NSA/MWRP/C1 - IRT readings bias
The MWRP IRT appeared to not be reaching its lower limit (-50 C / 223.15 K). The readings stayed around 230 K although the sky was clear. On 6/16 the site technicians noticed that the gold mirror was scratched and appeared to have a deposit on it. The mirror was replaced and on 6/17 the lens was cleaned. These actions solved the problem.
Use data from a co-located IRT.