Euclid. IV. The NISP Calibration Unit
Abstract
The near-infrared calibration unit (NI-CU) on board Euclid's Near-Infrared Spectrometer and Photometer (NISP) is the first astronomical calibration lamp based on light-emitting diodes (LEDs) to be operated in space. Euclid is a mission in ESA's Cosmic Vision 2015-2025 framework, to explore the dark universe and provide a next-level characterisation of the nature of gravitation, dark matter, and dark energy. Calibrating photometric and spectrometric measurements of galaxies to better than 1.5% accuracy in a survey homogeneously mapping ~14000 deg^2 of extragalactic sky requires a very detailed characterisation of near-infrared (NIR) detector properties, as well their constant monitoring in flight. To cover two of the main contributions - relative pixel-to-pixel sensitivity and non-linearity characteristics - as well as support other calibration activities, NI-CU was designed to provide spatially approximately homogeneous (<12% variations) and temporally stable illumination (0.1%-0.2% over 1200s) over the NISP detector plane, with minimal power consumption and energy dissipation. NI-CU is covers the spectral range ~[900,1900] nm - at cryo-operating temperature - at 5 fixed independent wavelengths to capture wavelength-dependent behaviour of the detectors, with fluence over a dynamic range of >=100 from ~15 ph s^-1 pixel^-1 to >1500 ph s^-1 pixel^-1. For this functionality, NI-CU is based on LEDs. We describe the rationale behind the decision and design process, describe the challenges in sourcing the right LEDs, as well as the qualification process and lessons learned. We also provide a description of the completed NI-CU, its capabilities and performance as well as its limits. NI-CU has been integrated into NISP and the Euclid satellite, and since Euclid's launch in July 2023 has started supporting survey operations.
Keywords
Cite
@article{arxiv.2405.13494,
title = {Euclid. IV. The NISP Calibration Unit},
author = {Euclid Collaboration and F. Hormuth and K. Jahnke and M. Schirmer and C. G. -Y. Lee and T. Scott and R. Barbier and S. Ferriol and W. Gillard and F. Grupp and R. Holmes and W. Holmes and B. Kubik and J. Macias-Perez and M. Laurent and J. Marpaud and M. Marton and E. Medinaceli and G. Morgante and R. Toledo-Moreo and M. Trifoglio and Hans-Walter Rix and A. Secroun and M. Seiffert and P. Stassi and S. Wachter and C. M. Gutierrez and C. Vescovi and A. Amara and S. Andreon and N. Auricchio and C. Baccigalupi and M. Baldi and A. Balestra and S. Bardelli and P. Battaglia and R. Bender and C. Bodendorf and D. Bonino and E. Branchini and M. Brescia and J. Brinchmann and S. Camera and V. Capobianco and C. Carbone and V. F. Cardone and J. Carretero and R. Casas and S. Casas and M. Castellano and G. Castignani and S. Cavuoti and A. Cimatti and C. Colodro-Conde and G. Congedo and C. J. Conselice and L. Conversi and Y. Copin and L. Corcione and F. Courbin and H. M. Courtois and A. Da Silva and H. Degaudenzi and G. De Lucia and J. Dinis and M. Douspis and F. Dubath and F. Ducret and X. Dupac and S. Dusini and M. Fabricius and M. Farina and S. Farrens and F. Faustini and S. Fotopoulou and N. Fourmanoit and M. Frailis and E. Franceschi and P. Franzetti and M. Fumana and S. Galeotta and B. Garilli and K. George and B. Gillis and C. Giocoli and A. Grazian and L. Guzzo and S. V. H. Haugan and H. Hoekstra and I. Hook and A. Hornstrup and P. Hudelot and M. Jhabvala and E. Keihänen and S. Kermiche and A. Kiessling and M. Kilbinger and T. Kitching and R. Kohley and M. Kümmel and M. Kunz and H. Kurki-Suonio and D. Le Mignant and S. Ligori and P. B. Lilje and V. Lindholm and I. Lloro and G. Mainetti and E. Maiorano and O. Mansutti and S. Marcin and O. Marggraf and K. Markovic and M. Martinelli and N. Martinet and F. Marulli and R. Massey and S. Maurogordato and H. J. McCracken and S. Mei and M. Melchior and Y. Mellier and M. Meneghetti and E. Merlin and G. Meylan and J. J. Mohr and M. Moresco and P. W. Morris and L. Moscardini and E. Munari and R. Nakajima and C. Neissner and R. C. Nichol and S. -M. Niemi and J. W. Nightingale and C. Padilla and K. Paech and S. Paltani and F. Pasian and K. Pedersen and W. J. Percival and V. Pettorino and S. Pires and G. Polenta and M. Poncet and L. A. Popa and F. Raison and R. Rebolo and A. Renzi and J. Rhodes and G. Riccio and E. Romelli and M. Roncarelli and E. Rossetti and B. Rusholme and R. Saglia and Z. Sakr and A. G. Sánchez and D. Sapone and B. Sartoris and M. Sauvage and J. A. Schewtschenko and P. Schneider and T. Schrabback and E. Sefusatti and G. Seidel and S. Serrano and C. Sirignano and G. Sirri and G. Smadja and L. Stanco and J. Steinwagner and P. Tallada-Crespí and D. Tavagnacco and A. N. Taylor and H. I. Teplitz and I. Tereno and F. Torradeflot and I. Tutusaus and L. Valenziano and T. Vassallo and A. Veropalumbo and Y. Wang and J. Weller and A. Zacchei and G. Zamorani and F. M. Zerbi and E. Zucca and A. Biviano and M. Bolzonella and A. Boucaud and E. Bozzo and C. Burigana and M. Calabrese and D. Di Ferdinando and J. A. Escartin Vigo and R. Farinelli and J. Gracia-Carpio and M. V. Kazandjian and N. Mauri and V. Scottez and M. Tenti and M. Viel and M. Wiesmann and Y. Akrami and V. Allevato and S. Anselmi and E. Aubourg and M. Ballardini and M. Bethermin and A. Blanchard and L. Blot and S. Borgani and A. S. Borlaff and E. Borsato and S. Bruton and R. Cabanac and A. Calabro and G. Canas-Herrera and A. Cappi and C. S. Carvalho and P. Casenove and T. Castro and K. C. Chambers and Y. Charles and S. Contarini and A. R. Cooray and O. Cucciati and S. Davini and B. De Caro and S. de la Torre and G. Desprez and A. Díaz-Sánchez and J. J. Diaz and S. Di Domizio and H. Dole and S. Escoffier and A. G. Ferrari and P. G. Ferreira and I. Ferrero and F. Finelli and A. Fontana and F. Fornari and L. Gabarra and K. Ganga and J. García-Bellido and E. Gaztanaga and F. Giacomini and G. Gozaliasl and A. Hall and W. G. Hartley and H. Hildebrandt and J. Hjorth and M. Huertas-Company and O. Ilbert and J. Jacobson and A. Jimenez Muñoz and S. Joudaki and J. J. E. Kajava and V. Kansal and D. Karagiannis and C. C. Kirkpatrick and F. Laudisio and L. Legrand and G. Libet and A. Loureiro and G. Maggio and M. Magliocchetti and C. Mancini and F. Mannucci and R. Maoli and C. J. A. P. Martins and S. Matthew and L. Maurin and R. B. Metcalf and M. Miluzio and C. Moretti and S. Nadathur and Nicholas A. Walton and L. Patrizii and A. Pezzotta and M. Pöntinen and V. Popa and C. Porciani and D. Potter and I. Risso and P. -F. Rocci and R. P. Rollins and M. Sahlén and C. Scarlata and A. Schneider and M. Schultheis and M. Sereno and A. Shulevski and A. Silvestri and P. Simon and A. Spurio Mancini and J. Stadel and C. Tao and G. Testera and R. Teyssier and S. Toft and S. Tosi and A. Troja and M. Tucci and C. Valieri and J. Valiviita and D. Vergani and G. Verza and L. Zalesky and M. Archidiacono and F. Atrio-Barandela and T. Bouvard and F. Caro and P. Dimauro and Y. Fang and A. M. N. Ferguson and A. Finoguenov and T. Gasparetto and A. M. C. Le Brun and J. Le Graet and T. I. Liaudat and A. Montoro and C. Murray and M. Oguri and L. Pagano and D. Paoletti and E. Sarpa and K. Tanidis and F. Vernizzi and A. Viitanen and I. Kova{č}ić and J. Lesgourgues and J. Martín-Fleitas and A. Mora},
journal= {arXiv preprint arXiv:2405.13494},
year = {2025}
}
Comments
Paper accepted for publication in A&A as part of the special issue 'Euclid on Sky', which contains Euclid key reference papers and first results from the Euclid Early Release Observations