The recent upgrade to MWAX necessitates verification that the system is capable of observing high time resolution phenomena, such as pulsars. To this end, we put in a successful proposal for an MWA observing campaign to being in the end of 2021 and into the beginning of 2022. The requested observations fall into two categories:

1. commissioning observations, and
2. the remaining SMART observations.

This page details the progress made in taking the observations and performing the tests to complete the commissioning phase. Progress with the SMART survey is detailed elsewhere.

Commissioning Observations

Goals & Target Pulsars

The stated goals of the commissioning observations are:

1. To develop and test the tied-array beamformer for the new VCS data format
2. Verification of frequency labelling
3. Data recording and timing stability
4. Polarimetric verification and leakage assessment
5. Full coherent beam sensitivity and timing accuracy
6. The voltage dump and trigger mode (in response to external triggers)
7. Correlation and imaging of data recorded in the new VCS format

A partial list of requested observations to satisfy the above goals are:

Observations

The following link performs a query on the MWA observation database, showing the details of the observations made so far:

https://ws.mwatelescope.org/metadata/find/?search=search&html=1&pagesize=100&projectid=G0057&mintime_utc=2021-12-13T01%3A00&maxtime_utc=2021-12-29T01%3A00

The following table is a summary of the same observations, and which of the goals (see the table above) that they are intended to satisfy:

*VCSBeam version is the earliest version that was successfully used for the processing. For calibration observations, this means using mwa_plot_calibration, and for the VCS observations, make_mwa_tied_array_beam.

Processing details

1323690320

Run Hyperdrive

Create Hyperdrive batch script:

#!/bin/bash -l
#SBATCH --job-name=hyp-$1
#SBATCH --output=hyperdrive.out
#SBATCH --nodes=1
#SBATCH --ntasks-per-node=40
#SBATCH --time=01:00:00
#SBATCH --clusters=garrawarla
#SBATCH --partition=gpuq
#SBATCH --account=mwavcs
#SBATCH --export=NONE
#SBATCH --gres=tmp:50g
#SBATCH --gres=gpu:1

# Load the Hyperdrive module
module use /pawsey/mwa/software/python3/modulefiles
module load hyperdrive

set -eux
which hyperdrive

# The location of the correlated visibility FITS files:
DATADIR=/astro/mwavcs/asvo/253001

# The path to the associated metafits file
CAL_METAFITS=${DATADIR}/1323690320.metafits

# The base source list (you shouldn't need to change this)
SRCLIST=/pawsey/mwa/software/python3/srclists/master/srclist_pumav3_EoR0aegean_fixedEoR1pietro+ForA_phase1+2.txt

# If it hasn't been done already, run Hyperdrive in "srclist-by-beam" to get just the subset of sources in the beam
if [[ ! -r srclist_1000.yaml ]]; then
   hyperdrive srclist-by-beam \
       -n 1000 \
       -m ${CAL_METAFITS} \
       /pawsey/mwa/software/python3/srclists/master/srclist_pumav3_EoR0aegean_fixedEoR1pietro+ForA_phase1+2.txt \
       srclist_1000.yaml
fi

# Run Hyperdrive to generate a calibration solution
hyperdrive di-calibrate \
    -s srclist_1000.yaml \
    -d ${DATADIR}/*.fits \
    ${CAL_METAFITS}

Run the Hyperdrive script (on Garrawarla):

cd /astro/mwavcs/vcs/1323690320/hyperdrive
sbatch hyperdrive.sbatch

Run VCSBeam plotting

VCSBeam: v3.3.30_edafd20

Create VCSBeam plotting script:

#!/bin/bash -l
#SBATCH --job-name=plot_calsol
#SBATCH --output=plot_calsol.out
#SBATCH --nodes=1
#SBATCH --ntasks-per-node=2
#SBATCH --time=01:00:00
#SBATCH --clusters=garrawarla
#SBATCH --partition=gpuq
#SBATCH --account=mwavcs
#SBATCH --export=NONE
#SBATCH --gres=tmp:50g
#SBATCH --gres=gpu:1

# Load the VCSBeam module
module use /pawsey/mwa/software/python3/modulefiles
module load vcsbeam

# The location of the correlated visibility FITS files:
DATADIR=/astro/mwavcs/asvo/253001

# The paths to the associated metafits files
CAL_METAFITS=${DATADIR}/1323690320.metafits
OBS_METAFITS=/astro/mwavcs/asvo/253008/1323690616.metafits # <-- This is the observation for which the calibration solution is needed

# Use VCSBeam to plot the solutions
srun -N 1 -n 1 mwa_plot_calibration -m ${OBS_METAFITS} -c ${CAL_METAFITS} -C hyperdrive_solutions.bin -R NONE -U 0,0 -O -X -z nan > plot_data.txt

# The following will have to be done on your own computer (not on Garrawarla)
# Download
#    (1) plot_calibration.py (use "which plot_calibration.py" to find out where it is)
#    (2) plot_data.txt
# and then run the following
#plot_calibration.py  --phases_png phases.png  --amps_png amps.png  plot_data.txt

Run plotting script:

cd /astro/mwavcs/vcs/1323690320/hyperdrive
sbatch plot.sbatch

Plot the calibration solutions (on your local computer, after downloading a copy of plot_calibration.py and plot_data.txt:

plot_calibration.py  --phases_png phases.png  --amps_png amps.png  plot_data.txt

Iterative step

It looks like the solutions are probably fine for most, if not all the antennas (except possibly HexE23, since there's a lot of power in the off-diagonal terms, Dpq and Dqp), but the curviness of the phases makes it hard to tell. Therefore, I will choose a reference antenna to plot all the phases relative to that. Since there's a bunch of tiles whose phases are strongly sloped (in the middle), I'll choose a reference tile with a negative slope as well, but whose gradient is not as steep... HexE25 will do. To do this, I need to re-run the plotting script with the following change:

-R NONE --> -R HexE25

If I want to keep the old plots, I just make sure I rename the various output files to something different. Remaking the plots gives:

These solutions look fine (the on-diagonal terms, Dpp and Dqq, look straight). At the moment, I'm not trying to do polarimetry, so I don't need to worry about either the reference antenna or the PQ phase. By default, I should probably get rid of the cross terms (taking guidance from the imaging team). Therefore, I should be able to simply apply this solution with the following options to make_mwa_tied_array_beam:

-R NONE -U 0,0
# (and without -X)

1323690616

1323708616

1323708912

1323709032

1323776720

1323776840