The NHI (Normalized Hotspot Indices; Marchese et al., 2019) are defined as:
NHISWIR= (L2.2-L1.6)/(L2.2+L1.6)
NHISWNIR= (L1.6-L0.8)/(L1.6+L0.8)
where, L2.2, L1.6, and L0.8 are the TOA radiaces [W⸱m-2⸱sr-1⸱m-1] measured, for each pixel of the scene, at around 2.2 µm (SWIR2), 1.6 µm (SWIR1), and 0.8 µm (NIR). The two indices are combined according to that detailed in Marchese et al., (2019) to map high-temperature features in daytime through MSI and OLI/OLI2 observations (standard NHI algorithm). The algorithm configuration described in Falconieri et al., (2025) is used to detect these features by means of daytime and night-time SLSTR data.