Source code for casatasks.calibration.gaincal

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[docs]def gaincal(vis, caltable='', field='', spw='', intent='', selectdata=True, timerange='', uvrange='', antenna='', scan='', observation='', msselect='', solint='inf', combine='', preavg=-1.0, refant='', refantmode='flex', minblperant=4, minsnr=3.0, solnorm=False, normtype='mean', gaintype='G', smodel='', calmode='ap', solmode='', rmsthresh='', corrdepflags=False, append=False, splinetime=3600.0, npointaver=3, phasewrap=180.0, docallib=False, callib='', gaintable='', gainfield='', interp='', spwmap='', parang=False): r""" Determine temporal gains from calibrator observations [`Description`_] [`Examples`_] [`Development`_] [`Details`_] Parameters - vis_ (string) - Name of input visibility file - caltable_ (string='') - Name of output gain calibration table - field_ (string='') - Select field using field id(s) or field name(s) - spw_ (string='') - Select spectral window/channels - intent_ (string='') - Select observing intent - selectdata_ (bool=True) - Other data selection parameters .. raw:: html <details><summary><i> selectdata = True </i></summary> - timerange_ (string='') - Select data based on time range - uvrange_ (variant='') - Select data by baseline length. - antenna_ (string='') - Select data based on antenna/baseline - scan_ (string='') - Scan number range - observation_ ({string, int}='') - Select by observation ID(s) - msselect_ (string='') - Optional complex data selection (ignore for now) .. raw:: html </details> - solint_ (variant='inf') - Solution interval - combine_ (string='') - Data axes which to combine for solve (obs, scan, spw, and/or field) - preavg_ (double=-1.0) - Pre-averaging interval (sec) (rarely needed) - refant_ (string='') - Reference antenna name(s) - refantmode_ (string='flex') - Reference antenna mode - minblperant_ (int=4) - Minimum baselines _per antenna_ required for solve - minsnr_ (double=3.0) - Reject solutions below this SNR - solnorm_ (bool=False) - Normalize (squared) solution amplitudes (G, T only) .. raw:: html <details><summary><i> solnorm = True </i></summary> - normtype_ (string='mean') - Solution normalization calculation type: mean or median .. raw:: html </details> - gaintype_ (string='G') - Type of gain solution (G,T,GSPLINE,K,KCROSS) .. raw:: html <details><summary><i> gaintype = GSPLINE </i></summary> - splinetime_ (double=3600.0) - Spline timescale(sec); All spw\'s are first averaged. - npointaver_ (int=3) - The phase-unwrapping algorithm - phasewrap_ (double=180.0) - Wrap the phase for jumps greater than this value (degrees) .. raw:: html </details> - smodel_ (doubleArray='') - Point source Stokes parameters for source model. - calmode_ (string='ap') - Type of solution" (\'ap\', \'p\', \'a\') - solmode_ (string='') - Robust solving mode: (\'\', \'L1\', \'R\',\'L1R\') - rmsthresh_ (doubleArray='') - RMS Threshold sequence (for solmode=\'R\' or \'L1R\'; see help) - corrdepflags_ (bool=False) - Respect correlation-dependent flags - append_ (bool=False) - Append solutions to the (existing) table - docallib_ (bool=False) - Use callib or traditional cal apply parameters .. raw:: html <details><summary><i> docallib = False </i></summary> - gaintable_ (stringArray='') - Gain calibration table(s) to apply on the fly - gainfield_ (stringArray='') - Select a subset of calibrators from gaintable(s) - interp_ (stringArray='') - Interpolation parameters for each gaintable, as a list - spwmap_ (intArray='') - Spectral window mappings to form for gaintable(s) .. raw:: html </details> .. raw:: html <details><summary><i> docallib = True </i></summary> - callib_ (string='') - Cal Library filename .. raw:: html </details> - parang_ (bool=False) - Apply parallactic angle correction .. _Description: Description The complex time-dependent gains for each antenna/spwid are determined from the ratio of the data column (raw data), divided by the model column, for the specified data selection. The gains can be obtained for a specified solution interval for each spectral window, or by a spline fit to all spectral windows simultaneously. Any specified prior calibrations (e.g., bandpass) will be applied on the fly. .. rubric:: Introduction The fundamental calibration to be done on your interferometer data is to calibrate the antenna-based gains as a function of time, using **gaincal**. Systematic time-dependent complex gain errors are almost always the dominant calibration effect, and a solution for them is almost always necessary before proceeding with any other calibration solve. Traditionally, this calibration type has been a catch-all for a variety of similar effects, including: the relative amplitude and phase gain for each antenna/polarization, phase and amplitude drifts in the electronics of each antenna, amplitude response as a function of elevation (gain curve), and tropospheric amplitude and phase effects. In CASA, it is possible to handle many of these specific effects separately, as available information, circumstances, and required accuracy warrant, but if accuracy is not paramount it is still possible to solve for the net effect using a quick-and-dirty **gaincal**. In fact, **gaincal** is often used for an initial exploration of a dataset, to find data problems, etc. Also, a provisional gaincal solution can be used as prior calibration to optimize bandpass calibration. Such gaincal solutions are typically discarded. It is best to have determined a (constant or slowly-varying) bandpass from the frequency channels by solving for the **bandpass**, and to include any other ancillary calibration that may be available via **gencal** (e.g., gaincurve, antenna position corrections, opacity, etc.). .. rubric:: Common calibration solve parameters See `Solving for Calibration <../../notebooks/synthesis_calibration.ipynb#Solve-for-Calibration>`__ for more information on the task parameters **gaincal** shares with all solving tasks, including data selection, general solving properties and arranging prior calibration. Also see the **rerefant** task documentation for the behavior of reference antenna application. Below we describe parameters unique to **gaincal**, and those common parameters with unique properties. .. rubric:: Gain calibration types: *gaintype* The *gaintype* parameter selects the type of gain solution to compute. For complex gain calibration, the choices are *'T'*, *'G'*, and *'GSPLINE'*. The **gaincal** task also supports rudimetary delay solutions using *'K'* and *'KCROSS'*. .. rubric:: Polarization-dependent sampled gain (*gaintype='G'*) Generally speaking, *gaintype='G'* can represent any multiplicative polarization- and time-dependent complex gain effect downstream of the polarizers. (Polarization- and time-independent effects upstream of the polarizers may also be treated implicitly with G.) Multi-channel data (per spectral window) will be averaged in frequency before solving (use calibration type B to solve for frequency-dependent effects within each spectral window). .. rubric:: Polarization-independent sampled gain (*gaintype='T'*) At high radio frequencies (>10 GHz), it is often the case that the most rapid time-dependent gain errors are introduced by the troposphere, and are polarization-*independent*. It is therefore unnecessary to solve for separate time-dependent solutions for both polarizations, as is the case for *gaintype='G'*. Thus *gaintype='T'* is available to calibrate such tropospheric effects, differing from G only in that a single common solution for both polarizations is determined. In cases where only one polarization is observed, *gaintype='T'* is adequate to describe the time-dependent complex multiplicative gain calibration entirely. For the dual-polarization case, it is necessary to ensure that the two polarizations are, in fact, coherent by using a prior G or (unnormalized) bandpass calibration. .. rubric:: Spline gains (*gaintype='GSPLINE'*) At high radio frequencies, where tropospheric phase fluctuates rapidly, it is often the case that there is insufficient signal-to-noise to obtain robust G or T solutions on timescales short enough to track the variation. In this case it is desirable to solve for a best-fit functional form for each antenna using the GSPLINE solver. This fits a time-series of cubic B-splines to the phase and/or amplitude of the calibrator visibilities. The *combine* parameter can be used to combine data across spectral windows, scans, and fields. Note that if you want to use *combine='field'*, then all fields used to obtain a GSPLINE amplitude solution must have models with accurate relative flux densities. Use of incorrect relative flux densities will introduce spurious variations in the GSPLINE amplitude solution. The GSPLINE solver requires a number of unique additional parameters, compared to ordinary G and T solving. The sub-parameters are: :: gaintype = 'GSPLINE' # Type of solution (G, T, or GSPLINE) splinetime = 3600.0 # Spline (smooth) timescale (sec), default=1 hours npointaver = 3 # Points to average for phase wrap phasewrap = 180 # Wrap phase when greater than this The duration of each spline segment is controlled by *splinetime*. The *splinetime* will be adjusted automatically such that an integral number of equal-length spline segments will fit within the overall range of data. Phase splines require that cycle ambiguities be resolved prior to the fit; this operation is controlled by *npointaver* and *phasewrap*. The *npointaver* parameter controls how many contiguous points in the time-series are used to predict the cycle ambiguity of the next point in the time-series, and *phasewrap* sets the threshold phase jump (in degrees) that would indicate a cycle slip. Large values of *npointaver* improve the SNR of the cycle estimate, but tend to frustrate ambiguity detection if the phase rates are large. The *phasewrap* parameter may be adjusted to influence when cycles are detected. Generally speaking, large values (>180 degrees) are useful when SNR is high and phase rates are low. Smaller values for *phasewrap* can force cycle slip detection when low SNR conspires to obscure the jump, but the algorithm becomes significantly less robust. More robust algorithms for phase-tracking are under development (including traditional fringe-fitting). .. warning:: GSPLINE solutions cannot be used in fluxscale. You should do at least some long-timescale G amplitude solutions to establish the flux scale, then do GSPLINE in phase before or after to fix up the short timescale variations. Note also that the phase tracking algorithm in GSPLINE needs some improvement. .. rubric:: Single- and multi-band delay (*gaintype='K'*) With *gaintype='K'* **gaincal** solves for simple antenna-based delays via Fourier transforms of the spectra on baselines to (only) the reference antenna. This is not a global fringe fit but will be useful for deriving delays from data of reasonable SNR. If *combine* includes *'spw'*, multi-band delays solved jointly from all selected spectral windows will be determined, and will be identified with the first spectral window id in the output *caltable*. When applying a multi-band delay table, a non-trivial *spwmap* is required to distribute the solutions to all spectral windows (fan-out is not automatic). As of CASA 5.6, multi-band delays can be solved using heterogeneous spws (e.g., with differing bandwidths, channelizations, etc.). After solving for delays, a subsequent **bandpass** is recommended to describe higher-order channel-dependent variation in the phase and amplitude. .. rubric:: Cross-hand delays (*gaintype='KCROSS'*) With *gaintype='KCROSS',* **gaincal** solves for a global cross-hand delay. This is used only when doing polarimetry. Use *parang=T* to apply prior gain and bandpass solutions. This mode assumes that all cross-hand data (per spw) share the same cross-hand delay residual, which should be the case for a proper gain/bandpass calibration. See sections on polarimetry for more information on use of this mode. Multi-band cross-hand delays are only supported for homogeneous spws (same bandwidths, channelizations, etc.). .. rubric:: Solution normalization: *solnorm, normtype* Nominally, gain solution amplitudes are implicitly scaled in amplitude to satisfy the the effective amplitude ratio between the visiibility data and model (as pre-corrected or pre-corrupted, respectively, by specified prior calibrations). If *solnorm=True*, the solution amplitudes will be normalized so as to achieve an effective time- and antenna-relative gain calibration that will minimally adjust the global amplitude scale of the visibility amplitudes when applied. This is desirable when the model against which the calibration is solved is in some way incomplete w.r.t. the net amplitude scale, but a antenna- and time-relative calibration is desired, e.g., amplitude-sensitive self-calibration when not all of the total flux density has been recovered in the visibility model. The normalization factor is calculated from the power gains (squared solution amplitudes) for all antennas and times (per spw) according to the the setting of *normtype*. If *normtype='mean'*, (the default), the square root of the mean power gain is used to normalize the amplitude gains. If *normtype='median'*, the median is used instead, which can be useful to avoid biasing of the normalization by outlier amplitudes. The default for *solnorm* is *solnorm=False*, which means no normalization. .. rubric:: Robust solving: *solmode, rmsthresh* .. warning:: Robust solving modes in gaincal are considered experimental in CASA 5.5. With more experience and testing in the coming development cycles, we will provide more refined advice for use of these options. Nominally (*solmode=''*), gaincal performs an iterative, steepest-descent chi-squared minimization for its antenna-based gain solution, i.e., minimizaiton of the L2 norm. Visibility outliers (i.e., data not strictly consistent with the assumption of antenna-based gains and the supplied visibility model within the available SNR) can significantly distort the chi-squared gradient calculation, and thereby bias the resulting solution. For an outlier on a single baseline, the solutions for the antennas in that baseline will tend to be biased in the direction of the outlier, and all other antenna solutions in the other direction (by a lesser amount consistent with the fraction of normal, non-outlying baselines to them). It is thus desirable to dampen the influence of such outliers, and solmode/rmshresh provide a mechanism for achieving this. These options apply only to *gaintype='G'* and *'T'*, and will be ignored for other options. Use of *solmode='L1'* invokes an approximate form of minimization of the aggregate absolute deviation of visibilities with respect to the model, i.e., the L1 norm. This is achieved by accumulating the nominal chi-squared and its gradient using weights divided by (at each iteration of the steepest descent process) the current per-baseline absolute residual (i.e., the square-root of each baseline's chi-square contribution). (NB: It is not possible to analytically accumulate the gradient of L1 since the absolute value is not differentiable.) To avoid an over-reliance on baselines with atypically small residuals at each interation, the weight adjustments are clamped to a minimum (divided) value, and the steepest descent convergence is repeated three times with increasingly modest clamping. The net effect is to gently but effectively render the weight of relative outliers to appropriately damped influence in the solution. Using *solmode='R'* invokes the normal L2 solution, but attempts to identify outliers (relative to apparent aggregate rms) upon steepest descent convergence, flag them, and repeat the steepest descent. Since outliers will tend to bias the rms calculation initially (and thus possibly render spuriously large rms residuals for otherwise good data), outlier detection and re-covergence is repeated with increasingly aggressive rms thresholds, a sequence specifiable in *rmsthresh*. By default *(rmsthresh=[])* invokes a sequence of 10 thresholds borrowed from a traditional implementation found in AIPS: [7.0,5.0,4.0,3.5,3.0,2.8,2.6,2.4,2.2,2.5]. Note that the lower threshold values are likely to cull visibilites not formally outliers, but merely with modestly large residuals still consistent with gaussian statistitics, and thereby unnecessarily decrease net effective sensitivity in the gain solution (cf normal L2), especially for larger arrays where the number of baselines likely implies a larger number of visibility residuals falling in the modest wings of the distribution. Thus, it may be desirable to set *rmsthresh* manually to a more modest sequence of thresholds. Optimization of *rmsthresh* for modern arrays and conditions is an area of ongoing study. Use of *solmode='L1R'* combines both the L1 and R modes described above, with the iterative clamped L1 loop occuring inside the R outliner excision threshold sequence loop. .. _Examples: Examples To solve for G on, say, fields 1 & 2, on a 90s timescale, and do so relative to gaincurve and bandpass corrections: :: gaincal('data.ms', caltable='cal.G90s', # Write solutions to disk file 'cal.G' field='0,1', # Restrict field selection solint='90s', # Solve for phase and amp on a 90s timescale gaintable=['cal.B','cal.gc'], # prior bandpass and gaincurve tables refant='3') # reference antenna To solve for more rapid tropopheric gains (3s timescale) using the above G solution, use *gaintype='T'*: :: gaincal(vis='data.ms', caltable='cal.T', # Output table name gaintype='T', # Solve for T (polarization-independent) field='0,1', # Restrict data selection to calibrators solint='3s', # Obtain solutions on a 3s timescale gaintable=['cal.B','cal.gc','cal.G90s'], # all prior cal refant='3') # reference antenna To solve for GSPLINE phase and amplitudes, with splines of duration 600 seconds: :: gaincal('data.ms', caltable='cal.spline.ap', gaintype='GSPLINE' # Solve for GSPLINE calmode='ap' # Solve for amp & phase field='0,1', # Restrict data selection to calibrators splinetime=600.) # Set spline timescale to 10min .. _Development: Development No additional development details .. _Details: Parameter Details Detailed descriptions of each function parameter .. _vis: | ``vis (string)`` - Name of input visibility file | Default: none | Example: vis='ngc5921.ms' .. _caltable: | ``caltable (string='')`` - Name of output gain calibration table | Default: none | Example: caltable='ngc5921.gcal' .. _field: | ``field (string='')`` - Select field using field id(s) or field name(s) | Default: '' (all fields) | | Use 'go listobs' to obtain the list id's or | names. If field string is a non-negative integer, | it is assumed a field index, otherwise, it is | assumed a field name. | Examples: | field='0~2'; field ids 0,1,2 | field='0,4,5~7'; field ids 0,4,5,6,7 | field='3C286,3C295'; field named 3C286 and | 3C295 | field = '3,4C*'; field id 3, all names | starting with 4C .. _spw: | ``spw (string='')`` - Select spectral window/channels | Default: '' (all spectral windows and channels) | Examples: | spw='0~2,4'; spectral windows 0,1,2,4 (all | channels) | spw='<2'; spectral windows less than 2 | (i.e. 0,1) | spw='0:5~61'; spw 0, channels 5 to 61, | INCLUSIVE | spw='*:5~61'; all spw with channels 5 to 61 | spw='0,10,3:3~45'; spw 0,10 all channels, spw | 3, channels 3 to 45. | spw='0~2:2~6'; spw 0,1,2 with channels 2 | through 6 in each. | spw='0:0~10;15~60'; spectral window 0 with | channels 0-10,15-60. (NOTE ';' to separate | channel selections) | spw='0:0~10^2,1:20~30^5'; spw 0, channels | 0,2,4,6,8,10, spw 1, channels 20,25,30 .. _intent: | ``intent (string='')`` - Select observing intent | Default: '' (no selection by intent) | Example: intent='*BANDPASS*' (selects data | labelled with BANDPASS intent) .. _selectdata: | ``selectdata (bool=True)`` - Other data selection parameters | Default: True | Options: True|False .. _timerange: | ``timerange (string='')`` - Select data based on time range | Subparameter of selectdata=True | Default = '' (all) | Examples: | timerange = | 'YYYY/MM/DD/hh:mm:ss~YYYY/MM/DD/hh:mm:ss' | (Note: if YYYY/MM/DD is missing date defaults | to first day in data set.) | timerange='09:14:0~09:54:0' picks 40 min on | first day | timerange= '25:00:00~27:30:00' picks 1 hr to 3 | hr 30min on NEXT day | timerange='09:44:00' pick data within one | integration of time | timerange='>10:24:00' data after this time .. _uvrange: | ``uvrange (variant='')`` - Select data by baseline length. | Default = '' (all) | Examples: | uvrange='0~1000klambda'; uvrange from 0-1000 kilo-lambda | uvrange='>4klambda';uvranges greater than 4 kilo-lambda | uvrange='0~1000km'; uvrange in kilometers .. _antenna: | ``antenna (string='')`` - Select data based on antenna/baseline | Subparameter of selectdata=True | Default: '' (all) | If antenna string is a non-negative integer, it | is assumed an antenna index, otherwise, it is | assumed as an antenna name | | Examples: | antenna='5&6'; baseline between antenna | index 5 and index 6. | antenna='VA05&VA06'; baseline between VLA | antenna 5 and 6. | antenna='5&6;7&8'; baselines with | indices 5-6 and 7-8 | antenna='5'; all baselines with antenna index | 5 | antenna='05'; all baselines with antenna | number 05 (VLA old name) | antenna='5,6,10'; all baselines with antennas | 5,6,10 index numbers .. _scan: | ``scan (string='')`` - Scan number range | Subparameter of selectdata=True | Default: '' = all | Check 'go listobs' to insure the scan numbers are | in order. .. _observation: | ``observation ({string, int}='')`` - Select by observation ID(s) | Subparameter of selectdata=True | Default: '' = all | Example: observation='0~2,4' .. _msselect: | ``msselect (string='')`` - Optional complex data selection (ignore for now) .. _solint: | ``solint (variant='inf')`` - Solution interval | Default: 'inf' (infinite, up to boundaries | controlled by combine); | Options: 'inf' (~infinite), 'int' (per | integration), any float or integer value with or | without units | Examples: | solint='1min'; solint='60s', solint=60 (i.e., | 1 minute); solint='0s'; solint=0; solint='int' | (i.e., per integration); solint-'-1s'; | solint='inf' (i.e., ~infinite, up to | boundaries enforced by combine) .. _combine: | ``combine (string='')`` - Data axes which to combine for solve | Default: 'scan' (solutions will break at obs, | field, and spw boundaries) | Options: '','obs','scan','spw',field', or any | comma-separated combination in a single string | Example: combine='scan,spw' - Extend solutions | over scan boundaries (up to the solint), and | combine spws for solving .. _preavg: | ``preavg (double=-1.0)`` - Pre-averaging interval (sec) | Default: -1.0 (none) | Rarely needed. Will average data over periods | shorter than the solution interval first. .. _refant: | ``refant (string='')`` - Reference antenna name(s); a prioritized list may be | specified | Default: '' (No refant applied) | Examples: | refant='4' (antenna with index 4) | refant='VA04' (VLA antenna #4) | refant='EA02,EA23,EA13' (EVLA antenna EA02, | use EA23 and EA13 as alternates if/when EA02 | drops out) | Use taskname=listobs for antenna listing .. _refantmode: | ``refantmode (string='flex')`` - Reference antenna mode .. _minblperant: | ``minblperant (int=4)`` - Minimum number of baselines required per antenna for each | solve | Default: 4 | Antennas with fewer baselines are excluded from | solutions. | Example: minblperant=10 --> Antennas | participating on 10 or more baselines are | included in the solve | minblperant = 1 will solve for all baseline | pairs, even if only one is present in the data | set. Unless closure errors are expected, use | taskname=gaincal rather than taskname=blcal to | obtain more options in data analysis. .. _minsnr: | ``minsnr (double=3.0)`` - Reject solutions below this SNR | Default: 3.0 .. _solnorm: | ``solnorm (bool=False)`` - Normalize (squared) solution amplitudes (G, T only) | Default: False (no normalization) .. _normtype: | ``normtype (string='mean')`` - Solution normalization calculation type: mean or median | Default: 'mean' .. _gaintype: | ``gaintype (string='G')`` - Type of gain solution (G,T,GSPLINE,K,KCROSS) | Default: 'G' | Example: gaintype='GSPLINE' | * 'G' means determine gains for each polarization and sp_wid | * 'T' obtains one solution for both polarizations; | Hence. their phase offset must be first removed | using a prior G. | * 'GSPLINE' makes a spline fit to the calibrator | data. It is useful for noisy data and fits a | smooth curve through the calibrated amplitude and | phase. However, at present GSPLINE is somewhat | experimental. Use with caution and check | solutions. | * 'K' solves for simple antenna-based delays via | FFTs of the spectra on baselines to the reference | antenna. (This is not global fringe-fitting.) | If combine includes 'spw', multi-band delays are | determined; otherwise, per-spw single-band delays | will be determined. | * 'KCROSS' solves for a global cross-hand delay. | Use parang=T and apply prior gain and bandpass | solutions. Multi-band delay solves | (combine='spw') not yet supported for KCROSS. .. _smodel: | ``smodel (doubleArray='')`` - Point source Stokes parameters for source model | (experimental). | Default: [] (use MODEL_DATA column) | Example: [1,0,0,0] (I=1, unpolarized) .. _calmode: | ``calmode (string='ap')`` - Type of solution" ('ap', 'p', 'a') | Default: 'ap' (amp and phase) | Options: 'p' (phase) ,'a' (amplitude), 'ap' | (amplitude and phase) | Example: calmode='p' .. _solmode: | ``solmode (string='')`` - Robust solving mode: | Options: '', 'L1', 'R', 'L1R' .. _rmsthresh: | ``rmsthresh (doubleArray='')`` - RMS Threshold sequence | Subparameter of solmode='R' or 'L1R' | See CASA Docs for more information | (https://casa.nrao.edu/casadocs/) .. _corrdepflags: | ``corrdepflags (bool=False)`` - If False (default), if any correlation is flagged, treat all correlations in | the visibility vector as flagged when solving (per channel, per baseline). | If True, use unflagged correlations in a visibility vector, even if one or more | other correlations are flagged. | | Default: False (treat correlation vectors with one or more correlations flagged as entirely flagged) | | Traditionally, CASA has observed a strict interpretation of | correlation-dependent flags: if one or more correlations | (for any baseline and channel) is flagged, then all available | correlations for the same baseline and channel are | treated as flagged. However, it is desirable in some | circumstances to relax this stricture, e.g., to preserve use | of data from antennas with only one good polarization (e.g., one polarization | is bad or entirely absent). Solutions for the bad or missing polarization | will be rendered as flagged. .. _append: | ``append (bool=False)`` - Append solutions to the (existing) table | Default: False (overwrite existing table or make | new table) | Appended solutions must be derived from the same | MS as the existing caltable, and solution spws | must have the same meta-info (according to spw | selection and solint) or be non-overlapping. .. _splinetime: | ``splinetime (double=3600.0)`` - Spline timescale(sec); All spw\'s are first averaged. | Subparameter of gaintype='GSPLINE' | Default: 3600 (1 hour) | Example: splinetime=1000 | Typical splinetime should cover about 3 to 5 | calibrator scans. .. _npointaver: | ``npointaver (int=3)`` - Tune phase-unwrapping algorithm | Subparameter of gaintype='GSPLINE' | Default: 3; Keep at this value .. _phasewrap: | ``phasewrap (double=180.0)`` - Wrap the phase for jumps greater than this value | (degrees) | Subparameter of gaintype='GSPLINE' | Default: 180; Keep at this value .. _docallib: | ``docallib (bool=False)`` - Control means of specifying the caltables | Default: False (Use gaintable, gainfield, interp, | spwmap, calwt) | Options: False|True | If True, specify a file containing cal library in | callib .. _callib: | ``callib (string='')`` - Specify a file containing cal library directives | Subparameter of docallib=True .. _gaintable: | ``gaintable (stringArray='')`` - Gain calibration table(s) to apply on the fly | Default: '' (none) | Subparameter of docallib=False | Examples: | gaintable='ngc5921.gcal' | gaintable=['ngc5921.ampcal','ngc5921.phcal'] .. _gainfield: | ``gainfield (stringArray='')`` - Select a subset of calibrators from gaintable(s) | Default: '' (all sources on the sky) | 'nearest' ==> nearest (on sky) available field in | table otherwise, same syntax as field | Examples: | gainfield='0~2,5' means use fields 0,1,2,5 | from gaintable | gainfield=['0~3','4~6'] means use field 0 | through 3 .. _interp: | ``interp (stringArray='')`` - Interpolation parmameters (in time[,freq]) for each gaintable, as a list of strings. | Default: '' --> 'linear,linear' for all gaintable(s) | Options: Time: 'nearest', 'linear' | Freq: 'nearest', 'linear', 'cubic', | 'spline' | Specify a list of strings, aligned with the list of caltable specified | in gaintable, that contain the required interpolation parameters | for each caltable. | * When frequency interpolation is relevant (B, Df, | Xf), separate time-dependent and freq-dependent | interp types with a comma (freq_after_ the | comma). | * Specifications for frequency are ignored when the | calibration table has no channel-dependence. | * Time-dependent interp options ending in 'PD' | enable a "phase delay" correction per spw for | non-channel-dependent calibration types. | * For multi-obsId datasets, 'perobs' can be | appended to the time-dependent interpolation | specification to enforce obsId boundaries when | interpolating in time. | * Freq-dependent interp options can have 'flag' appended | to enforce channel-dependent flagging, and/or 'rel' | appended to invoke relative frequency interpolation | Examples: | interp='nearest' (in time, freq-dep will be | linear, if relevant) | interp='linear,cubic' (linear in time, cubic | in freq) | interp='linearperobs,splineflag' (linear in | time per obsId, spline in freq with | channelized flagging) | interp='nearest,linearflagrel' (nearest in | time, linear in freq with with channelized | flagging and relative-frequency interpolation) | interp=',spline' (spline in freq; linear in | time by default) | interp=['nearest,spline','linear'] (for | multiple gaintables) .. _spwmap: | ``spwmap (intArray='')`` - Spectral window mappings to form for gaintable(s) | Only used if callib=False | default: [] (apply solutions from each calibration spw to | the same MS spw only) | Any available calibration spw can be mechanically mapped to any | MS spw. | Examples: | spwmap=[0,0,1,1] means apply calibration | from cal spw = 0 to MS spw 0,1 and cal spw 1 to MS spws 2,3. | spwmap=[[0,0,1,1],[0,1,0,1]] (use a list of lists for multiple | gaintables) .. _parang: | ``parang (bool=False)`` - Apply parallactic angle correction | Default: False | If True, apply the parallactic angle correction | (required for polarization calibration) """ pass