Session 113 - Neutron Stars & Pulsars.
Oral session, Saturday, January 10
International Ballroom East,

## [113.07] Pulsar Survey and Timing with the Penn State Pulsar Machines

We present two new filterbank spectrometers designed specifically for pulsar timing and surveys with large to medium sized radio telescopes. The Penn State Pulsar Machine (PSPM) is a 2 \times 128 \times 60 kHz filterbank designed for observations at intermediate radio frequencies around 400 MHz and is currently installed at Arecibo Observatory in Puerto Rico. The Penn State Pulsar Machine II (PSPM\,II) is a 2 \times 64 \times 3 MHz filterbank built for observing pulsars at frequencies above 1 GHz with the 32 meter radiotelescope in Toru\'n, Poland. The control software developed for the new filterbanks incorporates a graphical interface which can be run over the Internet for monitoring and remote control of observations.

Our drift survey of 2000 deg^2 of the sky with the PSPM at Arecibo is the first of its kind to achieve \sim 1 mJy sensitivity to pulsars with periods shorter than 1 ms. Theory predicts that a neutron star will begin to shed mass at rotation periods less than about 0.5 ms. The discovery of a pulsar rotating with a period less than a millisecond will help constrain neutron star equations of state. To date, the Penn State surveys at Arecibo have discovered a 4.6 millisecond pulsar, PSR J1709+23, that appears to be in a low mass binary system with a 22.7 day orbital period, and the young pulsar, PSR J0538+2817, possibly associated with the supernova remnant S147 located in the direction of the Galactic anticenter.

Calibration timing observations with the PSPM typically show factor of two improvement in timing accuracy for low-DM millisecond pulsars like PSR B1257+12 and PSR B1640+22, as compared to the previous most sensitive pulsar timing backend at Arecibo. Our timing observations of PSR B0329+54 with the PSPM\,II clearly disprove the existence of a planetary companion with a 16.8 year orbit, recently proposed for that pulsar.