q CASA

Known Issues CASA 4.4.0

  • Most Important Issues for CASA 4.4.0
    • cvel, cvel2, and mstransform with regridms do not regrid properly for channel widths > or = 2 x the native channel width
    • blcal and polcal with poltype='X' will cause some previously flagged data in the applycal step to be unflagged. A workaround for polcal is to use poltype='Xf'. (fixed in CASA 4.5)
    • If you want to use a data set filled with CASA 4.3.0 or later in CASA 4.2.2, you may encounter an error about missing spws. To fix, run "!fixspwbackport msname" within CASA on Linux. msname is the name of the MeasurementSet.
    • In some cases, the virtual model is not calculated correctly and does not represent the true model (e.g. for flux calibrator models). gridmode=widefield in clean also produces an erroneous virtual model. We recommend the use of the true visibility model column invoked with usescratch=True for workarounds. (fixed in CASA 4.5)
    • Restructuring of the clean task is ongoing and an experimental tclean is actively being developed. Use with care, being aware of its experimental nature (bugs will not be responded to at this stage)
    • Currently, gaincal will not find good solutions if any correlation (including cross-correlation) in the data is completely flagged. As an interim solution one may split the unflagged data in a separate file and then perform gaincal
    • ALMA observatory ephemerides: CASA 4.4 is not yet able to process ephemeris tables included in ALMA data reliably. If you have an ASDM which includes ephemerides, you will need to discard those and instead use the fixplanets task to attach the correct geocentric ephemeris. Please refer to the cookbook on how to do that.
    • statwt has twice the rms than it should have (fixed in CASA 4.5).
  • bandpass ---
    • Currently, bandpass will not find good solutions if any correlation (including cross-correlation) in the data is completely flagged. As an interim solution one may split the unflagged data in a separate file and then perform bandpass
  • polcal ---
    • Polarization angle calibration poltype='X' is sensitive to any position shift in the source model relative to the phase center with respect to the phase center in intensity.
  • setjy ---
    • sometimes setjy does not properly overwrite a current model in the header of the ms (virtual scratch column). It is recommended to use delmod if a model exists and shall be overwritten.
  • plotms ---
    • plotms transform=True produces an incorrect x-axis scale when avgchannel is also set
  • plotcal (also check the matplotlib section for plotcal issues) ---
    • When plotcal does not release a calibration table properly but keeps it in lock, try to hit the quit button in the plotcal GUI first. Then redisplay the table.
    • If you use plotcal on a caltable, it will then be put into the cache of the table system. If you try to re-run a solve (e.g. gaincal, bandpass, blcal, polcal) with the same caltable name and append=F to overwrite, then when it tries to delete the original caltable it cannot due to the cache. You will see an error like:
                     SEVERE  gaincal::Calibrater::solve 
                     Caught exception: Invalid Table operation: SetupNewTable
                     ngc5921.demo.gcal is already opened 
                     (is in the table cache)
                     
      Either use a different output caltable name, or restart you casapy session (exit and start again) to free up the cache. Update: As of Patch 4, you can use the rmtables task to delete tables.
    • BPOLY solutions from bandpass must be plotted versus frequency and not channel. BPOLY and B solutions can only be overlaid if xaxis = 'freq'.
    • GSPLINE and G solutions from gaincal can be overlaid, though this has not been extensively tested.
    • Currently, plotcal needs to know the MS from which the caltable was derived to get indexing information. It does this using the name stored inside the table, which does not include the full path, but assumes the MS is in the same directory as the cal-table and has the same name it had when the cal-table was created.
    • If there are flagged channels at the lower edge of the data, say, 0~4, and you select a channel and 'locate' it from plotcal, it will give the incorrect channel number (will count from the first unflagged channel, not zero).
  • uvcontsub ---
    • fitorder should be kept low (<= 1) unless the line band is relatively narrow compared to the fit bands. If the image rms markedly rises in the middle line channels after uvcontsub, fitorder should probably be lowered.
    • fitorder > 0 does not work with solint > 'int'
  • delmod ---
    • The task Delmod field selection works only with field_ids i.e delmod(...., field='2~5', ...) There is a case sensitive comparison bug ...so that delmod (...., field='3C2*' , ....) may not work
  • wvrgcal ---
    • under OSX: It was not possible to deliver CASA with the same version of the external Boost package for OSX and for Linux. For person-power reasons (and because OSX is not of operational importance to ALMA), it was therefore not possible to make the wvrgcal task (which internally heavily relies on Boost, in particular for the random number generation for the Bayesian determination of fit parameters) produce the same output as on Linux. It was, however, verified that the results agree within the statistical errors.
  • msmd ---
    • The behavior of the msmd.*forscan methods differs in CASA 4.4 and 4.5 compared to earlier and later versions. In CASA 4.4, with the addition of the obsid parameter and its default of 0, only scans belonging to the first observation ID will be found if obsid is not specified. Starting in 4.6, the obsid parameter defaults to -1, meaning that all scans in all observations will be searched, restoring the behavior of CASA 4.3 and earlier.
  • VLA Switched Power In CASA v4.2.2 and higher, the weight calibration for EVLA switched power/Tsys corrections is still being investigated. Visibility corrections are ok. Since switched power calibration is not used by the EVLA pipeline (except for requantizer gain corrections, for which this problem is irrelevant), and since calwt=F remains the general recommendation, this bug will be fixed in CASA v4.3, and users should rely on statwt to generate appropriate data weights.
  • Synthesis Imaging:
    • clean ---
      • In the clean task, when the modelimage parameter is specified, and a previous model exists on disk with the name 'imagename.model', they are both added before prediction. This can happen if you restart clean to continue a deconvolution, but don't set modelimage='' before doing so.
      • clean expects that all input polarizations are present. E.g. if you have RR and LL dual polarization data and you flagged parts of RR but not LL, clean will ignore both polarizations in slice. It is possible to split out a polarization product with split and image separately. But you will not be able to combine these part-flagged data in the uv-domain. We will remove that restriction in a future CASA release.
      • Facets do not always work on Mac OS X. This is frequently due to a built in limit for the number of open files. Per default the setting is usually 256 (use ulimit -a to check). For facets in clean it might be required to set to a higher number, e.g. ulimit -n 2048. All commands must be issued from a bash shell outside CASA.
      • Mask editing in interactive clean does not work reliably when the input MS is in reference frames other than LSRK or TOPO. Two incarnations of the problem were encountered so far: (a) when working in GEO, as on solar system objects, mask editing is impossible. (b) When working in BARY, masks created in CASA 4.0 cannot be edited when they are used as input masks for interactive clean in CASA 4.1. and higher.
      • The Mac OS compilers are different to Linux compilers and some options are not available (e.g. opemmp and sincos). This causes some of the clean procedures, in particularly mosaicking, to be slower on MacOS than on Linux.
  • Visualization:
    • viewer ---
      • The CASA viewer does not yet support the entire region shapes and parameters at this stage.
      • Viewer may not properly open saved region files
      • With the new region panel being used now, It may be advisable to rename the $HOME/.casa/viewer/rc file that stores previous configurations of the viewer.
      • Viewer - labels are not shown - this can be caused by a conflict between an installed version of PGPLOT and the version of PGPLOT that comes with the non-root version of CASA. If you do have PGPLOT installed in a standard location (e.g. /usr/lib), you may try moving it aside and see if it resolves the problems. If you do encounter this problem, please report it to the CASA team.
      • Some X11 settings can make the viewer unstable. We identified that the line
        Load "glx"
        in /etc/X11/xorg.conf
        is such a setting. If you don't need this line for aother applications, it would be better to have it removed.
    • matplotlib (see also plotcal, plotant or any other program that uses matplotlib) ---
      • On some configurations of Mac 10.6 OS unwanted windows may appear when a task based on matplotlib. The tasks may also throw errors (see the help file in the dmg). The solution to this is the set "backend: TkAgg" in your ~/.matplotlib/matplotlibrc file.
      • If some plotting windows are not appearing (e.g. plotants or plotcal), and are accompanied with errors in your terminal (which may end with "TypeError: coercing to Unicode: need string or buffer, dict found"), try removing the fontList.cache file typically found in either ~/.casa/matplotlib, or ~/.matplotlib directories.
      • There seems to be a bug in the font_manager.py file of the current matplotlib distribution, you may see errors like:
        TypeError: coercing to Unicode: need string or buffer, dict found
        SEVERE [msplot::plot()] Exception Reported: TablePlot: CasaPyInterpreter: From Python : SEVERE :
        SEVERE + pl.draw()

        to fix this, do the following:
        In a casapy session, type "matplotlib.font_manager.__file__". This will print the location of the font_manager.py file that casapy is using. Edit that file, around line 1220, to change
        result = self.defaultFont
        to
        result = self.defaultFont[fontext]
      • pl.show() command displays 'ASAP plotter' even if users have never invoke plotting command on it. This issue should be fixed in the next release.
      • The matplotlib window will not close on Mac 10.7. on pressing the close button at the top of the window.
  • Analysis:
    • msmoments ---
      • task only accepts MS data (not Scantable). The input MS have a few limitations to work with msmoments task: 1. MS must have FLOAT_DATA column 2. Number of polarizations (correlations) must be same in all rows
    • uvmodelfit ---
      • When running uvmodelfit, the output componentlist does not contain the uncertainty in flux that the task calculates (and displays at the end of the fitting process).
  • Simulation:
    • simobserve/analyze ---
      • corruption of simulated MS by an atmospheric phase screen is only available from the toolkit. simobserve and sm: Under some circumstances, running sm.setnoise and sm.corrupt, or simobserve with thermal noise, twice using the same project name, the noise can be applied a second time, doubling the noise level. Be sure to use different project names for creating different simulations with noise. see casaguides.nrao.edu for the latest simulation information
  • Single Dish
    • sdflagmanager ---
      • Due to a limitation of current implementation, row or channel flag status may not be restored properly. This may happen when any rows are flagged.
    • sflag and sdplot ---
      • Data selection by raster causes an error when it is used in combination with field and/or timerange selection.
    • sdimaging ---
      • sdimaging task may fail when more than several MSes are chosen as inputs (infiles) to create single output image. It is because the file descriptor opened by the task exceeds the limit defined by OSes. You can relax the limit of the number of open file descriptors by the command, e.g., ulimit -n 4096 . Note the typical number of file descriptors opened by the task is 35/MS.
    • tsdbaseline ---
      • Values in MASKLIST column of baseline table would be incorrect for spectra n-sigma clipping do not converge. This issue is not expected to have an impact on the application of baseline table which will be supported in future releases.
    • The following single dish tasks with the old task interfaces are removed: sdbaselineold, sdcalold, sdcal2old, sdfitold, sdflagold, sdflag2old, sdgridold, sdimagingold, sdmathold, sdplotold, sdreduceold, sdsaveold, sdsmoothold, and sdstatold.
    • The following issues in the previous releases are fixed.
      • sdaverage: polaverage did not work properly for row flagged spectra.
      • sdbaseline raised an error when the input data set contains a spectrum in which all channels are flagged.
      • sdcal2 did not recognize CM10 as an ALMA antenna
      • sdcal2: calmode='otf' and 'otfraster' did not work properly if any data selection parameters (iflist, scanlist, pollist, etc.) are specified
      • sdcal2: calmode='tsys' had a bug that frequency labeling is not properly handled when multiple spectral windows are defined for Tsys measurement.
      • sdflag and sdplot: raster row/map selection did not work when input data is in MS format.
      • sdgrid: the data gridded by sdgrid could not be imaged using sdimaging

    See also the Alert notices in the CASA User Reference & Cookbook and the Casaguides Wiki Pages for more details on known problems and workarounds.

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