Abstract:
Aditya-L1 is India’s first solar mission with the Visible Emission Line Coronagraph (VELC),
which consists of three spectral channels taking high-resolution spectroscopic
observations of the inner corona up to 1.5 Rʘ at 5,303, 7,892, and 10,747 Å. In this
work, we present a strategy for the slit width optimization of the VELC using synthetic line
profiles by taking into account the instrument characteristics and coronal conditions for
log(T) varying from 6 to 6.5. The synthetic profiles are convolved with simulated
instrumental scattered light and noise to estimate the signal-to-noise ratio (SNR),
which will be crucial to designing the future observation plans. We find that the
optimum slit width for VELC turns out to be 50 μm, providing sufficient SNR for
observations in different solar conditions. We also analyzed the effect of plasma
temperature on the SNR at different heights in the VELC field of view for the optimized
slit width. We also studied the expected effect of the presence of a CME on the spectral
channel observations. This analysis will help to plan the scientific observations of VELC in
different solar conditions.
