expected integer as timestamp

[jp1995]

I'm trying to push some data to prometheus through pushgateway:

newline=$'\n'
rtts=""
targets=('google.com' 'cloudflare.com' 'twitter.com')
for site in "${targets[@]}"; do
    rtt=$(fping -C1 -q "$site" 2>&1 | cut -d ' ' -f 3)
    rtts+="pgw_pinger{site=\"$site\"} $rtt "
done
rtts=${rtts%?}
curl -X POST -H  "Content-Type: text/plain" --data "$rtts$newline" http://localhost:9091/metrics/job/top/instance/machine

Resulting data:
pgw_pinger{site="google.com"} 4.24 pgw_pinger{site="cloudflare.com"} 2.36 pgw_pinger{site="twitter.com"} 32.9

And I receive the following error:
text format parsing error in line 1: expected integer as timestamp, got "pgw_pinger{site=\"cloudflare.com\"}"

This is strange because I'm successfully sending other data with seemingly identical structure, like this:
pgw_mem_usage{process="/sbin/init", pid="1"} 0.5 pgw_mem_usage{process="[kthreadd]", pid="2"} 0.0 pgw_mem_usage{process="[rcu_gp]", pid="3"} 0.0

I'm sure it's not a bug and that I'm just missing something, but I cannot see it. I'd appreciate a nudge. Using version 1.5.1.

[jp1995]

Okay I read the instructions more and figured it out, nevermind me!