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Calibration

The goal of the calibration is to estimate and correct for the instrumental gain in order to have an unbiased estimate of the true visibilities. We use a simplified version of the radio-interferometry measurement equation. The (complex) visibility $ \widetilde{V}_{ijk}$ measured on the baseline from antenna $ i$ to antenna $ j$ at frequency channel $ k$ is related to the true object visibility $ V_{ij}$ by

$\displaystyle \widetilde{V}_{ijk} = g_i(t) g_j^*(t) b_{ijk}(t) V_{ij}(u_k(t),v_k(t)) + noise term$ (1)

where $ u_k(t)$ and $ v_k(t)$ are the spatial frequencies corresponding to baseline $ ij$ at time $ t$ and frequency $ k$ , and we assume the object has a flat spectrum. Calibrating the data is computing the complex ``calibration curves'' $ g_i(t)$ and $ b_{ijk}(t)$ .



Gildas manager 2022-01-17