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Knowledgebase: Archive & Data Retrieval
How are ALMA data products packaged?
Posted by Anand Crossley, Last modified by Rein Warmels on 16 March 2017 01:33 PM

Both raw data and processed data are ingested into the archive as tar files. 

A more detailed description of the data products can be found in the document ALMA QA2 Data Products that can be found on the Documents page in the Science Portal.

Raw data

The raw data are written in ALMA Science Data Model (ASDM) format with file names

<ASDM UID>.asdm.sdm.tar
example: uid___A002_X7d44e7_X956.asdm.sdm.tar

Processed data

Processed data sets include:

  1. FITS images
  2. Calibration and imaging scripts
  3. Quality Assurance (QA) plots
  4. Calibration tables
  5. README file

The processed data have file names

<PROJECT CODE>_<OUS UID>_<X>_of_<Y>.tar
example: 2012.1.00919.S_uid___A002_X609170_X30_001_of_001.tar

Where the OUS UID is the unique identifier for the Observing Unit Set (OUS), X is the file number, and Y is the total number of tar files for this OUS.

A CASA measurement set of calibrated visibilities can be created using the scripts contained in the processed data set by following the instructions outlined in this KB article: How do I obtain a file of calibrated visibilities ("measurement set") for ALMA data?

Cycle 0

In Cycle 0, raw and processed data were ingested within the same tar file (some early deliveries to PIs in Cycle 1 were also made this way, but are not retrievable from the archive).  These tar files contained processed products 1-5 listed above, plus:

  1. Raw CASA measurement set
  2. Calibrated CASA measurement set
The older tar files have file names

<PROJECT CODE>_<DATA DELIVERY DATE>_<X>_of_<Y>.tar
example: 2011.0.00465.S_2012-08-03_009_of_011.tar

As a consequence of including the raw and calibrated measurement sets, these older tar files are much larger than the processed data files currently ingested.  The raw ASDM was not included in these older files but can still be obtained by submitting a query to the ALMA Helpdesk.
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