R. Laureijs, R. Vavrek, G. Racca, R. Kohley, P. Ferruit, V. Pettorino, T. Bönke, A. Calvi, L. Gaspar Venancio, L. Campos, E. Maiorano, O. Piersanti, S. Prezelus, U. Ragnit, P. Rosato, C. Rosso, H. Rozemeijer, A. Short, P. Strada, D. Stramaccioni, M. Szafraniec, B. Altieri, G. Buenadicha, X. Dupac, P. Gómez Cambronero, K. Henares Vilaboa, C. Hernandez de la Torre, J. Hoar, M. Lopez-Caniego Alcarria, P. Marcos Arenal, J. Martin Fleitas, M. Miluzio, A. Mora, S. Nieto, R. Perez Bonilla, P. Teodoro Idiago, F. Cordero, J. Mendes, F. Renk, A. Rudolph, M. Schmidt, J. Schwartz, Y. Mellier, H. Aussel, M. Berthé, P. Casenove, M. Cropper, J. Cuillandre, J. Dinis, A. Gregorio, K. Kuijken, T. Maciaszek, L. Miller, R. Scaramella, M. Schirmer, I. Tereno, A. Zacchei, S. Awan, G. Candini, P. Liebing, R. Nakajima, S. Dusini, P. Battaglia, E. Medinaceli, C. Sirignano, I. Baldry, C. Baugh, F. Bernardeau, F. Castander, A. Cimatti, W. Gillard, L. Guzzo, H. Hoekstra, K. Jahnke, T. Kitching, E. Martin, J. Mohr, W. Percival, J. Rhodes
During its 6-year nominal mission, Euclid shall survey one third of the sky, enabling us to examine the spatial distributions of dark and luminous matter during the past 10 Gyr of cosmic history. The Euclid satellite was successfully launched on a SpaceX Falcon 9 launcher from Cape Canaveral on 1 July 2023 and is fully operational in a halo orbit around the Second Sun-Earth Lagrange point. We present an overview of the expected and unexpected findings during the early phases of the mission, in the context of technological heritage and lessons learnt. The first months of the mission were dedicated to the commissioning of the spacecraft, telescope and instruments, followed by a phase to verify the scientific performance and to carry out the in-orbit calibrations. We report that the key enabling scientific elements, the 1.2-meter telescope and the two scientific instruments, a visual imager (VIS) and a near-infrared spectrometer and photometer (NISP), show an inorbit performance in line with the expectations from ground tests. The scientific analysis of the observations from the Early Release Observations (ERO) program done before the start of the nominal mission showed sensitivities better than the prelaunch requirements. The nominal mission started in December 2023, and we allocated a 6-month early survey operations phase to closely monitor the performance of the sky survey. We conclude with an outlook of the activities for the remaining mission in the light of the in-orbit performance.
Euclid, an ESA mission designed to characterise dark energy and dark matter, passed its Mission Critical Design Review in November 2018. It was demonstrated that the project is ready to start integration and test of the main systems, and that it has the ability to fulfil its top-level mission requirements. In addition, based on the performances at M-CDR, the scientific community has verified that the science requirements can be achieved for the Weak Lensing and Galaxy Clustering dark energy probes, namely a dark energy Figure of Merit of 400 and a 2% accuracy in the growth factor exponent gamma. We present the status of the main elements of the Euclid mission in the light of the demanding high optical performance which is the essential design driver is the to meet the scientific requirements. We include the space segment comprising of a service module and payload module hosting the telescope and its two scientific instruments, and the ground segment, which encompasses the operational and science ground segment. The elements for the scientific success of the mission for a timely release of the data are shortly presented: the processing and calibration of the data, and the design of the sky survey. Euclid is presently on schedule for a launch in September 2022.
K. Honscheid, A. Elliott, E. Buckley-Geer, B. Abreshi, F. Castander, L. da Costa, S. Kent, D. Kirkby, R. Marshall, E. Neilsen, R. Ogando, D. Rabinowitz, A. Roodman, S. Serrano, D. Brooks, M. Levi, G. Tarle
The Dark Energy Spectroscopic Instrument (DESI) is a new instrument currently under construction for the Mayall 4-m telescope at Kitt Peak National Observatory. It will consist of a wide-field optical corrector with a 3.2 degree diameter field of view, a focal plane with 5,000 robotically controlled fiber positioners and 10 fiber-fed broad-band spectrographs. The DESI Instrument Control System (ICS) coordinates fiber positioner operations, interfaces to the Mayall telescope control system, monitors operating conditions, reads out the 30 spectrograph CCDs and provides observer support and data quality monitoring. In this article, we summarize the ICS design, review the current status of the project and present results from a multi-stage test plan that was developed to ensure the system is fully operational by the time the instrument arrives at the observatory in 2019.
The Dark Energy Spectroscopic Instrument (DESI) is under construction to measure the expansion history of the Universe using the Baryon Acoustic Oscillation technique. The spectra of 40 million galaxies over 14,000 sq. deg. will be measured during the life of the experiment. A new prime focus corrector for the KPNO Mayall telescope will deliver light to 5000 fiber optic positioners. The fibers in turn feed ten broad-band spectrographs. We describe the ProtoDESI experiment, planned for installation and commissioning at the Mayall telescope in the fall of 2016, which will test the fiber positioning system for DESI. The ProtoDESI focal plate, consisting of 10 fiber positioners, illuminated fiducials, and a guide, focus and alignment (GFA) sensor module, will be installed behind the existing Mosaic prime focus corrector. A Fiber View Camera (FVC) will be mounted to the lower surface of the primary mirror cell and a subset of the Instrument Control System (ICS) will control the ProtoDESI subsystems, communicate with the Telescope Control System (TCS), and collect instrument monitoring data. Short optical fibers from the positioners will be routed to the back of the focal plane where they will be imaged by the Fiber Photometry Camera (FPC) or back-illuminated by a LED system. Target objects will be identified relative to guide stars, and using the GFA in a control loop with the ICS/TCS system, the guide stars will remain stable on pre-identified GFA pixels. The fiber positioners will then be commanded to the target locations and placed on the targets iteratively, using the FVC to centroid on back-illuminated fibers and fiducials to make corrective delta motions. When the positioners are aligned with the targets on-sky, the FPC will measure the intensities from the positioners’ fibers which can then be dithered to look for intensity changes, indicating how well the fibers were initially positioned on target centers. The final goal is to operate ProtoDESI on the Mayall telescope for a 6-hour period during one night, successfully placing targets on the intended fibers for the duration of a typical DESI science exposure.
PAUCam is a large field of view camera designed to exploit the field delivered by the prime focus corrector of the William Herschel Telescope, at the Observatorio del Roque de los Muchachos. One of the new features of this camera is its filter system, placed within a few millimeters of the focal plane using eleven trays containing 40 narrow band and 6 broad band filters, working in vacuum at an operational temperature of 250K and in a focalized beam. In this contribution, we describe the performance of these filters both in the characterization tests at the laboratory.
This paper describes the engineering and mechanical considerations in the design and construction of a carbon fiber containment vessel for a photometric camera. The camera is intended for installation on the 4 m William Herschel Telescope, located in Palma, Spain. The scientific objective of the camera system is to measure red-shifts of a large sample of galaxies using the photometric technique. The paper is broken down into sections, divided by the principal engineering challenges of the project; the carbon fiber vacuum vessel, the cooling systems and the precision movement systems.
K. Honscheid, A. Elliott, L. Beaufore, E. Buckley-Geer, F. Castander, L. daCosta, A. Fausti, S. Kent, D. Kirkby, E. Neilsen, K. Reil, S. Serrano, A. Slozar
The Dark Energy Spectroscopic Instrument (DESI) , a new instrument currently under construction for the Mayall 4m telescope at Kitt Peak National Observatory, will consist of a wide-field optical corrector with a 3.2 degree diameter field of view, a focal plane with 5,000 robotically controlled fiber positioners and 10 fiber fed broadband spectrographs. This article describes the design of the DESI instrument control system (ICS). The ICS coordinates fiber positioner operations, interfaces to the Mayall telescope control system, monitors operating conditions, reads out the 30 spectrograph CCDs and provides observer support and data quality monitoring.
H. T. Diehl, E. Neilsen, R. Gruendl, B. Yanny, T. M. Abbott, J. Aleksić, S. Allam, J. Annis, E. Balbinot, M. Baumer, L. Beaufore, K. Bechtol, G. Bernstein, S. Birrer, C. Bonnett, D. Brout, C. Bruderer, E. Buckley-Geer, D. Capozzi, A. Carnero Rosell, F. Castander, R. Cawthon, C. Chang, L. Clerkin, R. Covarrubias, C. Cuhna, C. D'Andrea, L. da Costa, R. Das, C. Davis, J. Dietrich, A. Drlica-Wagner, A. Elliott, T. Eifler, J. Etherington, B. Flaugher, J. Frieman, A. Fausti Neto, M. Fernández, C. Furlanetto, D. Gangkofner, D. Gerdes, D. Goldstein, K. Grabowski, R. Gupta, S. Hamilton, H. Head, J. Helsby, D. Hollowood, K. Honscheid, D. James, M. Johnson, S. Jouvel, T. Kacprzac, S. Kent, R. Kessler, A. Kim, E. Krause, C. Krawiec, A. Kremin, R. Kron, S. Kuhlmann, N. Kuropatkin, O. Lahav, J. Lasker, T. Li, E. Luque, N. Maccrann, M. March, J. Marshall, N. Mondrik, E. Morganson, D. Mudd, A. Nadolski, P. Nugent, P. Melchior, F. Menanteau, D. Nagasawa, B. Nord, R. Ogando, L. Old, A. Palmese, D. Petravick, A. Plazas, A. Pujol, A. Queiroz, K. Reil, A. Romer, R. Rosenfeld, A. Roodman, P. Rooney, M. Sako, A. Salvador, C. Sánchez, E. Sánchez Álvaro, B. Santiago, A. Schooneveld, M. Schubnell, E. Sheldon, A. Smith, R. Smith, M. Soares-Santos, F. Sobreira, M. Soumagnac, H. Spinka, S. Tie, D. Tucker, V. Vikram, K. Vivas, A. Walker, W. Wester, M. Wiesner, H. Wilcox, P. Williams, A. Zenteno, Y. Zhang, Z. Zhang
The Dark Energy Survey (DES) is an operating optical survey aimed at understanding the accelerating expansion of the universe using four complementary methods: weak gravitational lensing, galaxy cluster counts, baryon acoustic oscillations, and Type Ia supernovae. To perform the 5000 sq-degree wide field and 30 sq-degree supernova surveys, the DES Collaboration built the Dark Energy Camera (DECam), a 3 square-degree, 570-Megapixel CCD camera that was installed at the prime focus of the Blanco 4-meter telescope at the Cerro Tololo Inter-American Observatory (CTIO). DES has completed its third observing season out of a nominal five. This paper describes DES “Year 1” (Y1) to “Year 3” (Y3), the strategy, an outline of the survey operations procedures, the efficiency of operations and the causes of lost observing time. It provides details about the quality of the first three season's data, and describes how we are adjusting the survey strategy in the face of the El Niño Southern Oscillation.
The focal plane of the PAU camera is composed of eighteen 2K x 4K CCDs. These devices, plus four spares, were
provided by the Japanese company Hamamatsu Photonics K.K. with type no. S10892–04(X). These detectors are 200
μm thick fully depleted and back illuminated with an n-type silicon base. They have been built with a specific coating to
be sensitive in the range from 300 to 1,100 nm. Their square pixel size is 15 μm.
The read-out system consists of a Monsoon controller (NOAO) and the panVIEW software package. The deafualt CCD
read-out speed is 133 kpixel/s. This is the value used in the calibration process.
Before installing these devices in the camera focal plane, they were characterized using the facilities of the ICE (CSIC–
IEEC) and IFAE in the UAB Campus in Bellaterra (Barcelona, Catalonia, Spain).
The basic tests performed for all CCDs were to obtain the photon transfer curve (PTC), the charge transfer efficiency
(CTE) using X-rays and the EPER method, linearity, read-out noise, dark current, persistence, cosmetics and quantum
efficiency.
The X-rays images were also used for the analysis of the charge diffusion for different substrate voltages (VSUB).
Regarding the cosmetics, and in addition to white and dark pixels, some patterns were also found. The first one, which
appears in all devices, is the presence of half circles in the external edges. The origin of this pattern can be related to the
assembly process. A second one appears in the dark images, and shows bright arcs connecting corners along the vertical
axis of the CCD. This feature appears in all CCDs exactly in the same position so our guess is that the pattern is due to
electrical fields.
Finally, and just in two devices, there is a spot with wavelength dependence whose origin could be the result of a
defectous coating process.
The Dark Energy Camera (DECam) is a new 520 Mega Pixel CCD camera with a 3 square degree field of view built for
the Dark Energy Survey (DES). DECam is mounted at the prime focus of the Blanco 4-m telescope at the Cerro-Tololo
International Observatory (CTIO). DES is a 5-year, high precision, multi-bandpass, photometric survey of 5000 square
degrees of the southern sky that started August 2013. In this paper we briefly review SISPI, the data acquisition and
control system of the Dark Energy Camera and follow with a discussion of our experience with the system and the
lessons learned after one year of survey operations.
The Physics of the Accelerating Universe (PAU) is a project whose main goal is the study of dark energy. For this purpose, a new large field of view camera (the PAU Camera, PAUCam) is being built. PAUCam is designed to carry out a wide area imaging survey with narrow and broad band filters spanning the optical wavelength range. The PAU Camera is now at an advance stage of construction. PAUCam will be mounted at the prime focus of the William Herschel Telescope. With the current WHT corrector, it will cover a 1 degree diameter field of view. PAUCam mounts eighteen 2k×4k Hamamatsu fully depleted CCDs, with high quantum efficiency up to 1 μm. Filter trays are placed in front of the CCDs with a technologically challenging system of moving filter trays inside the cryostat. The PAU Camera will use a new set of 42 narrow band filters ranging from ~4400 to ~8600 angstroms complemented with six standard broad-band filters, ugrizY. With PAUCam at the WHT we will carry out a cosmological imaging survey in both narrow and broad band filters that will perform as a low resolution spectroscopic survey. With the current survey strategy, we will obtain accurate photometric redshifts for galaxies down to iAB~22.5 detecting also galaxies down to iAB~24 with less precision in redshift. With this data set we will obtain competitive constraints in cosmological parameters using both weak lensing and galaxy clustering as main observational probes.
The Dark Energy Camera (DECam) is a new 520 Mega Pixel CCD camera with a 3 square degree field of view designed
for the Dark Energy Survey (DES). DES is a high precision, multi-bandpass, photometric survey of 5000 square degrees
of the southern sky. DECam is currently being installed at the prime focus of the Blanco 4-m telescope at the Cerro-
Tololo International Observatory (CTIO). In this paper we describe SISPI, the data acquisition and control system of the
Dark Energy Camera. SISPI is implemented as a distributed multi-processor system with a software architecture based
on the Client-Server and Publish-Subscribe design patterns. The underlying message passing protocol is based on
PYRO, a powerful distributed object technology system written entirely in Python. A distributed shared variable system
was added to support exchange of telemetry data and other information between different components of the system. We
discuss the SISPI infrastructure software, the image pipeline, the observer console and user interface architecture, image
quality monitoring, the instrument control system, and the observation strategy tool.
The Physics of the Accelerating Universe (PAU) is a new project whose main goal is to study dark energy surveying the
galaxy distribution. For that purpose we need to determine the galaxy redshifts. The most accurate way to determine the
redshift of a galaxy and measure its spectral energy distribution (SED) is achieved with spectrographs. The PAU
collaboration is building an instrument (PAUCam) devoted to perform a large area survey for cosmological studies using
an alternative approach. SEDs are sampled and redshifts determined using narrow band filter photometry. For efficiency
and manufacturability considerations, the filters need to be placed close to the CCD detector surfaces on segmented filter
trays. The most innovative element of PAUCam is a set of 16 different exchangeable trays to support the filters arranged
in a jukebox-like changing mechanism inside the cryostat. The device is designed to operate within the range of
temperatures from 150K to 300K at the absolute pressure of 10-8mbar, being class-100 compliant.
The Physics of the Accelerating Universe (PAU) collaboration aims at conducting a competitive cosmology experiment.
For that purpose it is building the PAU Camera (PAUCam) to carry out a wide area survey to study dark energy.
PAUCam has been designed to be mounted at the prime focus of the William Herschel Telescope with its current optical
corrector that delivers a maximum field of view of ~0.8 square degrees. In order to cover the entire field of view
available, the PAUCam focal plane will be populated with a mosaic of eighteen CCD detectors. PAUCam will be
equipped with a set of narrow band filters and a set of broad band filters to sample the spectral energy distribution of
astronomical objects with photometric techniques equivalent to low resolution spectroscopy. In particular it will be able
to determine the redshift of galaxies with good precision and therefore conduct cosmological surveys. PAUCam will also
be offered to the broad astronomical community.
K. Honscheid, J. Eiting, A. Elliott, J. Annis, M. Bonati, E. Buckley-Geer, F. Castander, L. da Costa, M. Haney, W. Hanlon, I. Karliner, K. Kuehn, S. Kuhlmann, S. Marshall, M. Meyer, E. Neilsen, R. Ogando, A. Roodman, T. Schalk, G. Schumacher, M. Selen, S. Serrano, J. Thaler, W. Wester
In this paper we describe the data acquisition and control system of the Dark Energy Camera (DECam),
which will be the primary instrument used in the Dark Energy Survey (DES). DES is a high precision multibandpath
wide area survey of 5000 square degrees of the southern sky. DECam currently under construction
at Fermilab will be a 3 square degree mosaic camera mounted at the prime focus of the Blanco 4m telescope
at the Cerro-Tololo International Observatory (CTIO). The DECam data acquisition system (SISPI) is
implemented as a distributed multi-processor system with a software architecture built on the Client-Server
and Publish-Subscribe design patterns. The underlying message passing protocol is based on PYRO, a
powerful distributed object technology system written entirely in Python. A distributed shared variable
system was added to support exchange of telemetry data and other information between different components
of the system. In this paper we discuss the SISPI infrastructure software, the image pipeline, the observer
interface and quality monitoring system, and the instrument control system.
K. Honscheid, T. Abbott, J. Annis, E. Buckley-Geer, F. Castander, J. Eiting, M. Gladders, M. Haney, I. Karliner, D. Kau, K. Kuehn, S. Kuhlmann, T. Qian, M. Selen, J. Thaler, D. Tucker, A. Zhao
KEYWORDS: Control systems, Cameras, Telescopes, Databases, Image quality, Data acquisition, Charge-coupled devices, Camera shutters, Image processing, Computing systems
We describe the data acquisition and control system of the Dark Energy Camera (DECam), which will be the
primary instrument used in the Dark Energy Survey (DES). DECam will be a 3 sq. deg. mosaic camera
mounted at the prime focus of the Blanco 4m telescope at the Cerro-Tololo International Observatory (CTIO).
The DECam data acquisition system (SISPI) is implemented as a distributed multi-processor system with a
software architecture built on the Client-Server and Publish-Subscribe design patterns. The underlying
message passing protocol is based on the SML inter-process communication software developed at CTIO [1].
For the DECam read-out and control system this software package was ported from LabVIEW to the Python
and C programming languages. A shared variable system was added to support exchange of telemetry data
and other information between different components of the system. In this paper we discuss the SISPI
architecture, new concepts used in the design of the infrastructure software and provide an overview of the
remaining components of the DES read-out and control system.
The Physics of the Accelerating Universe (PAU) is a new project whose main goal is to measure the baryon
acoustic oscillations (BAO) in the galaxy distribution to characterize dark energy. For this purpose, it will build
a new large field of view camera (the PAU Camera) to carry out a wide area imaging survey with narrow band
filters spanning the optical wavelength range. The PAU Camera is at an early stage of design. Currently, it is
designed to have a focal plane field of view of approximately 45cm in diameter, that will be densely populated
by state of the art CCDs. The PAU Camera will use a new set of approximately 45 narrow band filters ranging
from ~4200 to ~8700 angstroms with two additional wide band filters at the blue and red ends of the spectrum.
The camera will operate in drift-scan mode. The PAU Camera is expected to be mounted either in a purposely
designed 2.5m class wide field telescope or in an existing telescope that could be adapted to deliver a wide field.
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