Table 1.
Hα archives analysed in this study.
Observatory | Acronym | Detector | Instrument | Period | Images | SW | Pixel scale | Ref. |
---|---|---|---|---|---|---|---|---|
[Å] | [″/pixel] | |||||||
Arcetri | Ar | Plate | SHG | 1931–1968 | 5416 | 0.3 | 2.3–4.8 (a) | 1, 2 |
Big Bear | BB | CCD | Filter | 1988–2022 | 9527 | 0.5 | 4.3, 1.0 (b) | 3 |
Boulder | Bo | Plate | Filter | 1967–1994 | 6864 | 0.5 | 3.7 | 4 |
Catania | CT | CCD | Filter | 2002–2022 | 8026 | 0.5 | 2.1, 1.3, 1.1 (c) | 5 |
Coimbra | Co | Plate/CCD (d) | SHG | 1977–2021 | 8931 | 0.26 | 1.0, 2.2 (e) | 6 |
Kanzelhöhe | Ka | Plate/CCD (f) | Filter | 1973–2022 | 37 276 | 0.7 | 3.0, 2.1, 2.3, 1.0 (g) | 7, 8 |
Kharkiv | Kh | Plate/CCD (h) | SHG | 1938–2005 | 256 | 0.5 | 1.8, 4.0 (i) | 9 |
Kodaikanal | Ko | Plate | SHG | 1912–2007 | 30 506 | 0.5 | 0.89 | 10 |
Larissa | La | CCD | Filter | 2008–2015 | 100 | 0.5 | 1.5, 0.8 (j) | 11 |
McMath-Hulbert | MM | Plate | SHG | 1948–1966 | 3728 | 0.5 | 3.0 | 12 |
Meudon | MD | Plate/CCD (k) | SHG | 1909–2022 | 26 069 | 0.25, 0.15 (l) | 0.7–4.8, 1.56, 1.1 (m) | 13 |
Mitaka | Mi | Plate/CCD (n) | Filter | 1957–2022 | 34 836 | 0.75, 0.5, 0.25 (o) | 2.8, 4.5, 2.8, 1.1 (p) | 14 |
Pic du Midi | PM | CCD | Filter | 2011–2022 | 3149 | 0.5 | 1.2 | 15 |
Sacramento Peak | SP | Plate | SHG | 1960–2002 | 5477 | 0.5 | 1.2 | 16 |
Upice | UP | CCD | Filter | 2002–2022 | 1912 | 1.6 | 4, 2.5 (q) | 17 |
Notes. Columns are the name of the observatory, abbreviation, type of detector, type of instrument, period of observations, number of images, spectral width of the spectrograph/filter, pixel scale of the image, and the bibliography entry.
Some images from 1940 and 1931 have a pixel scale of ∼4.8″ and ∼3.3″, respectively, while all other observations have a pixel scale of ∼2.5″.
The values correspond to the periods [23 July 2002–25 July 2006], [26 July 2006–20 September 2012], and since 21 September 2012, respectively.
The observations were stored on photographic plates up to 13 January 2007, while observations with a CCD camera started on 1 July 2008.
The observations were stored on photographic plates up to 10 March 2000, while observations with a CCD camera started on 24 September 1998.
The values correspond to the periods [5 May 1973–31 May 1975], [1 June 1975–10 March 2000], [24 September 1998–22 September 2010], and since 1 June 2008, respectively.
The observations since 1994 were performed with a CCD camera, while the earlier observations were stored on photographic plates.
The two values correspond to the data stored on photographic plates and those taken with a CCD camera.
The observations were stored on photographic plates up to 27 September 2002, while observations with a CCD camera started on 13 May 2002.
The values refer to the periods [1 January 1909–14 June 2017] and [14 June 2017–31 December 2020].
The values refer to the periods [1 January 1909–27 September 2002], [13 May 2002–14 June 2017], and [14 June 2017–31 December 2020].
The observations were stored on photographic plates up to 23 April 1992, while observations with a CCD camera started on 28 September 1991.
0.75 Å was used for the data from the Monochromatic Heliograph before 20 October 1971 and since 29 March 1974. 0.5 Å was used for the data from the Monochromatic Heliograph between 20 October 1971 and 28 March 1974 as well as those from the Automatic Flare Patrol Telescope (1991–2019, although in this work, we used the data only up to 5 May 2011). 0.25 Å was used for the Solar Flare Telescope since 6 June 2011.
The values correspond to the periods [1 October 1957–23 April 1992], [28 September 1991–28 January 2003], [25 September 2008–5 June 2011], and since 6 June 2011 respectively.
The two values correspond to the period before and after 1 January 2018, when the CCD camera was upgraded.
References. (1) Ermolli et al. (2009b); (2) Righini & Godoli (1950); (3) Denker et al. (1999); (4) Wu et al. (1975); (5) Romano et al. (2022); (6) Lourenço et al. (2019); (7) Pötzi (2008); (8) Pötzi et al. (2021); (9) Belkina et al. (1996); (10) Chatterjee et al. (2017); (11) https://www.larissa.gov.gr/dsites/larobs/SUN.htm; (12) Mohler & Dodson (1968); (13) Malherbe & Dalmasse (2019); (14) Hanaoka et al. (2020); (15) Koechlin et al. (2019); (16) Tlatov et al. (2009); (17) Klimeš et al. (1999).
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