Revealing Planetary Nebulae in Narrow Bands: A homogeneous Hα imaging catalogue for morphological studies

Abstract Planetary nebulae (PNe) display a remarkable diversity of morphologies that offer insights into the physical processes acting during the final stages of stellar evolution. Despite the large number of Galactic PNe currently catalogued, a substantial fraction remains poorly characterised due to heterogeneous imaging of variable depth and angular resolution. We present a homogeneous Hα narrow-band imaging catalogue of 86 Galactic PNe observed with the Gemini Multi-Object Spectrographs (GMOS) on the 8.1 m Gemini North and South telescopes, applying a consistent morphological classification framework to a predominantly poorly studied sample. Images were acquired through multiple Gemini programmes between 2020 and 2024. The classification scheme provides primary morphological classes alongside an extensive set of secondary structural descriptors, based solely on Hα emission geometry without physical interpretation. The sample spans six primary classes; elliptical and round morphologies are the most frequent (∼38% and ∼23%, respectively), while bipolar and irregular structures account for ∼19% and ∼14%. A wide variety of secondary features-including halos, equatorial tori, ansae, barrel-shaped central regions, and point-symmetric configurations-were identified, revealing structural complexity previously overlooked in shallower surveys. Systematic discrepancies with classifications in the HASH database were found, attributable to the greater depth and homogeneity of the present dataset. The catalogue provides a uniform descriptive reference for a predominantly underexplored sample of Galactic PNe and establishes a foundation for future spectroscopic and kinematic studies of structurally interesting objects.