Representative spectra of K4-47, measured with the IRAM 30 m. The top panel displays the full spectrum between ∼125.6 and ∼133.4 GHz (lower sideband) and ∼141.3 and ∼149.1 GHz (upper sideband). Various lines of HC₃N and its ¹³C-substituted species are apparent in the data as well as some unidentified (“U”) lines. The lower panel shows an expanded version of a section of the USB spectrum, identifying features arising from H₂CO, c-C₃H₂, and CH₃CN. All spectra are smoothed to 2 MHz resolution. A V_LSR of −27.0 km s⁻¹ was assumed. Many of the molecular identifications are new discoveries in PNe, including CH₃CN.