/
2021-04-01

2021-04-01

Apr 02, 2021

Present:

  • Keegan Smith (KS)

  • Susmita Sett (SS)

  • Sam McSweeney (SM)

  • Ramesh Bhat (RB)

  • Marcin Sokolowski (MS)

  • Isaac Colleran (IC)

  • Willem van Straten (WvS)

  • Ian Morrison (IM)

  • Nicholas Swainston (NS)

  • Ryan Shannon (RS)

Announcements:

  • RB has invited Shi Dai to SMART collaboration. Shi has accepted.

Discussion:

MWA upgrade (Ramesh)

  • Phase 2 had compact and extended modes

  • New Phase 3 has new hardware, new signal chain

  • Luckily, will still have compact configuration in the short term

  • Paper on new pulsar is in press

    • ICRAR will do a press release + news item, to coincide with publication (in a few weeks)

    • Tentative date 20/21 April

    • RB thanks all who helped with the paper!

    • Lessons: new finds with MWA can rely on Parkes, etc for follow up

    • First time pulsar has been timed with MWA -- an important milestone

    • New GMRT and Parkes proposals in the works

    • GMRT proposal is about scintillation studies at high Galactic latitudes -- successful!

  • MWA is back online since last Friday.

    • Reason: new hardware procurement is delayed a few months

    • An opportunity for us to cover more SMART survey obs's

    • MWA will be in compact configuration for the rest of the year

    • 1PPS is not there yet (as of this week), so timing might be compromised for incoming data over the next few months

  • Review of observations completed so far (see slides for info-graphic)

    • Still in "shallow" search mode. Prospects for new finds are still good!

  • Shared risk proposal has been submitted

    • Bhat, McSweeney, Swainston, Smith, Xue.

  • Name SM as "SMART Survey Project Scientist"

Processing Update (Nick)

  • Data processing:

    • "Quick check" 41 obs processed, 93 known pulsars detected

    • "Shallow search" 23 obs searched (on Garrawarla and OzStar)

    • Benchmarks: Table given in slides

    • Used LOFAR's single pulse search software and found RRAT J0410-31

      • Vindication that LOFAR's software works well.

  • RB: J0410-31 is a HTRU discovery.

    • Comforting that back-of-the-envelope calculations suggest that single pulse sensitivity is ~few Jy

  • RS: 7 sigma pulse? Is that LOFAR's detection sigma?

    • NS: Not sure where that number comes from.

    • RB: Lots not understood -- e.g. side/grating lobe detection? It's 10 deg away from pencil beam.

  • WvS: One of the plots was time vs DM, and it shows an interesting trace. What does it mean? Is it expected?

    • NS: Not sure, but it's one of the less useful diagnostics in my experience.

    • RB: Common theme: using LOFAR software -- maybe buggy, maybe not optimised. Question is, is it worth the effort to understand it very thoroughly?

    • RB: could be good for student project!

Software upgrade update (Sam)

  • MWA upgrade means that we will be served coarse channelised data instead of fine channelised data

  • If we want a homogeneous data set, we will need to do our own offline PFB

  • Opportunity to change software paradigm from "limited-mode pulsar backend system" to "flexible, exploratory research tool"

  • Modular design will greatly ease extension development down the line

  • Script-based interface, where individual steps are translated to a sequence of GPU kernel calls

  • Development period until June, then testing and commissioning, ready in time for MWA hardware upgrade.

  • WvS: How many people involved in development?

    • SM: Me and Keegan. But it's not a complete rewrite (obviously already have a working beamformer to draw from)

    • IM: My online beamformer is being currently developed as well. Perhaps combining our efforts, or at least liaising with each other may be beneficial to both.

MWAX/HTR commissioning (Ramesh)

  • Primary objectives:

    • New data format

    • Time stamping

    • Frequency labelling

    • Timing stability

    • Polarimetric verification and leakage

    • Calibration

    • Full coherent beam sensitivity

  • Using Targets:

    • J0034-0721, J1752-2806, J2241-5236, J0437-4715, J2145-0750, B0628-28, B0737-40, B0740-28, B1749-28, J0036-1033

  • Time frame for fifth survey campaign = Sept-Oct (if all goes well, fingers crossed)

  • Proposal was sent out to SMART collarboration (but only at the same time that it was submitted, due to compressed time line)

  • RS: How much is dependent on new hardware arriving on time?

    • SM: Actually, delays in hardware are good for us.

    • RM: Significant delays probably not likely, and in any case doesn't change our long-term plan.

ML classifier (Isaac)

  • GAN model (Generative adversarial network) not fully working as of the end of 2021

  • New model being investigated: Transformers

  • Problems with GAN: didn't work well with large data cubes as inputs

  • WvS: Two words of caution: (1) Not sure how well these work in noisy regimes, (2) Class imbalance problem

    • IC: On (2), GANs offer natural solution by generating "true" candidates

Web-app development (Nick/Sam):

  • Time scale for system coming online is a 1-2 months.

  • Will be able to invite collaborators to participate in candidate checking efforts easily.

Administrative issues and future plans:

  • May want SMART telecons on a more regular basis.

  • Have to continue scientific output.

    • Three papers planned for 2021:

      1. Survey description paper (Bhat et al)

      2. Population study paper (Swainston et al)

      3. Low-frequency profile paper (Smith et al)

  • WvS: Single pulse timeseries will be available?

    • No automation for that right now. Currently would have to process "manually" from raw data.

    • WvS: Data outputs might be large, but perhaps only statistical information need be kept.

    • WvS: We can revisit this idea if plucky students come along looking for science projects.

    • RB: Should prove existence of "user base" first.