Final published version
Licence: CC BY: Creative Commons Attribution 4.0 International License
Research output: Contribution to Journal/Magazine › Journal article › peer-review
Research output: Contribution to Journal/Magazine › Journal article › peer-review
}
TY - JOUR
T1 - Euclid IV. The NISP Calibration Unit
AU - Euclid Collaboration
AU - Hormuth, F.
AU - Jahnke, K.
AU - Schirmer, M.
AU - Lee, C.G.-Y.
AU - Scott, T.
AU - Barbier, R.
AU - Ferriol, S.
AU - Gillard, W.
AU - Grupp, F.
AU - Holmes, R.
AU - Holmes, W.
AU - Kubik, B.
AU - Macias-Perez, J.
AU - Laurent, M.
AU - Marpaud, J.
AU - Marton, M.
AU - Medinaceli, E.
AU - Morgante, G.
AU - Toledo-Moreo, R.
AU - Trifoglio, M.
AU - Rix, H.-W.
AU - Secroun, A.
AU - Seiffert, M.
AU - Stassi, P.
AU - Wachter, S.
AU - Gutierrez, C.M.
AU - Vescovi, C.
AU - Amara, A.
AU - Andreon, S.
AU - Auricchio, N.
AU - Baccigalupi, C.
AU - Baldi, M.
AU - Balestra, A.
AU - Bardelli, S.
AU - Battaglia, P.
AU - Bender, R.
AU - Bodendorf, C.
AU - Hook, I.
AU - Morris, P.W.
AU - Taylor, A.N.
AU - Wang, Y.
AU - Weller, J.
AU - Ferrari, A.G.
AU - Hall, A.
AU - Hartley, W.G.
AU - Potter, D.
AU - Tao, C.
AU - Fang, Y.
AU - Murray, C.
AU - Mora, A.
PY - 2025/4/30
Y1 - 2025/4/30
N2 - 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 ~14 000 deg2 of extragalactic sky requires a very detailed characterisation of near-infrared (NIR) detector properties as well as constant monitoring of them in flight. To cover two of the main contributions – relative pixel-to-pixel sensitivity and non-linearity characteristics – and to support other calibration activities, NI-CU was designed to provide spatially approximately homogeneous (<12% variations) and temporally stable illumination (0.1–0.2% over 1200 s) over the NISP detector plane with minimal power consumption and energy dissipation. NI-CU covers the spectral range ~[900,I900] nm – at cryo-operating temperature – at five 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, the challenges in sourcing the right LEDs, and 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, it has started supporting survey operations.
AB - 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 ~14 000 deg2 of extragalactic sky requires a very detailed characterisation of near-infrared (NIR) detector properties as well as constant monitoring of them in flight. To cover two of the main contributions – relative pixel-to-pixel sensitivity and non-linearity characteristics – and to support other calibration activities, NI-CU was designed to provide spatially approximately homogeneous (<12% variations) and temporally stable illumination (0.1–0.2% over 1200 s) over the NISP detector plane with minimal power consumption and energy dissipation. NI-CU covers the spectral range ~[900,I900] nm – at cryo-operating temperature – at five 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, the challenges in sourcing the right LEDs, and 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, it has started supporting survey operations.
U2 - 10.1051/0004-6361/202450345
DO - 10.1051/0004-6361/202450345
M3 - Journal article
VL - 697
JO - Astronomy and Astrophysics
JF - Astronomy and Astrophysics
SN - 1432-0746
M1 - A4
ER -