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ARCHIVE - Forecast relative to the night starting on 2024/11/21 MST

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

LINC-NIRVANA

LINC-NIRVANA is the layer-oriented MCAO system of LBT in which the two DMs are conjugated at 126 m and 7.1 km above ground layer. The wind speed at which the system is therefore sensible is the integral of the wind speed of each turbulence layers developed inside the depth of field weighted by the correspondent C_N², normalized by the turbulence developed in the whole depth of field (see Eq.1). The total depth of field ΔH is defined as ΔH = 2 (d/θ) centred at the conjugated plane height, where d is the distance between two adjacent actuators projected on the pupil (or metapupil) of the telescope and θ is the FOV. In the specific case the depths of field are:

for DM1: ΔH_126m = [-163,415]m = 578m
for DM2: ΔH_7.1km = [5072,9127]m = 4055m

where we considered FOV_DM1=6 arcmin and FOV_DM2=2 arcmin.

$V_{eq} = \left[ \frac{\int_{H_{min}}^{H_{max}} |v(h)|^{5/3} C_N^2(h) dh}{\int_{H_{min}}^{H_{max}} C_N^2(h) dh} \right]^{3/5}$

(1)

H_min and H_max are the extremes of the vertical slabs. Fig.1 and Fig.2 show the equivalent wind speed V_eq temporal evolution integrated on the respective depth of field ΔH_i between the sunset and the sunrise as indicated in Eq.1 during the night.
Astronomical dusk and dawn are shown too. On the x-axis is time in UT (bottom), in MST (top). Raw data points frequency is equal to the model time-step (typically from a fraction of second up to a few seconds depending on the model configuration used). Data points are re-sampled at a frequency of 20 minutes after a 1-hour moving average. The error bars are the sigma over the 20 minutes sampling, computed before the moving average. V_eq gives us an information on how fast/slow an AO system has to run.


Fig. 1: V_eq temporal evolution between the sunset and the sunrise related to the atmospheric slab sensed by DM1.	Fig. 2: V_eq temporal evolution between the sunset and the sunrise related to the atmospheric slab sensed by DM2.