The Magdalena Ridge Observatory Interferometer (MROI) has been under development for almost two decades. Initial funding for the facility started before the year 2000 under the Army and then Navy, and continues today through the Air Force Research Laboratory. With a projected total cost of substantially less than $200M, it represents the least expensive way to produce sub-milliarcsecond optical/near-infrared images that the astronomical community could invest in during the modern era, as compared, for instance, to extremely large telescopes or space interferometers. The MROI, when completed, will be comprised of 10 x1.4m diameter telescopes distributed on a Y-shaped array such that it will have access to spatial scales ranging from about 40 milliarcseconds down to less than 0.5 milliarcseconds. While this type of resolution is not unprecedented in the astronomical community, the ability to track fringes on and produce images of complex targets approximately 5 magnitudes fainter than is done today represents a substantial step forward. All this will be accomplished using a variety of approaches detailed in several papers from our team over the years. Together, these two factors, multiple telescopes deployed over very long-baselines coupled with fainter limiting magnitudes, will allow MROI to conduct science on a wide range and statistically meaningful samples of targets. These include pulsating and rapidly rotating stars, mass-loss via accretion and mass-transfer in interacting systems, and the highly-active environments surrounding black holes at the centers of more than 100 external galaxies. This represents a subsample of what is sure to be a tremendous and serendipitous list of science cases as we move ahead into the era of new space telescopes and synoptic surveys. Additional investigations into imaging man-made objects will be undertaken, which are of particular interest to the defense and space-industry communities as more human endeavors are moved into the space environment.<p> </p> In 2016 the first MROI telescope was delivered and deployed at Magdalena Ridge in the maintenance facility. Having undergone initial check-out and fitting the system with optics and a fast tip-tilt system, we eagerly anticipate installing the telescope enclosure in 2018. The telescope and enclosure will be integrated at the facility and moved to the center of the interferometric array by late summer of 2018 with a demonstration of the performance of an entire beamline from telescope to beam combiner table shortly thereafter. At this point, deploying two more telescopes and demonstrating fringe-tracking, bootstrapping and limiting magnitudes for the facility will prove the full promise of MROI. A complete status update of all subsystems follows in the paper, as well as discussions of potential collaborative initiatives.
We present the design of the HARPS3 software system – a distributed, event-driven control system for robotic operation of the HARPS3 spectrograph at the Isaac Newton Telescope (INT). We also describe our approach to integrating the control software components incrementally at various stages of development, using a simulation framework. HARPS3 will be a high resolution (R = 115, 000) echelle spectrograph operating at wavelengths from 380 nm to 690 nm, with a design based on the successful HARPS and HARPS-N instruments. It is being built as part of the Terra Hunting Experiment (THE) – a planned 10 year radial velocity measurement programme to discover Earth-like exoplanets around Sun-like stars.
The Magdalena Ridge Observatory Interferometer (MROI) software system contains distributed systems managed by a centralized Supervisory System. Interface software is generated from spreadsheets that describe commands, monitor points, and fault conditions for each subsystem. The Supervisory System consists of an Executive, Operator, Database Manager; one or more Supervisors plus Fault Manager, and Data Collectors. System-wide simulations are discussed: (1) a test framework is generated from the spreadsheets characterizing a subsystem; (2) a detailed simulation of the actual hardware in a subsystem; (3) a system-wide simulation of collecting astronomical data based on executing observing projects. The first two levels have been implemented.
We present a description of a new instrument development, HARPS3, planned to be installed on an upgraded and roboticized Isaac Newton Telescope by end-2018. HARPS3 will be a high resolution (R≃115,000) echelle spectrograph with a wavelength range from 380-690 nm. It is being built as part of the Terra Hunting Experiment - a future 10- year radial velocity measurement programme to discover Earth-like exoplanets. The instrument design is based on the successful HARPS spectrograph on the 3.6m ESO telescope and HARPS-N on the TNG telescope. The main changes to the design in HARPS3 will be: a customised fibre adapter at the Cassegrain focus providing a stabilised beam feed and on-sky fibre diameter ≈1:4 arcsec, the implementation of a new continuous ow cryostat to keep the CCD temperature very stable, detailed characterisation of the HARPS3 CCD to map the effective pixel positions and thus provide an improved accuracy wavelength solution, an optimised integrated polarimeter and the instrument integrated into a robotic operation. The robotic operation will optimise our programme which requires our target stars to be measured on a nightly basis. We present an overview of the entire project, including a description of our anticipated robotic operation.
The Magdalena Ridge Observatory Interferometer (MROI) was the most ambitious infrared interferometric facility conceived of in 2003 when funding began. Today, despite having suffered some financial short-falls, it is still one of the most ambitious interferometric imaging facilities ever designed. With an innovative approach to attaining the original goal of fringe tracking to H = 14<sup>th</sup> magnitude via completely redesigned mobile telescopes, and a unique approach to the beam train and delay lines, the MROI will be able to image faint and complex objects with milliarcsecond resolutions for a fraction of the cost of giant telescopes or space-based facilities. The design goals of MROI have been optimized for studying stellar astrophysical processes such as mass loss and mass transfer, the formation and evolution of YSOs and their disks, and the environs of nearby AGN.<p> </p> The global needs for Space Situational Awareness (SSA) have moved to the forefront in many communities as Space becomes a more integral part of a national security portfolio. These needs drive imaging capabilities ultimately to a few tens of centimeter resolution at geosynchronous orbits. Any array capable of producing images on faint and complex geosynchronous objects in just a few hours will be outstanding not only as an astrophysical tool, but also for these types of SSA missions. With the recent infusion of new funding from the Air Force Research Lab (AFRL) in Albuquerque, NM, MROI will be able to attain first light, first fringes, and demonstrate bootstrapping with three telescopes by 2020.<p> </p> MROI’s current status along with a sketch of our activities over the coming 5 years will be presented, as well as clear opportunities to collaborate on various aspects of the facility as it comes online. Further funding is actively being sought to accelerate the capability of the array for interferometric imaging on a short time-scale so as to achieve the original goals of this ambitious facility
The advent of low-dark-current eAPD arrays in the near infrared ushers in the possibility for photon-counting, high quantum efficiency detectors at these wavelengths. Such detectors would revolutionise the sensitivity of interferometry because near-infrared wavelengths are at the "sweet spot" between the corrupting effects of atmospheric seeing at shorter wavelengths and thermal noise at longer wavelengths. We report on laboratory experiments with cooled Selex Saphira detectors aimed at demonstrating photon-counting performance with these devices by exploiting enhanced avalanche gain and multiple non-destructive readouts. We explain the optimum modes for employing these detectors in interferometry.
The Magdalena Ridge Observatory Interferometer has been designed to be a 10 × 1.4 m aperture long-baseline optical/near-infrared interferometer in an equilateral "Y" configuration, and is being deployed west of Socorro, NM on the Magdalena Ridge. Unfortunately, first light for the facility has been delayed due to the current difficult funding regime, but during the past two years we have made substantial progress on many of the key subsystems for the array. The design of all these subsystems is largely complete, and laboratory assembly and testing, and the installation and site acceptance testing of key components on the Ridge are now underway. This paper serves as an overview and update on the facility's present status and changes since 2012, and the plans for future activities and eventual operations of the facilities.
The loop is closed on ICONN, the Magdalena Ridge Observatory Interferometer fringe tracker. Results from laboratory experiments demonstrating ICONN's ability to track realistic, atmospheric-like path difference perturbations in real-time are shown. Characterizing and understanding the behavior and limits of ICONN in a controlled environment are key for reaching the goals of the MROI. The limiting factors in the experiments were found to be the light delivery system and temporary path length correction mechanism; not the on-sky components of ICONN. ICONN was capable of tracking fringes with a coherence loss below 5%; this will only improve in its final deployment.
The fast tip-tilt (FTT) correction system for the Magdalena Ridge Observatory Interferometer (MROI) is being developed by the University of Cambridge. The design incorporates an EMCCD camera protected by a thermal enclosure, optical mounts with passive thermal compensation, and control software running under Xenomai real-time Linux. The complete FTT system is now undergoing laboratory testing prior to being installed on the first MROI unit telescope in the fall of 2014. We are following a twin-track approach to testing the closed-loop performance: tracking tip-tilt perturbations introduced by an actuated flat mirror in the laboratory, and undertaking end-to-end simulations that incorporate realistic higher-order atmospheric perturbations. We report test results that demonstrate (a) the high stability of the entire opto-mechanical system, realized with a completely passive design; and (b) the fast tip-tilt correction performance and limiting sensitivity. Our preliminary results in both areas are close to those needed to realise the ambitious stability and sensitivity goals of the MROI which aims to match the performance of current natural guide star adaptive optics systems.
The Magdalena Ridge Observatory Interferometer has been designed to be a 10 x 1.4 m aperture long-baseline
optical/near-infrared interferometer in an equilateral "Y" configuration, and is being deployed west of Socorro, NM on
the Magdalena Ridge. Unfortunately, first light for the facility has been delayed due to the current difficult funding
regime, but during the past two years we have made substantial progress on many of the key subsystems for the array.
The design of all these subsystems is largely complete, and laboratory assembly and testing, and the installation of many of its components on the Ridge are now underway. This paper serves as an overview and update on the facility's present status, and the plans for future funding and eventual operations of the facilities.
The characterization of ICoNN, the Magdalena Ridge Observatory Interferometer's fringe tracker, through labor tory simulations is presented. The performance limits of an interferometer are set by its ability to keep the optical path difference between combination partners minimized. This is the job of the fringe tracker. Understanding the behavior and limits of the fringe tracker in a controlled environment is key to maximize the science output. This is being done with laboratory simulations of on-sky fringe tracking, termed the closed-loop fringe experi ment. The closed-loop fringe experiment includes synthesizing a white light source and atmospheric piston with estimation of the tracking error being fed back to mock delay lines in real-time. We report here on the progress of the closed-loop fringe experiment detailing its design, layout, controls and software.
The fast tip-tilt correction system for the Magdalena Ridge Observatory Interferometer (MROI) is being designed and fabricated by the University of Cambridge. The design of the system is currently at an advanced stage and the performance of its critical subsystems has been verified in the laboratory. The system has been designed to meet a demanding set of specifications including satisfying all performance requirements in ambient temperatures down to -5 °C, maintaining the stability of the tip-tilt fiducial over a 5 °C temperature change without recourse to an optical reference, and a target acquisition mode with a 60” field-of-view. We describe the important technical features of the system, which uses an Andor electron-multiplying CCD camera protected by a thermal enclosure, a transmissive optical system with mounts incorporating passive thermal compensation, and custom control software running under Xenomai real-time Linux. We also report results from laboratory tests that demonstrate (a) the high stability of the custom optic mounts and (b) the low readout and compute latencies that will allow us to achieve a 40 Hz closed-loop bandwidth on bright targets.
The delay lines for the Magdalena Ridge Observatory Interferometer in New Mexico are required to provide up to 380m
optical path delay with an OPD jitter of better than 15nm, in vacuum, using a single adjustable stroke. In order to meet
these demanding requirements in a cost-effective manner a unique combination of techniques has been used in the design
and construction of the delay line trolley which operates continuously within 190m of evacuated pipe. These features
include contactless delivery of power and control signals, active control of the cat's eye optics and the use of composite
materials to achieve good thermal stability. A full-size prototype trolley has been built and fully tested and the first
production trolley is under construction. We describe the system's key design features and review the construction and
alignment of the delay line trolley. Results obtained with the trolley operating in an evacuated 20m-long test rig under
the full range of conditions required for successful astronomical observations are presented. An OPD jitter of typically
10nm is achieved over the total tracking velocity range from 0 to 15mm/s.
The Magdalena Ridge Observatory Interferometer is a 10 x 1.4 meter aperture long baseline optical and near-infrared
interferometer being built at 3,200 meters altitude on Magdalena Ridge, west of Socorro, NM. The interferometer layout
is an equilateral "Y" configuration to complement our key science mission, which is centered on imaging faint and
complex astrophysical targets. This paper serves as an overview and update on the status of the observatory and our
progress towards first light and first fringes in 2012.
The delay lines for the Magdalena Ridge Observatory Interferometer (MROI) will provide remote control of
optical delays of up to 380m with sub-wavelength precision in vacuum. The delay-line prototype is now fully
functional, all features having been demonstrated in a 20m long evacuated test rig. We describe the architecture,
design and performance of the delay line software: this features distributed real-time control and flexible remote
logging of diagnostic data from the delay line hardware components at up to 5 kHz.
We report on test results on the delay line system for the MRO Interferometer, currently under construction
in Cambridge, UK. The delay lines are designed to provide 380 metres of vacuum path delay in a single stage,
offering rapid star-to-star slews, high throughput and high transmitted wavefront quality. Details of the final
design adopted for these delay lines are presented, together with lessons learnt from successful performance tests
of the full-scale prototype trolley in a 20-metre long vacuum test rig. Delivery of the first production trolley is
expected in New Mexico in early 2009.
The Magdalena Ridge Observatory Interferometer is a 10-element 1.4 meter aperture optical and near-infrared
interferometer being built at 3,200 meters altitude on Magdalena Ridge, west of Socorro, NM. The
interferometer layout is an equilateral "Y" configuration to complement our key science mission, which is
centered around imaging faint and complex astrophysical targets. This paper serves as an overview and
update on the status of the observatory and our progress towards first light and first fringes in the next few
The delay lines currently under development for the MRO Interferometer will provide up to 380m of optical delay
with only 3 reflections. We describe the novel aspects of the delay line design which include using the inside walls
of the vacuum pipes as "rails", active shear compensation, and replacing dragged cables with contactless power
transfer and communication. We describe the results of tests of various of these design concepts, and progress
on the design and construction of the prototype trolley.
We present an outline of the automated alignment system for the 350m baseline Magdalena Ridge Observatory
Interferometer (MROI) which will manage the simultaneous alignment of its six principal optical subsystems
(telescopes, beam relay trains, delay lines, beam reducing telescopes, switchyards, and beam combiners). Many of these
components will be held under vacuum, will be subject to varying thermal loads and will use different coatings
(optimized for either optical or near-IR wavelengths). We review the proposed architecture of our scheme and discuss
the procedures, tools, and optical analyses we have used to design it.
We present a summary of activity at the Cambridge Optical Aperture Synthesis Telescope (COAST) group
during the period 2004-2006. Our main program has focused on technical design and prototyping for future
facility arrays such as the VLTI and Magdalena Ridge Observatory Interferometer, but with a small parallel
effort of focused astronomical observations with COAST, in particular multi-wavelength studies of supergiants.
We report on progress on these and other technical areas over the past 2 years.
Accurate knowledge of the spatial and temporal seeing has become increasingly important as AO systems move from being specialised instruments to standard equipment at large ground-based telescopes. While monitors that measure the spatial seeing scale are now commonplace, devices capable of measuring temporal seeing parameters are much rarer since the sampling requirements are severe. Nevertheless, such information is vital if the bandwidth and control requirements for active and adaptive systems at state-of-the-art telescopes and optical/IR interferometers are to be correctly specified. In this paper we describe a cheap, yet robust, Differential Image Motion Monitor Which Is Transportable (DIMMWIT) that can make both spatial and temporal seeing measurements. It samples starlight at rates up to 500Hz but contains no mechanical parts and uses only technology available to amateur astronomers. We review the design and performance of the device and present examples of results from routine use at the Cambridge Optical Aperture Synthesis Telescope (COAST) site in the UK. An identical system is also being tested at the Magdalena Ridge Optical Interferometer (MROI) site in New Mexico.
The DIMMWIT (Differential Image Motion Monitor, Which Is Transportable) is a portable DIMM that can measure the Fried
parameter r<sub>0</sub> and the average wind speed of the turbulent layers. Analysing DIMM images to calculate r<sub>0</sub> is a standard procedure, but wind speeds have rarely been calculated from differential image motion before. Here, we describe how wind speeds can be derived from either differential image motion power spectra or differential image velocities. The DIMMWIT wind speeds are then compared with a wind speed derived from the coherence times, t<sub>0</sub>, of interferometric fringes recorded simultaneously at COAST (Cambridge Optical Aperture Synthesis Telescope). Although t<sub>0</sub>, and hence the wind speed, is routinely measured by the interferometer at the COAST site, the Fried parameter had not been studied. The results of seeing campaigns at COAST and MROI (Magdalena Ridge Observatory Interferometer) are presented, along with a comparison of DIMMWIT r<sub>0</sub> measurements with the FWHM of long exposure images recorded at the same time.
We present a summary of the activity of the Cambridge Optical Aperture
Synthesis Telescope (COAST) team and review progress on the
astronomical and technical projects we have been working on in the
period 2002--2004. Our current focus has now moved from operating
COAST as an astronomical instrument towards its use as a test-bed for
strategic technical development for future facility arrays. We have
continued to develop a collaboration with the Magdalena Ridge
Observatory Interferometer, and we summarise the programmes we expect
to be working on over the next few years for that ambitious
project. In parallel, we are investigating a number of areas for the
European Very Large Telescope Interferometer and these are outlined
The astronomical site parameters for the Magdalena Ridge Observatory (MRO) are being studied from numerous aspects including meteorological, environmental, seismic and sky quality (e.g. "seeing", cloud cover). Results to date indicate that MRO is an excellent site for astronomical observing. Seeing measurements of less that 1 arc second in the optical are routinely obtained. Seismic conditions on the mountain ridge are below levels that will cause any major problems for construction and operation of an optical interferometer. Nighttime "allsky" camera imagery indicates a large percentage of clear nights.
We present a summary of the status of the Cambridge Optical Aperture
Synthesis Telescope, and review developments at the array through the
period 2000-2002. Summaries of the astronomical and technical
programmes completed, together with an outline of those that are
currently in progress are presented. Since our last report two years
ago in 2000, there have been significant changes in the context for
astronomical interferometry in the UK. We review these developments,
and describe our plans for the near and intermediate term at COAST,
and with colleagues in Europe at the VLTI and in the USA at the
Magdalena Ridge Observatory in New Mexico.
The Cambridge DIMMWIT was developed for the site of COAST (the Cambridge Optical Aperture Synthesis Telescope), a prototype optical interferometer. Unlike other differential image motion monitors, this design is portable in order to carry out seeing campaigns at the site of any optical inteferometer. Of particular interest is the site of a second-generation interferometer proposed by the MRO (Magdalena Ridge Observatory) consortium. The DIMMWIT design
has two objectives: to measure the Fried parameter <i>r</i><sub>0</sub> and the speckle lifetime tau<sub>0</sub>, and to be easily transportable. Here, we outline the theory of differential image motion, the design of the DIMMWIT, describe how turbulence parameters can be measured with COAST, and compare measurements of the seeing conditions made simultaneously by the monitor and COAST.
The Sydney University Stellar Interferometer (SUSI) is a long baseline optical interferometer located at the Paul Wild Observatory in northern New South Wales, some 400 km NNW of Sydney. An extensive observational and development program is in progress. The status of the observational program, data reduction techniques, and recent results are reported. Instrumental developments including the development and installation of new tip-tilt mirrors and the design and implementation of a red beam-combination system that includes a group-delay tracker will be described. Auxiliary instrumentation to provide complementary data for the interpretation of SUSI observations has been installed alongside SUSI and this will be outlined briefly.