Euclid preparation. I. The Euclid Wide Survey
Aussel, H.; Cimatti, A.; Schultheis, M.; Aghanim, N.; Baccigalupi, C.; Burigana, C.; Dole, H.; Douspis, M.; Dupac, X.; Finelli, F.; Frailis, M.; Franceschi, E.; Galeotta, S.; Ganga, K.; Kunz, M.; Kurki-Suonio, H.; Lilje, P. B.; Maino, D.; Maris, M.; Morgante, G.; Pasian, F.; Pettorino, V.; Polenta, G.; Rebolo, R.; Renzi, A.; Rosset, C.; Valenziano, L.; Valiviita, J.; Zacchei, A.; Schrabback, T.; Taylor, A. N.; Jahnke, K.; Paltani, S.; Nichol, R. C.; Schirmer, M.; Carretero, J.; Castander, F. J.; Desai, S.; Fosalba, P.; Andreon, S.; Popa, L.; Castellano, M.; Sauvage, M.; Merlin, E.; Roncarelli, M.; Rix, H. -W.; Grazian, A.; Hoekstra, H.; Martinet, N.; Castignani, G.; McCracken, H. J.; Cropper, M.; Cuillandre, J. -C.; Conversi, L.; Mainetti, G.; Mohr, J. J.; Kümmel, M.; Bozzo, E.; Meneghetti, M.; Moscardini, L.; Scaramella, R.; Zamorani, G.; Lahav, O.; Serrano, S.; Carlberg, R. G.; Haugan, S. V. H.; Euclid Collaboration; Cuby, J.; Amara, A.; Auricchio, N.; Bodendorf, C.; Bonino, D.; Branchini, E.; Brau-Nogue, S.; Brescia, M.; Capobianco, V.; Carbone, C.; Cavuoti, S.; Cledassou, R.; Congedo, G.; Conselice, C. J.; Copin, Y.; Corcione, L.; Costille, A.; Da Silva, A.; Degaudenzi, H.; Dubath, F.; Duncan, C. A. J.; Dusini, S.; Farrens, S.; Ferriol, S.; Fumana, M.; Garilli, B.; Gillis, B.; Giocoli, C.; Granett, B. R.; Grupp, F.; Holmes, W.; Hormuth, F.; Hudelot, P.; Kermiche, S.; Kiessling, A.; Kilbinger, M.; Kitching, T.; Kohley, R.; Ligori, S.; Lloro, I.; Maiorano, E.; Mansutti, O.; Marggraf, O.; Markovic, K.; Marulli, F.; Massey, R.; Maurogordato, S.; Meylan, G.; Moresco, M.; Munari, E.; Niemi, S. M.; Padilla, C.; Pedersen, K.; Pires, S.; Poncet, M.; Pozzetti, L.; Raison, F.; Rhodes, J.; Rossetti, E.; Saglia, R.; Schneider, P.; Secroun, A.; Seidel, G.; Sirignano, C.; Sirri, G.; Stanco, L.; Tallada-Crespí, P.; Tereno, I.; Toledo-Moreo, R.; Torradeflot, F.; Wang, Y.; Welikala, N.; Weller, J.; Zoubian, J.; Bardelli, S.; Camera, S.; Graciá-Carpio, J.; Medinaceli, E.; Mei, S.; Romelli, E.; Sureau, F.; Tenti, M.; Vassallo, T.; Zucca, E.; Balaguera-Antolínez, A.; Biviano, A.; Cabanac, R.; Cappi, A.; Carvalho, C. S.; Casas, S.; Colodro-Conde, C.; Coupon, J.; Courtois, H. M.; Di Ferdinando, D.; Farina, M.; Flose-Reimberg, P.; Fotopoulou, S.; Gozaliasl, G.; Keihanen, E.; Kirkpatrick, C. C.; Lindholm, V.; Martinelli, M.; Maturi, M.; Metcalf, R. B.; Nucita, A.; Patrizii, L.; Potter, D.; Riccio, G.; Sánchez, A. G.; Sapone, D.; Scottez, V.; Teyssier, R.; Tutusaus, I.; Viel, M.; Bender, R.; Scodeggio, M.; Tavagnacco, D.; Fabricius, M.; Farinelli, R.; Melchior, M.; Starck, J. L.; Cardone, V. F.; Mellier, Y.; Nightingale, J.; Trifoglio, M.; Laureijs, R.; de la Torre, S.; Franzetti, P.; Courbin, F.; Teplitz, H. I.; Vavrek, R.; Percival, W. J.; Gillard, W.; Valentijn, E. A.; Borgani, S.; Miller, L.; Nakajima, R.; Verdoes Kleijn, G. A.; Hoar, J.; Fabbian, G.; Skottfelt, J.; Hook, I. M.; Baldi, M.; Guzzo, L.; Boucaud, A.; Schewtschenko, J. A.; Fourmanoit, N.; Balestra, A.; Battaglia, P.; Dinis, J.; Kubik, B.; Neissner, C.; Maciaszek, T.; Liebing, P.; Azzollini, R.; Wachter, S.; Casas, R.; Wetzstein, M.; Amiaux, J.; Derosa, A.; Boenke, T.; Buenadicha, G.; Gaspar Venancio, L. M.; Gómez-Álvarez, P.; Lorenzo Alvarez, J.; Racca, G. D.; Saavedra-Criado, G.; Schwartz, J.; Ealet, A.; Pottinger, S.; Auphan, T.; Awan, S.; Candini, G. P.; Morin, B.; Peacock, J.; Ferreira, P. G.; Vriend, W.; Whittaker, L.
Italy, France, Portugal, Netherlands, Spain, Germany, United Kingdom, Canada, United States, Switzerland, Norway, Finland, Denmark, Romania, India, Chile
Abstract
Euclid is a mission of the European Space Agency that is designed to constrain the properties of dark energy and gravity via weak gravitational lensing and galaxy clustering. It will carry out a wide area imaging and spectroscopy survey (the Euclid Wide Survey: EWS) in visible and near-infrared bands, covering approximately 15 000 deg2 of extragalactic sky in six years. The wide-field telescope and instruments are optimised for pristine point spread function and reduced stray light, producing very crisp images. This paper presents the building of the Euclid reference survey: the sequence of pointings of EWS, deep fields, and calibration fields, as well as spacecraft movements followed by Euclid as it operates in a step-and-stare mode from its orbit around the Lagrange point L2. Each EWS pointing has four dithered frames; we simulated the dither pattern at the pixel level to analyse the effective coverage. We used up-to-date models for the sky background to define the Euclid region-of-interest (RoI). The building of the reference survey is highly constrained from calibration cadences, spacecraft constraints, and background levels; synergies with ground-based coverage were also considered. Via purposely built software, we first generated a schedule for the calibrations and deep fields observations. On a second stage, the RoI was tiled and scheduled with EWS observations, using an algorithm optimised to prioritise the best sky areas, produce a compact coverage, and ensure thermal stability. The result is the optimised reference survey RSD_2021A, which fulfils all constraints and is a good proxy for the final solution. The current EWS covers ≈14 500 deg2. The limiting AB magnitudes (5σ point-like source) achieved in its footprint are estimated to be 26.2 (visible band IE) and 24.5 (for near infrared bands YE, JE, HE); for spectroscopy, the Hα line flux limit is 2 × 10−16 erg−1 cm−2 s−1 at 1600 nm; and for diffuse emission, the surface brightness limits are 29.8 (visible band) and 28.4 (near infrared bands) mag arcsec−2.