Meter-wavelength VLBI. III - Pulsars

view Abstract Citations (15) References (18) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Meter-wavelength VLBI. III. Pulsars. Vandenberg, N. R. ; Clark, T. A. ; Erickson, W. C. ; Resch, G. M. ; Broderick, J. J. Abstract Observations of pulsars, especially the Crab Nebula pulsar, made in very long baseline interferometry (VLBI) experiments are discussed. Based on a crude 144 MHz visibility curve which is consistent with a Gaussian brightness distribution, the measured visibilities at 196, 111, and 74 MHz were interpreted to yield apparent angular diameters (at half-power) of about 0.03 sec, 0.07 sec, and 0.18 sec, respectively. These sizes scale approximately as wavelength-squared, and the 74 MHz size agrees with recent observations using interplanetary scintillation techniques. The total flux densities lie on the extrapolation from higher frequencies of the pulsing flux densities. Variations in the total flux density up to 25 per cent were observed. A lack of fine structure other than the pulsar in the nebula is indicated by the simple visibility curves. The pulse shapes are similar to single-dish measurements at 196 MHz but reveal a steady, nonpulsing component at 111 MHz. The ratio of pulsing to total power was approximately equal to one-half but varied with time. It was found that four strong, low-dispersion pulsars were only slightly resolved. Publication: The Astrophysical Journal Pub Date: August 1976 DOI: 10.1086/154563 Bibcode: 1976ApJ...207..937V Keywords: Crab Nebula; Interferometry; Pulsars; Size (Dimensions); Brightness; Diameters; Fine Structure; Pulse Duration; Radio Sources (Astronomy); Visibility; Astronomy full text sources ADS | data products SIMBAD (8)