Dark Energy Survey Year 6 Results: improved mitigation of spatially varying observational systematics with masking for the MagLim++ lens sample
Year: 2026
Type: article
Abstract: As photometric surveys reach unprecedented statistical precision, systematic uncertainties increasingly dominate large-scale structure probes relying on galaxy number density. Defining the final survey footprint is critical, as it excludes regions affected by artefacts or suboptimal observing conditions. For galaxy clustering, spatially varying observational systematics, such as seeing, are a leading source of bias. Template maps of contaminants are used to derive spatially dependent corrections, but extreme values may fall outside the applicability range of mitigation methods, compromising correction reliability. The complexity and accuracy of systematics modelling depend on footprint conservativeness, with aggressive masking enabling simpler, robust mitigation. We present a unified approach to define the DES Y6 JOINT footprint, integrating observational systematics templates and artefact indicators that degrade mitigation performance. This removes extreme values from an initial footprint, leading to the final JOINT evaluating the DES Y6 lens sample MagLim++ on this footprint, we enhance the Iterative Systematics Decontamination (ISD) method, detecting non-linear systematic contamination and improving correction accuracy. While the mask’s impact on clustering is less significant than systematics decontamination, it remains non-negligible, comparable to statistical uncertainties in certain w(theta) scales and redshift bins. Supporting coherent analyses of galaxy clustering and cosmic shear, the final footprint spans 4,031.04 deg^2, setting the basis for DES Y6 1x2pt, 2x2pt, and 3x2pt analyses. This work highlights how targeted masking strategies optimise the balance between statistical power and systematic control in Stage-III and -IV surveys.
Source: The Open Journal of Astrophysics
DOI: 10.33232/001c.172767
Authors: M. Rodríguez-Monroy, N. Weaverdyck, J. Elvin-Poole, I. Sevilla-Noarbe, A. Carnero Rosell, A. Drlica-Wagner, D. Anbajagane, E. Sanchez, M. R. Becker, K. Bechtol, M. Crocce, A. Ferté, M. Gatti, J. Mena-Fernández, A. Porredon, D. Sanchez Cid, M. Yamamoto, M. Aguena, S. S. Allam, O. Alves, F. Andrade-Oliveira, D. Bacon, J. Blazek, S. Bocquet, D. Brooks, R. Camilleri, J. Carretero, R. Cawthon, C. Chang, L. N. da Costa, M. E. da Silva Pereira, S. Desai, H. T. Diehl, P. Doel, C. Doux, S. Everett, B. Flaugher, P. Fosalba, J. Frieman, J. García-Bellido, R. A. Gruendl, K. Herner, S. R. Hinton, D. L. Hollowood, K. Honscheid, D. Huterer, D. J. James, K. Kuehn, O. Lahav, S. Lee, J. L. Marshall, R. Miquel, J. Muir, J. Myles, R. L. C. Ogando, A. A. Plazas Malagón, J. Prat, S. Avila, T. Schutt, M. Smith, E. Suchyta, M. E. C. Swanson, C. To, M. A. Troxel, D. L. Tucker, V. Vikram
Language: English
Subfield: Astronomy and Astrophysics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: diamond
Funders: National Science Foundation, U.S. Department of Energy, University of Pennsylvania, Ohio State University, University of Chicago, University of Portsmouth, Centres de Recerca de Catalunya, University College London, European Commission, University of Sussex, Deutsche Forschungsgemeinschaft, Generalitat de Catalunya, Ministério da Ciência, Tecnologia e Inovação, Conselho Nacional de Desenvolvimento Científico e Tecnológico, Fundação Carlos Chagas Filho de Amparo à Pesquisa do Estado do Rio de Janeiro, Financiadora de Estudos e Projetos, Ministerio de Ciencia e Innovación, Institut de Física d'Altes Energies, University of Illinois at Urbana-Champaign, Office of Science, Science and Technology Facilities Council, European Regional Development Fund, Centro de Investigaciones Energéticas, Medioambientales y Tecnológicas, Office of Advanced Cyberinfrastructure, High Energy Physics, Integrated Electronics Engineering Center, Binghamton University, Argonne National Laboratory, Fermilab, Lawrence Berkeley National Laboratory, SLAC National Accelerator Laboratory
Awards: G1054097061, G1336129044, G1453181110, G1746333638, G179674260, Track 4: Advanced CI Coordination Ecosystem: Monitoring and Measurement Services, G2011917337, G2233160401, G2376186588, G2554159582, G2817899265, G2848635288, G2885514473, G302750986, G3154116105, G3251540411, G3439265645, G3562386289, The Dark Energy Survey Data Management Operations, G3870743921, G3927959030, G3993056153, Track 1: ACCESS Resource Allocations Marketplace and Platform Services (RAMPS), G4010157413, G4471177777, G454676879, G4655338613, ACO: An Open CI Ecosystem to Advance Scientific Discovery (OpenCI), Track 3: COre National Ecosystem for CyberinfrasTructure (CONECT), G5098925467, G5367127336, G5464919783, G5574724152, G5602398950, G5704573845, G6247045938, G6471802762, G6513613686, G656518222, G6676276723, G6709186444, G6754955425, G6941735741, G7257956838, G754761654, G7788408655, G7835623888, G8284171658, Track 2: Customized Multi-tier Assistance, Training, and Computational Help (MATCH) for End User ACCESS to CI, Collaborative Research: The Dark Energy Survey Data Management Operations, G8562358136, G8851268641, G8920660035, G946511789
OpenAlex ID: W4414566655