Bull, PhilipCamera, StefanoEngelbrecht, BrandonFonseca, JoséIrfan, MelisLi, YichaoPourtsidou, AlkistisSantos, MarioSpinelli, MartaWang, JingyingWitzemann, Amadeus2025-10-272025-10-272025M. Barberi-Squarotti, J. L. Bernal, P. Bull, S. Camera, I. P. Carucci, Z. Chen, et al. 2025. MeerKLASS L-band deep-field intensity maps: entering the H I dominated regime. Monthly Notices of the Royal Astronomical Society, 537, 3632-3661.https://doi.org/10.1093/mnras/staf195https://hdl.handle.net/10566/21142We present results from MeerKAT single-dish HI intensity maps, the final observations to be performed in L-band in the MeerKAT Large Area Synoptic Survey (MeerKLASS) campaign. The observations represent the deepest single-dish HI intensity maps to date, produced from 41 repeated scans over 236 deg2, providing 62 h of observational data for each of the 64 dishes before flagging. By introducing an iterative self-calibration process, the estimated thermal noise of the reconstructed maps is limited to ∼ 1.21 mK (1.2 × the theoretical noise level). This thermal noise will be subdominant relative to the HI fluctuations on large scales (k ≲ 0.15 h Mpc−1), which demands upgrades to power spectrum analysis techniques, particularly for covariance estimation. In this work, we present the improved MeerKLASS analysis pipeline, validating it on both a suite of mock simulations and a small sample of overlapping spectroscopic galaxies from the Galaxy And Mass Assembly (GAMA) survey. Despite only overlapping with ∼ 25 per cent of the MeerKLASS deep field, and a conservative approach to covariance estimation, we still obtain a > 4 σ detection of the cross-power spectrum between the intensity maps and the 2269 galaxies at the narrow redshift range 0.39 < z < 0.46. We briefly discuss the HI autopower spectrum from these data, the detection of which will be the focus of follow-up work. For the first time with MeerKAT single-dish intensity maps, we also present evidence of HI emission from stacking the maps onto the positions of the GAMA galaxies.enCosmology: observationsLarge scale structure of UniverseMethods: data analysisMethods: statisticalRadio lines: generalArticle