A Catalog of Faculae, Prominences, and Filaments for the Period 1929–1944 from the Astronomical Observatory of the University of Coimbra

Carrasco, V. M. S.; Vaquero, J. M.

doi:10.3847/1538-4365/ac85dd

Cited by 4 publications

(6 citation statements)

References 39 publications

(41 reference statements)

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“…Bocchino 1933;Carrasco et al 2021, with such analyses extending information on prominences back to 1869 with observations by Respighi, Secchi, Tacchini, and Donati from Rome, Palermo, and Florence), and with disc-blocked or narrow-bandwidth Ca ii K observations (e.g. Chatterjee et al 2020;Carrasco & Vaquero 2022). Filaments can also be seen both in Hα and Ca ii K observations, but they are less prominent in Ca ii K data and can only be seen in observations acquired with relatively narrow bandwidths (e.g.…”

Section: Introductionmentioning

confidence: 87%

“…Filaments can also be seen both in Hα and Ca ii K observations, but they are less prominent in Ca ii K data and can only be seen in observations acquired with relatively narrow bandwidths (e.g. as reported in the catalogues of the observatory of Coimbra between 1929Coimbra between -1944Lourenço et al 2021;Carrasco & Vaquero 2022;Wan & Li 2022). Therefore, most of the current knowledge on filaments comes from analyses of observations in the Hα line (e.g.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Analysis of full-disc Hαobservations: Carrington maps and filament properties in 1909–2022

Chatzistergos,

Ermolli,

Banerjee

et al. 2023

A&A

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Context.Full-disc observations of the Sun in the Hαline provide information about the solar chromosphere, and in particular, about the filaments, which are dark and elongated features that lie along magnetic field polarity-inversion lines. This makes them important for studies of solar magnetism. Because full-disc Hαobservations have been performed at various sites since the second half of the 19th century, with regular photographic data having started at the beginning of the 20th century, they are an invaluable source of information on past solar magnetism.Aims.We derive accurate information about filaments from historical and modern full-disc Hαobservations.Methods.We consistently processed observations from 15 Hαarchives spanning 1909–2022. The analysed datasets include long-running ones such as those from Meudon and Kodaikanal, but also previously unexplored datasets such as those from Arcetri, Boulder, Larissa, and Upice. Our data processing includes photometric calibration of the data stored on photographic plates, the compensation for limb-darkening, and the orientation of the data to align solar north at the top of the images. We also constructed Carrington maps from the calibrated Hαimages.Results.We find that filament areas, similar to plage areas in Ca IIK data, are affected by the bandwidth of the observation. Thus, a cross calibration of the filament areas derived from different archives is needed. We produced a composite of filament areas from individual archives by scaling all of them to the Meudon series. Our composite butterfly diagram very distinctly shows the common features of filament evolution, that is, the poleward migration as well as a decrease in the mean latitude of filaments as the cycle progresses. We also find that during activity maxima, filaments cover ∼1% of the solar surface on average. The change in the amplitude of cycles in filament areas is weaker than in sunspot and plage areas.Conclusions.Analysis of Hαdata for archives with contemporaneous Ca IIK observations allowed us to identify and verify archive inconsistencies, which also have implications for reconstructions of past solar magnetism and irradiance from Ca IIK data.

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Section: Introductionmentioning

confidence: 87%

Section: Introductionmentioning

confidence: 99%

Analysis of full-disc Hαobservations: Carrington maps and filament properties in 1909–2022

Chatzistergos,

Ermolli,

Banerjee

et al. 2023

A&A

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“…This allowed various studies to determine plage areas without following the processing steps described in Section 3 (e.g. Kuriyan et al, 1983;Seguí et al, 2019;de Paula and Curto, 2020;de Paula et al, 2021, de Paula et al, 2022Carrasco and Vaquero, 2022). Plage areas in these studies were counted manually from the physical photographs, typically by overlaying transparencies with circles of known areas.…”

Section: Plage Areasmentioning

confidence: 99%

Full-disc Ca ii K observations—A window to past solar magnetism

Chatzistergos

Krivova

Ermolli

2022

Front. Astron. Space Sci.

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Full-disc observations of the Sun in the Ca ii K line provide one of the longest collections of solar data. First such observations were made in 1892 and since then various sites around the world have carried out regular observations, with Kodaikanal, Meudon, Mt Wilson, and Coimbra being some of the most prominent ones. By now, Ca ii K observations from over 40 different sites allow an almost complete daily coverage of the last century. Ca ii K images provide direct information on plage and network regions on the Sun and, through their connection to solar surface magnetic field, offer an excellent opportunity to study solar magnetism over more than a century. This makes them also extremely important, among others, for solar irradiance reconstructions and studies of the solar influence on Earth’s climate. However, these data also suffer from numerous issues, which for a long time have hampered their analysis. Without properly addressing these issues, Ca ii K data cannot be used to their full potential. Here, we first provide an overview of the currently known Ca ii K data archives and sources of the inhomogeneities in the data, before discussing existing processing techniques, followed by a recap of the main results derived with such data so far.

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“…We have compared the MPS with sunspot number values provided by SILSO, the solar radio flux at 10.7 cm, sunspot area series by Mandal et al (2020) and the prominence series by Carrasco and Vaquero (2022) from the Astronomical Observatory of the University of Coimbra. The highest correlation was found between the prominence series of Madrid and Coimbra (r = 0.71).…”

Section: Discussionmentioning

confidence: 99%

“…We compared the annual MPS with other indicators of solar activity. First, we show the comparison between MPS and the prominence series computed by Carrasco & Vaquero (2022) from the observations made at the Astronomical Observatory of the University of Coimbra (CPS) for the period 1929 -1944 (Figure 3).…”

Section: Comparison With Other Indices Of Solar Activitymentioning

confidence: 99%

Rediscovering the observations of solar prominences from 1906 to 1957 recorded at the Madrid Astronomical Observatory

Aparicio¹,

Carrasco²,

Gallego³

et al. 2023

J. Space Weather Space Clim.

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The Madrid Astronomical Observatory implemented a solar observation program from 1876 to 1986. In addition to sunspots, the observers at this observatory recorded other solar features such as prominences. In this work, we have consulted the documentary sources of the Madrid Astronomical Observatory (the information is not digitally available), digitized the records of the observers on the annual number of prominences, and constructed a homogeneous series of the total and hemispheric annual number of prominences with heights of 25’’ and more for the period 1906 – 1957. To evaluate the quality of the data and assess their potential, we have compared the Madrid prominence series with the number of prominences recorded by the Astronomical Observatory of the University of Coimbra and other time series such as the sunspot number index, solar radio flux at 10.7 cm, and sunspot areas. We have also analyzed the hemispheric prominence numbers and the asymmetry index. We obtained the strongest correlation between Madrid and Coimbra prominence series (r = 0.7), whereas the correlations between Madrid prominence series and the other solar activity time series are similar (r ≈ 0.6). In addition, we found that the correlation coefficient between the Madrid prominence series and the sunspot number is lower than that from Coimbra prominence series and the sunspot number. We suggest that these differences are a consequence of the way prominences were counted in the Madrid Astronomical Observatory.

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A Catalog of Faculae, Prominences, and Filaments for the Period 1929–1944 from the Astronomical Observatory of the University of Coimbra

Cited by 4 publications

References 39 publications

Analysis of full-disc Hαobservations: Carrington maps and filament properties in 1909–2022

Analysis of full-disc Hαobservations: Carrington maps and filament properties in 1909–2022

Full-disc Ca ii K observations—A window to past solar magnetism

Rediscovering the observations of solar prominences from 1906 to 1957 recorded at the Madrid Astronomical Observatory

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