RFI and Pulsar Data Rai Yuen QTT 18

RFI and Pulsar Data Rai Yuen QTT, 18 December 2014

The omni-presence RFI • A look at database revealed pulsar profiles are inconsistent. • Common to find 5 -6 out of 10 observation data that are heavily contaminated with RFI. • Worse, don’t know the characteristic of the RFI -> removal is hard. • A discount of 10 yr data – but still good.

Some RFI information • RFI originates from many sources: – 3 G signal can be up to million Jy, while pulsar signals are in the order of m. Jy. – from satellites, mobile phones and car sparks. • Characteristics: – narrowband: communication systems and TV, can be anywhere within the bandpass; lasts for < 1 to > few hundreds of second; power up to +50 d. B. – wideband • pulse bursts: power line; 1 - ~50 pulses each bursts; power up to +50 d. B. • single pulse: ignition (car sparks); lasts from microsecond to hours; power up to +50 d. B. • Ways to deal with them but we need to know their nature.

Pulse profile for PSR J 0837+0610 (B 0834+06) • There may be moderate to high RFI, but we do see the pulse. – – speculate on the pulse width. unsure of the pulse components. hard for statistical studies. Fit for pulsar timing, centre of pulse. • If RFI, probably need to discard it as it is too close to the real signal.

The same pulsar • Stockert 25 m radio telescope. • Now we are talking! • But how to remove the RFI?

RFI Mitigation plan • Our telescope has stepped up to 26 m, and need a long-term effective RFI mitigation plan. – Local: • potentially controllable. • regulatory protocols; • identify the signatures of RFI from our equipments. – External: • little we can do. • regularly monitoring of the changes in RFI. • again, identify their signatures and occurrences. • Best - establish a radio quiet zone.

Conclusions • RFI is everywhere! • What makes a telescope famous is not only for the dish size but equally due to having an effective plan for dealing with RFI. • • RFI investigations have begun at XAO with several results. Required equipments are in place. We have the required expertises. It is just a matter of time and collaboration before we have an effective RFI mitigation plan.