Stephan Prantner’s Sunspot Observations during the Dalton Minimum

Lost sunspot cycle in the beginning of Dalton minimum: New evidence and consequences

[1] We have recently suggested that one solar cycle was lost in the beginning of the Dalton minimum during 1790s [Usoskin et al., 2001]. Earlier, this cycle has been combined with the preceding activity to form the exceptionally long solar cycle 4 in 1784-1799 with an irregular phase evolution. Here we show that historical data of auroral occurrence provide independent evidence for the existenc...

Cyclic behaviour of sunspot activity during the Maunder minimum

We study the behaviour of sunspot activity in 16101750, i.e. just prior to, during and slightly after the Maunder minimum, using the new series of group sunspot numbers (Hoyt & Schatten 1998). We apply the delayed component technique and show that, while the transition from the normal cyclic evolution to the minimum was very abrupt, the recovery from the minimum was gradual, proceeding through ...

spectral solar irradiance lower during the recent low sunspot minimum ?

Was UV spectral solar irradiance lower during the recent low sunspot minimum?

[1] A detailed analysis is presented of solar UV spectral irradiance for the period between May 2003 and August 2005, when data are available from both the Solar Ultraviolet Spectral Irradiance Monitor (SUSIM) instrument (on board the Upper Atmosphere Research Satellite (UARS) spacecraft) and the Solar Stellar Irradiance Comparison Experiment (SOLSTICE) instrument (on board the Solar Radiation ...

Finding the sources of irradiance variation at sunspot minimum

In 2006-2007 the Solar Bolometric Imager (SBI) will operate in the polar stratosphere where near-space conditions can be attained for 10 to 30 days. The instrument will provide bolometric (wavelength-integrated light) and color temperature images of the Sun. At the upcoming sunspot minimum, SBI observations will be able to detect subtle sources of solar irradiance variation with the least confu...