. 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. Spectral index parameters are entered as: x = log10 (freq / 1 GHz) F = F0 * exp ((Spix + Dspix * x) * x) where F is the flux and F0 is the flux at 1.0 GHz. The model fluxes at the reference frequency are converted to fluxes at 1 GHz.