The Maunakea Spectroscopic Explorer Book 2018

(Abridged) This is the Maunakea Spectroscopic Explorer 2018 book. It is intended as a concise reference guide to all aspects of the scientific and technical design of MSE, for the international astronomy and engineering communities, and related agencies. The current version is a status report of MSE's science goals and their practical implementation, following the System Conceptual Design Review, held in January 2018. MSE is a planned 10-m class, wide-field, optical and near-infrared facility, designed to enable transformative science, while filling a critical missing gap in the emerging international network of large-scale astronomical facilities. MSE is completely dedicated to multi-object spectroscopy of samples of between thousands and millions of astrophysical objects. It will lead the world in this arena, due to its unique design capabilities: it will boast a large (11.25 m) aperture and wide (1.52 sq. degree) field of view; it will have the capabilities to observe at a wide range of spectral resolutions, from R2500 to R40,000, with massive multiplexing (4332 spectra per exposure, with all spectral resolutions available at all times), and an on-target observing efficiency of more than 80%. MSE will unveil the composition and dynamics of the faint Universe and is designed to excel at precision studies of faint astrophysical phenomena. It will also provide critical follow-up for multi-wavelength imaging surveys, such as those of the Large Synoptic Survey Telescope, Gaia, Euclid, the Wide Field Infrared Survey Telescope, the Square Kilometre Array, and the Next Generation Very Large Array.Comment: 5 chapters, 160 pages, 107 figure

Local Turbulence: Effects and causes

International audienceDome seeing is a known source of image quality degradation, but despite tremendous progress in wavefront control with the development of adaptive optics and environmental control through implementation of dome venting, surprisingly little is known about it quantitatively. We have found evidence of non-Kolmogorov dome turbulence from our observations with the imaka wide field adaptive optics system; PSFs seem to indicate an excess of high spatial frequencies and turbulence profiles reveal turbulence at negative conjugations. This has motivated the development of a new type of optical turbulence sensor called AIR-FLOW, Airborne Interferometric Recombiner: Fluctuations of Light at Optical Wavelengths. It is a non-redundant mask imaging interferometer that samples the optical turbulence passing through a measurement cell and it measures the two-dimensional optical Phase Structure Function. This is a useful tool to characterise different types of turbulence (e.g. Kolmogorov, diffusive turbulence, etc.). By fitting different models, we can determine parameters such as Cn 2 , r0, L0 or deviation from fully developed turbulence. The instrument was tested at the Canada France Hawaii Telescope, at the University of Hawaii 2.2-meter telescope (UH88") and at the Observatoire de la Côte d'Azur. It is ruggedised and sensitive enough to detect changes with different dome vent configurations, as well as slow local variations of the index of refraction in the UH88" telescope tube. The instrument is portable enough that it can be used to locate sources of turbulence inside and around domes, but it can also be used in an operational setting without affecting observations to characterise the local optical turbulence responsible for dome seeing. Thus, it could be used in real-time observatory control systems to configure vents and air handlers to effectively reduce dome seeing. We believe it could also be a tool for site surveys to evaluate dome seeing mitigation strategies in situ

Direct measure of dome seeing with a localized optical turbulence sensor

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Astronomical Image Quality Prediction based on Environmental and Telescope Operating Conditions

4 pages, 3 figures. Accepted to Machine Learning and the Physical Sciences Workshop at the 34th Conference on Neural Information Processing Systems (NeurIPS)International audienceIntelligent scheduling of the sequence of scientific exposures taken at ground-based astronomical observatories is massively challenging. Observing time is over-subscribed and atmospheric conditions are constantly changing. We propose to guide observatory scheduling using machine learning. Leveraging a 15-year archive of exposures, environmental, and operating conditions logged by the Canada-France-Hawaii Telescope, we construct a probabilistic data-driven model that accurately predicts image quality. We demonstrate that, by optimizing the opening and closing of twelve vents placed on the dome of the telescope, we can reduce dome-induced turbulence and improve telescope image quality by (0.05-0.2 arc-seconds). This translates to a reduction in exposure time (and hence cost) of $\sim 10-15\%$. Our study is the first step toward data-based optimization of the multi-million dollar operations of current and next-generation telescopes

Uncertainty-Aware Learning for Improvements in Image Quality of the Canada-France-Hawaii Telescope

We leverage state-of-the-art machine learning methods and a decade's worth of archival data from the Canada-France-Hawaii Telescope (CFHT) to predict observatory image quality (IQ) from environmental conditions and observatory operating parameters. Specifically, we develop accurate and interpretable models of the complex dependence between data features and observed IQ for CFHT's wide field camera, MegaCam. Our contributions are severalfold. First, we collect, collate and reprocess several disparate data sets gathered by CFHT scientists. Second, we predict probability distribution functions (PDFs) of IQ, and achieve a mean absolute error of ∼ 0.07 for the predicted medians. Third, we explore data-driven actuation of the 12 dome "vents", installed in 2013-14 to accelerate the flushing of hot air from the dome. We leverage epistemic and aleatoric uncertainties in conjunction with probabilistic generative modeling to identify candidate vent adjustments that are in-distribution (ID) and, for the optimal configuration for each ID sample, we predict the reduction in required observing time to achieve a fixed SNR. On average, the reduction is ∼ 15%. Finally, we rank sensor data features by Shapley values to identify the most predictive variables for each observation. Our long-term goal is to construct reliable and real-time models that can forecast optimal observatory operating parameters for optimization of IQ. Such forecasts can then be fed into scheduling protocols and predictive maintenance routines. We anticipate that such approaches will become standard in automating observatory operations and maintenance by the time CFHT's successor, the Maunakea Spectroscopic Explorer (MSE), is installed in the next decade

Uncertainty-Aware Learning for Improvements in Image Quality of the Canada-France-Hawaii Telescope

We leverage state-of-the-art machine learning methods and a decade's worth of archival data from the Canada-France-Hawaii Telescope (CFHT) to predict observatory image quality (IQ) from environmental conditions and observatory operating parameters. Specifically, we develop accurate and interpretable models of the complex dependence between data features and observed IQ for CFHT's wide field camera, MegaCam. Our contributions are severalfold. First, we collect, collate and reprocess several disparate data sets gathered by CFHT scientists. Second, we predict probability distribution functions (PDFs) of IQ, and achieve a mean absolute error of ∼ 0.07 for the predicted medians. Third, we explore data-driven actuation of the 12 dome "vents", installed in 2013-14 to accelerate the flushing of hot air from the dome. We leverage epistemic and aleatoric uncertainties in conjunction with probabilistic generative modeling to identify candidate vent adjustments that are in-distribution (ID) and, for the optimal configuration for each ID sample, we predict the reduction in required observing time to achieve a fixed SNR. On average, the reduction is ∼ 15%. Finally, we rank sensor data features by Shapley values to identify the most predictive variables for each observation. Our long-term goal is to construct reliable and real-time models that can forecast optimal observatory operating parameters for optimization of IQ. Such forecasts can then be fed into scheduling protocols and predictive maintenance routines. We anticipate that such approaches will become standard in automating observatory operations and maintenance by the time CFHT's successor, the Maunakea Spectroscopic Explorer (MSE), is installed in the next decade

Introduction to the CFHT Legacy Survey final release (CFHTLS T0007)

The Canada-France-Hawaii Telescope Legacy Survey (CFHTLS) is a high impact scientific program which will see its final official release open to the world in 2012. That release will seal the legacy aspect of the survey which has already produced a large collection of scientific articles with topics ranging from cosmology to the Solar system. The survey core science was focused on dark energy and dark matter: the full realization of the scientific potential of the data set gathered between 2003 and 2009 with the MegaCam wide-field imager mounted at the CFHT prime focus is almost complete with the Supernovae Legacy Survey (SNLS) team preparing its third and last release (SNLS5), and the CFHTLenS team planning the release based around the cosmic shear survey later this year. While the data processing center TERAPIX offered to the CFHTLS scientific community regular releases over the course of the survey in its data acquisition phase (T0001-T0006), the final release took three years to refine in order to produce a pristine data collection photometrically calibrated at better than the percent both internally and externally over the total survey surface of 155 square degrees in all five photometric bands (u*, g', r', i', z'). This final release, called T0007, benefits from the various advances in photometric calibration MegaCam has benefited through the joint effort between SNLS and CFHT to calibrate MegaCam at levels unexplored for an optical wide-field imager. T0007 stacks and catalogs produced by TERAPIX will be made available to the world at CADC while the CDS will offer a full integration of the release in its VO tools from VizieR to Aladin. The photometric redshifts have been produced to be released in phase with the survey. This proceeding is a general introduction to the survey and aims at presenting its final release in broad terms.Peer reviewed: YesNRC publication: Ye

Maunakea spectroscopic explorer design development from feasibility concept to baseline design

International audienceThe Maunakea Spectroscopic Explorer is designed to be the largest non-ELT optical/NIR astronomical telescope, and will be a fully dedicated facility for multi-object spectroscopy over a broad range of spectral resolutions. The MSE design has progressed from feasibility concept into its current baseline design where the system configuration of main systems such as telescope, enclosure, summit facilities and instrument are fully defined. This paper will describe the engineering development of the main systems, and discuss the trade studies to determine the optimal telescope and multiplexing designs and how their findings are incorporated in the current baseline design

The Detailed Science Case for the Maunakea Spectroscopic Explorer: the Composition and Dynamics of the Faint Universe

210 pages, 91 figures. Exposure draft. Appendices to the Detailed Science Case can be found at http://mse.cfht.hawaii.edu/docs/MSE is an 11.25m aperture observatory with a 1.5 square degree field of view that will be fully dedicated to multi-object spectroscopy. More than 3200 fibres will feed spectrographs operating at low (R ~ 2000 - 3500) and moderate (R ~ 6000) spectral resolution, and approximately 1000 fibers will feed spectrographs operating at high (R ~ 40000) resolution. MSE is designed to enable transformational science in areas as diverse as tomographic mapping of the interstellar and intergalactic media; the in-situ chemical tagging of thick disk and halo stars; connecting galaxies to their large scale structure; measuring the mass functions of cold dark matter sub-halos in galaxy and cluster-scale hosts; reverberation mapping of supermassive black holes in quasars; next generation cosmological surveys using redshift space distortions and peculiar velocities. MSE is an essential follow-up facility to current and next generations of multi-wavelength imaging surveys, including LSST, Gaia, Euclid, WFIRST, PLATO, and the SKA, and is designed to complement and go beyond the science goals of other planned and current spectroscopic capabilities like VISTA/4MOST, WHT/WEAVE, AAT/HERMES and Subaru/PFS. It is an ideal feeder facility for E-ELT, TMT and GMT, and provides the missing link between wide field imaging and small field precision astronomy. MSE is optimized for high throughput, high signal-to-noise observations of the faintest sources in the Universe with high quality calibration and stability being ensured through the dedicated operational mode of the observatory. (abridged