CO SLED of BRI 0952, normalized to the CO(5–4) line. Local universe representatives are a sample of ULIRGs from Rosenberg et al. (2015) where 1σ errors are shown by the shaded regions for class I, II, and III (purple diamonds), a sample of normal and starburst galaxies from Liu et al. (2017; pink pentagons). High-redshift sources are J2310+1855 (Li et al. 2020), J1148+5251 (Gallerani et al. 2014), and APM 08279+5255 (Weiß et al. 2007; Bradford et al. 2011). J1148+5251 has been normalized to the CO(6–5) transition. APM 08279+5255 has been normalized to an inferred value for the CO(5–4) transition by averaging the adjacent CO transitions (namely the CO(4–3) and CO(6–5) transitions). We show BRI 0952 including a lower limit on the CO(16–15) from the partial line wing detected in the band 7 data.