Bibcode
Euclid Collaboration; Paterson, K.; Schirmer, M.; Okumura, K.; Venemans, B.; Jahnke, K.; Aghanim, N.; Altieri, B.; Amara, A.; Andreon, S.; Baccigalupi, C.; Baldi, M.; Balestra, A.; Bardelli, S.; Battaglia, P.; Biviano, A.; Bonchi, A.; Branchini, E.; Brescia, M.; Brinchmann, J.; Camera, S.; Cañas-Herrera, G.; Capobianco, V.; Carretero, J.; Casas, S.; Castellano, M.; Castignani, G.; Cavuoti, S.; Chambers, K. C.; Cimatti, A.; Colodro-Conde, C.; Congedo, G.; Conselice, C. J.; Conversi, L.; Copin, Y.; Courbin, F.; Courtois, H. M.; Da Silva, A.; da Silva, R.; Degaudenzi, H.; De Lucia, G.; Di Giorgio, A. M.; Dinis, J.; Dole, H.; Dubath, F.; Dupac, X.; Dusini, S.; Ealet, A.; Escoffier, S.; Farina, M.; Farinelli, R.; Faustini, F.; Ferriol, S.; Finelli, F.; Fotopoulou, S.; Fourmanoit, N.; Frailis, M.; Franceschi, E.; Franzetti, P.; Galeotta, S.; George, K.; Gillard, W.; Gillis, B.; Giocoli, C.; Gracia-Carpio, J.; Granett, B. R.; Grazian, A.; Grupp, F.; Guzzo, L.; Haugan, S. V. H.; Hoekstra, H.; Holmes, W.; Hormuth, F.; Hornstrup, A.; Hudelot, P.; Jhabvala, M.; Keihänen, E.; Kermiche, S.; Kiessling, A.; Kohley, R.; Kubik, B.; Kümmel, M.; Kunz, M.; Kurki-Suonio, H.; Le Brun, A. M. C.; Le Mignant, D.; Ligori, S.; Lilje, P. B.; Lindholm, V.; Lloro, I.; Mainetti, G.; Maino, D.; Maiorano, E.; Mansutti, O.; Marcin, S.; Marggraf, O.; Markovic, K.; Martinelli, M.; Martinet, N.; Marulli, F. et al.
Bibliographical reference
Astronomy and Astrophysics
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3
2026
Journal
Citations
0
Refereed citations
0
Description
The Near-Infrared Spectrometer and Photometer (NISP) on board Euclid includes several optical elements in its path that introduce artefacts into the data from non-nominal light paths. To ensure uncontaminated source photometry, these artefacts must be accurately accounted for. This paper focuses on two specific optical features in NISP's photometric data (NISP-P): ghosts caused by the telescope's dichroic beamsplitter, and the bandpass filters within the NISP fore-optics. Both ghost types exhibit a characteristic morphology and are offset from the originating stars. The offsets are well modelled using 2D polynomials; only stars brighter than approximately 10 magnitudes in each filter produce significant ghost contributions. The masking radii for these ghosts depend on both the source-star brightness and the filter wavelength, ranging from 20 to 40 pixels. We present the final relations and models used in the near-infrared (NIR) processing function (PF) to mask these ghosts for Euclid's Quick Data Release (Q1).