Image cutouts centred at the position of MCXC J0012.9-0853, from RASS (left), Swift (centre), and SDSS9-i (right). We identified this SGP cluster, previously without redshift, with the SZ cluster ACT-CL J0012.8-0855 at ɀ_spec = 0.3377 (ACT, magenta circle). This is a case of a complex structure with SZ clusters (PSZ2/ACT, green cross and magenta circles), and optical clusters (white circles) at very close redshifts, just South of the SGP position. In addition, there is bright QSO (WISEA J001247.92-084700.6 at ɀ = 0.22 from NED, cyan circle in the right panel) well resolved in RASS (as 1RXS J001248.7-084705), to the North, slightly beyond the R₅₀₀ aperture (red circle). The contour of the wavelet-filtered image shows extended emission toward the cluster counterpart(s), with the SGP position likely biased North by the emission from the QSO. This would explain the offset. The SDSS image further illustrates the complexity of the cluster structure(s). In the right-hand panel, the galaxies with spectroscopic redshift from SDSS around ɀ_spec = 0.338 are marked with blue circles, as well as the ACT cluster (magenta circles), the PSZ2 detection (green cross) and the optical clusters (white circles). The richest optical cluster is WHL J001248.9-085535 (WH, ɀ_spec = 0.3356, R_L,500 = 118.2, likely corresponding to WHY J001250.9-085537 (WHY1) at ɀ_phot = 0.3791, located slightly North of the position of ACT-CL J0012.8-0855, with a consistent redshift. Another ACT cluster, ACT-CL J0012.9-0857 (ɀ_spec = 0.3520), slightly less massive, coincides with the redMaPPer cluster, RM J001240.4-085628.3 (RM2), which lies at ɀ_spec = 0.3370 from the BCG. Both components likely contribute to the X-ray emission, and also to the Planck source PSZ2 G094.46-69.65 (ɀ_phot = 0.3521). The PSZ2 redshift comes from cross-identification with the second redMaPPer cluster, RM J001257.7-085829.5 (RM1) in the West. In addition, there is a fourth optical cluster, WHY J001306.5-085308 (WHY2) at ɀ_phot = 0.3655 lying to the East. All components likely contribute to the SGP cluster detection. For MCXC-II, the redshift is taken from that of the most massive component.