Feb. 16, 2016
12:20 p.m.
The NIST file doesn't contain a copyright information, neither. So where does the idea come from that the NIST file is in the public domain, but the IERS file isn't?
I believe works funded by the US federal government are public domain by default.
Produced by rather than funded by, but yes, works produced by US government officials in the course of their duties are ineligible for copyright in the US. It's 17 US Code ยง105, for those who are interested. - Adam