VLBA Observational Status Summary 2025A

VLBA capabilities 2025 February - 2025 July

Post-Processing Software

AIPS: The Astronomical Image Processing System, a set of programs for the analysis of continuum and line observations, is widely used with VLBA and VLBI data. These programs are supported on a variety of computer operating systems, including Linux and Mac-OS/X. The AIPS Cookbook (NRAO staff, 2014) includes an entire chapter on reducing VLBI data, including discussion of VLBA calibration, space VLBI, polarimetry, and phase referencing; Appendix C provides a step-by-step guide to calibrating many types of VLBA data in AIPS, including VLBA+VLA datasets.

A new "frozen" version of AIPS is produced each year, and a newer version is updated and made available throughout the calendar year. Observers are encouraged to use a very recent version of AIPS, in order to keep up with ongoing  developments in VLBA instrumentation. AIPS home page: http://aips.nrao.edu.

CASA: Common Astronomy Software Applications is the new data reduction package for the Jansky VLA and ALMA. It does not yet offer an end-to-end reduction path for all types of VLBA projects.  CASA should not be used for VLBA projects that involve astrometry, polarimetry, or low frequencies (below about 4 GHz).  However, CASA does contain imaging and calibration tools that may be of use for most basic phase-referenced VLBI data. CASA home page: http://casa.nrao.edu.  CASA VLBA Basic Phase-referencing tutorial (including self-calibration): https://casaguides.nrao.edu/index.php?title=VLBA_Basic_Phase-referencing_Calibration_and_Imaging.

Difmap: Difmap (Shepherd 1997), developed as part of the Caltech VLBI Analysis Programs. Provides editing, imaging, self-calibration, and pipelining capabilities in an interactive package. Development has been frozen, and continued support is limited primarily to assistance in installation. Difmap download site: ftp://ftp.astro.caltech.edu/pub/difmap/difmap.html. Contact: M.C. Shepherd, mcs@astro.caltech.edu.

References

A list of papers and articles referred to in this document follows.  Numerous citations are made to two particular conference proceedings volumes:

  • VLBI & the VLBA = Very Long Baseline Interferometry and the VLBA, Astronomical Society of the Pacific Conference Series, Volume 82, 1995, eds. J.A. Zensus, P.J. Diamond, & P.J. Napier.
This conference, held 1993 June 23-20, was the inaugural meeting held as the VLBA entered operational service.  An overview of the entire proceedings volume is available.  Links in the citations below will retrieve preprints of the relevant chapter, in gzipped PostScript format.
  • Synthesis II = Synthesis Imaging in Radio Astronomy II, Astronomical Society of the Pacific Conference Series, Volume 180, 1999, eds. G.B. Taylor, C.L. Carilli, & R.A. Perley.

 

  1. Beasley, A.J., & Conway, J.E. 1995, in VLBI & the VLBA, p. 327
  2. Beasley, A.J., Gordon, D., Peck, A.B., Petrov, L., MacMillan, D.S., Fomalont, E.B., & Ma, C. 2002, Astrophysical Journal Supplement, 141, 13
  3. Bridle, A.H., & Schwab, F.R. 1999, in Synthesis II, p. 371.
  4. Briggs, D.S., Schwab, F.R., & Sramek, R.A. 1999, in Synthesis II, p. 127.
  5. Brisken, W. 2008, VLBA Sensitivity Upgrade Memo # 23.
  6. Brisken, W., & Deller, A. 2010, VLBA Sensitivity Upgrade Memo # 32.
  7. Conway, J.E., & Sault, R.J. 1995, in VLBI & the VLBA, p. 309.
  8. Cornwell, T.J. 1995, in VLBI & the VLBA, p. 39.
  9. Cornwell, T.J., Braun, R., & Briggs, D.S. 1999, in Synthesis II, p. 151.
  10. Cornwell, T.J., & Fomalont, E.B. 1999, in Synthesis II, p. 187.
  11. Cotton, W.D. 1995a, in VLBI & the VLBA, p. 189.
  12. Cotton, W.D. 1995b, in VLBI & the VLBA, p. 289.
  13. Cotton, W.D. 1999a, in Synthesis II, p. 111.
  14. Cotton, W.D. 1999b, in Synthesis II, p. 357.
  15. Cotton, W.D., Dallacasa, D., Fanti, C., Fanti, R., Foley, A.R., Schilizzi, R.T., & Spencer, R. E. 1997a, Astronomy & Astrophysics, 325, 493.
  16. Cotton, W.D., Fanti, C., Fanti, R., Dallacasa, D., Foley, A.R., Schilizzi, R.T., & Spencer, R. E. 1997b, Astronomy & Astrophysics, 325, 479.
  17. Deller, A.T., Tingay, S.J., Bailes, M., & West, C. 2007, Publications of the Astronomical Society of the Pacific, 119, 318.
  18. Deller, A.T., Brisken, W.F., Phillips, C.J., Morgan, J., Alef, W. Cappallo, R., Middleberg, E., Romney, J., Rotmann, H., Tingay, S. J., & Wayth, R., 2011, Publications of the Astronomical Society of the Pacific, 123, 275.
  19. Diamond, P.J. 1995, in VLBI & the VLBA, p. 227.
  20. Fiedler, R., Dennison, B., Johnston, K.J., Waltman, E.B., & Simon, R.S. 1994a, Astrophysical Journal, 430, 581.
  21. Fiedler, R., Pauls, T., Johnston, K.J., & Dennison, B. 1994b, Astrophysical Journal, 430, 595.
  22. Fomalont, E., & Kogan, L. 2005, AIPS Memo No. 111.
  23. Garrett, M. A., Porcas, R. W., Pedlar, A., Muxlow, T. W. B., & Garrington, S. T. 1999, New Astronomy Reviews, 43, 519.
  24. Greisen, E. W. 2009, AIPS Memo 114.
  25. Hronek, A., & Walker, R.C. 1996, VLBA Test Memo No. 51.
  26. Kemball, A.J. 1999, in Synthesis II, p. 499.
  27. Kemball, A.J., Diamond, P.J., & Cotton, W.D. 1995, Astronomy & Astrophysics Supplement Series, 110, 383.
  28. Kogan, L. 1995a, VLBA Scientific Memo No. 9.
  29. Kogan, L. 1995b, VLBA Scientific Memo No. 12. 
  30. Leppänen, K.J. 1993, VLBA Scientific Memo No. 1.
  31. Leppänen, K.J., Zensus, J.A., & Diamond, P.J. 1995, Astronomical Journal, 110, 2479.
  32. Linford, J., & Brisken, W. 2020, VLBA Sensitivity Upgrade Memo # 51
  33. Markowitz, A., & Wurnig, J. 1998, VLBA Test Memo No. 60, and the associated webpage.
  34. Mioduszewski, A. 2004, AIPS Memo No. 110.
  35. Moran, J.M., & Dhawan, V. 1995, in VLBI & the VLBA, p. 161.
  36. Napier, P.J. 1995, in VLBI & the VLBA, p. 59.
  37. Napier, P.J., Bagri, D.S., Clark, B.G., Rogers, A.E.E., Romney, J.D., Thompson, A.R., & Walker, R.C. 1994, Proc. IEEE, 82, 658.
  38. NRAO staff, 2012, AIPS Cookbook.
  39. Perley, R.A. 1999a, in Synthesis II, p. 275.
  40. Perley, R.A. 1999b, in Synthesis II, p. 383.
  41. Reid, M.J. 1995, in VLBI & the VLBA, p. 209.
  42. Reid, M.J. 1999, in Synthesis II, p. 481.
  43. Rogers, A.E.E. 1995, in VLBI & the VLBA, p. 93.
  44. Romney, J.D. 1999, internal NRAO document reissued as VLBA Sensitivity Upgrade Memo # 2.
  45. Romney, J.D. 2000, internal NRAO document reissued as VLBA Sensitivity Upgrade Memo # 3.
  46. Romney, J.D., & Reid, M.J. 2005, Future Directions in High Resolution Astronomy, Astronomical Society of the Pacific Conference Series, Volume 340, 2005.
  47. Romney, J.D. 2007, VLBA Sensitivity Upgrade Memo # 1.
  48. Sault, R.J., & Conway, J.E. 1999, in Synthesis II, p. 419.
  49. Schilizzi, R.T. 1995, in VLBI & the VLBA, p. 397.
  50. Shepherd, M.C. 1997, ADASS IV, Astronomical Society of the Pacific Conference Series, Volume 125, eds. G. Hunt & H.E. Payne, p. 77.  http://www.nrao.edu/meetings/proceedings.shtml
  51. Taylor, G.B. 1998, Astrophysical Journal, 506, 637.
  52. Taylor, G.B. 2000, Astrophysical Journal, 533, 95.
  53. Taylor, G.B., Lonsdale, C.J., et al. 2004, Mapping the Future of VLBI Science in the U.S.
  54. Taylor, G.B., & Myers, S.T. 2000, VLBA Scientific Memo No. 26.
  55. Thompson, A.R. 1995, in VLBI & the VLBA, p. 73.
  56. Walker, R.C. 1995a, in VLBI & the VLBA, p. 133.
  57. Walker, R.C. 1995b, in VLBI & the VLBA, p. 247.
  58. Walker, R.C. 1999, in Synthesis II, p. 433.
  59. Walker, R.C. & Chatterjee, S. 1999, VLBA Scientific Memo No. 23.
  60. Walker, C., Durand, S., Kutz, C., & Hayward, R. 2007a, VLBA Sensitivity Upgrade Memo # 10.
  61. Walker, C., Romney, J., Brisken, W., & Durand, S. 2007b, VLBA Sensitivity Upgrade Memo # 15.
  62. Walker, C., Durand, S., Kutz, C., & Hayward, R. 2008, VLBA Sensitivity Upgrade Memo # 21.
  63. Walker, R.C. 2011 et seq., The SCHED User Manual. http://www.aoc.nrao.edu/software/sched/
  64. Wrobel, J.M. 1995, in VLBI & the VLBA, p. 411.
  65. Wrobel, J.M., & Walker, R.C. 1999, in Synthesis II, p. 171.
  66. Wrobel, J.M., Walker, R.C., Benson, J.M., & Beasley, A.J. 2000, VLBA Scientific Memo No. 24.
  67. Zensus, J.A., Taylor, G.B., & Wrobel, J.M. 1998, IAU Colloquium 164: Radio Emission from Galactic and Extragalactic Compact Sources, Astronomical Society of the Pacific Conference Series, Volume 144. http://www.nrao.edu/meetings/past.shtml

Editor's Notes

The VLBA Observational Status Summary is the collective work of innumerable individuals who wrote and edited the text, commented on draft material, and implemented the capabilities described herein, during the almost 30 years since the VLBA's dedication in 1993.  We thank these many colleagues for their contributions. For questions on the content, or suggestions that would enhance the clarity of this guide, we recommend contacting the NRAO Helpdesk.

Versions issued prior to July 2012 were based on a LaTeX source, from which PS and PDF versions were produced. A hypertext version was generated using the LaTeX2HTML translator. The LaTeX version of January 2012 was ported to Plone in April 2012.

VLBA Observational Status Summary 2025A Complete Manual

References

A list of papers and articles referred to in this document follows.  Numerous citations are made to two particular conference proceedings volumes:

  • VLBI & the VLBA = Very Long Baseline Interferometry and the VLBA, Astronomical Society of the Pacific Conference Series, Volume 82, 1995, eds. J.A. Zensus, P.J. Diamond, & P.J. Napier.
This conference, held 1993 June 23-20, was the inaugural meeting held as the VLBA entered operational service.  An overview of the entire proceedings volume is available.  Links in the citations below will retrieve preprints of the relevant chapter, in gzipped PostScript format.
  • Synthesis II = Synthesis Imaging in Radio Astronomy II, Astronomical Society of the Pacific Conference Series, Volume 180, 1999, eds. G.B. Taylor, C.L. Carilli, & R.A. Perley.

 

  1. Beasley, A.J., & Conway, J.E. 1995, in VLBI & the VLBA, p. 327
  2. Beasley, A.J., Gordon, D., Peck, A.B., Petrov, L., MacMillan, D.S., Fomalont, E.B., & Ma, C. 2002, Astrophysical Journal Supplement, 141, 13
  3. Bridle, A.H., & Schwab, F.R. 1999, in Synthesis II, p. 371.
  4. Briggs, D.S., Schwab, F.R., & Sramek, R.A. 1999, in Synthesis II, p. 127.
  5. Brisken, W. 2008, VLBA Sensitivity Upgrade Memo # 23.
  6. Brisken, W., & Deller, A. 2010, VLBA Sensitivity Upgrade Memo # 32.
  7. Conway, J.E., & Sault, R.J. 1995, in VLBI & the VLBA, p. 309.
  8. Cornwell, T.J. 1995, in VLBI & the VLBA, p. 39.
  9. Cornwell, T.J., Braun, R., & Briggs, D.S. 1999, in Synthesis II, p. 151.
  10. Cornwell, T.J., & Fomalont, E.B. 1999, in Synthesis II, p. 187.
  11. Cotton, W.D. 1995a, in VLBI & the VLBA, p. 189.
  12. Cotton, W.D. 1995b, in VLBI & the VLBA, p. 289.
  13. Cotton, W.D. 1999a, in Synthesis II, p. 111.
  14. Cotton, W.D. 1999b, in Synthesis II, p. 357.
  15. Cotton, W.D., Dallacasa, D., Fanti, C., Fanti, R., Foley, A.R., Schilizzi, R.T., & Spencer, R. E. 1997a, Astronomy & Astrophysics, 325, 493.
  16. Cotton, W.D., Fanti, C., Fanti, R., Dallacasa, D., Foley, A.R., Schilizzi, R.T., & Spencer, R. E. 1997b, Astronomy & Astrophysics, 325, 479.
  17. Deller, A.T., Tingay, S.J., Bailes, M., & West, C. 2007, Publications of the Astronomical Society of the Pacific, 119, 318.
  18. Deller, A.T., Brisken, W.F., Phillips, C.J., Morgan, J., Alef, W. Cappallo, R., Middleberg, E., Romney, J., Rotmann, H., Tingay, S. J., & Wayth, R., 2011, Publications of the Astronomical Society of the Pacific, 123, 275.
  19. Diamond, P.J. 1995, in VLBI & the VLBA, p. 227.
  20. Fiedler, R., Dennison, B., Johnston, K.J., Waltman, E.B., & Simon, R.S. 1994a, Astrophysical Journal, 430, 581.
  21. Fiedler, R., Pauls, T., Johnston, K.J., & Dennison, B. 1994b, Astrophysical Journal, 430, 595.
  22. Fomalont, E., & Kogan, L. 2005, AIPS Memo No. 111.
  23. Garrett, M. A., Porcas, R. W., Pedlar, A., Muxlow, T. W. B., & Garrington, S. T. 1999, New Astronomy Reviews, 43, 519.
  24. Greisen, E. W. 2009, AIPS Memo 114.
  25. Hronek, A., & Walker, R.C. 1996, VLBA Test Memo No. 51.
  26. Kemball, A.J. 1999, in Synthesis II, p. 499.
  27. Kemball, A.J., Diamond, P.J., & Cotton, W.D. 1995, Astronomy & Astrophysics Supplement Series, 110, 383.
  28. Kogan, L. 1995a, VLBA Scientific Memo No. 9.
  29. Kogan, L. 1995b, VLBA Scientific Memo No. 12. 
  30. Leppänen, K.J. 1993, VLBA Scientific Memo No. 1.
  31. Leppänen, K.J., Zensus, J.A., & Diamond, P.J. 1995, Astronomical Journal, 110, 2479.
  32. Linford, J., & Brisken, W. 2020, VLBA Sensitivity Upgrade Memo # 51
  33. Markowitz, A., & Wurnig, J. 1998, VLBA Test Memo No. 60, and the associated webpage.
  34. Mioduszewski, A. 2004, AIPS Memo No. 110.
  35. Moran, J.M., & Dhawan, V. 1995, in VLBI & the VLBA, p. 161.
  36. Napier, P.J. 1995, in VLBI & the VLBA, p. 59.
  37. Napier, P.J., Bagri, D.S., Clark, B.G., Rogers, A.E.E., Romney, J.D., Thompson, A.R., & Walker, R.C. 1994, Proc. IEEE, 82, 658.
  38. NRAO staff, 2012, AIPS Cookbook.
  39. Perley, R.A. 1999a, in Synthesis II, p. 275.
  40. Perley, R.A. 1999b, in Synthesis II, p. 383.
  41. Reid, M.J. 1995, in VLBI & the VLBA, p. 209.
  42. Reid, M.J. 1999, in Synthesis II, p. 481.
  43. Rogers, A.E.E. 1995, in VLBI & the VLBA, p. 93.
  44. Romney, J.D. 1999, internal NRAO document reissued as VLBA Sensitivity Upgrade Memo # 2.
  45. Romney, J.D. 2000, internal NRAO document reissued as VLBA Sensitivity Upgrade Memo # 3.
  46. Romney, J.D., & Reid, M.J. 2005, Future Directions in High Resolution Astronomy, Astronomical Society of the Pacific Conference Series, Volume 340, 2005.
  47. Romney, J.D. 2007, VLBA Sensitivity Upgrade Memo # 1.
  48. Sault, R.J., & Conway, J.E. 1999, in Synthesis II, p. 419.
  49. Schilizzi, R.T. 1995, in VLBI & the VLBA, p. 397.
  50. Shepherd, M.C. 1997, ADASS IV, Astronomical Society of the Pacific Conference Series, Volume 125, eds. G. Hunt & H.E. Payne, p. 77.  http://www.nrao.edu/meetings/proceedings.shtml
  51. Taylor, G.B. 1998, Astrophysical Journal, 506, 637.
  52. Taylor, G.B. 2000, Astrophysical Journal, 533, 95.
  53. Taylor, G.B., Lonsdale, C.J., et al. 2004, Mapping the Future of VLBI Science in the U.S.
  54. Taylor, G.B., & Myers, S.T. 2000, VLBA Scientific Memo No. 26.
  55. Thompson, A.R. 1995, in VLBI & the VLBA, p. 73.
  56. Walker, R.C. 1995a, in VLBI & the VLBA, p. 133.
  57. Walker, R.C. 1995b, in VLBI & the VLBA, p. 247.
  58. Walker, R.C. 1999, in Synthesis II, p. 433.
  59. Walker, R.C. & Chatterjee, S. 1999, VLBA Scientific Memo No. 23.
  60. Walker, C., Durand, S., Kutz, C., & Hayward, R. 2007a, VLBA Sensitivity Upgrade Memo # 10.
  61. Walker, C., Romney, J., Brisken, W., & Durand, S. 2007b, VLBA Sensitivity Upgrade Memo # 15.
  62. Walker, C., Durand, S., Kutz, C., & Hayward, R. 2008, VLBA Sensitivity Upgrade Memo # 21.
  63. Walker, R.C. 2011 et seq., The SCHED User Manual. http://www.aoc.nrao.edu/software/sched/
  64. Wrobel, J.M. 1995, in VLBI & the VLBA, p. 411.
  65. Wrobel, J.M., & Walker, R.C. 1999, in Synthesis II, p. 171.
  66. Wrobel, J.M., Walker, R.C., Benson, J.M., & Beasley, A.J. 2000, VLBA Scientific Memo No. 24.
  67. Zensus, J.A., Taylor, G.B., & Wrobel, J.M. 1998, IAU Colloquium 164: Radio Emission from Galactic and Extragalactic Compact Sources, Astronomical Society of the Pacific Conference Series, Volume 144. http://www.nrao.edu/meetings/past.shtml

Editor's Notes

The VLBA Observational Status Summary is the collective work of innumerable individuals who wrote and edited the text, commented on draft material, and implemented the capabilities described herein, during the almost 30 years since the VLBA's dedication in 1993.  We thank these many colleagues for their contributions. For questions on the content, or suggestions that would enhance the clarity of this guide, we recommend contacting the NRAO Helpdesk.

Versions issued prior to July 2012 were based on a LaTeX source, from which PS and PDF versions were produced. A hypertext version was generated using the LaTeX2HTML translator. The LaTeX version of January 2012 was ported to Plone in April 2012.

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