article published yes Göran Östlin author Pablo G. Pérez-González author Jens Melinder author Steven Gillman author Edoardo Iani author 4053390a-6b68-11ef-9828-a3b8adef8d0a0000-0001-8386-3546 Luca Costantin author Leindert A. Boogaard author Pierluigi Rinaldi author Luis Colina author Hans Ulrik Nørgaard-Nielsen author Daniel Dicken author Thomas R. Greve author Gillian Wright author Almudena Alonso-Herrero author Javier Álvarez-Márquez author Marianna Annunziatella author Arjan Bik author Sarah E.I. Bosman author Karina I. Caputi author Alejandro Crespo Gomez author Andreas Eckart author Macarena Garcia-Marin author Jens Hjorth author Olivier Ilbert author Iris Jermann author Sarah Kendrew author Alvaro Labiano author Danial Langeroodi author Olivier Le Fevre author Mattia Libralato author Romain A. Meyer author Thibaud Moutard author Florian Peissker author John P. Pye author Tuomo V. Tikkanen author Martin Topinka author Fabian Walter author Martin Ward author Paul Van Der Werf author Ewine F. Van Dishoeck author Manuel Güdel author Thomas Henning author Pierre Olivier Lagage author Tom P. Ray author Bart Vandenbussche author JoMa department Context. The recently launched James Webb Space Telescope (JWST) is opening new observing windows on the distant Universe. Among JWST’s instruments, the Mid Infrared Instrument (MIRI) offers the unique capability of imaging observations at wavelengths of λ > 5 μm. This enables unique access to the rest frame near-infrared (NIR, λ ≥ 1 μm) emission from galaxies at redshifts of z > 4 and the visual (λ ≳ 5000 Å) rest frame for z > 9. We report here on the guaranteed time observations (GTO), from the MIRI European Consortium, of the Hubble Ultra Deep Field (HUDF), forming the MIRI Deep Imaging Survey (MIDIS), consisting of an on source integration time of ∼41 hours in the MIRI/F560W (5.6 μm) filter. The F560W filter was selected since it would produce the deepest data in terms of AB magnitudes in a given time. To our knowledge, this constitutes the longest single filter exposure obtained with JWST of an extragalactic field as of yet. Aims. The HUDF is one of the most observed extragalactic fields, with extensive multi-wavelength coverage, where (before JWST) galaxies up to z ∼ 7 have been confirmed, and at z > 10 suggested, from HST photometry. We aim to characterise the galaxy population in HUDF at 5.6 μm, enabling studies such as: the rest frame NIR morphologies for galaxies at z ≲ 4.6, probing mature stellar populations and emission lines in z > 6 sources, intrinsically red and dusty galaxies, and active galactic nuclei (AGNs) and their host galaxies at intermediate redshifts. Methods. We reduced the MIRI data using the official JWST pipeline, augmented by in-house custom scripts. We measured the noise characteristics of the resulting image. Galaxy photometry was obtained, and photometric redshifts were estimated for sources with available multi-wavelength photometry (and compared to spectroscopic redshifts when available). Results. Over the deepest part of our image, the 5σ point source limit is 28.65 mag AB (12.6 nJy), ∼0.35 mag better than predicted by the JWST exposure time calculator. We find ∼2500 sources, the overwhelming majority of which are distant galaxies, but we note that spurious sources likely remain at faint magnitudes due to imperfect cosmic ray rejection in the JWST pipeline. More than 500 galaxies with available spectroscopic redshifts, up to z ≈ 11, have been identified, the majority of which are at z < 6. More than 1000 galaxies have reliable photometric redshift estimates, of which ∼25 are at 6 < z < 12. The point spread function in the F560W filter has a full width at half maximum (FWHM) of ≈0.2″ (corresponding to 1.4 kpc at z = 4), allowing the NIR rest frame morphologies and stellar mass distributions to be resolved for z < 4.5. Moreover, > 100 objects with very red NIRCam vs MIRI (3.6–5.6 μm > 1 mag) colours have been found, suggestive of dusty or old stellar populations at high redshifts. Conclusions. We conclude that MIDIS surpasses preflight expectations and that deep MIRI imaging has great potential to characterise the galaxy population from cosmic noon to dawn. https://research-explorer.ista.ac.at/download/19845/19865/2025_AstronomyAstrophysics_Oestlin.pdf application/pdfno EDP Sciences2025 eng 0004-6361 1432-0746 2411.19686 00145978030000510.1051/0004-6361/202451723 696 Östlin, G., Pérez-González, P. G., Melinder, J., Gillman, S., Iani, E., Costantin, L., … Vandenbussche, B. (2025). MIRI Deep Imaging Survey (MIDIS) of the Hubble Ultra Deep Field: Survey description and early results for the galaxy population detected at 5.6 µm. <i>Astronomy &#38; Astrophysics</i>. EDP Sciences. <a href="https://doi.org/10.1051/0004-6361/202451723">https://doi.org/10.1051/0004-6361/202451723</a> Östlin, Göran, et al. “MIRI Deep Imaging Survey (MIDIS) of the Hubble Ultra Deep Field: Survey Description and Early Results for the Galaxy Population Detected at 5.6 Μm.” <i>Astronomy &#38; Astrophysics</i>, vol. 696, A57, EDP Sciences, 2025, doi:<a href="https://doi.org/10.1051/0004-6361/202451723">10.1051/0004-6361/202451723</a>. Östlin G, Pérez-González PG, Melinder J, Gillman S, Iani E, Costantin L, Boogaard LA, Rinaldi P, Colina L, Nørgaard-Nielsen HU, Dicken D, Greve TR, Wright G, Alonso-Herrero A, Álvarez-Márquez J, Annunziatella M, Bik A, Bosman SEI, Caputi KI, Gomez AC, Eckart A, Garcia-Marin M, Hjorth J, Ilbert O, Jermann I, Kendrew S, Labiano A, Langeroodi D, Le Fevre O, Libralato M, Meyer RA, Moutard T, Peissker F, Pye JP, Tikkanen TV, Topinka M, Walter F, Ward M, Van Der Werf P, Van Dishoeck EF, Güdel M, Henning T, Lagage PO, Ray TP, Vandenbussche B. 2025. MIRI Deep Imaging Survey (MIDIS) of the Hubble Ultra Deep Field: Survey description and early results for the galaxy population detected at 5.6 µm. Astronomy &#38; Astrophysics. 696, A57. Östlin G, Pérez-González PG, Melinder J, et al. MIRI Deep Imaging Survey (MIDIS) of the Hubble Ultra Deep Field: Survey description and early results for the galaxy population detected at 5.6 µm. <i>Astronomy &#38; Astrophysics</i>. 2025;696. doi:<a href="https://doi.org/10.1051/0004-6361/202451723">10.1051/0004-6361/202451723</a> G. Östlin <i>et al.</i>, “MIRI Deep Imaging Survey (MIDIS) of the Hubble Ultra Deep Field: Survey description and early results for the galaxy population detected at 5.6 µm,” <i>Astronomy &#38; Astrophysics</i>, vol. 696. EDP Sciences, 2025. Östlin, Göran, Pablo G. Pérez-González, Jens Melinder, Steven Gillman, Edoardo Iani, Luca Costantin, Leindert A. Boogaard, et al. “MIRI Deep Imaging Survey (MIDIS) of the Hubble Ultra Deep Field: Survey Description and Early Results for the Galaxy Population Detected at 5.6 Μm.” <i>Astronomy &#38; Astrophysics</i>. EDP Sciences, 2025. <a href="https://doi.org/10.1051/0004-6361/202451723">https://doi.org/10.1051/0004-6361/202451723</a>. G. Östlin, P.G. Pérez-González, J. Melinder, S. Gillman, E. Iani, L. Costantin, L.A. Boogaard, P. Rinaldi, L. Colina, H.U. Nørgaard-Nielsen, D. Dicken, T.R. Greve, G. Wright, A. Alonso-Herrero, J. Álvarez-Márquez, M. Annunziatella, A. Bik, S.E.I. Bosman, K.I. Caputi, A.C. Gomez, A. Eckart, M. Garcia-Marin, J. Hjorth, O. Ilbert, I. Jermann, S. Kendrew, A. Labiano, D. Langeroodi, O. Le Fevre, M. Libralato, R.A. Meyer, T. Moutard, F. Peissker, J.P. Pye, T.V. Tikkanen, M. Topinka, F. Walter, M. Ward, P. Van Der Werf, E.F. Van Dishoeck, M. Güdel, T. Henning, P.O. Lagage, T.P. Ray, B. Vandenbussche, Astronomy &#38; Astrophysics 696 (2025). 198452025-06-15T22:01:30Z2026-02-16T12:10:36Z