Sunspot Catalogue of the Observatory of the University of Coimbra (1929 – 1941)

Abstract

A sunspot catalogue was published by the Coimbra Astronomical Observatory (Portugal), now named Geophysical and Astronomical Observatory of the University of Coimbra, for the period 1929-1941. We digitalized data included in that catalogue and provide a machine-readable version. We show the reconstructions for the (total and hemispheric) sunspot number index and sunspot area according to this catalogue, comparing it with the sunspot number index (version 2) and Balmaceda sunspot area series (Balmaceda et al., J. Geophys. Res. 114, A07104, 2009). Moreover, we also compared the Coimbra catalogue with records made at the Royal Greenwich Observatory. The results demonstrate that the historical catalogue compiled by the Coimbra Astronomical Observatory contain reliable sunspot data and therefore can be considered for studies about solar activity.

Solar observatory Einstein Tower: Data release of the digitized solar full‐disk photographic plate archive

“…The coelostat is composed of two mirrors with diameters of 40 and 30.5 cm. Carrasco et al (2018a) cataloged the historical sunspots observation for the period 1921–1941 and estimated their extent in longitude and latitude limits, as well as the umbral area of sunspots. The catalog of full‐disk data comprises 20,505 Ca ii K line‐core images, 11,612 images of the minima in the emission core of the Ca ii K line, 8,719 H α line‐core images accompanied by 3,889 nearby continuum images, and 3,024 dopplergrams (Lourenço et al 2019).…”

Eric Strach: Four Decades of Detailed Synoptic Solar Observations (1969‐2008)

“…The reference observatory in sunspot observations during the 20th century and the last quarter of the 19th century was the Royal Greenwich Observatory (Erwin et al, ; Willis et al, ; Willis et al, ; Willis et al, ). Other important historical observatories of that time related with the sunspot observations were, for example, Mount Wilson (Lefebvre et al, ), Kodaikanal (Mandal et al, ), Debrecen (Baranyi et al, ), and the Iberian observatories (Aparicio et al, ; Carrasco et al, ; Carrasco et al, ; Curto et al, ). However, there are several historical examples of single astronomers with a long observation series.…”

A Sunspot Catalog for the Period 1952 – 1986 from Observations Made at the Madrid Astronomical Observatory

“…In recent years, an effort has been made to retrieve solar data from different observatories around the world including Coimbra (Carrasco et al, 2018), Ebro (Curto et al, 2016), Greenwich (Willis, Wild, and Warburton, 2016), Locarno (Cortesi et al, 2016), Kodaikanal (Mandal et al 2017) and Valencia . In the context of this collective effort, different datasets preserved in several libraries and archives related to the solar and magnetic observations made at the Madrid Observatory during more than one century are being digitalized and analyzed.…”