Nginx - Forward root-level URL (eg, favicon.ico) to Amazon S3?

Nginx - Forward root-level URL (eg, favicon.ico) to Amazon S3?

I'm trying to configure my nginx server to serve root level assets, like
www.domain.com/favicon.ico, from S3.
I think, but am not sure, that I'm supposed to proxy_pass to accomplish
this. I'm also stuck on the location regex:
server {
listen 80;
server_name *.domain.com
# This is where I'm trying to catch URLs like /favicon.ico
location ~* /*\.(xml|txt|png|ico)$ { # wrong
proxy_pass http://<s3_bucket>?? # wrong
}
# Everything else goes to gunicorn/Django.
location / {
proxy_pass http://127.0.0.1:8000;
proxy_set_header Host $host;
proxy_set_header X-Real-IP $remote_addr;
proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
}
}