Composite IR spectrum of a red CMZ object (SSTGC 799887) and modelling of the SED. The observed spectra are shown as a solid red line, constructed by combining near-IR data from Gemini/GNIRS with mid-IR data from Spitzer/IRS. Circles represent photometric measurements from UKIDSS and Spitzer/IRAC, which were used to set the flux scale of the spectra (see text). The solid blue line shows the best-fitting model to the observed spectra, which included the following components: (1) a template of an M5.5-type giant from the IRTF/SpeX spectral library (Rayner et al. 2009) (green line); (2) a two-component blackbody continuum (dashed blue and orange lines); (3) the 3 μm band of solid H₂O ice, using the template from GC IRS 7 (Jang et al. 2022); and (4) the 10 μm and 18 μm silicate bands from the GC IRS 3 spectrum (Kemper et al. 2004). Other weaker absorption features were not included in the modelling. Spectra and their best-fitting models for the additional objects are shown in Appendix A.