Challenge: Low frequency foreground – hot, confused sky

• HI 21cm signal ~ 10 mK

• Foreground: T ~ 100z)^-2.6 K

• Highly ‘confused’: 1 source/deg^2 with S140 > 1 Jy

• Synch. smooth ~ 100MHz vs. 21cm lines ~ 1 MHz

0.5 to 5.0 GHz

Chromatic aberration: Frequency differencing with MHz channels doesn’t work well due to frequency dependent far-out sidelobes

142, 174 MHz

6C source counts > 1Jy (Smax = 200 Jy)

Simulation: effects of residual calibration errors

UVSUB ~ ‘real-time’ source removal

IMLIN ~ post-processing freq fitting (3rd order)

Datta+ 09

0.1% 1%

For errors constant over 1 day: DNR requirement ~ 0.2% calibration errors

300 hours0.1% calibration errors

Datta + Bowman in prep

UVSUB

IMLIN

• Focus: Reionization (power spec,CSS,abs)

• Very wide field: single dipole + screen

• Correlator: FPGA-based from Berkeley wireless lab

• Staged engineering: maintain GB test installation PWA PSA

J. Aguirre, D. Jacobs (Penn), C. Carilli (NRAO)J. Aguirre, D. Jacobs (Penn), C. Carilli (NRAO)

PAPER: Staged Engineering• Broad band sleeve dipole + flaps

• FPGA-based ‘pocket correlator’ from Berkeley wireless lab

• S/W Imaging, calibration, PS analysis: AIPY + Miriad/AIPS => Python + CASA, including ionospheric ‘peeling’ calibration

100MHz 200MHz

BEE2: 5 FPGAs, 500 Gops/s

Beam response

Western Australian deployment in 2008

CygA 1e4Jy

PAPER/WA -- 4 Ant, July 2007

RMS ~ 1Jy; DNR ~ 1e4

Parsons et al. 2009

120MHz 180MHz

Paper – South Africa• Karoo site • 16 elements by Nov 1, 2009• 32 elements possible by Jan 1

PGB 16 dipole, 3x24hr

• scale -10 to 10 Jy• rms ~ 100 mJy• FWHM ~ 20’