ASKAP Early Science Workshop

1. ASKAP Early Science Workshop ASTRONONY & SPACE SCIENCE Lisa Harvey-Smith & Aidan Hotan| ASKAP Project Scientists August 5th 2013

2. Rationale • ASKAP funding, fabrication, integration, commissioning is phased. • Science can also be phased. • Reasons to do early science observing: • Provides stringent early test of techniques & technology • Takes place in parallel with construction • Many super science fellows, postdocs available now-2016 ASKAP Early Science | Lisa Harvey-Smith

3. Guiding Principles • Early science will be a 'best-efforts' affair • Priority continues to be: • Completing ASKAP to scope and • Enabling the original survey science projects to take place • Early science plans may evolve as we • Refine the build-out schedule and • Learn and improve the capabilities of the telescope ASKAP Early Science | Lisa Harvey-Smith

4. This workshop will allow us to • Gauge the interest of user community • Identify a range of possible observing strategies • Plot a course – a plan for early science (via advisory bodies, CASS Chief) • Assignment of observing time • Scheduling of specific projects • Provision of certainty This workshop will not lead to ASKAP Early Science | Lisa Harvey-Smith

5. Dear Colleague, • I am pleased to inform you that your abstract for the ASKAP early science workshop has been accepted. • Please note that this is a workshop with a very specific focus, so take the time to re-read the attached information in order to make the workshop a successful as possible. In particular, your talk should address the following questions where relevant: • • What unique discovery space can be explored with ASKAP-12? • • What are the minimum requirements in your area of interest? • • What science topics could be tackled with a short (~hours) amount of observing time? • • Are there short observations that can tackle a number of different topics simultaneously? • • What could be achieved with a longer survey? • • What is the potential for commensal science? • • How does ASKAP-12 compare with other existing telescopes? • • What is the likely scientific impact of the observations? • • Are observations ‘high-risk’ or ‘low-risk’ in terms of implementation? • • What are the likely minimum requirements with respect to observing time? • • Do the observations have advanced data processing, imaging or calibration requirements? • • Are there any requirements that are different from those of the ASKAP SSPs or the intended specifications or deliverables?  • […] • Best wishes, ASKAP Early Science | Lisa Harvey-Smith

6. What I want to know • How do we maximise the impact of early science? • Do one thing really well? • Lots of small, single-target or single-field observations? • One large survey? • How do we measure the impact of ASKAP early science? • Number of papers? • Scientific discovery potential? • Training opportunities provided? • How would you like to interact with CSIRO during early science? ASKAP Early Science | Lisa Harvey-Smith

7. ADE-12 System Overview ASKAP Antenna MRO Central Building Phased Array Feed 188 chequerboard elements Low-noise amplifiers Band-select filters RF over Fibre transmission Digitiser / PFB 300MHz bandwidth 1 MHz channels Beamformer 36 dual-pol beams Pawsey Centre Correlator 5-second visibilities 18.5 kHz channels Central Processor / Archive Ingest Pipeline: CASA measurement sets Image pipeline: Calibration & deconvolution ASKAP Commissioning Update | Aidan Hotan

8. Hardware Capabilities • 12 ADE PAFs with 50K intrinsic Tsys across the ASKAP band. • Allow for imperfect illumination efficiency on the antennas. • 36 simultaneous beams (2 polarisations each) per PAF. • 300 MHz of instantaneous bandwidth. • 18.5 kHz fine channel resolution. • No initial support for transient capture, zoom modes, etc. • (Anything that requires changes to the basic firmware). ASKAP Commissioning Update | Aidan Hotan

9. Software Capabilities • Automated monitoring and safety overrides. • Wind / storm stow, cooling systems, power supply, etc. • Control of telescope via scheduling blocks (python based). • Tracking, scanning, frequency selection. • Ingest pipeline that produces measurement sets (with metadata) from correlator output in real time. • Image pipeline that calibrates and images the measurement sets. • Includes a suite of software tools that can be run manually, but with limited documentation. • Advanced features like source catalogue creation & sky model will still be in experimental stages. ASKAP Commissioning Update | Aidan Hotan

10. Expected Limitations During Early Science • Beam setup / maintenance will probably be a manual operation. • Imaging pipeline calibration will be marginal with 12 antennas. • Manual intervention required to make best images. • ASKAP imager assumes beam shape is uniform and unchanging. • Early images will have artefacts. • Errors likely to be time variable. • Full-resolution measurement sets will be large. • Disk / memory / network requirements mean that bulk processing needs to be done on the Pawsey machine. Accounts, queue scheduling required. • Some scope for the extraction of subsets and local caching at the MRO. • Support and training resources for SST members will be limited. • Interface to be decided. Nominate 1-2 representatives from key SSTs? ASKAP Commissioning Update | Aidan Hotan

11. The Need for BETA • Over the next 12-18 months, we will be learning many things: • How to best measure the characteristics (pattern shape, etc.) of a PAF beam. • How to optimise a PAF beam for circular symmetry, low side-lobe levels, low polarisation leakage, etc. • How often beamformer weights must be updated to keep all of the above properties as constant as possible. • How to best synthesise a uniform field consisting of multiple beams (which of the above beam characteristics results in the best image?). • How to best calibrate an array with a small number of antennas (low sensitivity and poor UV coverage makes self-cal difficult). • How much of the total observing time will be required for beamforming and calibration work. • This learning process will extend into the ADE early science period. ASKAP Commissioning Update | Aidan Hotan

12. Radio Frequency Interference • The MRO is a fantastic radio quiet site, but it is not RFI-free. • Thuraya 3 – mobile telecommunications. • Broadcast capability over 1525-1559 MHz and 1626.5-1660.5 MHz bands. • Observed at MRO around 1550 MHz. • ADSB transponders – onboard aircraft position broadcast. • 1090 MHz transmission. ASKAP Commissioning Update | Aidan Hotan

13. ASKAP Commissioning Update | Aidan Hotan