INNAME Input UV data INCLASS Input UV data (class) INSEQ Input UV data (seq. #) INDISK Input UV data disk drive # SOURCES Source (pointings) list QUAL -10.0 Source qualifier -1=>all CALCODE Calibrator code ' '=>all TIMERANG Time range to process. SELBAND Bandwidth to select (kHz) SELFREQ Frequency to select (MHz) FREQID Freq. ID to select. BIF 0.0 100.0 Lowest IF number 0=>all EIF 0.0 100.0 Highest IF number 0=>all BCHAN 0.0 2048.0 Lowest channel number 0=>all ECHAN 0.0 2048.0 Highest channel number 0=>all SUBARRAY 0.0 1000.0 Subarray, 0=>all DOCALIB -1.0 101.0 > 0 calibrate data & weights > 99 do NOT calibrate weights GAINUSE CL/SN table to apply DOPOL -1.0 10.0 If >0 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 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. UVRANGE 0. Min & max baseline (klambda) SOLINT Time interval (sec) SCANLENG Scan length (sec) REFANT Reference antenna for VDIF OPTYPE 'VDIF', 'VRFI', 'TIME' DOROBUST -1.0 1.0 > 0 -> robust spectral avg DOCAT -1.0 1.0 > 0 => keep the XX file DOCRT -3.0 132.0 > 0 -> use the terminal, > 72 => terminal width 0 -> no printing else use the line printer OUTPRINT Printer disk file to save PRTLEV > 0 => debug messages BADDISK -1.0 1000.0 Disks to avoid for scratch. ARRAY2 @ Answers from first source: @ ARRAY2(1-5,1) robust averages @ ARRAY2(6-10,1) rms of robust @ averages @ ARRAY2(11-20,1) fraction of @ closure error by tenths. @ ARRAY2(1-5,2) # > 10 sigma @ ARRAY2(6-10,2) # > 20 sigma @ ARRAY2(11,2) # orphans @ ARRAY2(12,2) total # samples

FINDR Type: Task Use: This task computes the average weight, visibility amplitude and rms fluctuations in each baseline and correlator over a specified range of spectral channels and time. It then converts the baseline-based quantities into apparent antenna-based quantities. Finally, using robust averaging, it determines the "normal" amplitude, weight, and rms and deviations in these quantities. It returns the normal values and some estimates of the extremes found in the selected subset of the data. The VDIF OPTYPE computes the average weight and complex visibility in each baseline and correlator over a specified range of spectral channels and time. It then converts the baseline-based quantities into apparent antenna-based quantities. Then it determines the amplitude of the vector difference between each visibility and the median of the visibilities in a window (in time) surrounding the visibility. Adverbs: INNAME.....Input UV data file INCLASS....Input UV data file (class). Standard defaults. INSEQ......Input UV data file (seq. #). 0 => highest. INDISK.....Input UV data file disk drive #. 0 => any. SOURCES....List of sources (pointings) to be processed. '*' or blank = all; a "-" before a source name means all except ANY source named. QUAL.......Only sources with a source qualifier number in the SU table matching QUAL will be used if QUAL is not -1. CALCODE...."sources" may be selected on the basis of the calibrator code given in the SU table. ' ' => any calibrator code selected '* ' => any non blank code (cal. only) '-CAL' => blank codes only (no calibrators) NB: The CALCODE test is applied in addition to the other tests, i.e. SOURCES and TIMERANG, in the selection of sources to process. CALCODE affects only the selection of calibrators. TIMERANG...Time range of the data to be processed. In order: Start day, hour, min. sec, end day, hour, min. sec. Days relative to reference 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 overide that of FREQID. However, setting SELBAND and SELFREQ may result in an ambiguity. In that case, the task will request that you use FREQID. 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). BIF........First IF to select. 0=>all. EIF........Highest IF to select. 0=>all higher than BIF BCHAN......First channel to select. 0=>all. ECHAN......Highest channel to select. The spectral channels are used as separate samples of the visibility to provide better statistics in determining the rms. SUBARRAY...Subarray number to consider. 0=>1. GAINUSE....CL table version number to apply. 0=> highest. DOPOL......If > 0.5 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 appply. <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. A new FG table is created to hold the new flags; if FLAGVER >= 0, the FG table used on the data is copied into the output file before the new flags are computed. 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. BPVER......Specifies the version of the BP table 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). UVRANGE....(Minimum,Maximum) baseline (kilo-lambda) to process. SOLINT.....The interval over which the rms is determined. 0 => 60 seconds. SCANLENG...Length of "scan" for VDIF in seconds. The vector average of the visibilities over the scan is differenced from the individual visibility to make the "vector difference". REFANT.....Reference antenna suggestion for VDIF. OPTYPE.....Choice of methods for examining the data: 'TIME' -> (default) It computes the baseline amplitudes and rmses in each SOLINT and converts them to antenna- based values. A robust method is used and closure failure statistics maintained. It then saves them for later. When all data have been read, the antenna-based results are analyzed, source by source, antenna by antenna. Regression is used to compute the mean antenna amplitude and mean rms and the rmses in these parameters. Outliers are then counted and reported. Statistics on the failure statistics are also reported. 'VDIF' -> It computes the baseline reals, imaginaries, and weights in each SOLINT and converts then to antenna-based values. A robust method is used and closure failure statistics maintained. It saves them for later. When all data have been read, the antenna-based results are analyzed source by source, correlator by correlator. First the visbility at each time is differenced with the average of the visibilities surrounding it. The weights, amplitudes, and amplitudes of the differences are then averaged and reported. Outliers are counted and reported. Statistics on the failure statistics are also reported. 'VRFI' -> It computes the baseline reals, imaginaries, and weights in each SOLINT and saves as many as it can for later. When the source changes, the buffer is full, or all data have been read, the baseline-based results are analyzed correlator by correlator. First the visbility at each time is differenced with the average of the visibilities surrounding it. The weights, amplitudes, and amplitudes of the differences are then averaged and reported. Outliers are counted and reported. DOROBUST...> 0 => Do robust averaging of the spectral channels in each time and baseline. Normal averaging is done over time. <= 0 => Normal averaging (all samples included) is done over all channels as well as time. DOCAT......> 0 => keep the XX extension file generated by the TIME OPTYPE. Otherwise delete it on exit. DOCRT......Zero means write the flag table without comment. False (< 0) use the line printer if OUTPRINT = ' ' else write named OUTPRINT file only. When OUTPRINT is not blank, DOCRT=-2 suppresses the page-feed character on page headers and DOCRT=-3 suppresses page headers and most other header information. True (> 0) use the terminal interactively. The task will use the actual terminal width as a display limit unless 72 < DOCRT < width. In that case, the display limit will be DOCRT characters. OUTPRINT...Disk file name in which to save the line printer output. ' ' => use scratch and print immediately for interactive jobs - batch jobs use OUTPRINT = 'PRTFIL:BATCHjjj.nnn' (jjj= job #, nnn = user #). When OUTPRINT is not blank, multiple outputs are concatenated, and the file is not actually printed. PRTLEV.... Set > 0 to get various messages: 1 Print the robust averages over time for each antenna, IF, and polarization and print the number of samples that would be self flagged and the number that would be flagged using the global averages. 2. Also print the antenna-based amplitudes, rms's, and weights for each antenna, IF, polarization, and time. (You could keep the XX table and use PRTAB but this may be easier and neater.) 3. Also print failure information from the routine that converts baseline-based data to antenna-based. 4. Also print the antenna-based solutions from the solver. This is for desperate programmers mainly. BADDISK....This array contains the numbers of disks on which it is desired that scratch files not be located. Output adverbs: ARRAY2.....(We will probably rename this someday but for now we use this already known scratch adverb). Using the first source (or the average of all sources with GAIN) From the robust average of robust antenna averages ( 1,1) Vector-averaged amplitude or gain ( 2,1) Vector-averaged data rms or amplitude of the vector difference on VDIF/VRFI ( 3,1) Scalar-averaged amplitude or gain ( 4,1) Scalar-averaged data rms ( 5,1) Weight ( 6,1) RMS in Vector-averaged amplitude or gain ( 7,1) RMS in Vector-averaged data rms or amplitude of the vector difference on VDIF/VRFI ( 8,1) RMS in Scalar-averaged amplitude or gain ( 9,1) RMS in Scalar-averaged data rms (10,1) RMS in Weight (11,1) Fraction of data with closure failure fraction > 0, < 0.1 (12,1) Fraction of data with closure failure fraction >= 0.1, < 0.2 ... (20,1) Fraction of data with closure failure fraction >= 0.9, <= 1.0 Number of antenna time averages that differ from the overall average (ARRAY2(I,1)) in parameter I (I=1-5) by more than N times the RMS (ARRAY2(5+I,1)) in that parameter: ( 1,2) N = 10 * RMS in Vector-averaged amplitude/gain ( 2,2) N = 10 * RMS in Vector-averaged data rms/Vdif ( 3,2) N = 10 * RMS in Scalar-averaged amplitude/gain ( 4,2) N = 10 * RMS in Scalar-averaged data rms ( 5,2) N = 10 * RMS in Weight ( 6,2) N = 20 * RMS in Vector-averaged amplitude/gain ( 7,2) N = 20 * RMS in Vector-averaged data rms/Vdif ( 8,2) N = 20 * RMS in Scalar-averaged amplitude/gain ( 9,2) N = 20 * RMS in Scalar-averaged data rms (10,2) N = 20 * RMS in Weight (11,2) Number of one-sample "averages" for which there is no rms = number of orphans (12,2) Total number of time averages * Number IFs * Number polarizations ARRAY2(3,1), (4,1), (8,1), (9,1) (3,2), (4,2), (8,2), (9,2), and (11,2) are zero on VDIF and VRFI.

Explanation of the methods used FINDR starts by averaging the calibrated and flagged data over a period of SOLINT seconds. Data with a time difference <= SOLINT are included. Thus, a SOLINT of 60 with records every 10 seconds will include 7 records; to get only 6 set SOLINT to something > 50 and < 60 such as 55. The data from each included antenna pair, IF, and polarization are kept separate, but the spectral channels from BCHAN through ECHAN are averaged together. For OPTYPEs other than VDIF and VRFI: During the averaging, the apparent rms and average weight are found including all data (no outlier rejection). The rms and amplitude are averaged by both vector and scalar means. For OPTYPEs VDIF and VRFI: The averaging is done to determine the "individual" records to be compared with the "scan" averages of such records in a region of time centered on the individual records. Typically, with decent signal-to-noise, one will set SOLINT for VDIF to less than the time between records. The "scan" averaging is done over the scan interval using parameter SCANLENG and is done by finding the median real and imaginary parts which should be less sensitive to outliers. Failures in antenna-based solutions are marked as such and regarded as data that would be flagged by FLAGR. =============== OPTYPE 'TIME' The default. The task converts the average amplitudes, rms's, and weights of the antenna pairs into antenna-based values using the assumption that Amp(A1,A2,I,P) = SQRT (Amp(A1,I,P) * Amp(A2,I,P)) Sig(A1,A2,I,P) = SQRT (Sig(A1,I,P) * Sig(A2,I,P)) Wt(A1,A2,I,P) = SQRT (Wt(A1,I,P) * Wt(A2,I,P)) It uses robust methods (outliers ignored) to compute the antenna-based values and then counts the fraction [Fr(A,I,P)] of baselines for each antenna that are more than 3 times the rms away from the final solution. The values of Amp(A,I,P), Sig(A,I,P), Wt(A,I,P) and Fr(A,I,P) are then written to an XX table (which may be saved by setting DOCAT > 0). When all of the data have been read and averaged and the antenna-based results written to the XX table, these results are read back into memory. One source at a time, the task determines the robust average of each of the five parameters (vector amplitude, vector rms, scalar amplitude, scalar rms, weight) and the robust rms's in each of these robust averages for each antenna, IF, and polarization. By "robust" average, we mean an average determined by repeated passes through the data with the averaging process discarding outlier points. The robust average of these robust averages is then determined and printed in the message window and returned in ARRAY2(I,1). For each source and one antenna, IF, and polarization at a time, the task loops over time counting the "questionable" data. A sample is questionable if ABS(Par(A,I,P,t)-AvPar(A,I,P)) > N * AvParrms(A,I,P)) where Par(A,I,P,t) is the parameter value of antenna A at IF I, polarization P, averaged at time t; AvPar(A,I,P) is the robust average over time of that antenna, IF, and polarization, AvParrms(A,I,P) is the uncertainty in that average over time. Two values of N are used - 5 and 10 and the numbers of questionable samples are reported (if PRTLEV >= 1). The process is then repeated to compare the SOLINT-average samples in each parameter with the global (over all antennas, IFs, polarizations) averages. For each source and one antenna, IF, and polarization at a time, the task loops over time counting the "questionable" data. A sample is questionable if ABS(Par(A,I,P,t)-GlobalAvPar) > N * GlobalAvParrms(A,I,P)) where Par(A,I,P,t) is the parameter value of antenna A at IF I, polarization P, averaged at time t; GlobalAvPar is the robust average over antenna, IF, and polarization of the robust averages over time; and GlobalAvParrms is the uncertainty in that average over A, I, and P. The values of N used are 10 and 20 and the numbers of questionable samples are reported (if PRTLEV >= 1) and are returned in ARRAY2(1-10,2). The task also computes the fraction of failure fractions having value exactly 0 and 1 and in bins of width 0.1. These are reported and the binned values returned in ARRAY2(11,1) through ARRAY2(20,1). =============== OPTYPE 'VDIF' The task converts the average weights and complex visibilities of the antenna pairs into antenna-based values using the assumption that Amp(A1,A2,I,P) = SQRT (Amp(A1,I,P) * Amp(A2,I,P)) Phs(A1,A2,I,P) = Phs(A1,I,P) - Phs(A2,I,P) Wt(A1,A2,I,P) = SQRT (Wt(A1,I,P) * Wt(A2,I,P)) It uses robust methods (outliers ignored) to compute the antenna-based values and then counts the fraction [Fr(A,I,P)] of baselines for each antenna that are more than 2.5 times the rms away from the final solution. The values of Amp(A,I,P), Phs(A,I,P) (as real and imaginary), Wt(A,I,P), Fr(A,I,P), and reference antennas (I,P) are then written to an XX table (which may be saved by setting DOCAT > 0). When all of the data have been read and averaged and the antenna-based results written to the XX table, these results are read back into memory. If needed, the data are put on a consistent reference antenna basis. One source at a time, the task then loops over each antenna, IF, and polarization converting the time sequence of reals and imaginaries into time sequences of amplitudes and amplitudes of the "vector difference" between the current antenna visibility and the vector average of antenna visibilities within SCANLENG/2 of the current time. Note that, in this case, the averages are generated by finding the median value of the reals and the median value of the imaginaries. This should be somewhat less succeptible to outliers than straight averaging and better than robust averaging as well for the small number of samples which will be normal. Once source at a time, the task determines the robust averages and rmses of the amplitudes, amplitudes of the vector differences, and the weights over all antennas, IFs, and polarizations and reports them. It then reports the number of samples more than 10 and 20 times this rms from the mean for each antenna, IF, and polarization. The averages, rmses, and total number of deviant points are returned to AIPS in ARRAY2 for the first source. The task also computes the fraction of failure fractions having value exactly 0 and 1 and in bins of width 0.1. These are reported and the binned values returned in ARRAY2(11,1) through ARRAY2(20,1). =============== OPTYPE 'VRFI' The task accumulates SOLINT averages in memory until the source changes, the data ends, or the number of times that it can hold is exhausted. For each time, the task then loops over each antenna pair, IF, and polarization finding the amplitude of the "vector difference" between the current visibility and the vector average of visibilities for that antenna pair within SCANLENG/2 of the current time. Note that, in this case, the averages are generated by finding the median value of the reals and the median value of the imaginaries. This should be somewhat less succeptible to outliers than straight averaging and better than robust averaging as well for the small number of samples which will be normal. The task determines the robust averages and rmses of the visibility amplitudes, the amplitudes of the vector differences, and the weights and reports them. It also counts the samples that are more than 10 and 20 times the rms away from the robust averages and reports them. The task then loops for another source or buffer load as appropriate. The averages of the averages and rmses and the sums of the number of deviations are returned to AIPS in ARRAY2.