This directory contains Sun Spot Number data, both from Wolf (Zurich) and Brussel observation and the newly (from July 1, 2015) available corrected data, the so-called Revised GN (group number). This correction should make more compatible Brussel (Wolf) SN and Hoyt and Schatten (1998a) GN values.

The revision is well documented in a 80-pages paper (Clette et al., 2014; Clette F., Svalgaard L., Vaquero J.M., Cliver E.W: Revisiting the Sunspot Number . and effectively divergence between SN and GN appears to be reduced.

  • The counter-side is that the Modern Maximum (from cycles 17 to 22, except 20) must be re-thinked, beeing due to would essentially result from time-integration effects (system inertia), since exceptionally high amplitudes of the solar magnetic cycle cannot be invoked anymore.

    Anything in the paper is well documented, but I'm sure that the Monks who corrected older manuscript while copying them, have similar convincing reasons (at least at their own eyes...) like faith, Holy Bible, Aristotelic prescriptions, Ptolemaic system of celestial spheres, etc.
    For these reasons I saved here the original files, actually (June 27, 2015) available at WDC-SILSO.

    The new revised data on sunspot number are available at [Credits: SILSO data/image, Royal Observatory of Belgium, Brussels]

  • New SunSpot data (v2.0) are: SN_m_tot_V2.0.txt and SN_y_tot_V2.0.txt for monthly and yearly data, respectively.
  • Old SunSpot data (through 5/2015) are: monthssn.dat and yearssn.dat
  • Here I've used SN_y_tot_V2.0.txt as new data, with the file name changed to sn-v2-y.txt

    Please note:
    SILSO images and data can be freely downloaded as public data. However, any public use, web based or paper publication of those data must include an explicit credit to the source: (SILSO data/image, Royal Observatory of Belgium, Brussels)

    Page written: August 11, 2015