Celestia 1.7 on Arch Linux:
Edit /etc/pacman.conf and add the following (note that the order of repositories in pacman.conf is important, since pacman always downloads the first found package):
[home_munix9_celestia_1.7_Arch]
Server = https://download.opensuse.org/repositories/home:/munix9:/celestia:/1.7/Arch/$arch
Then run the following as root
key=$(curl -fsSL https://download.opensuse.org/repositories/home:munix9:celestia:1.7/Arch/$(uname -m)/home_munix9_celestia_1.7_Arch.key)
fingerprint=$(gpg --quiet --with-colons --import-options show-only --import --fingerprint <<< "${key}" | awk -F: '$1 == "fpr" { print $10 }')
pacman-key --init
pacman-key --add - <<< "${key}"
pacman-key --lsign-key "${fingerprint}"
pacman -Sy home_munix9_celestia_1.7_Arch/celestia
See also the download package site on OBS for celestia.