Potential signatures of an interaction with circumstellar hydrogen. Top: Low-resolution optical- +116 days and middle: echelle NIR +97 days spectra of SN 2016adj. The optical and NIR spectra have been color-corrected to match coeval broad-band photometry. Both spectra are de-reddened using the reddening parameters estimated in Sect. 4.2. The positions of conspicuous hydrogen features are marked with vertical lines and labeled. Bottom: Zoom in velocity space of the Balmer, Paschen and Bracket series features. The Paschen features exhibit P Cygni profiles with −v_abs values ∼1500 − 3000 km s⁻¹ and v_FWHM ∼ 1000 km s⁻¹. The red lines correspond to pseudo-continuum fits determined by Monte Carlo simulations. We note that the flux of the nebular [N II] λλ6548,6584 lines on either side of Hα is not included in its emission-line flux measurement.