Table 2
Optical spectral observations of λ Cep used in the present work.
| Dates | Telescope | Spectrograph | Resolution | Coverage (Å) | Exp. time (min) | N | S/N |
|
|
|||||||
| 1989 Oct. 17−21 | Calar Alto, 2.2 m | 90 cm f/3 camera | 25 000 | 4600−4730 | 7−10 | 109a | 500 |
| Kitt Peak, 0.9 m | camera #5 | 22 000 | 4650−4735 | 10−15 | 71a | 300 | |
| 2007 Nov. 20−22, | BOAO, 1.8 m | BOES | 45 000 | 3830−8260 | 3−5 | 30 | 300 |
| Dec. 16 | |||||||
| 2012 Oct. 8−14 | Mercator, 1.2 m | HERMES | 85 000 | 3770−9000 | 3.3 | 23 | 150 |
| 2013 Oct. 9−15 | Mercator, 1.2 m | HERMES | 85 000 | 3770−9000 | 3.3 | 42 | 150 |
Notes. The columns list respectively the dates, telescope, name of spectrograph, spectral resolution λ/ Δλ, wavelength coverage in Å, exposure time in min, number of spectra acquired (N), and average signal-to-noise ratio (S/N) of the unbinned data.
After rebinning all 180 spectra in the time domain, in total 33 spectra were finally utilized for the analysis, see Sect. 6.2.
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