per manual page https://www.gnu.org/software/guix/manual/en/html_node/Running-Guix-in-a-VM.html

$ wget https://ftp.gnu.org/gnu/guix/guix-system-vm-image-1.0.0.system.xz
--2019-05-02 22:20:33--  https://ftp.gnu.org/gnu/guix/guix-system-vm-image-1.0.0.system.xz
Resolving ftp.gnu.org (ftp.gnu.org)... 209.51.188.20, 2001:470:142:3::b
Connecting to ftp.gnu.org (ftp.gnu.org)|209.51.188.20|:443... connected.
HTTP request sent, awaiting response... 404 Not Found
2019-05-02 22:20:33 ERROR 404: Not Found.