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Sunspot Numbers from ISOON: A Ten-Year Data Analysis

  • Sunspot Number Recalibration
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Abstract

Sunspot numbers are important tracers of historical solar activity. They are important in predicting the oncoming solar maximum, in the design of lifetimes of space assets, and in assessing the extent of solar-radiation impact on the space environment. Historically, sunspot numbers have been obtained visually from sunspot drawings. The availability of digital images from the US Air Force Improved Solar Optical Observing Network (ISOON) prototype telescope concurrent to observer-dependent sunspot numbers recorded at the National Solar Observatory (NSO) has provided a basis for comparing sunspot numbers determined from the two methods. We compare sunspot numbers from visual and digital methods observed nearly simultaneously. The advantages of digital imagery are illustrated.

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References

  • Allen, C.W.: 1991, Astrophysical Quantities, Athlone Press, London.

    Google Scholar 

  • Balasubramaniam, K.S.: 2002, Astrophys. J. 575, 553.

    Article  ADS  Google Scholar 

  • Balasubramaniam, K.S., Pevtsov, A.A.: 2011, In: Solar Physics and Space Weather Instrumentation, Proc. SPIE 8148.

    Google Scholar 

  • Cliver, E.W., Clette, F., Svalgaard, L.F.: 2013, Cent. Eur. Astrophys. Bull. 37, 401.

    ADS  Google Scholar 

  • Györi, L., Baranyi, T., Ludmány, A.: 2010, In: Choudhary, D.P., Strassmeier, K.G. (eds.) The Physics of Sun and Star Spots Proc. IAU Symp. 273, Cambridge University Press, Cambridge, 403. ADS . DOI .

    Google Scholar 

  • Hathaway, D.H.: 2010, Living Rev. Solar Phys. 12, 4. DOI .

    Article  ADS  Google Scholar 

  • Hathaway, D.H., Wilson, R.M., Reichman, E.J.: 1999, J. Geophys. Res. 104, 22375.

    Article  ADS  Google Scholar 

  • Henry, T.W.: 2015, Solar ephemeris applications and image analysis. MS thesis, Texas Tech University, Lubbock, TX.

  • Hoyt, D.V., Schatten, K.H.: 1998, Solar Phys. 179, 189. ADS . DOI .

    Article  ADS  Google Scholar 

  • Hoyt, D.V., Schatten, K.H., Nesme-Ribes, E.: 1994, Geophys. Res. Lett. 21(18), 2067.

    Article  ADS  Google Scholar 

  • Neidig, F., Henry, T.: 2004, Comparing sunspot numbers between NSO and ISOON: NSO/Sac peak projection board drawings vs. ISOON semi-automatic procedure. NSO Internal Technical Document (private communication).

  • Neidig, D., Wiborg, P., Confer, M., Haas, B., Dunn, R., Balasubramaniam, K.S., Gullixson, C., Craig, D., Kaufman, M., Hull, W., McGraw, R., Henry, T., Rentschler, R., Keller, C., Jones, H., Coulter, R., Gregory, S., Schimming, R., Smaga, B.: 1998, In: Balasubramaniam, K.S., Harvey, J., Rabin, D. (eds.) Synoptic Solar Physics CS-140, Astron. Soc. Pac., San Francisco, 519.

    Google Scholar 

  • Pötzi, W., Veronig, A.M., Temmer, M., Baumgartner, D., Freislich, H., Strutzmann, H.: 2016, Solar Phys. DOI .

    Google Scholar 

  • Sivaraman, K.R., Gupta, S.S., Howard, R.F.: 1993, Solar Phys. 146, 27. ADS . DOI .

    Article  ADS  Google Scholar 

  • Smith, H.J., Smith, E.P.: 1963, Solar Flares, Macmillan Co., New York.

    Google Scholar 

  • Tlatov, A.G., Vasil’eva, V.V., Markova, V.V., Otkidychev, P.A.: 2014, Solar Phys. 289, 1403. ADS . DOI .

    Article  ADS  Google Scholar 

Download references

Acknowledgments

This work was supported by the Space Vehicles Directorate, Air Force Research Laboratories (AFRL) and The Air Force Office of Scientific Research; AFRL. We are grateful to Donald Neidig and numerous members of joint AFRL–NSO ISOON Team, the AFRL Space Vehicles Directorate, and the NSO for developing and operating the ISOON prototype telescope for a decade and preserving its data. Particularly, Neidig’s insights into calibration of the data and into sunspot-counting techniques have inspired this article. We thank Ed Cliver, Frédéric Clette, Leif Svalgaard, and numerous colleagues for sustaining the important sunspot-number research through these workshops.

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Authors and Affiliations

  1. Air Force Research Laboratory, Space Vehicles Directorate, Kirtland AFB, NM, USA

    K. S. Balasubramaniam

  2. Boston College at Air Force Research Laboratory, Kirtland AFB, NM, USA

    T. W. Henry

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  1. K. S. Balasubramaniam
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  2. T. W. Henry
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Correspondence to K. S. Balasubramaniam.

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The authors declare that they have no conflicts of interest.

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Sunspot Number Recalibration

Guest Editors: F. Clette, E.W. Cliver, L. Lefèvre, J.M. Vaquero, and L. Svalgaard

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Balasubramaniam, K.S., Henry, T.W. Sunspot Numbers from ISOON: A Ten-Year Data Analysis. Sol Phys 291, 3123–3138 (2016). https://doi.org/10.1007/s11207-016-0874-5

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  • DOI: https://doi.org/10.1007/s11207-016-0874-5

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