Optical spectra from the HCT for HCG15-C (upper and left panels) and HCG15-F (right panels). The spectrum for each Grism is shown separately, with Grism-7 in the upper row and Grism-8 in the lower row. All wavelengths are quoted in the observer frame. Known emission and absorption features are marked at their observed wavelengths using the best-fit recession velocities of 6803 ± 12 km s⁻¹ for HCG15-C and 6133 ± 98 km s⁻¹ for HCG15-F, with green for absorption features and blue for emission lines. The shaded red region marks a known sky absorption feature. Note that in the spectrum of HCG15-C, no emission lines are detected, only the marked NaD, Mg, G-band and Ca H & K absorption features. Conversely for HCG15-F the only detected feature is the Hα emission line, with a tentative sign of the [N II] doublet; no absorption features are detected.