We examine the capabilities of a fast and simple method to infer line-of-sight ( LOS ) velocities from observations of the photospheric Si i 10827 Å line .
This spectral line is routinely observed together with the chromospheric He i 10830 Å triplet as it helps to constrain the atmospheric parameters .
We study the accuracy of bisector analysis and a line core fit of Si i 10827 Å .
We employ synthetic profiles starting from the Bifrost enhanced network simulation .
The profiles are computed solving the radiative transfer equation , including non-local thermodynamic equilibrium effects on the determination of the atomic level populations of Si i .
We found a good correlation between the inferred velocities from bisectors taken at different line profile intensities and the original simulation velocity at given optical depths .
This good correlation means that we can associate bisectors taken at different line-profile percentages with atmospheric layers that linearly increase as we scan lower spectral line intensities .
We also determined that a fit to the line-core intensity is robust and reliable , providing information about atmospheric layers that are above those accessible through bisectors .
Therefore , by combining both methods on the Si i 10827 Å line , we can seamlessly trace the quiet-Sun LOS velocity stratification from the deep photosphere to higher layers until around \log \tau = -3.5 in a fast and straightforward way .
This method is ideal for generating quick-look reference images for future missions like the Daniel K. Inoue Solar Telescope and the European Solar Telescope , for example .