Wavefront coherence time - τ₀

Wavefront Coherence Time (τ₀) Maps Averages

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Forecast relative to the night starting on 2026/06/14 MST

Note: click on a figure to magnify the image. Date of figures refers to the start of night in MST.

Wavefront coherence time horizontal map extended on a 50km x 50km square centred on LBT (represented with a black dot). The seeing is integrated over three different vertical slabs:

TOTAL WAVEFRONT COHERENCE TIME (τ_0,TOT) – [dome-20000]m
BOUNDARY LAYER WAVEFRONT COHERENCE TIME (τ_0,BL) – [dome-600]m
FREE ATMOSPHERE WAVEFRONT COHERENCE TIME (τ_0,FA) – [600-20000]m

The wavefront coherence time in each pixel is obtained integrating the C_N² and wind speed along the zenith and covering the temporal range [dusk,dawn]. The black iso-lines represent the heights of the Digital Elevation Model (DEM).

τ_0,TOT AVERAGES:

Averages are computed over the whole night [<dusk> – <dawn>] UT and also in the first, central and last part of the night (see partition).

Fig. 1: τ_0,TOT over the whole night [<dusk> – <dawn>]UT time frame

Fig. 2: τ_0,TOT over the “first part of the night”.

Fig. 3: τ_0,TOT over the “central part of the night”.

Fig. 4: τ_0,TOT over the “last part of the night”.

τ_0,BL NIGHT AVERAGES:

Averages are computed over the whole night [<dusk> – <dawn>] UT and also in the first, central and last part of the night (see partition).

Fig. 5: τ_0,BL over the whole night [<dusk> – <dawn>]UT time frame

Fig. 6:τ_0,BL over the “first part of the night”.

Fig. 7: τ_0,BL over the “central part of the night”.

Fig. 8: τ_0,BL over the “last part of the night”.

τ_0,FA AVERAGES:

Averages are computed over the whole night [<dusk> – <dawn>] UT and also in the first, central and last part of the night (see partition).

Fig. 9: τ_0,FA over the whole night [<dusk> – <dawn>]UT time frame

Fig. 10: τ_0,FA over the “first part of the night”.

Fig. 11: τ_0,FA over the “central part of the night”.

Fig. 12: τ_0,FA over the “last part of the night”.