Sunspot Photometry (All ftp)

Rapid changes in the total solar irradiance from space borne sensors are largely due to the passage of large sunspots across the disk. The effects of sunspots have often been modeled using ground-based observations by the use of a Photometric Sunspot Index (PSI), usually assuming all sunspots have the same thermal structure. The SFO data measure the mean temperature or bolometric contrast and corrected hemispherical areas, incorporating these into the PSI calculation. The PSI is calculated for each sunspot group and then summed over all groups present on the solar disk. For more recent data, please visit the San Fernando Observatory website.

• Description of database (text)
  
• Data listings by year
  
  • 1985 1986 1987 1988 1989
  • 1990 1991 1992 1993 1994 1995 1996 1997 1998