This is a summary of some details related to CASA single dish. Placed here so I don't need to keep finding the same e-mails to remind myself what I've previously found.

This is obviously incomplete.

Single Dish section of the CASA User's Guide (cookbook)

  • single dish section (this link may get stale, but should be findable via the next link)
  • Top of CASA User's Guide
  • Data can be read in using "sdsave".
    • If outform is "MS" then a MS results.
    • If outform is "ASAP" then an ASAP table results.


  • The original CASA-related single dish processing package.
  • It involves it's own table format.
    • Data can be moved into it from a MS or from an external FITS file (or from the FITS-like RPFITS format)
    • ASAP table data can be moved out to a MS
    • Imaging is done from the MS copy
  • There is no continuum capability in ASAP, but continuum data can be moved into the table and from there to the MS for imaging purposes.
  • CASA sdimaging can be used to make continuum images
  • There are rumors of a CLASS-to-ASAP conversion script, but so far no copies of it have been located.
  • Document describing ASAP format
  • Example FITS file that can be read in to CASA/ASAP.
    • Example ATNF SDFITS that can be read by CASA sdsave: OrionS _rawACSmod_cal2123.fits.gz
    • It claims to be SDFITS, but it's not the form produced by the GBT. It probably more closely resembles the internal ASAP table format.
    • ASAP v2 format summary: ASAPv2dataformat.pdf
    • The above attached document may be useful in interpreting the meaning of the columns in this example FITS file.
    • Use scantable to import into an ASAP table (I think sdsave will also do that if outform is "ASAP").
    • If "sdsave" is used to export from an ASAP and outform is "SDFITS", the resulting FITS file will look this example.


  • Calibrated GBT data in an SDFITS format written by GBT tools (sdfits, gbtpipeline) can be read into a MS.
  • It requires additional tweaking of the MS to be useful for imaging.
  • The most significant work-around is that the MS does not support multi-feed data.
    • This workaround involves assigning the data from each GBT feed to a unique range of times/dates and artificially offsetting the times of the feeds so that there is no overlap in the resulting combined MS used for imaging. So long as those times are not used except as indexes into the various subtables (e.g. not used to recalculated az/el, or the line of sight frame velocity to calculate an alternate spectral window) then this hack works.
  • This has only been tested for spectral line GBT data. Continuum GBT data may behave differently if read in to a CASA MS.

-- BobGarwood - 2014-05-09
Topic attachments
I Attachment Action Size Date Who Comment
ASAPv2dataformat.pdfpdf ASAPv2dataformat.pdf manage 91 K 2014-05-09 - 11:42 BobGarwood ASAP v2 format summary
OrionS_rawACSmod_cal2123.fits.gzgz OrionS_rawACSmod_cal2123.fits.gz manage 1 MB 2014-05-09 - 12:07 BobGarwood Example ATNF SDFITS that can be read by CASA sdsave
Topic revision: r1 - 2014-05-09, BobGarwood
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