PrepSKA WP2, Manchester WvC 20/10/2011

APERTIF

• APERTIF increases the survey speed of the WSRT 25x • Enables new astronomical science, especially large surveys • Operational in 2012

Frequency range 1000 – 1750 MHz

Instantaneous bandwidth 300 MHz System temperature < 55 K Aperture efficiency 75% Polarization Dual linear Beamforming Digital Simultaneous beams 37 dual pol Field of view 8 deg2 Reflectors 12 x 25m

PrepSKA WP2, Manchester WvC 20/10/2011

High efficiency

PrepSKA WP2, Manchester WvC 20/10/2011

Measured sensitivity over field of view

• Measured sensitivity of prototype over field of view at 3 frequencies

1009 MHz

Tsys/ηap= 79 K

1416 MHz

Tsys/ηap= 85 K

1613MHz

Tsys/ηap= 106 K

PrepSKA WP2, Manchester WvC 20/10/2011

Temporal stability

• Measured temporal variation of mainbeam at half-power point • 1400 MHz, 2.5 hour duration

1

PrepSKA WP2, Manchester WvC 20/10/2011

Dual-beam pulsar observation

• 3.8 degrees apart (HPBW = 0.5 degrees)

PrepSKA WP2, Manchester WvC 20/10/2011

Low Noise Amplifier • First LNA fulfilling APERTIF requirements has been built and

measured – David Smith, postdoc from Stellenbosch, SA

• To do: design for manufacturing

PrepSKA WP2, Manchester WvC 20/10/2011

Design for manufacturing

• Prototypes demonstrated functionality • To design for easy production, installation and maintenance.

1-channel down-convertor 32-channel rack

• Avoid small component values

(e.g. no 0.5 pF C’s) • Squeezing the last

Kelvin • Fine-tuning gain to

final cable lengths • Test points on pcb • Include monitoring

and control • From LOFAR IF to

APERTIF IF • Higher level of

integration • Slide-on instead of

screw connectors

PrepSKA WP2, Manchester WvC 20/10/2011

ADC and digital beamforming subrack

• Link ADC to UniBoard is up & running

• Full subrack ordered and ready at end of 2011 (ADCs, backplane, clock, UniBoards)

SFP+10GbE

SFP+10GbE

SFP+10GbE

SFP+10GbE

2x2 RJ454x1GbE

FPGA FPGA

FPGA FPGA

FPGA FPGA

FPGA FPGA

Power

Diff Out

Diff Out

Diff Out

Diff Out

Diff Out

Diff Out

Diff Out

Diff Out

PWR

DDR3 Memory

DDR3 Memory

DDR3 Memory

DDR3 Memory

DDR3 Memory

DDR3 Memory

DDR3 Memory

DDR3 Memory

DDR3 Memory

DDR3 Memory

DDR3 Memory

DDR3 Memory

DDR3 Memory

DDR3 Memory

DDR3 Memory

DDR3 Memory

ADCFilter FPGA

Diff Out

PWR

FilterCLK DIST

Power Dist

ADCFilter FPGA

Diff Out

FilterCLK DIST

Power Dist

ADCFilter FPGA

Diff Out

FilterCLK DIST

Power Dist

ADCFilter FPGA

Diff Out

FilterCLK DIST

Power Dist

Power DistCLK DIST

ADU UniBoard

2 3 4 5 6 7 8 9 10

x 108

-100

-90

-80

-70

-60

-50

-40

-30

-20

-10

0

X: 6.006e+008Y: -1.13

Out

put p

ower

(dB

)

finput (Hz)

X: 4.287e+008Y: -4.569

X: 7.72e+008Y: -4.515

X: 8.893e+008Y: -51.45

X: 3.67e+008Y: -39.03

X: 5.76e+008Y: -2.182

CH 0CH 1CH 2CH 3CH 4CH 5CH 6CH 7

PrepSKA WP2, Manchester WvC 20/10/2011

Polarimetric calibration

• Collaborative effort ASTRON, Chalmers and BYU

Soon to be verified by measurements.

Simulated cross-correlation measured on an unpolarized source. Requirement < -20

dB.

Simulated beam stability from measured element-to-element

variations. Requirement is < 1%

PrepSKA WP2, Manchester WvC 20/10/2011

Software

• Optimally re-use existing WSRT + LOFAR software

• E.g. dish pointing from WSRT, LOFAR framework for RFI flagging, MAC, calibration and imaging, archive

PrepSKA WP2, Manchester WvC 20/10/2011

Calibration and imaging pipeline

• Pipeline has been defined. Verifying critical steps with WSRT data (e.g. robustness of solving for direction dependent effects)

• First images of WSRT data with LOFAR BBS have been made and are looking good. Using NVSS as input model for calibration for flux and bandpass calibration.

Differences < 10%.

PrepSKA WP2, Manchester WvC 20/10/2011

Calibration and imaging pipeline

• Pipeline has been defined. Verifying critical steps with WSRT data (e.g. robustness of solving for direction dependent effects)

• First images of WSRT data with LOFAR BBS have been made and are looking good. Using NVSS as input model for calibration for flux and bandpass calibration.

Differences < 10%.

PrepSKA WP2, Manchester WvC 20/10/2011

ALTA: APERTIF Long Term Archive

• The ALTA will be the main interface to the users

• Activities: – Inventory of possibilities for archive:

• what do we (want to) store and how? – LOFAR archive: what does it offer and what not?

• With LOFAR:

– VO standards. There are only a few for radio – Develop user model – Astronomer friendly interface. Involve astronomers & survey

teams

PrepSKA WP2, Manchester WvC 20/10/2011

Planning

• 2011 Start of site preparation (fiber to dishes) • 2012 Hardware procurement, production & testing • Early 2013 Start PAF installation