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 # SRCNAME Source name QUAL -10.0 Calibrator qualifier -1=>all CALCODE Calibrator code ' '=>all STOKES Stokes of output ' ' -> HALF TIMERANG Time range to use SELBAND Bandwidth to select (kHz) SELFREQ Frequency to select (MHz) FREQID Freq. ID to select. ANTENNAS Antennas to copy 0=>all BASELINE Baselines with ANTENNAS 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. NMAPS 0.0 4096.0 No. maps to use for model. NGAUSS 0.0 Number Gaussians in NMAPS IN2NAME Cleaned map name (name) IN2CLASS Cleaned map name (class) IN2SEQ 0.0 9999.0 Cleaned map name (seq. #) IN2DISK Cleaned map disk unit # INVERS -1.0 46655.0 CC file version #. 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',' ' SMODEL Source model, 1=flux,2=x,3=y See HELP SMODEL for models. (1) not 0 -> ignore IN2NAME < 0 => solve for flux from SU table (-2 curvature) SPECINDX If SMODEL, spectral index SPECURVE If SMODEL, spectra curvature DOOUTPUT -1.0 1.0 > 0 save the UV files from model subtraction & division OUTNAME Output files name OUTSEQ Output files sequence OUTDISK Output files disk SOLINT Closure averaging (min) 0 => do not do closure DOPLOT > 0 => plot Re vs Im maps = 2 => plot histograms too CELLSIZE Cell size in asec (if SMODEL) APARM 2-D Re/Im plot controls (1) Plot subtracted data over +/-APARM(1)*RMS(sub) (2) Plot divided data over +/- APARM(2)*RMS(div) (3) Number pixels on a side for these images (4) Gaussian smoothing size PIXRANGE Intensity range to use FUNCTYPE 'LG' use logarithms in plot of image intensities LTYPE type of labeling DOTV > 0 use TV, else plot file GRCHAN TV graphics channel to use BADDISK Disks to avoid for scratch @ Output adverbs RPARM @ Results (see help)

EVAUV Task: Subtracts and divides a model 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 will compute the model and then both subtract it from the input UV data and divide it into the UV data. It then reports on statistical attributes of the two data sets. The mean and rms of the real and imaginary parts and the amplitude are reported for the model subtracted data set and for the divided data set (after a constant 1.0 is subtracted from the real part). The amplitude mean is computed in a robust fashion and controls which samples enter into the real and imaginary part averages. Then the number of samples more than 3 rms away from the mean amplitude, the total number of samples, and the average of the absolute difference of the bad samples and the mean are reported. The model will use Clean Components if they are present and otherwise will do the image. No correction for convolution by the Clean Beam (if any) are made in the latter case. Offset sub-images are not supported. Following the UV analysis, the robust mean and rms over the images are determined and reported. Note that this mean and rms should omit any real source signals. Model images made with both values of IMAGR's DO3DIMAG option are handled correctly, as are multi-scale images. Set NMAPS = NFIELD * NGAUSS. EVAUV works only on single-source files. Sample output: -------------- Image mean -7.3490E-07 rms 1.5078E-04 method real part imaginary part amplitude subtract 0.0002 +- 0.157 0.0002 +- 0.157 0.1977 +- 0.103 divide-1 -0.0040 +- 6.770 0.0017 +- 6.770 7.9390 +- 5.364 method # bad samples total samples avg bad amp subtract 79124 5333006 0.3918 divide-1 267058 5333006 27.1805 -------------- The optional plots are 1. The average and rms of the model subtracted data in bins of UV-plane radius. 2. The average and rms of the model divided - 1.0 data in bins of UV-plane radius. 3. The histogram of image pixels over a pixel value range selected by the user or the first of the model images. 4. The histogram of image pixels over a pixel range of plus/minus 5 times the rms of the first of the model images. 5. The real vs imaginary visibilities of the model subtracted data over a range of APARM(1) times the amplitude rms. The plot is a contour in logarithmic intervals of the 2-D histogram image controlled by APARM. Contours are drawn at 0.5, 1, 1.5, 2, 2.5, 3, etc in the log of the counts. 6. The real and imaginary gains minus (1,0) of the model divided data over a range of APARM(2) times the amplitude rms. Logarithmic contours also. Actually plots 5 and 6 cover somewhat larger areas but some data samples will not be plotted (totals on and off the plot are reported). The task will now compute and report closure phase and amplitude statistics from the "visibilties" of the gain data set (produced by division of the input data by the model, not subtracting (1,0)). It will do this only when the STOKES value is appropriate: HALF, RRLL, RR, LL, VVHH, VV, and HH and when SOLINT is not zero.. It will do these as a function of IF. Closure amplitude in the quadrangle of antennas a, b, c, and d is defined as LN [ (amp_ab * amp_cd) / (amp_ac * amp_bd) ] which should be independent of any antenna-based instrumental gains. Closure phase in the triangle of antennas a, b, and c is defined as Phase_ab - Phase_ac + Phase_bc which should be independent of any antenna-based instrumental phases. Since these apply to the RR and LL, closure amplitude and phase are only meaningful in the STOKES values listed above. The data/model data set should ideally be a point source at the coordinate origin and so these closure parameters should be zero, if the model is perfect. The use of closure statistics to evaluate potential calibration sources is discussed in detail in the paper Xu, M.H., Anderson, J.M., Heinkelmann, R., Lunz, S., Schuh, H., Wang, G.L., 2019, "Structure Effects for 3417 Celestial Reference Frame Radio Sources", Ap. J. Suppl., 242:5. Available via: https://doi.org/10.3847/1538-4365/ab16ea Closure information is produced by the following tasks: CLPLT Plots closure phases for individual triangles as a funtion of time. CAPLT Plots closure amplitudes for individual quadrangles as a funtion of time. EVACL Computes the RMS of closure phase and amplitude as a function of IF for an individual Stokes. EVAUV Computes two data sets: data-model and data/model. The closure RMSes of the latter may be computed as functions of polarization and IF. Other statistics are computed and plotted. CLOSE Computes the RMS closure phase or amplitude as a function of spectral and IF channel. A plot is produced and a text file may be written. 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. SRCNAME....Source name to be gridded. Must specify if input is a multi-source data set, otherwise all sources are included. QUAL.......Qualifier of source to be processed. -1 => all. CALCODE....Calibrator code of source to be processed. ' '=> all. 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. ANTENNAS...A list of the antennas to list. If any number is negative then all antenna numbers in ANTENNAS are NOT desired and all others are. All 0 => list all. Note that antenna numbers that do not appear in the relevant antenna file(s) or which appear with a name containing the string 'OUT' are not displayed. BASELINE...Baselines are specified for the LIST option using BASELINE. Eg. baselines 1-6,1-8, 2-6 and 2-8 use ANTENNAS=1,2; BASELINE=6,8. SUBARRAY...Sub-array number to process. 0=>all (okay if not calibration) BIF........Start IF; 0 -> 1 EIF........End IF; 0 -> max BCHAN......Start channel; 0 -> 1 ECHAN......End channel; 0 -> max NCHAV......Number of channels to average. Note that ECHAN is adjusted if necessary to make (ECHAN-BCHAN+1) and integer multiple of NCHAV. 0 -> 1. 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). 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. NGAUSS.....Number of Gaussians in NMAPS. 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. WARNING: SMODEL overrides the above model map specification. INVERS.....CC file ver. number. 0 => highest. 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! 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) at header frequency 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) If SMODEL(1) < 0, EVAUV will try to solve for the spectrum using the SU table. SMODEL(1) < -1.5 means to include curvature in the solution. SPECINDX...Spectral index to use with SMODEL(1) > 0. Alternatively it will be solved using the SU table if SMODEL(1) < 0. Not used when SMODEL(1) = 0. SPECURVE...Spectral curvature to use with SMODEL when SMODEL(1) > 0. log(T(f)/T(f0) = S * log(f/f0) + C(1) * (log(f/f0))^2 + C(2) * (log(f/f0))^3 + C(3) * (log(f/f0))^4 where S is SPECINDEX and C is SPECURVE, f0 is the header frequency and all logs are base 10. Will be solved from the SU table if SMODEL(1) < -1.5. DOOUTPUT...> 0 => save the residual (data minus model) and gain (data divided by model) files as cataloged files. <=0 => delete these files at the end of the task. OUTNAME....Output files name (name). ' ' -> INNAME The classes will be EVAUVS and EVAUVD for subtracted and divided data sets. OUTSEQ.....Output files name (seq #). 0 -> next highest OUTDISK....Output files disk number. 0 -> highest with space. SOLINT.....= 0 => do not do closure phases and amplitudes If SOLINT > 0, the time interval (minutes) over which to average the data in order to form the closure phase and amplitude. This function works on the gain (data / model) which should, with an ideal model, be (1, 0). Use of a very small value of SOLINT (but > 0) will cause inadequately aligned data to be discarded in order to avoid misleadingly high closure phases and amplitudes. However larger SOLINTs appear to go faster. If SOLINT < 0, the task will form a closure phase/amplitude as soon as it has accumulated at least one sample for each of the three/four baselines in the triangle/quadrangle. These are then averaged over abs(SOLINT) minutes. DOPLOT.....> 0 => Plot the two real versus imaginary histogram images as contour maps with contours in the log at intervals of 0.5, 1, 1.5, 2.0, 2.5 etc > 1.5 => Also plot two plots showing the mean and rms residual and (gain-1) versus baseline length and two plots of the image histogram. <= 0 => no plots CELLSIZE...Cell size of images in arc seconds. Used when there are no model images (i.e. when using SMODEL) to scale histograms of data versus radius in UV plane. Default 0.1 asec which is not likely to be useful. APARM......The real parts of the model subtracted and model divided data are plotted against the corresponding imaginary parts in two contour plots of the 2-D histogram images. The contour intervals are 0.5 in the logarithm of the counts in each cell of the images. APARM controls the extent of these images, their size, and whether they are smoothed: (1)....The model subtracted data are plotted over a range of +/- APARM(1) times the subtracted amplitude rms. 0 -> 5 (2)....The model divided data are plotted over a range of +/- APARM(2) times the divided amplitude rms. 0 -> 10 (3)....The plots are summed in images of APARM(3) pixels on a side. 0 -> SQRT (Nvis * Nchan / 10) <= 1024 (4)....The images are smoothed by a Gaussian kernel of APARM(4) pixels on a side before plotting. 0 -> no smoothing - will be set to an odd number <= 33. Hints: For large numbers of samples, you may wish to set APARM(1) and APARM(2) to higher numbers, e.g. 15 and 25 and you will want to smooth by e.g. 5 or 9 before plotting. For a small data set, a small image is a good idea. PIXRANGE...The range of image intensities to be used in the histogram that is intended to encompass the full interesting range of the image(s). 0 => use the range in the header of the first image. FUNCTYPE...'LG' => use logarithms in the plots of the image histograms, else do a linear plot. LTYPE.......Labelling type, see HELP LTYPE for details: 1 = border, 2 = no ticks, 3 or 7 = standard, 4 or 8 = relative to ref. pixel, 5 or 9 = relative to subimage (BLC, TRC) center, 6 or 10 = pixels. 7-10 all labels other than tick numbers and axis type are omitted. Less than 0 is the same except that the plot file version number and create time are omitted. Add n * 100 to alter the metric scaling. DOTV.......> 0 => plot on the TV, else make plot files. GRCHAN.....If plotting on the TV, use graphics plane GRCHAN. 0 => use more than one graphics plane, separating portions of the plot by color. BADDISK....The disk numbers to avoid for scratch files. RPARM......Output adverb with results ( 1, 2) Subtracted real part mean, rms ( 3, 4) Subtracted imag part mean, rms ( 5, 6) Subtracted ampl part mean, rms ( 7, 8) Subtracted fraction bad and average bad ( 9,10) Divided - 1 real part mean, rms (11,12) Divided - 1 imag part mean, rms (13,14) Divided - 1 ampl part mean, rms (15,16) Divided - 1 fraction bad and average bad (17,20) Image mean, rms of mean, rms, rms of rms (21,23) Average phase & amplitude closure pol #1 (24,25) Average phase & amplitude closure pol #2 (26) SMODEL(1) actually used (if > 0) (27) SPECINDX if SMODEL used (28,30) SPECURVE if SMODEL used