ASKAP Commissioning – steady strides towards a major milestone
ASKAP commissioning continues towards the delivery of Array Release 3 – an 18 antenna array and the commencement of phase two early science observations. This array will be a major milestone on the path to full operations and includes the addition of a zoom mode (high resolution). As part of this work we have:
1) Commissioned a new, synchronous fringe rotator update system that reduces the amount of flagged data and provides improvedsupport for automated configuration changes
2) Commissioned the final frequency band, allowing access to 1400 – 1800 MHz as part ofroutine operations
3) Integratedcorrection of electronic beam weights (using our newly-commissioned on-dish calibrationsystem) into the operations workflow
4) Increased the correlator bandwidth to 288 MHz and demonstrated stable data capture at this rate with 16 antennas
5) Delivered another batch of digital electronics to the observatory, allowing integration of four more antennas
In the coming months we will be integrating between 8 and 12 more antennas into the main array. We will also complete work on zoom mode support(allowing bandwidth to be traded for frequency resolution) and independent phase tracking per beam, which are the final features required for array release 3. This will open up new possibilities for early science.
In the lead-up to full operations, we have also been planning a pilot survey program that will commence when all 36 antennas have been integrated. This program will test full scale operations for the first time and allow the science teams to validate their survey strategies, processing pipeline parameters anddata quality metrics. We plan to begin these pilot surveys in the first quarter of next year.
Pilot Transient Survey
A team led by Shivani Bhandari (Swinburne Uni/CSIRO) has undertaken a pilot search for variable and transient sources at 1.4 GHz with ASKAP. The search was performed in a 30 square degree field centred on the NGC 7232 galaxy group over eight epochs and observed with a near-daily cadence. It yielded nine potential variable sources among the 3817 sources detected above the flux density limit of ∼1.5 mJy. The nine sources are identified with active galactic nuclei and the variability in these objects is consistent with refractive interstellar scintillation. A source displaying high variability over the decade between the Sydney University Molonglo Sky Survey (SUMSS) and the ASKAP observations, was also identified, with this behaviour consistent with the properties of long-term variability of a quasar.
No transients were detected on time-scales of days and an upper limit was placed on their occurrence rate. The future VAST-Wide survey with 36-ASKAP dishes will probe the transient phase space with similar cadence to this pilot survey, but with better sensitivity, and will detect and monitor rarer, brighter events.
Answering the ASKAP data deluge with machine learning research
ASKAP’s large continuum survey, the Evolutionary Map of the Universe (EMU), will produce a catalogue of about 70 million galaxies, which is about 30 times the total number of radio sources detected by all radio telescopes over the entire history of radio astronomy. But to extract the science from that data, we need to match these radio sources against other multiwavelength catalogues, and measure redshifts. We also need to mine the data for those unexpected “WTF” discoveries that historically dominate the major paradigm shifts in astronomy. Conventional techniques cannot cope with that number of galaxies, so we have built a vigorous machine learning research group, spanning CSIRO, Western Sydney University (WSU), and other institutions.
CSIRO postdoc Tim Galvin has used the “Self-Organised Maps” algorithm to classify radio sources, and WSU student Nic Ralph has extended that technique by adding a “Convolutional Autoencoder” algorithm. WSU student Kieran Luken has found that even relatively simple algorithms such as “k-Nearest Neighbours” and “Random Forest” can use the optical and infrared photometry from NASA‘s Wide-field Infrared Survey Explorer (WISE) space telescope and ANU’s SkyMapper telescope to obtain redshifts for the majority of EMU sources.
In all this work, a major challenge has been to obtain sets of data to train and test the algorithms. Fortunately, we have been able to use the “Australia Telescope Large Area Survey” (ATLAS) data, which is closely matched to EMU in sensitivity and resolution, but limited in area and number of sources. To obtain a large sample which has been matched and classified by human eye, we are fortunate in being able to use the “Radio Galaxy Zoo” data, in which tens of thousands of sources have been examined and classified by a team of thousands of “Citizen Scientists”.
Our informal “Machine Learning in Astronomy” group meets by videocon every 2 weeks, with participants from all over the world. If you would like to drop in for a chat, see times and connection details on www.mlprojects.pbworks.com
This week Australia farewells one of our ASKAP HI Research Assistants, Dane Kleiner, who is leaving CSIRO to take up a position with INAF in Sardinia, to work on the MeerKAT Fornax project; led by Paolo Serra (also formerly of CSIRO). For the past 18 months, Dane has been working with the WALLABY survey science team doing both science (imaging the nearby spiral galaxy IC 5201) and working with commissioning the telescope and its software.
The Fornax cluster is being observed by both ASKAP and MeerKAT and Dane says this is a great opportunity to use observations from these new pathfinder telescopes, to do new cutting edge science.
“Each telescope has its own strengths, where MeerKAT has superior sensitivity and ASKAP is a powerful wide-field imager. ASKAP will have the ability to identify new targets on the outskirts of the cluster that MeerKAT can image with follow up observations.” says Dane.
Dane joins a small, elite group of astronomers who have experience working with both telescopes and says this project will simultaneously make use of the best assets of both ASKAP and MeerKAT – something to look forward to with the SKA!
“The experience I’m taking with me from CSIRO is being able to reduce and analyse data from a new radio telescope – no other telescope has been built like ASKAP with its unique phased array feeds.”
As part of the globally agile astronomy workforce, Dane follows in the footsteps of others who have worked on SKA pathfinders in Australia, including Ian Heywood (who recently led the creation of the stunning MeerKAT image of the Galactic Centre) and Xinyu Wu an expert ASKAP programmer, who recently took two years leave to join the MeerKAT software team in Cape Town.
Arrivederci e buona fortuna (good-bye and good luck) Dane!
ASKAP Project Manager wins national award
Dr Adrian Rispler, leader of the ASKAP production team for CSIRO’s Astronomy and Space Science (CASS) has been awarded Project Professional of the Year 2018, by the Project Management Institute (Australia).
The award specifically recognises practical demonstration of advanced skills and understanding in the areas of Agile, Lean, Digital, and Innovation. Criteria includes; significant achievement or sustained performance in contribution to the completion of projects, and achievement demonstrated initiative and leadership. In his acceptance speech, Adrian made clear the effort and support of the entire ASKAP team, the benefits of diversity across all project stakeholders, as well as the importance of family and maintaining work-life balance for sustainable performance.
The PMI awards event was held in conjunction with Australia’s Premier Project Management Conference and showcases the latest ideas and thinking around key project management topics, all highly relevant to the SKA project and its pre-cursors. Adrian was joined by CASS Major Project Specialist, Dr Phil Crosby, in a conference presentation, showcasing ASKAP and the SKA mega-project. The talk was enthusiastically received, with many follow-up questions and post-session discussions.