Error adding qgis.org repository public key to apt keyring

Based on old notes, the following seems to work:

sudo apt-key adv --keyserver keyserver.ubuntu.com --recv-key 51F523511C7028C3

-- Update --

As of August 2020:

sudo apt-key adv --keyserver keyserver.ubuntu.com --recv-key F7E06F06199EF2F2

After you have verified the fingerprint you forgot to add the key to apt with:

gpg --export --armor 51F523511C7028C3 | sudo apt-key add -  

Read the QGIS documentation. All the instructions are:

wget -O - https://qgis.org/downloads/qgis-2019.gpg.key | gpg --import
gpg --fingerprint 51F523511C7028C3
gpg --export --armor 51F523511C7028C3 | sudo apt-key add -