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ASKAP Capabilities
John Reynolds on behalf of the SEIC and ASKAP team
CSIRO. ASKAP Capabilities
14 May 2009
• Design and construction well underway – many capabilities set
• To ensure highest priority science is delivered fluidity is retained
• Announcement of Opportunity, Oct 2008
• Proposals due in mid-June 2009, evaluation by Aug 2009
• Crystallisation thereafter towards BETR (2010), ASKAP (2013)
ASKAP Capability life-cycle
CSIRO. ASKAP Capabilities
14 May 2009
• “Mode 1” capabilities already defined• Matching anticipated survey requirements• Continuum imaging• Standard spectral line imaging• Slow transients
• Post-commissioning• Advanced imaging modes (e.g. postage stamps)• “Zoom” (high spectral resolution) modes• VLBI & other “fast transients”
Rollout
CSIRO. ASKAP Capabilities
14 May 2009
Original capabilities, EoI
CSIRO. ASKAP Capabilities
14 May 2009
ASKAP Sensitivity (EoI)
CSIRO. ASKAP Capabilities
14 May 2009
Basics
• 36 antennas (configuration by Gupta, Johnston, Feain 2008)
• 32 beams/antenna• 30deg2 FOV up to ~1.5GHz• 50K Tsys, 80% Aperture Efficiency • 300MHz instantaneous BW, 20 kHz frequency resolution• Frequency range 700 – 1800 MHz, • tunable in 16 MHz steps• Full polarization (auto/cross products on all beams)• 5 second integration time in standard mode
CSIRO. ASKAP Capabilities
14 May 2009
ASKAP antenna design
12m – prime focus, f/D = 0.5
Alt+Az+polarisation axes (Sky mount)
Surface accuracy 1mm RMS (10 GHz)
Slew speeds 3/1/3 degs/secAcceleration 3/1/3 degs/sec/sec
Settling time < 5 seconds
CSIRO. ASKAP Capabilities
14 May 2009
Typical u-v histogram for deep image
δ = -50ºT=10h
CSIRO. ASKAP Capabilities
14 May 2009
PAF design
• 188 elements in octagonal configuration
• 32 x 2 pol formed beams
• Independently steerable
• 30 square degrees up to ~1.5GHz
• Optimal disposition for tesselation not entirely clear
• Interlacing (“dithering”) may be required for flatness of field
CSIRO. ASKAP Capabilities
14 May 2009
Preliminary design of ASKAP-sized array
11x10 minus some corner elements
188 active pairs
CSIRO. ASKAP Capabilities
14 May 2009
5 x 6 channel = 30 units13 x 8 channel = 104 units7 x 10 channel = 70 units
Available beams = 188
25 Multi channel LNA PCB's
Total number of LNA's = 204
188 channel FPA LNA Filtercard assembly
CSIRO. ASKAP Capabilities
14 May 2009
FOV vs # beamsBeams touching at the 3dB points
Beams touching at the 3dB*0.92 points
CSIRO. ASKAP Capabilities
14 May 2009
Overall ASKAP System
Beamfomer and Fine filterbank
Antenna 1
192 fibre connection
Beamfomer and Fine filterbank
Antenna 2
192 fibre connection
A/D and Coarse
FilterbankAntenna 36
Beamfomer and Fine filterbank
Antenna 36
192 Analogue
inputs
192 fibre connection
Correlator Band 1
Correlator Band 2
Correlator Band 16
Tied Array Post processing
(VLBI and Pulsars)
To Computing Centre
Central Site at MRO
Cross connect between
beamformers and correlator
Represents a single Advanced TCA
chassisAll Identical
To Computing Centre
To Computing Centre
To VLBI network
or pulsar processors
A/ Ds located in Antenna Pedestal
A/D and Coarse
FilterbankAntenna 36
192 Analogue
inputs
A/D and Coarse
FilterbankAntenna 36
192 Analogue
inputs
CSIRO. ASKAP Capabilities
14 May 2009
Mode 1 imaging capabilities
Continuum1 channel + spectral index/curvature OR 256 spectral channelsFull Stokes parameters (IQUV)4k x 4k pixels (2km array) or 12k x 12k (6km array)Real-time source cataloguing
Spectral Line16384 channels (df=18kHz)2 Stokes (I, V)4k x 4k pixels (2km array)Visibilities not archivedLimited number of cubes per day
Slow transients snapshots : 16-channel, 4k x 4k pixel, 2 Stokes
searched every 5 seconds selected images retained
CSIRO. ASKAP Capabilities
14 May 2009
Modes 2+
Advanced imaging Will be driven by Survey Science Project Design Study (2009-2011)
e.g. “postage stamps”, full 30dB polarization dynamic range
“Zoom” modes16k channels in 4~8 sub-bands, 0.6kHz(*2n) resolution, e.g.;
HI + 1612MHz + (1665-1667MHz)
VLBI – 2~3 tied-array beam voltages,
recorded off-site
frequency standard (H-maser vs Rb)
Fast transientsdiverse requirements vs fluid capabilities
active community consultation happening now
CSIRO. ASKAP Capabilities
14 May 2009
Fast Transients – capabilities
Flexible correlator – access to; single-dish autocorrelations,
tied-array Voltages or Power,
visibilities (optionally averaging)
formed-beam voltages
flexible user-determined averaging, nStok, nBit …
some on-board capacity for processing, buffering
Constraints
on-site space, power limits & costs
bandwidth to Geraldton (40Gb/s initially, shared)
calibration (requires processing engine)
FPGA programming effort (+testing, commissioning)
CSIRO. ASKAP Capabilities
14 May 2009
The end