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Table 2.

Hα intensity, area and lifetime thresholds for Ellerman bomb selection and resulting detection rates in recent literature.

Intensity threshold Size Lifetime
Single/ Contrast value(s) Hα wing Reference threshold threshold Detection rate
Study Double (IEB/Iref) (Å) (arcsec2) (s) (arcmin−2 min−1)
Zachariadis et al. 1987 (a) Single 1.28 −0.75/−1.0 Sub-FOV 0.6 480 12.50
Georgoulis et al. 2002 Single 1.05/1.08/1.20 −0.8 Per pixel N/A N/A 5.76/2.86/0.28
Watanabe et al. 2011 (b),(c) Single 1.16/1.27 ±(0.9–1.1) Sub-FOV 0.025 240 1.42
Nelson et al. 2013 Single 1.30 ±0.7 Full FOV 0.037 N/A 15.49
Vissers et al. 2013 (c) Double 1.55 & 1.40 ±(0.9–1.1) Full FOV 0.018 45, 55 1.92, 1.30
Nelson et al. 2015 Single 1.50 ±(0.9–1.2) Nearby QS 0.014 N/A 0.79
Vissers et al. 2015a (c), (d) Double 1.55 & 1.40 ±(0.9–1.1) Full FOV 0.018 22 0.82, 1.08
1.45 & 1.30 23 1.14
Reid et al. 2016 (e) Double 1.45 & 1.30 ±1.0 Nearby QS 0.052 45 1.34
Chen et al. 2017 (f) Single 1.52 +1.0 Full FOV 0.114 100 0.55
Present study(e) Double 1.45 & 1.30 ±(0.9–1.1) Masked QS 0.035 60 1.11

Notes. The fourth column (Hα wing) specifies the wavelength offset with respect to line centre used for Ellerman bomb identification. Values in the last two columns that correspond to different data sets within a study are comma-separated, while in the last column the rates for different contrast thresholds are separated by slashes (/).

(a)

The values in this study are not formal thresholds, but rather the average of manually selected events.

(b)

This study specified a threshold of 3σ (for non-plage) and 5σ (for plage) above the local average of the considered sub-fields-of-view, corresponding to the contrast values given here.

(c)

Intensity thresholding was performed on the combined wing-average of the blue and red wings (Iw as defined in Sect. 3.1.2).

(d)

This study specified different intensity thresholds for two data sets versus the third, here split into two rows where values differ.

(e)

Intensity thresholding was performed on the blue and red wings separately.

(f)

This study specified a threshold of 4σ above the average, which corresponds to the contrast value given here (Yajie Chen, priv. comm.).

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