2003/06/24 by J. E. J. Lovell, J. Lovell, D. L. Jauncey +11 · 2 citations
Chemistry · Physics and Astronomy · #Amplitude #Astronomy #Astrophysics #Astrophysics and Cosmic Phenomena #Brightness #Chemistry #Detector #Flux (metallurgy) #Galaxies: Formation, Evolution, Phenomena #Galaxy #Interstellar medium #Optics #Physics #Radio Astronomy Observations and Technology #Scintillation #Very-long-baseline interferometry #astro-ph
paper · pdf · doi:10.1086/378053
published as Astron.J.126:1699,2003 · 18 pages, 5 figures. To appear in the Astronomical Journal
arxiv created 2003/06/24 · openalex publication_date 2003/10/01 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
We are undertaking a large-scale, microarcsecond scintillation-induced variability survey, MASIV, of the northern sky (decl. > 0°) at 4.9 GHz with the VLA. Our objective is to construct a sample of 100 to 150 scintillating extragalactic sources with which to examine both the microarcsecond structure and the parent populations of these sources, and to probe the turbulent interstellar medium responsible for the scintillation. We report on our first epoch of observations, which revealed variability on timescales ranging from hours to days in 85 of 710 compact flat-spectrum sources. The number of highly variable sources, those with rms flux density variations greater than 4% of the mean, increases with decreasing source flux density, but rapid, large-amplitude variables such as J1819+3845 are very rare. When compared with a model for the scintillation due to irregularities in an electron layer 500 pc thick, our preliminary results indicate maximum brightness temperatures ∼10 12 K, similar to those obtained from VLBI surveys even though interstellar scintillation is not subject to the same angular resolution limit.