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Knowledgebase : Historical Articles
Yes, there are three main issues to be aware of for Cycle 0 data: * A major refactor of the calibration table format and functionality took place between CASA 3.3 and CASA 3.4. Calibration tables created in CASA 3.3 (and earlier) cannot be used in CAS...
In order to tell for sure which version of CASA was used for calibration and imaging, check the data reduction script. The data were calibrated and imaged in, for example, CASA 3.4 if the script contains the line: if re.search('^3.4', casadef.casa_versio...
Cycle 0 data reduction was done using CASA versions 3.3 and 3.4, which use the Butler-JPL-Horizons 2010 models to set the flux model for solar system objects.  The fluxes of science targets were then bootstrapped from these solar system object measurement...
Messages like    SEVERE setjy Leap second table TAI_UTC seems out-of-date.    SEVERE setjy Until table is updated (see aips++ manager) times and coordinates    SEVERE setjy derived from UTC could be wrong by 1s or more. on Linux installations of CASA in...
Before ALMA Cycle 3, the position reference frame in MeasurementSets and Images were given as J2000. However, the actual position reference frame of the phase calibrators used in the observations was ICRS, it was found that this label was misleading (alth...
The following two visibility flagging issues were found in the ALMA data analysis done with the CASA package. The issues do not invalidate science results but they may have reduced the sensitivity of your observation. Since delivered datasets did pass ALM...
ALMA Cycle 0 PI or Science Verification data may have been reduced in an earlier version of CASA. In this case, the scripts that were provided in the original data delivery will most likely not work with later versions of CASA (see the Knowledgebase artic...
Sometimes packages that are distributed within the CASA installation (such as IPython, numpy etc.) become confused with non-CASA installations upon starting or working in CASA. Error messages like CASA Version 4.2.2 (r30986)  Compiled on: Thu 2014/09/04 ...
For a short time during 2014, users running a version of Java 7 with an update number of 51 or higher found that the OT would not start because of the following security exception: "Missing required Permissions manifest attribute in main jar". This prob...
Certain types of observing program require special attention by an ALMA Staff Phase-2 Group (P2G) member after the Scheduling Blocks (SBs) have been generated, in order to ensure successful execution at the telescope and the highest possible quality data....
The symptom: On windows machines (particularly it seems, in EA-ARC), the OT may not open - often it simply closes itself down, before even the basic startup procedure. If the tarball version of the OT is run, the output of the /users//.almaot/...
This Knowledgebase article is a repository for information relevant to submission of Cycle-7 proposals. These items may affect how users write their proposals or set up their observations in the OT. The content may evolve rapidly as the 17 April, 2019 pro...
In CASA versions BEFORE 4.3 there is a problem with libxml on some Linux distributions other than RHEL 5 and 6, e.g. Ubuntu 13 and Fedora 20. The libxml version shipped with CASA does not work with other system libraries. You will need to do the following...
Channel (spectral or velocity) averaging is done by the task split, while the cvel task only interpolates the data onto a new frequency grid. To achieve both channel averaging and to move the data to a new frequency grid, one must combine split and cvel. ...
This is to notify all CASA users that a bug was discovered in the code underlying the field selection mechanism in the clean task. The bug is present in CASA 3.4, 4.0, and 4.1 and affects the flux scaling and restoring beam calculations in clean. This bu...
The OT does not allow users to specify a minimum angular resolution (i.e. restrict the range of angular resolutions such that a source will definitely be unresolved) because this considerably narrows the range of configurations that can be used, and compl...
The images that are included in the data delivery package may not include all spectral windows, or all channels, or all targets that were observed as part of the science program.  These images are meant to be representative, as described in Imaging Produc...
The CASA task _exportfits _sets the header keyword BUNIT as 'JY/BEAM' in CASA 4.2 and earlier, whereas it is 'Jy/beam' in CASA >=4.3. The BUNIT keyword is case-sensitive and 'Jy/beam' is adopted as FITS standard.  This change of the units can cause a pro...
Data from the correlator, together with monitor and weather data, are sent via dedicated optical fiber links (1-10 Gbit/s) to the OSF, where they are archived. A peak data rate of 66.6 MB/s can be sustained for short periods of time, i.e. days. This peak ...
Cycle 0 data was processed by ALMA science staff using CASA, with scripts that reflect the best practices in ALMA data reduction. However, improvements and bug fixes to CASA are made over time, and users may wish to reprocess their data with a more recent...