{"paper":{"title":"A calibration map for Wide Field Imager photometry","license":"","headline":"","cross_cats":[],"primary_cat":"astro-ph","authors_text":"A. Koch, E. K. Grebel, J. A. R. Caldwell, M. Odenkirchen","submitted_at":"2003-10-10T17:04:23Z","abstract_excerpt":"We present a prescription to correct large-scale intensity variations affecting imaging data taken with the Wide Field Imager (WFI) at the MPG/ESO 2.2 m telescope at the European Southern Observatory at La Silla in Chile. Such smoothly varying, large-scale gradients are primarily caused by non-uniform illumination due to stray light, which cannot be removed using standard flatfield procedures. By comparing our observations to the well-calibrated, homogeneous multi-colour photometry from the Sloan Digital Sky Survey we characterise the intensity gradients across the camera by second-order polyn"},"claims":{"count":0,"items":[],"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57"},"source":{"id":"astro-ph/0310301","kind":"arxiv","version":1},"verdict":{"id":null,"model_set":{},"created_at":null,"strongest_claim":"","one_line_summary":"","pipeline_version":null,"weakest_assumption":"","pith_extraction_headline":""},"integrity":{"clean":true,"summary":{"advisory":0,"critical":0,"by_detector":{},"informational":0},"endpoint":"/pith/astro-ph/0310301/integrity.json","findings":[],"available":true,"detectors_run":[],"snapshot_sha256":"c28c3603d3b5d939e8dc4c7e95fa8dfce3d595e45f758748cecf8e644a296938"},"references":{"count":0,"sample":[],"resolved_work":0,"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57","internal_anchors":0},"formal_canon":{"evidence_count":0,"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57"},"author_claims":{"count":0,"strong_count":0,"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57"},"builder_version":"pith-number-builder-2026-05-17-v1"}