This site requires javascript to be enabled to fuction correctly


How do I obtain a file of calibrated visibilities ("measurement set") for ALMA data?
Posted by Sarah Wood, Last modified by Sarah Wood on 15 March 2018 06:42 PM

ALMA raw data, data products (images or cubes), and auxiliary data (scripts, logs and quality assessment figures) are stored in the archive for each data delivery. This data includes the calibration and flagging tables. 

Users will need the calibrated visibilities if they wish to re-calibrate or re-image the data. To obtain the calibrated visibilities, follow these instructions, also found in the README inside the untarred project structure. More detailed information can also be found in the document "ALMA QA2 Data Products document" available from the Documents page in the Science Portal.

Download all tar files for a given delivery from the ALMA Science Archive and untar them. Then change into the "script" directory with the python scripts (e.g. 'scriptForPI.py' and 'scriptForImaging.py'):

cd */*/*/*/script

Start casa (or "casa --pipeline" for data reduced using the ALMA pipeline) and type

>execfile('scriptForPI.py')

This will apply the flagging and calibration tables to the raw data and thus result in a MS ready for imaging. In some cases a specific version of CASA is required. This version is specified in the README file.

That MS can then be processed with the commands in the "scriptForImaging.py" script. The "scriptForImaging.py" script may partially be interactive (for masking) and should be executed by copying and pasting the commands from the script to the casapy prompt, rather than by the "exec file" command.

If your data was calibrated using the ALMA Science Pipeline, please see the document "ALMA Science Pipeline Quickstart Guide" available from the Documents page of ALMA Science Portal  for more information.

 

(0 vote(s))
Helpful
Not helpful

Comments (0)