Nanoarcsecond single-dish imaging of the Vela pulsar

Macquart, J. -P.; Johnston, S.; Walker, M.; Stinebring, D.

Nanoarcsecond single-dish imaging of the Vela pulsar

Authors

Description

We have measured the properties of the diffractive scintillation toward the Vela pulsar under the extremely strong scattering conditions encountered at 660 MHz. We obtain a decorrelation bandwidth of $ν_d = 244 \pm 4$ Hz and diffractive decorrelation timescale of $t_{\rm diff} = 3.3\pm 0.3$ s. Our measurement of the modulation indices $m=0.87\pm 0.003\pm 0.05$ and $m=0.93\pm 0.03 \pm 0.05$ (one for each polarization stream), are at variance with the modulation index of the Vela pulsar obtained at 2.3 GHz by Gwinn et al. (1997) {\it if} the deviation from a modulation index of unity is ascribed to a source size effect.
4 pages, 1 figure, to appear in Proc. IAUC177 "Pulsar Astronomy - 2000 and Beyond" Eds. M. Kramer, N. Wex & R. Wielebinski (ASP Conf. Series; uses newpasp.sty)