1999/11/11 by B. M. Gaensler, R. W. Hunstead · 1 citation
Physics and Astronomy · #Active galactic nucleus #Astrophysics and Cosmic Phenomena #Galactic plane #Galaxies: Formation, Evolution, Phenomena #Interstellar medium #Observatory #Radio Astronomy Observations and Technology #Radio astronomy #Radio telescope #Scintillation #Spectral line #Telescope #astro-ph
paper · pdf · doi:10.1071/as00072
18 pages, 9 embedded EPS files. To appear in Publications of the Astronomical Society of Australia. Data available electronically at http://www.physics.usyd.edu.au/astrop/scan/
arxiv created 1999/11/11 · openalex publication_date 2000/01/01 · arxiv updated 2015/06/24 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/05
Abstract Before and after every 12 hour synthesis observation, the Molonglo Observatory Synthesis Telescope (MOST) measures the flux densities of ∼5 compact extragalactic radio sources, chosen from a list of 55 calibrators. From 1984 to 1996, the MOST made some 58,000 such measurements. We have developed an algorithm to process this dataset to produce a light curve for each source spanning this thirteen-year period. We find that 18 of the 55 calibrators are variable, on time scales between one and ten years. There is the tendency for sources closer to the Galactic Plane to be more likely to vary, which suggests that the variability is a result of refractive scintillation in the Galactic interstellar medium. The sources with the flattest radio spectra show the highest levels of variability, an effect possibly resulting from differing orientations of the radio axes to the line of sight.