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Results of a five-year program of multifrequency monitoring of low-frequency variable radio sourcesWe present the results of a detailed multifrequency monitoring program of low-frequency variable radio sources. This consists of light curves at 318, 430, 606, 880, and 1400 MHz over a 5 year period. The observations were carried out with the Arecibo 305 m radiotelescope and the Green Bank 91 m radio telescope. The spectral characteristics of the variations confirm the general picture that at least two mechanisms are responsible. The first is clearly intrinsic evolution of synchrotron-emitting components as it is manifested by variations that appear first and most strongly at high frequencies, subsequently drifting to lower frequencies with diminished amplitude. The more common type of low-frequency variability, however, dominates at frequencies below approximately 800 MHz, while the variations near 1 GHz are often quite weak. This spectral property is strong evidence that these variations are interstellar refractive scintillation.
Document ID
19950030388
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
External Source(s)
Authors
Mitchell, K. J.
(General Sciences Corp. Laurel, MD, United States)
Dennison, Brian
(Polytechnic Inst. & State Univ. Blacksburg, VA, United States)
Condon, J. J.
(Nat'l Radio Astronomy Observ., Charlottesville, VA United States)
Altschuler, Daniel R.
(Nat'l Astronomy and Ionosphere Center Arecibo, Puerto Rico)
Payne, H. E.
(Space Telescope Science Institute, Baltimore, MD United States)
O'Dell, S. L.
(NASA Marshall Space Flight Center Huntsville, AL, United States)
Broderick, J. J.
(Polytechnic Inst. & State Univ. Blacksburg, VA, United States)
Date Acquired
August 16, 2013
Publication Date
August 1, 1994
Publication Information
Publication: The Astrophysical Journal: Supplement Series
Volume: 93
Issue: 2
ISSN: 0067-0049
Subject Category
Astrophysics
Accession Number
95A61987
Funding Number(s)
CONTRACT_GRANT: NSF AST-81-17864
CONTRACT_GRANT: NSF AST-87-15532
Distribution Limits
Public
Copyright
Other

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