1. Baseband Processing and SKA Simulations using Supercomputers: Enhancing Australia‘s radio astronomy facilities and its bid for the SKA Steven Tingay Swinburne University of Technology MNRF Symposium: June 7, 2005 ATNF Marsfield

2. Goals Use supercomputers to demonstrate SKA- related techniques and technologies: process in software the sampled, digitised output of single dish and interferometric radio telescopes; Develop these techniques and technologies and integrate them into existing radio astronomy National Facilities; Enhance Australia’s bid for the SKA by supporting performance simulations relevant to Australia as an SKA site.

3. “Baseband” processing Parkes RF electronics ~ few GHz Δν = 16 MHz (56 – 72 MHz) Sample/ Digitise 101001010… Multibeam correlator Board (application- specific device) ATCA RF electronics Δν = 16 MHz (56 – 72 MHz) Sample/ Digitise 101001010… Dell server-class PC (generic processing device) Apple Xraid disks Cray XD-1 Beowulf cluster

4. Applications of baseband processing Pulsar timing at Parkes: –CPSR2 (Caltech Parkes Swinburne Recorder 2: 32 dual processor P4) Very Long Baseline Interferometry/eVLBI: –Swinburne supercomputer (304 P4 processors) –Cray XD-1 (12 Operton processors + 6 Xilinx FPGAs) –PC-based data recorders (Apple Xraid mass storage) RFI monitoring and characterisation: –“Mono” cluster at ATCA (16 dual processor P3)

5. VLBI/eVLBI We can now perform VLBI observations at up to x4 the bandwidth of S2 tape-based VLBI system (factor of 2 improved sensitivity): –Aim for 1 Gbps operation (x8 bandwidth) in real time via optical fibre in 2006 (SKA demonstration) Data are correlated in software on Swinburne supercomputer; New facilities are available as part of the VLBI National Facility from June 2005, supported by the MNRF team at Swinburne, the ATNF, and other VLBI partners: See http://www.atnf.csiro.au/observers/apply/avail.html First Trans-Tasman VLBI; Fringe-check software improves VLBI reliability.

6. Quasar J0006-0623: 2.3 GHz (4 x 16 MHz) ATCA, Parkes, Hobart, Ceduna, Mopra (LBAHDR) Hartebeestoek (Mark5) Kashima (K5, digitally filtered in software to match band) 2 milliarcsecond resolution Science paper in preparation

7. Quasar PKS 0438-436: 2.3 GHz (4 x 16 MHz) ATCA, Parkes, Hobart, Ceduna, Mopra, Tidbinbilla (LBAHDR) 10 milliarcsecond resolution

10. RFI monitoring and characterisation Use VLBI data acquisition hardware and cluster of machines at ATCA to provide autocorrelation spectrometer for RFI studies: –Retain digital samples: reprocess as necessary; –Arbitrary time and frequency resolution, dual-polarisation (linear or circular) ATCA RF electronics Δν = 16 MHz (56 – 72 MHz) Sample/ Digitise 101001010… FrequencyTime

11. Late March 2005, 5 hr ATCA observation: –Recorded data across entire ATCA frequency range (20 cm, 13 cm, 6 cm, 3 cm); –Autocorrelated on cluster; –Bandpass removal and “stitching” to form continuous spectra for 20 cm, 13 cm, 6 cm, 3 cm bands. Use temporal/frequency/polarisation characteristics to recognise RFI ; Produce RFI “masks” (function of time, frequency, polarisation) that can be used to flag ATCA datasets in MIRIAD; Run RFI monitoring software simultaneously with ATCA correlator for observation-specific RFI data and masks. 1520 MHz +/- 16 MHz Full 20 cm ATCA band

12. SKA simulations Uses Swinburne supercomputer and MIT Array Performance Software (MAPS: http://astronomy.swin.edu.au/ska/Simulator ): –Simulate characteristics of SKA arrays for potential Australian sites (reported to Australian Siting Working Group: available on request) Production of “SKA Array Configuration Studies – A Guide for Proposers” for the International SKA Project Office (available on request from the ISPO) + supporting software at: http://astronomy.swin.edu.au/ska/SSWG/CSTF-scripts

13. Online at: http://astronomy.swin.edu.au/~shoriuch/SKAcostsim/index_c.html SKA Cost calculation software Collaboration between SimWG and SEWG.

14. Summary Swinburne MNRF project is a big contributor to more efficient, robust, & cost-effective VLBI operations, now available to the general user community as a fully open National Facility: –Up to x4 time savings or x2 collecting area savings => $$$; –Robustness through real-time fringe-checking; –Aim at real-time, fibre-based eVLBI as a direct SKA demonstration. Working on RFI monitoring, characterisation, and masking for real ATCA observations and SKA technical demonstrations; Continuing SKA simulations work to make major contributions at national and international levels Last two years of MNRF program will see completion of RFI work at ATCA, full support for the enhanced VLBI National Facility, and continued simulations work toward the national site bid and the international SKA site selection process.