1. Timing with analytic frequency- dependent templates David Champion Gravitational Wave Meeting 2007

2. The 10-cm frequency slope Split the band into subbands Fit the individual bands using a template generated over the whole band Slope of 2x10 -6 s in the timing residuals Most clearly seen at the 10-cm band with 1 GHz bandwidth and J0437-4715

3. Possible origins Incorrect DM –A DM difference of -0.0083 pc cm -3 –Observations at 20cm suggest a correction of +0.0006 pc cm -3 Incorrect centre frequency –Could be explained by a shift of 3-4 MHz –Tested using 20-cm MB LO –Good to within a fraction of a MHz The DFB2 itself –This frequency slope was observed using other backends Profile evolution over the band

4. Why is this important? Can we not just integrate over the band and use a template that is also integrated over the band? Scintillation and RFI channel zapping causes a bias toward one end of the band introducing residuals in the timing data.

5. Profile evolution over the band Preliminary test using paas –Fit an analytic template to each subband individually –Evolution of the Von-Mise components that make up the template suggest linear trends Want to try a global fit over the band –Try allowing a component parameters to vary linearly over the band –Fit subbands individually given model

6. Frequency dependent analytic template fitting Use wrapped Gaussian components Levenberg-Marquardt non-linear fitting routine 8 subbands 9 components

7. A few complications Each subband is scaled independently at model fitting and at TOA determination pat is unable to fit using a multi-frequency template – requires a tweak to profile In order to refer to a specific frequency the observing frequency has to be corrected for the Doppler shift due to the Earth’s motion TEMPO2 man

8. Initial results Mono-frequencyMulti-frequency

9. The next steps Collaborate with EPTA Apply to more pulsars Apply to more frequency bands Can we link across the bands? Include polarisation Stop using linear constraint? Turn into usable PSRchive code Link to TEMPO2 directly Apply it to our data