DARK frames were replaced with those from the 202604 run because no dark frames were taken during the current run.
HSC-I2 SKY images were constructed by combining images from 134 visits across the current run (202606) and previous runs (202602 and 202510). 
HSC-Y SKY images were constructed by combining images from 115 visits from the current run (202606) and the 202502 run. 
NB0816 SKY images were replaced with those from the 202602 run because the number of available images from the current run was too small to construct new sky frames. 
NB0872 SKY images were replaced with those from the 202510 run because the number of available images from the current run was too small to construct new sky frames.
IB0945 SKY images will not be constructed. Please use local sky subtraction.
(Note: Although the 201812 run is mergeable, its Filter Exchanger Unit position differs and it was taken before the latest primary mirror coating in Aug 2022).