Convert data from a TART radio telescope to measurement set format. This module relies on the excellent dask-ms module as a helper to create the measurement sets. This packate requires python-casacore to be installed on your system
sudo aptitude install python3-casacore
sudo pip3 install tart2ms
Download data from the TART in real time via the RESTful API (defaults to using the API at https://tart.elec.ac.nz/signal):
tart2ms --ms data.ms
To convert a previously downloads JSON file to a measurement set (MS):
tart2ms --json data.json --ms data.ms
JSON-based datasets currently may only contain a single timestamp. This limits their usefulness when it comes to more general imaging. It is possible to make a concatenated database from multiple single-dump json databases, e.g.
tart2ms --json ../tart_data/NZ_2022_10_19_json/*.json
HDF5 format archive files may contain multiple timestamps and may also be concatenated into longer observations as is the case for JSON archive files.
tart2ms --hdf ../tart_data/NZ_2022_10_19/*.hdf
JSON databases may be exported from HDF5 archives using
tart_vis2json --vis ../NZ_2022_10_19/*.hdf
Currently each such exported JSON database will contain a single timestamp (thus multiple JSON databases may result from a single HDF5 archive).
Your telescope name may not be in the JPL list of recognized observatories which at present raises an error in casacore and hence some casa tasks like listobs or plotants, even though the antenna table contains valid ITRF coordinates for the antennae. We recommend that if problems are encountered the telescope name is changed to an existing observatory like kat-7 or MeerKAT.
tart2ms --json ../tart_data/NZ_2022_10_19_json/*.json -c --telescope_name 'kat-7'
Standard CASA tasks may be executed with the CASA memo 229-compliant (MSv2.0) databases written by tart2ms. These may include (tested):
To synthesize (using wsclean) the image from the measurement set:
wsclean -name test -size 1280 1280 -scale 0.0275 -niter 0 data.ms
This will create an image called test-image.fits. You will need to install wsclean on your system.
usage: tart2ms [-h] [--json JSON] [--ms MS] [--api API] [--catalog CATALOG]
[--vis VIS] [--pol2]
Generate measurement set from a JSON file from the TART radio telescope.
optional arguments:
-h, --help show this help message and exit
--json JSON Snapshot observation JSON file (visiblities, positions
and more). (default: None)
--hdf HDF Visibility hdf5 file (One minutes worth of visibility data). (default: None)
--ms MS Output MS table name. (default: tart.ms)
--api API Telescope API server URL. (default:
https://tart.elec.ac.nz/signal)
--catalog CATALOG Catalog API URL. (default:
https://tart.elec.ac.nz/catalog)
--vis VIS Use a local JSON file containing the visibilities for
visibility data (default: None)
--pol2 Fake a second polarization. Some pipelines choke if there
is only one. (default: False)
Thanks to Simon Perkins and Oleg Smirnov for help in interpreting the measurement set documentation.