install failure for nodejs 18 on Ubuntu 22.04.02

[John-L]

On Ubuntu 22.04.2, following the instructions here:

https://github.com/nodesource/distributions/blob/master/README.md#ubuntu-versions

with NODE_MAJOR=18, running sudo apt-get update produces:

Err:5 https://deb.nodesource.com/node_18.x nodistro InRelease
The following signatures couldn't be verified because the public key is not available: NO_PUBKEY 2F59B5F99B1BE0B4

Thanks in advance for any clarification you can provide.