@article{DierckeArltDenker2015,
  author    = {Diercke, Andrea and Arlt, Rainer and Denker, Carsten},
  title     = {Digitization of sunspot drawings by Sporer made in 1861-1894},
  series = {Astronomische Nachrichten = Astronomical notes},
  volume    = {336},
  journal   = {Astronomische Nachrichten = Astronomical notes},
  number    = {1},
  publisher = {Wiley-VCH},
  address   = {Weinheim},
  issn      = {0004-6337},
  doi       = {10.1002/asna.201412138},
  pages     = {53 -- 62},
  year      = {2015},
  abstract  = {Most of our knowledge about the Sun's activity cycle arises from sunspot observations over the last centuries since telescopes have been used for astronomy. The German astronomer Gustav Sporer observed almost daily the Sun from 1861 until the beginning of 1894 and assembled a 33-year collection of sunspot data covering a total of 445 solar rotation periods. These sunspot drawings were carefully placed on an equidistant grid of heliographic longitude and latitude for each rotation period, which were then copied to copper plates for a lithographic reproduction of the drawings in astronomical journals. In this article, we describe in detail the process of capturing these data as digital images, correcting for various effects of the aging print materials, and preparing the data for contemporary scientific analysis based on advanced image processing techniques. With the processed data we create a butterfly diagram aggregating sunspot areas, and we present methods to measure the size of sunspots (umbra and penumbra) and to determine tilt angles of active regions. A probability density function of the sunspot area is computed, which conforms to contemporary data after rescaling. (C) 2015 WILEY-VCH Verlag GmbH \& Co. KGaA, Weinheim},
  language  = {en}
}
@article{AmayaMussetAnderssonetal.2015,
  author    = {Amaya, Jorge and Musset, Sophie and Andersson, Viktor and Diercke, Andrea and Hoeller, Christian and Iliev, Sergiu and Juhasz, Lilla and Kiefer, Rene and Lasagni, Riccardo and Lejosne, Solene and Madi, Mohammad and Rummelhagen, Mirko and Scheucher, Markus and Sorba, Arianna and Thonhofer, Stefan},
  title     = {The PAC2MAN mission},
  series = {Journal of space weather and space climate},
  volume    = {5},
  journal   = {Journal of space weather and space climate},
  publisher = {EDP Sciences},
  address   = {Les Ulis},
  issn      = {2115-7251},
  doi       = {10.1051/swsc/2015005},
  pages     = {16},
  year      = {2015},
  abstract  = {An accurate forecast of flare and coronal mass ejection (CME) initiation requires precise measurements of the magnetic energy buildup and release in the active regions of the solar atmosphere. We designed a new space weather mission that performs such measurements using new optical instruments based on the Hanle and Zeeman effects. The mission consists of two satellites, one orbiting the L1 Lagrangian point (Spacecraft Earth, SCE) and the second in heliocentric orbit at 1AU trailing the Earth by 80 degrees (Spacecraft 80, SC80). Optical instruments measure the vector magnetic field in multiple layers of the solar atmosphere. The orbits of the spacecraft allow for a continuous imaging of nearly 73\% of the total solar surface. In-situ plasma instruments detect solar wind conditions at 1AU and ahead of our planet. Earth-directed CMEs can be tracked using the stereoscopic view of the spacecraft and the strategic placement of the SC80 satellite. Forecasting of geoeffective space weather events is possible thanks to an accurate surveillance of the magnetic energy buildup in the Sun, an optical tracking through the interplanetary space, and in-situ measurements of the near-Earth environment.},
  language  = {en}
}