2000/02/04 by C. R. Gwinn, J. E. Reynolds, Gwinn, C. R. +26
Engineering · Physics and Astronomy · #Astrophysics (astro-ph) #FOS: Physical sciences #GNSS positioning and interference #Pulsars and Gravitational Waves Research #Radio Astronomy Observations and Technology #astro-ph
paper · pdf · doi:10.48550/arxiv.astro-ph/0002090
4 pages, 2 figures, to appear in Proc. IAUC177 "Pulsar Astronomy - 2000 and Beyond," eds. M. Kramer, N. Wex & R. Wielebinski. Uses newpasp.sty Also available at http://www.physics.ucsb.edu/~cgwinn/pulsar.html
arxiv created 2000/02/04 · openalex publication_date 2000/02/04 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
We describe measurements of the size of the Vela pulsar via scintillation, using both fits to the distribution of intensity and measurements of the modulation index. We briefly discuss systematic effects other than source size that can affect the distribution, including gain variations, self-noise, scintillation shot noise, and correlator saturation. Modulation index, a single number, can be biased by all of these, whereas the distribution of intensity is affected in different ways by different effects, providing means of distinguishing among them. Self-noise and gain variations are likely more important at long observing wavelengths, and correlator saturation and scintillation shot noise at short wavelengths. We find a size of about 500 km at decimeter wavelengths. Interestingly, this agrees with measurements of modulation index by Roberts & Ables at the same wavelength. Their results (and more recently that reported by Macquart et al.) suggest that size decreases with increasing wavelength. Although consistent with the observations, this conclusion is perhaps surprising from the standpoint of the traditional radius-to-frequency mapping. However, these measurements are of size rather than height; and of course systematic effects may play a role.