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MOVIES Feasibility Study

Introduction

The Montreal-Ohio-Victoria Echelle Spectrograph (MOVIES) study was led by Alan McConnachie and managed by Les Saddlemyer at the National Research Council of Canada Herzberg. Main collaborators included Ohio State University and the Université de Montréal.   The study began in April 2015 and concluded in October 2015.

Executive Summary [Extracted from the MOVIES final report]

We present Gemini/MOVIES (the Montréal-Ohio-VIctoria Échelle Spectrograph). MOVIES is a broad bandwidth, moderate resolution (R3 - 10K) dual arm optical and near infrared (NIR) échelle spectrograph that simultaneously covers 0.36 - 2.45μm. It is supported by a rapid acquisition camera operating simultaneously in two optical and one NIR bands. MOVIES is designed for obtaining spectra of the faint Universe with high throughput, high efficiency and high reliability. MOVIES uses an optimized, low-risk, design with a minimum number of elements and mechanisms to ensure ease of calibration and high stability on long and short timescales. It will be the "go-to" long slit spectrograph for the follow-up of faint objects from future facilities such as LSST, WFIRST and DESI, and will be a valuable feeder instrument for the ELTs. MOVIES is fundamentally a time-domain spectrograph, a precision spectrophotometer, and a workhorse instrument for the Gemini community.

MOVIES has been developed with reference to several key science cases. The driving, defining science goals for MOVIES are those that take advantage of its ability for time domain science and for precision spectrophotometry. In particular, new science will be enabled through the discovery space that it opens up in the early-stage physics of explosive astrophysical phenomena. The optional inclusion of EMCCDs expands the potential of MOVIES in the time-domain by enabling unprecedented high-cadence spectroscopy of rapidly varying astrophysical targets. The ability of MOVIES to perform highly accurate spectrophotometry means that MOVIES will also be the premier facility for transit spectroscopy and the study of exoplanetary atmospheres at moderate resolutions, without some of the restrictions in target selection that frequently limit this science.

In addition to these defining science goals, reference was made throughout the MOVIES design to a large number of science themes, in particular: 

  • Transients and the time-variable Universe
  • The Outer Solar System
  • Low mass stars
  • Stellar populations
  • Galaxies and massive black holes
  • The high redshift Universe
  • Exoplanet atmospheres

MOVIES is conceived to address these cases by building on the intrinsic strengths of Gemini. An essential and defining characteristic of MOVIES is that it will capitalize on Gemini's "target of opportunity" mode. MOVIES will acquire targets (including starting the acquisition exposure, reading out the images, identifying the target, centering and verifying the object in the slit, switching to guiding mode and starting the science exposure) within 90 seconds. The acquisition and guiding cameras have large fields of view (3 x 3 arcmins) to ensure good sky coverage, to facilitate precise astrometry, and to enable blind acquisition when necessary. Two optical and one near-infrared acquisition images are obtained simultaneously, to easily acquire targets with an unknown spectral distribution. Further, they are designed to be used as simultaneous multi-band imagers to obtain "one-shot color-color diagrams", and they are an important science imaging capability in their own right. We anticipate that the spectrophotometric accuracy of MOVIES enabled by these cameras will be unparalleled among 8-m spectrographs in the 2020s.

MOVIES will be the premier spectrograph on 8 - 10m class facilities for observations of faint objects in the Universe. High throughput is achieved by the dual-arm design, where optimized optics in each arm and high efficiency gratings minimize light loss. The design has been developed to allow for a minimum number of optical elements per arm. Detectors optimized for broad wavelength ranges in the optical and NIR are used with coatings that further enhance their efficiency. For the optical arm, we further present an option of using a large format electron multiplying CCD as the primary science detector; when used in EM-mode (large gain), these detectors allow for a very significant increase in observing efficiency obtained relative to normal CCDs for faint targets. Further, zero read noise in these detectors gives the option of temporal and spectral binning postprocessing at potentially extremely high (hertz) cadence, opening up a new domain of high cadence optical spectroscopy for energetic, variable and/or transient observations.

MOVIES will capitalize on the NIR optimization of the Gemini telescopes. In addition to throughput, low emissivity and excellent sky subtraction are critically important for observing faint targets in the red. The latter is achieved by mounting at Cass and using a 10 arcsec slit (greatly preferred to fibre-fed designs). The former is achieved by careful design choices and benefits from Gemini's low-emissivity design. The NIR will assume new importance in the 2020s with the advent of the ELTs, JWST, Euclid and WFIRST, all requiring support from existing facilities. Here, MOVIES will occupy a critical role.

Our team is a collaboration of three Gemini-partner institutes with extensive experience in the design, build and integration of complex astronomical instruments, including near infrared and cryogenic system. The resulting collaboration has depth and strength in all necessary disciplines required to deliver a premier spectrograph to the community, from the science, to optics, mechanics, electrical, software, detectors, to the systems engineering and project management. MOVIES is a low risk instrument building on an extensive "tried-and-tested" design heritage. We have developed the science cases in tandem with the opto-mechanical, electrical, software and operational concepts, producing a clear flowdown from science requirements. This has allowed us to develop an understanding of the cost-complexity-science-schedule trade-offs, ensuring adoption of suitable risk-mitigation strategies where necessary.

The international suite of premier astronomical facilities is changing rapidly with the advent of many new and large facilities. Gemini can occupy a unique position within this new paradigm as the preferred follow-up telescope for faint targets at optical and NIR wavelengths. MOVIES is positioned to be a critical component of the future Gemini instrumentation suite, by providing a unique set of capabilities that enables a vast range of science, extends existing Gemini capabilities, and complements future astronomical facilities.

Deliverables

The MOVIES Deliverable are available to download: 

Contact Information

For more information of the MOVIES study, please contact the Principal Investigator:
Alan McConnachie:          alan.mcconnachie@nrc-cnrc.gc.ca

For more information about GIFS or Gen4#3, please contact the Gemini Instrumentation Program Manager:

Stephen Goodsell:            sgoodsell@gemini.edu 

Please visit the Gen 4#3 home page for the latest information.