Judd D. Bowman Hubble Fellow, Caltech Alan E. E. Rogers Haystack Observatory With support from: CSIRO/MRO and Curtin University Thanks to: The organizers and Murray Lewis and the NSF 31 March 2010 RFI2010 Groningen VHF-band RFI in Geographically Remote Areas

Outline Experiment to Detect the Global EoR Signature (EDGES) RFI at Murchison Radio-astronomy Observatory (MRO) Quick surveys in the US Rural New England Catlow Valley, Oregon A few words on meteor scattering

Experiment to Detect the Global Epoch of Reionization Signature (EDGES)

Exotic Telescopes Prepare to Probe Era of First Stars and Galaxies Science, Vol no. 5948, pp – 1619, 25 September 2009

The approach for LOFAR, MWA, PAPER, SKA… “Science with the MWA” Greenhill, Bowman, et al. (2010, in prep) Figure by Matt McQuinn

The approach for EDGES Pritchard & Loeb z [redshift] T b [mK] 21 cm global brightness temperature  [MHz]

EDGES

Bowman & Rogers (in prep)

Deep VHF-band integrations at the MRO

Murchison Radio-astronomy Observatory

Radio Frequency Interference (RFI)

Integrated spectrum at MRO by EDGES Murchison Radio-Astronomy Observatory (MRO) Aug 20 – Oct 20, wall-clock hours on sky ~50 hours actual integration +15 dB +40 dB

Orbcomm LEO satellite constellation ( MHz)

Total power in band vs. time Sum antenna temperature MHz Orbcomm band ~138 MHz

Anomalous propagation – DTV 7 and 9 EDGES Memo#058, AEER, 2010

Integrated RFI (time excision only – by broadband power level in FM, Orbcomm, DTV bands: 30% removal) Note: shows every channel that ever had RFI over 3 months Conservatively excise any channel that had RFI: 11% removal

Example excision rates

Shallow surveys in remote areas of the US

US TV and FM radio “pollution” D1 Array – Haystack Obs. West Forks, Maine

Rural New England, US D1 Array – Haystack Obs. West Forks, Maine EDGES Memo#044, AEER, 2009

US TV and FM radio “pollution”

Catlow Valley, Oregon, US 60 dB 10 dB 80 MHz 200 EDGES Memo#052, AEER, JDB, 2009

Meteor scattering

Time-variable FM RFI FM band

Meteor scatter rates vs. elevation angle EDGES Memo#054, AEER, 2009 horizon zenith

Summary 3 month deployment in MRO – Deepest broadband spectrum ever acquired: 5 mK rms (-220 dBW/m 2 /Hz) – First redshifted 21 cm EoR science – Simple time and spectral flagging sufficient to remove RFI – FM band a good indicator of anomalous transmission events – Total power in band varies strongly with Orbcomm and aircraft Quiet sites in US – not as good as MRO – Meteor scatter a significant source of RFI, dependent on elevation angle of sky coverage

Aircraft at MRO

FM at MRO

RFI observed in Oregon, US

Summary 3 month deployment in MRO – Deepest broadband spectrum ever acquired: 5 mK rms (-220 dBW/m 2 /Hz) – First redshifted 21 cm EoR science – Simple time and spectral flagging sufficient to remove RFI – FM band a good indicator of anomalous transmission events – Total power in band varies strongly with Orbcomm and aircraft Quiet sites in US – not as good as MRO – Meteor scatter a significant source of RFI, dependent on elevation angle of sky coverage