Hostname: page-component-cd9895bd7-gbm5v Total loading time: 0 Render date: 2024-12-27T10:19:48.707Z Has data issue: false hasContentIssue false
  • English
  • Français

Long-term Monitoring of Molonglo Calibrators

Published online by Cambridge University Press:  05 March 2013

B. M. Gaensler  and
R. W. Hunstead
B. M. Gaensler
Affiliation:
Center for Space Research, Massachusetts Institute of Technology, 70 Vassar Street, Cambridge, MA 02139, USA; bmg@space.mit.edu School of Physics, University of Sydney, NSW 2006, Australia
R. W. Hunstead
Affiliation:
School of Physics, University of Sydney, NSW 2006, Australia; rwh@physics.usyd.edu.au
Rights & Permissions [Opens in a new window]

Abstract

Core share and HTML view are not available for this content. However, as you have access to this content, a full PDF is available via the ‘Save PDF’ action button.

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.

Keywords

ISM: generalquasars: generalradio continuum: galaxies
Type
Research Article
Information
Publications of the Astronomical Society of Australia , Volume 17 , Issue 1 , 2000 , pp. 72 - 82
Copyright
Copyright © Astronomical Society of Australia 2000

References

Bertsch, D. L., et al. 1993, ApJ, 405, 21 Google Scholar
Brinkmann, W., Siebert, J., & Boller, T. 1994, A&A, 281, 355 Google Scholar
Burgess, A. M. 1998, PhD thesis, University of Sydney Google Scholar
Campbell-Wilson, D., & Hunstead, R. W. 1994, PASA, 11, 33 (Paper I)Google Scholar
Cawthorne, T. V., & Rickett, B. J. 1985, Nature, 315, 40 Google Scholar
di Serego Alighieri, S., Danziger, I. J., Morganti, R., & Tadhunter, C. N. 1994, MNRAS, 269, 998 CrossRefGoogle Scholar
Ghosh, T., & Rao, A. P. 1992, A&A, 264, 203 Google Scholar
Gregorini, L., Ficarra, A., & Padrielli, L. 1986, A&A, 168, 25 Google Scholar
Hughes, P. A., Aller, H. D., & Aller, M. F. 1992, ApJ, 396, 469 Google Scholar
Hunstead, R. W. 1972, ApJ Lett., 12, 193 Google Scholar
Hunstead, R. W. 1991, Aust. J. Phys., 44, 743 Google Scholar
Hunstead, R. W., & Murdoch, H. S. 1980, MNRAS, 192, 31P Google Scholar
Kaspi, V. M., & Stinebring, D. R. 1992, ApJ, 392, 530 Google Scholar
Kedziora-Chudczer, L., Jauncey, D. L., Wieringa, M. H., Walker, M. A., Nicolson, G. D., Reynolds, J. E., & Tzioumis, A. K. 1997, ApJ, 490, L9 Google Scholar
Kesteven, M. J. L., Bridle, A. H., & Brandie, G. W. 1976, AJ, 81, 919 Google Scholar
King, E. A., et al. 1993, in Sub-arcsecond Radio Astronomy, ed. R. J. Davis & R. S. Booth (Cambridge Univ. Press), p. 152 Google Scholar
Large, M. I., Campbell-Wilson, D., Cram, L. E., Davison, R. G., & Robertson, J. G. 1994, PASA, 11, 44 Google Scholar
Large, M. I., Mills, B. Y., Little, A. G., Crawford, D. F., & Sutton, J. M. 1981, MNRAS, 194, 6934 Google Scholar
Ma, C., et al. 1998, AJ, 116, 516 Google Scholar
Mills, B. Y. 1981, PASA, 4, 156 CrossRefGoogle Scholar
Mitchell, K. J., Dennison, B., Condon, J. J., Altschuler, D. R., Payne, H. E., O'Dell, S. L., & Broderick, J. J. 1994, ApJS, 93, 441 Google Scholar
Murphy, D. W., et al. 1993, in Sub-arcsecond Radio Astronomy, ed. R. J. Davis & R. S. Booth (Cambridge Univ. Press), p. 243 Google Scholar
Orr, M. J. L., & Browne, I. W. A. 1982, MNRAS, 200, 1067 Google Scholar
Preston, R. A., et al. 1989, AJ, 98, 1 Google Scholar
Qian, S. J., Britzen, S., Witzel, A., Krichbaum, T. P., Wegner, R., & Waltman, E. 1995, A&A, 295, 47 Google Scholar
Rickett, B. J., Coles, W. A., & Bourgois, G. 1984, A&A, 134, 390 Google Scholar
Robertson, J. G. 1991, Aust. J. Phys., 44, 729 Google Scholar
Shapirovskaya, N. Y. 1978, Sov. Astron., 22, 544 Google Scholar
Spangler, S., Fanti, R., Gregorini, L., & Padrielli, L. 1989, A&A, 209, 315 Google Scholar
Tingay, S. J., et al. 1996, ApJ, 464, 170 Google Scholar
Tingay, S. J., et al. 1997, AJ, 113, 2025 Google Scholar
Tzioumis, A. K. 1987, PhD thesis, University of Sydney Google Scholar