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Making Images

Creating images in TART is requires three things

Using the TART web interface​

The easiest way to make images is to use the web interface. A public web interface is available here.

This requires the tart_tools, tart2ms and disko python packages pip install tart_tools tart2ms disko,

Step 1: Download data to an HDF file

tart_download_data --n 1 --api https://tart.elec.ac.nz/UdM --vis --file tart_udm.hdf

Step 2: Turn the downloaded data into a measurement set using tart2ms

tart2ms --hdf tart_udm.hdf --ms tart_udm.ms --rephase "obs-midpoint" --single-field

Step 3: Create a disko image

disko --ms tart_udm.ms --healpix --fov 170deg --res 30arcmin --HDF tart_udm.h5 --lasso --alpha 0.003
disko_draw --SVG tart_udm.svg --show-sources --elevation 30 tart_udm.h5

The last step overlays the known sources only above elevation of 30 degrees, and generates an SVG file. You can convert this file to a JPEG photo using inkscape

Using DiSkO​

The disko python package is a tools designed to work with all-sky radio telescopes. It was developed along with the TART project. DiSkO stands for Discrete Sky Operator imaging. You should have some data from the TART in measurement set format. DiSkO can be installed like any other Python package.

    disko --healpix --fov 155deg --res 1deg --ms test_data/test.ms --field 1 --SVG --alpha=0.01 --lasso --title 'tart_lasso'

Using WSClean​

The wsclean package is a standard tool for creating images from measurement sets. If you have a measurement set (created by tart2ms), then the following command should make a FITS formatted image.

export OPENBLAS_NUM_THREADS=1; wsclean -weight briggs 0 -name test -pol RR -size 1000 1000 -scale 0.175 -niter 1000 -gain 0.1 -mgain 0.05 -padding 1.5 -auto-mask 7 test.ms

Making a movie​

Here is a little script that will run on linux, and make a movie from the TART data. First let us download some data

do
  tart_download_data --n 1 --vis
  tart_calibration_data --n 1 --file obs_$i.json
  sleep 120
done