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During his 1869 expedition down the Green River and through the Grand Canyon, Major John Powell made astronomical observations using a sextant and artificial horizon to fix the locations of key points along the rivers that were only poorly known at the time. Latitude was obtained from the altitude of Polaris or meridian transits of stars or Saturn. Local mean time was determined from equal altitude observations of the Sun. The swamping of one of the expedition's small boats ruined the chronometers, meaning that they could not be used to keep Greenwich mean time and hence find longitude. As a substitute a series of lunar distance observations were undertaken. In this paper observations recorded in Powell's journal are reduced and analysed.

The pulsar is a highly magnetized rotating neutron star that provides the first indirect evidence for the existence of gravitational waves and also provides the possibility to reveal extreme phenomena in neutron star astrophysics. Therefore, the identification of pulsars in the universe is a prerequisite for the study of pulsars and gravitational waves. At present, a large number of pulsar searches have produced millions of pulsar candidates. In the face of these large-scale data, if only relying on manual visual classification by experts in related fields, it will be a huge project. Since the emergence of machine learning, its theory and technology have become increasingly mature, and has been successfully applied to astronomical research fields such as pulsar candidate screening. This paper introduces the related machine learning theory of pulsar candidate recognition firstly, and then reviews the research status of pulsar candidate recognition based on machine learning in recent years. Finally, we discuss and prospect the identification of pulsars in the future.

BeiDou navigation satellite System (BDS), was the dedicated Chinese Global Navigation Satellite Systems (GNSS). The satellites in the BDS constellation can be tracked by many Satellite Laser Range (SLR) stations, making use of the onboard Laser Retro-reflector Array (LRA). Additionally, some of BDS satellites were also equipped with Laser Time Transfer (LTT) payloads. The measuring data from these instruments provided highly accurate estimations of satellites orbit, and time comparison between satellites and ground clocks.The performance of the BDS LRA and LTT payloads designed by Shanghai Astronomical Observatory (SHAO) were presented, as well as the SLR systems with a one meter-aperture telescope, which provided the ranging precision of centimeter levels for daylight ranging to BDS satellites at the synchronous orbit. For the first time, high precise LTT measurements at the synchronous orbit satellites were performed by the SHAO. The LTT data processing and analysis were presented with the time stability of 20ps at 500s, and a relative frequency stability of 10E-14.The further developments and improvements of Chinese LTT technology were also discussed. Global SLR tracking of BDS satellites were performed by the International Laser Ranging Service, providing accurate range data with global coverage. By using laser data, the accuracy of BDS satellite orbit and broadcast ephemeris were evaluated and the orbit error of BDS satellites was achieved at the meter level.

We describe the performance of the Boolardy Engineering Test Array (BETA), the prototype for the Australian Square Kilometre Array Pathfinder telescope ASKAP. BETA is the first aperture synthesis radio telescope to use phased array feed technology, giving it the ability to electronically form up to nine dual-polarization beams. We report the methods developed for forming and measuring the beams, and the adaptations that have been made to the traditional calibration and imaging procedures in order to allow BETA to function as a multi-beam aperture synthesis telescope. We describe the commissioning of the instrument and present details of BETA's performance: sensitivity, beam characteristics, polarimetric properties and image quality. We summarise the astronomical science that it has produced and draw lessons from operating BETA that will be relevant to the commissioning and operation of the final ASKAP telescope., Accepted for publication in PASA

After eight observing Cycles, the Atacama Large Millimeter-submillimeter Array (ALMA) is capable of observing in eight different bands (covering a frequency range from 84 to 950 GHz), with 66 antennas and two correlators. For the current Cycle (7), ALMA offers up to 4300 hours for the 12-m array, and 3000 hours on both the 7-m of the Atacama Compact Array (ACA) and TP Array plus 750 hours in a supplemental call. From the customer perspective (i.e., the astronomical community), ALMA is an integrated product service provider, i.e. it observes in service mode, processes and delivers the data obtained. The Data Management Group (DMG) is in charge of the processing, reviewing, and delivery of the ALMA data and consists of approximately 60 experts in data reduction, from the ALMA Regional Centers (ARCs) and the Joint ALMA Observatory (JAO), distributed in fourteen countries. Prior to their delivery, the ALMA data products go through a thorough quality assurance (QA) process, so that the astronomers can work on their science without the need of significant additional calibration re-processing. Currently, around 90% of the acquired data is processed with the ALMA pipeline (the so called pipeline-able data), while the remaining 10% is processed completely manually. The Level-1 Key Performance Indicator set by the Observatory to DMG is that 90% of the pipeline-able data sets (i.e. some 80% of the data sets observed during an observing cycle) must be processed, reviewed and delivered within 30 days of data acquisition. This paper describes the methodology followed by the JAO in order to process near 80% of the total data observed during Cycle 7, a giant leap with respect to approximately 30% in Cycle 4 (October 2016 - September 2017)., 18 pages, 11 figures, SPIE conference on Astronomical Telescopes and Instrumentation

This work presents a workflow for simulating and processing the full-scale low-frequency telescope data of the Square Kilometre Array (SKA) Phase 1. The SKA project will enter the construction phase soon, and once completed, it will be the world’s largest radio telescope and one of the world’s largest data generators. The authors used Summit to mimic an endto-end SKA workflow, simulating a dataset of a typical 6 hour observation and then processing that dataset with an imaging pipeline. This workflow was deployed and run on 4,560 compute nodes, and used 27,360 GPUs to generate 2.6 PB of data. This was the first time that radio astronomical data were processed at this scale. Results show that the workflow has the capability to process one of the key SKA science cases, an Epoch of Reionization observation. This analysis also helps reveal critical design factors for the next-generation radio telescopes and the required dedicated processing facilities.

Pagodas are common historical structures in China and some other Asian countries. Symmetries of the pagodas play an important role on cultural and structural aspects. In this paper, we proposed a method estimating the central axis of a typical ancient pagoda in China for examination of its symmetry. We developed a novel geometric model to fit to the point cloud of the pagoda obtained from photogrammetric reconstruction based on UAV imagery. More specifically, we developed a novel geometric model possessing 16 parameters to fit to the point cloud of different parts of the pagodas simultaneously to estimate a central axis for the symmetry. The results show that the proposed model is superior to the conventional cylindrical models for the central axis estimation. More importantly, the estimated parameters are in realistic ranges, as well as the reconstructed central axis and the sextant number are well visualized, so the symmetry of the pagodas can be readily analysed.

The basis of all recommended methods for obtaining position by using celestial bodies is the known altitude of the celestial body being observed. Accordingly, it is necessary to have a sextant, classic or with an artificial horizon, or some other device that can measure altitude. However, there is a way to obtain position using astronomical navigation without determining the altitude of a celestial body, and this method will be analysed in this paper. The introduced method requires only precise measurement of the azimuth, and is based on determining two positions close to the dead reckoning position and lying on the isoazimuthal curve, i.e. a curve of the same great circle azimuths of a celestial body. Furthermore, the model assumes that a part of this curve, between the selected positions, can be replaced by a straight line. Special attention will be given to the analysis of errors of the line of position for various azimuth errors and various dead reckoning (assumed) positions. It will also be shown how a modern Electronic Chart Display and Information System (ECDIS) can help in approximate position determination, knowing only the azimuths of celestial bodies.

Very-long baseline interferometry (VLBI) allows for exceptionally high-resolution imaging in radio astronomy. Ultimately the angular resolution of radio interferometers and telescopes is determined by the separation between antennas in the array. Building on this fundamental concept, potential uses of existing spacecraft radio systems for VLBI are explored. Coherent observations performed between ground radio telescopes (GRT) and spacecraft require stringent drift tolerances for timing and synchronization between the GRT and spacecraft. Observed data using the spacecraft antenna is then recorded and stored on-board before downlink. Among candidate spacecraft, a promising contender and focus of this paper is New Horizons. Currently at a distance greater than 45 AU, New Horizons offers an outstanding baseline for astronomical radio observation and provides necessary, configurable instrumentation for performing an extended baseline observation in conjunction with a GRT or other spacecraft. Communications with New Horizons are synchronized with a 30 MHz clock signal using an ultra-stable oscillator (USO), providing an exceptional Allan Deviation of $3\times 10^{-13}$ per one second integration time. Of the instruments on-board New Horizons, the Radio Science Experiment (REX) is of particular interest for its potential towards VLBI application. Developed for atmospheric measurements during occultations between the 7.182 GHz uplink from the 70 meter NASA Deep Space Network (DSN) antenna and Pluto/Charon, REX also successfully performed axial radiometric measurements of the Cygnus-A and Cassiopeia-A galaxies using the New Horizons high-gain antenna (HGA). The REX instrument's infusion with the New Horizons HGA allows for any radio measurement to be recorded, stored on-board, and ultimately to be downlinked to the DSN. For VLBI, New Horizons could receive command data for timed three-dimensional alignment synchronous to a ground-based observation. The observed data would then be recorded, downlinked, correlated, and processed for synthesized imaging. Using New Horizons for VLBI would be a proof-of-concept. With a fixed observation frequency, narrow bandwidth and receiver sensitivity of −177 dBm, New Horizons is limited as an extension for long-baseline radio interferometry. Given these restrictions, a successful VLBI measurement using New Horizons would still result in the highest angular resolution for any radio observation ever, at an astonishing 1.34 nanoarcseconds. Expanding the applications of New Horizons to VLBI observations encourages collaboration within the growing infrastructure for space-based astronomy.

Discovering pairs of related entities based on their spatio-temporal behavior has applications of scientific, commercial, and public interest. For example, inferring relationships between animals based on data collected from tracking devices can help biologists better understand group behavior and family structures; identifying commonalities in customer behavior can enable better targeted marketing; and discovering correlations in the movement patterns of maritime vessels can help crack down on illegal fishing or smuggling activity. However, this task becomes especially challenging when many entities are being observed simultaneously and when observations of different entities are made asynchronously and at different frequencies.We propose SEXTANT, a computational framework for performing spatio-temporal correlation at scale, implemented using efficient data structures over a distributed architecture. SEXTANT’s core capability consists of algorithms that, given a large set of time-stamped and geo-located observations, identify pairs of trajectories with high spatial proximity over time, demonstrating shared pattern-of-life behavior. Experiments on real-world and synthetic datasets demonstrate SEXTANT’s ability to efficiently capture correlated behavior at scale while being robust to asynchronicity, sparsity, and heterogeneity in the data, out-performing existing methods.

Space astronomical telescopes must test the image stabilization accuracy of their image stabilization system prior to entering the orbit. According to the position characteristics of the fine guidance sensor of telescopes required by the China National Space Administration, a simulation model of moving guide stars is proposed in this study to test the image stabilization accuracy of space telescopes. The simulation model for synchronous moving guide stars is based on the principle of mutual collimation of the diagonal field of view of the optical system of telescope. Realize the multi-field moving guide stars with high synchronization accuracy simulated by the same target source. Compared to traditional methods, this method requires simple manufacturing and has high flexibility. The error sources affecting the simulation accuracy of the moving guide stars are analyzed, and an error model is established. Analysis results show that the simulation accuracy of the moving guide stars can reach 0 . 046 ′ ′ . The simulation model of guide stars is verified through experiments in which the influence of the vibration isolation platform is considered. Experiment results show that the simulation accuracy of motion guide stars is 0 . 036 ′ ′ , satisfying the accuracy requirements ( < 0 . 08 ′ ′ ) of the accuracy test for the telescope image stabilization of telescopes.

To increase the spatial resolution while circumventing the problems of increased mass and volume of monolithic telescopes, a Fizeau imaging interferometer testbed (FIIT) with three individual subtelescopes was designed and constructed for high resolution astronomical observation. FIIT is intended to be mounted on a distributed small-satellite constellation with a formation fly configuration; thus the extremely stable pointing of the subtelescopes is the prerequisite for phased imaging, which is because the satellite suffers from some extent of detrimental jitters and drifts needs to be corrected by FIIT itself. FIIT makes use of a shared tip/tilt detection module with a cross-correlation algorithm, three fast-steering mirrors, and closed-loop control technology for pointing correction of three subtelescopes, which can make sure the images are coaligned for a long period of time used to image some faint astronomical objects. This study gives a detailed description of the detection algorithm of image shifts, the hardware design, and data processing flow, followed by closed-loop experiments of a wide-band white light point source. The results of residual errors on the detection camera and the beam-combining camera demonstrate the performance of the pointing correction function, which is a significant milestone for FIIT.

The present work of this research consists of the analysis of telescopic images provided by the International Astronomical Search Collaboration (IASC) to find asteroids that can be named. The concern in searching for asteroids helps the scientific community that promotes the collaboration of young students and astronomy fans get experience in finding asteroids through campaigns related to these. The Space Generation Advisory Council (SGAC) campaign in partnership with IASC has found around 1500 asteroids since the beginning of October 2006 as each year more than 1000 teams from different countries participate. The Astrometrica software was used which is in charge of receiving the images in FITS format. The configuration of the selected telescope is carried out so that they are later analyzed in greater detail. Finally, a clean and precise Minor Planet Center (MPC) report is made, which is what the campaign requires so that it can go on to a preliminary phase and subsequently be accepted by the international astronomical union. The asteroids that become named will be registered in the catalog of official minor planets of the world. In the campaign related to this study, one finds 28 possible asteroids.

It is a NASA Space Science Explorers program under the opportunity mission; it analyzes the electromagnetic, gravitational, and nuclear aspects of pulsars. NICER uses rotation-resolved spectroscopy in thermal and nonthermal emission spectra in the soft X-ray band with good precision and accuracy for detailed analysis of cosmic particle accelerators like in for quarks. It is also be used for X-ray navigation. Its advanced electronics helps it to analyze the data much efficiently (Davis et al. in J Geophys Res Oceans 99(C12):24383–24404) [1].

The ctools open-source software package was developed for the scientific analysis of astronomical data from Imaging Air Cherenkov Telescopes (IACTs), such as H.E.S.S., VERITAS, MAGIC, and the future Cherenkov Telescope Array (CTA). To date, the software has been mainly tested using simulated CTA data; however, upon the public release of a small set of H.E.S.S. observations of the Crab nebula, MSH 15-52, RX J1713.7-3946, and PKS 2155-304 validation using real data is now possible. We analysed the data of the H.E.S.S. public data release using ctools version 1.6 and compared our results to those published by the H.E.S.S. Collaboration for the respective sources. We developed a parametric background model that satisfactorily describes the expected background rate as a function of reconstructed energy and direction for each observation. We used that model, and tested all analysis methods that are supported by ctools, including novel unbinned and joint or stacked binned analyses of the measured event energies and reconstructed directions, and classical On-Off analysis methods that are comparable to those used by the H.E.S.S. Collaboration. For all analysis methods, we found a good agreement between the ctools results and the H.E.S.S. Collaboration publications considering that they are not always directly comparable due to differences in the datatsets and event processing software. We also performed a joint analysis of H.E.S.S. and Fermi-LAT data of the Crab nebula, illustrating the multi-wavelength capacity of ctools. The joint Crab nebula spectrum is compatible with published literature values within the systematic uncertainties. We conclude that the ctools software is mature for the analysis of data from existing IACTs, as well as from the upcoming CTA., Comment: 34 pages, 47 figures

Constitutional representative government, often mistakenly called “democracy”, was one of the greatest inventions of the eighteenth century. It rivals other eighteenth century inventions such as the sextant, the steam engine, the cotton gin, smallpox vaccination—and the guillotine—all of which changed the world in important ways. But all of them also have been superseded by vastly more powerful inventions, while constitutional representative government persists as a strange relic from the past, in more or less the same form, and certainly on the basis of the same mindset from which it originally emerged.

After the discovery of radiation from Galactic Hydrogen gas clouds in 1951, the 21cm wavelength HI line had become the best marker to study spectral profiles in radio astronomy. It has been utilized as an important tracer for the distribution and velocity of molecular gas clouds in the Interstellar that has helped enormously in the understanding of galactic structure. ICT based astronomy and astrophysics tools have been developed for decades for undergraduate level use including radio telescopes controllable over the Internet at minimal cost. These radio telescopes can effectively be used to study galactic structure and dynamics. This paper presents an observation to study galaxy dynamics and map its spiral structure which was carried out between galactic coordinate longitudes 6° to 225° and latitudes 0° to 35° with two low cost 2.3 meters Haystack model type radio frequency receiving systems called SALSA radio telescopes at Onsala Space Observatory in Sweden which is maintained by Chalmers University of Technology. Components of the velocity of Hydrogen gas clouds were calculated using different galactic longitudes and latitudes as a function of galactic distance from the center to plot spiral galactic arms and rotation curves. This radio observational experiment was done by remote operation over the Internet in frequency switching mode. Our project aims to prove the quality and importance of this type of ICT based tools for astronomical education and citizen science.

Observational astronomy is one of the oldest natural science. It involves the study of celestial objects and phenomena occurring outside the Earth's atmosphere. Astronomers use a telescope as a receiver to observe starlight at various frequency bands and investigate the universe. The process of collecting starlight is similar to the transmit-receive techniques employed in wireless communication. In this paper, we present the parallels between wireless communication and observational astronomy and extend the scope of wireless communication to astronomical observation. The new paradigm of wireless communication comprises (i) a remote sidereal star (modeled as the signal source), (ii) the Earth's atmospheric turbulence (modeled as time-varying channels), and (iii) a telescope with a camera behind it (modeled as the receiver). We propose fast algorithms to estimate the astronomical time-varying channels, which are highly potential to compensate for blurred astronomical images obtained due to poor astronomical seeing.

NASA's Neutron star Interior Composition Explorer (NICER) progressed smoothly through its final ground-test activities in 2016 and early 2017, in preparation for a spectacular launch and installation on the International Space Station in June 2017. Activation of the payload and initial calibration of its systems followed, rounding out Phase D, Testing and Commissioning, of the mission's development cycle. We describe the final ground verification measurements of NICER's key performance parameters, such as the X-ray Timing Instrument's photon energy resolution and time-stamping accuracy, as well as in-flight effective collecting area, pointing, background, and other calibration efforts. The payload meets all of its design requirements and is poised to deliver new insights in soft X-ray astrophysics; briefly, we touch on early science returns that showcase NICER's unique capabilities.

Starbugs are miniature piezoelectric walking robots that can be operated in parallel to position many payloads like optical fibers across a telescopes focal plane. They consist of two concentric piezoelectric ceramic tubes that walk with micron step size. In addition to individual optical fibers, Starbugs have moved a payload of 0.75kg at several millimeters per second. The Australian Astronomical Observatory previously developed prototype devices and tested them in the laboratory. Now we are optimizing the Starbug design for production and deployment in the TAIPAN instrument, which will be capable of configuring 300 optical fibers over a six degree field-of-view on the UK Schmidt Telescope within a few minutes. The TAIPAN instrument will demonstrate the technology and capability for MANIFEST (Many Instrument Fiber-System) proposed for the Giant Magellan Telescope. Design is addressing: connector density and voltage limitations, mechanical reliability and construction repeatability, field plate residues and scratching, metrology stability, and facilitation of improved motion in all aspects of the design for later evaluation. Here we present the new design features of the AAO TAIPAN Starbug., 10 Pages

Two micro satellites will be manufactured and launched to the farside of the Moon by piggybacking on the CHANG'E-4 mission to make astronomical super-long wavelength observation, taking the advantage of the excellent electromagnetic environment on the Moon-farside. This paper proposes a highly compact payload system for this purpose, regarding the extreme conditions of limited mass, volume, power and cost. The functional units of the proposed payload system and related key technologies are described in detail. Experimental results verify the functional performance of our design. This project will be part of Chinese first star-star interferometry astronomical observation.

Celestial navigation is an important type of autonomous navigation technology which could be used as an alternative to Global Navigation Satellite Systems (GNSS) when a vessel is at sea. After several centuries of development, a variety of astronomical vessel position (AVP) determination methods have been invented, but the basic concepts of these methods are all based on angular observations with a device such as a sextant, which has disadvantages including low accuracy, manual operation, and a limited period of observation. This paper proposes a new method that utilises a fisheye camera to image the celestial bodies and horizon simultaneously. Then, we calculate the obliquity of the fisheye camera's principal optical axis according to the image coordinates of the horizon. Next, we calculate the altitude of the celestial bodies according to the image coordinates of the celestial bodies and the obliquity. Finally, the AVP is determined by the altitudes according to the robust estimation method. Experimental results indicate that this method not only could realize automation and miniaturization of the AVP determination system, but could also greatly improve the efficiency of celestial navigation.

[Abridged] The Sardinia Radio Telescope (SRT) is the new 64-m dish operated by INAF (Italy). Its active surface will allow us to observe at frequencies of up to 116 GHz. At the moment, three receivers, one per focal position, have been installed and tested. The SRT was officially opened in October 2013, upon completion of its technical commissioning phase. In this paper, we provide an overview of the main science drivers for the SRT, describe the main outcomes from the scientific commissioning of the telescope, and discuss a set of observations demonstrating the SRT's scientific capabilities. One of the main objectives of scientific commissioning was the identification of deficiencies in the instrumentation and/or in the telescope sub-systems for further optimization. As a result, the overall telescope performance has been significantly improved. As part of the scientific commissioning activities, different observing modes were tested and validated, and first astronomical observations were carried out to demonstrate the science capabilities of the SRT. In addition, we developed astronomer-oriented software tools, to support future observers on-site. The astronomical validation activities were prioritized based on technical readiness and scientific impact. The highest priority was to make the SRT available for joint observations as part of European networks. As a result, the SRT started to participate (in shared-risk mode) in EVN (European VLBI Network) and LEAP (Large European Array for Pulsars) observing sessions in early 2014. The validation of single-dish operations for the suite of SRT first light receivers and backends continued in the following years, and was concluded with the first call for shared-risk/early-science observations issued at the end of 2015., 26 pages, 18 figures, accepted for publication in Section 13 'Astronomical instrumentation' of Astronomy & Astrophysics

The Transiting Exoplanet Survey Satellite (TESS) will be conducting a nearly all-sky, photometric survey over the course of two years, with a core mission goal to discover small transiting exoplanets orbiting nearby, bright stars. The satellite will obtain 30-minute cadence observations of all objects in the 26 TESS fields of view and 2-minute cadence observations of 200,000 to 400,000 selected stars. The choice of which stars to observe at the 2-min cadence is driven by the need to detect small, transiting planets, leading to the selection of primarily bright, cool dwarfs. We describe the integration of numerous astronomical catalogs and the algorithms used to assemble the TESS Input Catalog. We have created a preliminary Candidate Target List using a ranking system for all stars in the sky, according to the smallest transiting planet detectable. We also discuss additional factors that affect the ability to photometrically detect and dynamically confirm small planets.

The Stratospheric Observatory For Infrared Astronomy (SOFIA) is a 2.5-m telescope mounted inside of a Boeing 747SP. Planning and executing astronomical observations from an aircraft moving at 500 miles per hour has its own unique challenges and advantages. Scheduling and optimizing an entire year of science observations is a balancing act with target availability, instrument availability, and operational constraints. A SOFIA flight is well choreographed, and successfully executing observations on SOFIA requires many systems and people to work together- from the telescope assembly compensating for the continual vibration and movement of the plane in order to accurately point the telescope, the expertise of the telescope operators to prepare the telescope for use by the instrument operators, aircraft operations ensuring that the aircraft is ready for flight, and the mission systems control computers keeping track of all the data. In this paper we will discuss what it takes to plan a SOFIA flight, and what we do once we’re in the air. We will share a typical science flight, as well as more challenging and unique observations that require SOFIA being in the right place at the right time.

The South African Astronomical Observatory (SAAO) is designing and manufacturing a wide-field camera for use on two of its telescopes. The initial concept was of a Prime focus camera for the 74” telescope, an equatorial design made by Grubb Parsons, where it would employ a 61mmx61mm detector to cover a 23 arcmin diameter field of view. However, while in the design phase, SAAO embarked on the process of acquiring a bespoke 1-metre robotic alt-az telescope with a 43 arcmin field of view, which needs a homegrown instrument suite. The Prime focus camera design was thus adapted for use on either telescope, increasing the detector size to 92mmx92mm. Since the camera will be mounted on the Nasmyth port of the new telescope, it was dubbed WiNCam (Wide-field Nasmyth Camera). This paper describes both WiNCam and the new telescope. Producing an instrument that can be swapped between two very different telescopes poses some unique challenges. At the Nasmyth port of the alt-az telescope there is ample circumferential space, while on the 74 inch the available envelope is constrained by the optical footprint of the secondary, if further obscuration is to be avoided. This forces the design into a cylindrical volume of 600mm diameter x 250mm height. The back focal distance is tightly constrained on the new telescope, shoehorning the shutter, filter unit, guider mechanism, a 10mm thick window and a tip/tilt mechanism for the detector into 100mm depth. The iris shutter and filter wheel planned for prime focus could no longer be accommodated. Instead, a compact shutter with a thickness of less than 20mm has been designed in-house, using a sliding curtain mechanism to cover an aperture of 125mmx125mm, while the filter wheel has been replaced with 2 peripheral filter cartridges (6 filters each) and a gripper to move a filter into the beam. We intend using through-vacuum wall PCB technology across the cryostat vacuum interface, instead of traditional hermetic connector-based wiring. This has advantages in terms of space saving and improved performance. Measures are being taken to minimise the risk of damage during an instrument change. The detector is cooled by a Stirling cooler, which can be disconnected from the cooler unit without risking damage. Each telescope has a dedicated cooler unit into which the coolant hoses of WiNCam will plug. To overcome an inherent drawback of Stirling coolers, an active vibration damper is incorporated. During an instrument change, the autoguider remains on the telescope, and the filter magazines, shutter and detector package are removed as a single unit. The new alt-az telescope, manufactured by APM-Telescopes, is a 1-metre f/8 Ritchey-Chretien with optics by LOMO. The field flattening optics were designed by Darragh O'Donoghue to have high UV throughput and uniform encircled energy over the 100mm diameter field. WiNCam will be mounted on one Nasmyth port, with the second port available for SHOC (Sutherland High-speed Optical Camera) and guest instrumentation. The telescope will be located in Sutherland, where an existing dome is being extensively renovated to accommodate it. Commissioning is planned for the second half of 2016.

The Australian Astronomical Observatory's TAIPAN instrument deploys 150 Starbug robots to position optical fibres to accuracies of 0.3 arcsec, on a 32 cm glass field plate on the focal plane of the 1.2 m UK-Schmidt telescope. This paper describes the software system developed to control and monitor the Starbugs, with particular emphasis on the automated path-finding algorithms, and the metrology software which keeps track of the position and motion of individual Starbugs as they independently move in a crowded field. The software employs a tiered approach to find a collision-free path for every Starbug, from its current position to its target location. This consists of three path-finding stages of increasing complexity and computational cost. For each Starbug a path is attempted using a simple method. If unsuccessful, subsequently more complex (and expensive) methods are tried until a valid path is found or the target is flagged as unreachable., 10 pages, to be published in Proc. SPIE 9913, Software and Cyberinfrastructure for Astronomy IV; 2016

ISDEC-2 - IUCAA1 SIDECAR Drive Electronics Controller is an alternative for Teledyne make JADE2 based controller for HAWAII detectors. It is a ready to use complete package and has been developed keeping in mind general astronomical requirements and widely used observatory set-ups like preferred OS-Linux , multi-extension fits output with fully populated headers (with detector as well as telescope and observation specific information), etc. Actual exposure time is measured for each frame to a few tens of microsecond accuracy and put in the fits header. It also caters to several application specific requirements like fast resets, strip mode, multiple region readout with on board co-adding, etc. ISDEC-2 is designed to work at -40 deg. and is already in use at observatories worldwide. ISDEC-3 is an Artix-7 FPGA based SIDECAR Drive Electronics Controller currently being developed at IUCAA. It will retain all the functionality supported by ISDEC-2 and will also support the operation of H2RG in continuos, fast (32 output, 5 MSPS, 12 bit) mode. It will have a 5 Gbps USB 3.0 PC interface and 1 Gbps Ethernet interface for image data transfer from SIDECAR to host PC. Additionally, the board will have DDR-3 memory for on-board storage and processing. ISDEC-3 will be capable of handling two SIDECARs simultaneously (in sync) for H2RG slow modes.

The Canada-France-Hawaii-Telescope Corporation (CFHT) plans to repurpose its observatory on the summit of Maunakea and operate a (60 segment) 11.25m aperture wide field spectroscopic survey telescope, the Maunakea Spectroscopic Explorer (MSE). The prime focus telescope will be equipped with dedicated instrumentation to take advantage of one of the best sites in the northern hemisphere and offer its users the ability to perform large surveys. Central themes of the development plan are reusing and upgrading wherever possible. MSE will reuse the CFHT site and build upon the existing observatory infrastructure, using the same building and telescope pier as CFHT, while minimizing environmental impact on the summit. MSE will require structural support upgrades to the building to meet the latest building seismic code requirements and accommodate a new larger telescope and upgraded enclosure. It will be necessary to replace the current dome since a larger slit opening is needed for a larger telescope. MSE will use a thermal management system to remove heat generated by loads from the building, flush excess heat from lower levels, and maintain the observing environment temperature. This paper describes the design approach for redeveloping the CFHT facility for MSE. Once the project is completed the new facility will be almost indistinguishable on the outside from the current CFHT observatory. Past experience and lessons learned from CFHT staff and the astronomical community will be used to create a modern, optimized, and transformative scientific data collecting machine.

The Maunakea Laser Traffic Control System (LTCS) has been in use since 2002 providing a mechanism to prevent the laser guide star or Rayleigh scatter from a laser propagated from one telescope from interfering with science observations at any of the other telescopes that share the mountain. LTCS has also been adopted at several other astronomical sites around the world to address that same need. In 2014 the stakeholders on Maunakea began the process of improving LTCS capability to support common observing techniques with enhanced First On Target (FoT) equity. The planned improvements include support for non-sidereal observing, laser checkout at zenith, dynamic field of view size, dithering, collision calculations even when a facility is not laser impacted, multiple alert severity levels, and software refactoring. The design of these improvements was completed in early 2015, and implementation is expected to be completed in 2016. This paper describes the Maunakea LTCS collaboration and the design of these planned improvements.

State-of-the art astronomical facilities are costly to build and operate, hence it is essential that these facilities must be operated as much efficiently as possible, trying to maximize the scientific output and at the same time minimizing overhead times. Over the latest decades the scheduling problem has drawn attention of research because new facilities have been demonstrated that is unfeasible to try to schedule observations manually, due the complexity to satisfy the astronomical and instrumental constraints and the number of scientific proposals to be reviewed and evaluated in near real-time. In addition, the dynamic nature of some constraints make this problem even more difficult. The Atacama Large Millimeter/submillimeter Array (ALMA) is a major collaboration effort between European (ESO), North American (NRAO) and East Asian countries (NAOJ), under operations on the Chilean Chajnantor plateau, at 5.000 meters of altitude. During normal operations at least two independent arrays are available, aiming to achieve different types of science. Since ALMA does not observe in the visible spectrum, observations are not limited to night time only, thus a 24/7 operation with little downtime as possible is expected when full operations state will have been reached. However, during preliminary operations (early-science) ALMA has been operated on tied schedules using around half of the whole day-time to conduct scientific observations. The purpose of this paper is to explain how the observation scheduling and its optimization is done within ALMA, giving details about the problem complexity, its similarities and differences with traditional scheduling problems found in the literature. The paper delves into the current recommendation system implementation and the difficulties found during the road to its deployment in production.

The Mid-resolution InfRAreD Astronomical Spectrograph (MIRADAS) is a near-infrared multi-object echelle spectrograph for the 10.4-meter Gran Telescopio Canarias. The instrument has 12 pickoff mirror optics on cryogenic probe arms, enabling it to concurrently observe up to 12 user-defined objects located in its field-of-view. In this paper, a method to compute collision-free trajectories for the arms of MIRADAS is presented. We propose a sequential approach that has two stages: target to arm assignment and motion planning. For the former, we present a model based on linear programming that allocates targets according to their associated priorities. The model is constrained by two matrices specifying the targets’ reachability and the incompatibilities among each pair of feasible target-arm pairs. This model has been implemented and experiments show that it is able to determine assignments in less than a second. Regarding the second step, we present a prioritized approach which uses sampled-based roadmaps containing a variety of paths. The motions along a given path are coordinated with the help of a depth-first search algorithm. Paths are sequentially explored according to how promising they are and those not leading to a solution are skipped. This motion planning approach has been implemented considering real probe arm geometries and joint velocities. Experimental results show that the method achieves good performance in scenarios presenting two different types of conflicts.

The Large Millimeter Telescope/Gran Telescopio Milimetrico (LMT/GTM) is a bi-national project between INAOE in Mexico and UMASS in the USA. It is an open air radio telescope designed for astronomical observations in wavelengths ranging from 0.85 mm to 4 mm. Its 50-meter diameter primary reflector is so massive that its shape deviates from the theoretical parabola due to gravitational effect as it moves in elevation, which ultimately affects gain, one of the most important features of the telescope. To correct this elevation-dependent deformation, the primary surface is divided into 180 segments that are automatically positioned by means of four electro mechanical actuators. Unfortunately, the lifetime expectancy of the interim actuators installed in rings 1 to 3 during 2013, are below specs and the cost of substituting them with the new actuators, now under development for rings 4 and 5, may not be affordable. In this paper an alternative actuator control system that re uses most of the current electronics coupled to a completely redesigned mechanism is presented. The results of the performance tests under load show that the system is capable of achieving positioning with RMS error of 4 micron and that the accuracy is dominated by the LVDT characterization error.

The Giant Magellan Telescope (GMT) primary mirror consists of seven 8.4 m light-weight honeycomb mirrors that are being manufactured at the Richard F. Caris Mirror Lab (RFCML), University of Arizona. In order to manufacture the largest and most aspheric astronomical mirrors various high precision fabrication technologies have been developed, researched and implemented at the RFCML. The unique 8.4 m (in mirror diameter) capacity fabrication facilities are fully equipped with large optical generator (LOG), large polishing machine (LPM), stressed lap, rigid conformal lap (RC lap) and their process simulation/optimization intelligence called MATRIX. While the core capability and key manufacturing technologies have been well demonstrated by completing the first GMT off-axis segment, there have been significant hardware and software level improvements in order to improve and enhance the GMT primary mirror manufacturing efficiency. The new and improved manufacturing technology plays a key role to realize GMT, the next generation extremely large telescope enabling new science and discoveries, with high fabrication efficiency and confidence.

The Daniel K. Inouye Solar Telescope (DKIST), currently under construction on Haleakalā, in Maui, Hawai'i will be the largest solar telescope in the world and will use adaptive optics to provide the highest resolution view of the Sun to date. It is expected that DKIST data will enable significant and transformative discoveries that will dramatically increase our understanding of the Sun and its effects on the Sun-Earth environment. As a result of this, it is a priority of the DKIST Data Center team at the National Solar Observatory (NSO) to be able to deliver timely and accurately calibrated data to the astronomical community for further analysis. This will require a process which allows the Data Center to develop calibration pipelines for all of the facility instruments, taking advantage of similarities between them, as well as similarities to current generation instruments. There will also be a challenges which are addressed in this article, such as the large volume of data expected, and the importance of supporting both manual and automated calibrations. This paper will detail the current calibration development strategies being used by the Data Center team at the National Solar Observatory to manage this calibration effort, so as to ensure delivery of high quality scientific data routinely to users.

A space-qualified fast steering mirror (SQ-FSM) was designed, built, and tested at the National Astronomical Observatories of the Chinese Academy of Sciences for an image stabilization system of space astronomical telescopes, which is used for the tip-tilt correction of small jitter of the satellite platform; this achieved image stability in a closed-loop manner. Its design primarily faces four challenges involving (1) sustaining the specified sine and random vibration without launch lock, as well as shock response spectrum experiments; (2) surface form error of a clear aperture of ϕ120 mm less than 1/50λ root mean square (RMS, λ=632.8 nm) with a relatively rigid mirror support; (3) resonance frequency of at least 800 Hz and as high as possible; (4) minimum reaction force and torque in order to decrease its unfavorable influence on the satellite platform. To achieve these goals, the global optimizations and compromises have to be made throughout the design process. The study reviews the detailed design of the SQ-FSM with respect to the four challenges, mainly by keeping the mirror and its support lightweight, mirror bonding and solidification, actuator and its stiffness, flexure support of the mirror and its holder, material optimization for weight, stiffness, and coefficient of thermal expansion, as well as finite element analysis on statics and dynamics. The performances are also measured and expatiated, including the surface form, resonant frequency, tip-tilt stroke, vibration and shock response spectrum experiments, etc., which validate the performances of the SQ-FSM.

The Space multi-band Variable Object Monitor (SVOM) is a proposed Chinese astronomical satellite, dedicated to the detection, localization and measurement of the gamma-ray bursts (GRBs) on the cosmological scale. An efficient algorithm is developed for the purpose of onboard star extraction from the CCD images obtained with the Visible Telescope (VT) on board SVOM. The CCD pixel coordinates of the reference stars will be used to refine the astronomical position of the satellite, which will facilitate trigger rapid ground-based follow-up obsevations of the GRBs. In this algorithm, the image is divided into a number of grid cells and the "global" pixel-value maximum within each cell is taken as the first-guess position of a "bright" star. The correct center postion of a star is then computed using a simple iterative method. Applying two additional strategies, i.e., scanning the image only by even (or odd) lines or in a black-white chess board mode, are proposed to further reduce the time to extract the stars. To examine the efficiency of the above aglorithms, we applied them to the experimental images obtained with a ground-based telescope. We find that the accuracy of the astronomical positioning achieved by our method is comparable to that derived by using the conventional star-extraction method, while the former needs CPU time about 25 times less than the latter. This will significantly improve the performance of the SVOM VT mission., Comment: 5 pages, PDF only, accepted for publication in Science in China Series G

Galileo Galilei’s use of the newly invented telescope for astronomical observation resulted immediately in epochal discoveries about the physical nature of celestial bodies, but the advantage for astrometry came much later. The quadrant and sextant were pre-telescopic instruments for measurement of large angles between stars, improved by Tycho Brahe in the years 1570–1590. Fitted with telescopic sights after 1660, such instruments were quite successful, especially in the hands of John Flamsteed. The meridian circle was a new type of astrometric instrument, already invented and used by Ole Romer in about 1705, but it took a hundred years before it could fully take over. The centuries-long evolution of techniques is reviewed, including the use of photoelectric astrometry and space technology in the first astrometry satellite, Hipparcos, launched by ESA in 1989. Hipparcos made accurate measurement of large angles a million times more efficiently than could be done in about 1950 from the ground, and it will soon be followed by Gaia which is expected to be another one million times more efficient for optical astrometry.

The Sardinia Radio Telescope (SRT) is a 64-m fully-steerable radio telescope. It is provided with an active surface to correct for gravitational deformations, allowing observations from 300 MHz to 100 GHz. At present, three receivers are available: a coaxial LP-band receiver (305-410 MHz and 1.5-1.8 GHz), a C-band receiver (5.7-7.7 GHz) and a 7-feed K-band receiver (18-26.5 GHz). Several back-ends are also available in order to perform the different data acquisition and analysis procedures requested by scientific projects. The design and development of the SRT control software started in 2004, and now belongs to a wider project called DISCOS (Development of the Italian Single-dish COntrol System), which provides a common infrastructure to the three Italian radio telescopes (Medicina, Noto and SRT dishes). DISCOS is based on the Alma Common Software (ACS) framework, and currently consists of more than 500k lines of code. It is organized in a common core and three specific product lines, one for each telescope. Recent developments, carried out after the conclusion of the technical commissioning of the instrument (October 2013), consisted in the addition of several new features in many parts of the observing pipeline, spanning from the motion control to the digital back-ends for data acquisition and data formatting; we brie y describe such improvements. More importantly, in the last two years we have supported the astronomical validation of the SRT radio telescope, leading to the opening of the first public call for proposals in late 2015. During this period, while assisting both the engineering and the scientific staff, we massively employed the control software and were able to test all of its features: in this process we received our first feedback from the users and we could verify how the system performed in a real-life scenario, drawing the first conclusions about the overall system stability and performance. We examine how the system behaves in terms of network load and system load, how it reacts to failures and errors, and what components and services seem to be the most critical parts of our architecture, showing how the ACS framework impacts on these aspects. Moreover, the exposure to public utilization has highlighted the major flaws in our development and software management process, which had to be tuned and improved in order to achieve faster release cycles in response to user feedback, and safer deploy operations. In this regard we show how the introduction of testing practices, along with continuous integration, helped us to meet higher quality standards. Having identified the most critical aspects of our software, we conclude showing our intentions for the future development of DISCOS, both in terms of software features and software infrastructures.

Modern astronomy increasingly relies upon systematic surveys, whose dedicated telescopes continuously observe the sky across varied wavelength ranges of the electromagnetic spectrum; some surveys also observe non-electromagnetic "messengers," such as high-energy particles or gravitational waves. Stars and galaxies look different through the eyes of different instruments, and their independent measurements have to be carefully combined to provide a complete, sound picture of the multicolor and eventful universe. The association of an object's independent detections is, however, a difficult problem scientifically, computationally, and statistically, raising varied challenges across diverse astronomical applications. The fundamental problem is finding records in survey databases with directions that match to within the direction uncertainties. Such astronomical versions of the record linkage problem are known by various terms in astronomy: cross-matching, cross-identification, and directional, positional, or spatio-temporal coincidence assessment. Astronomers have developed several statistical approaches for such problems, largely independently of related developments in other disciplines. Here we review emerging approaches that compute (Bayesian) probabilities for the hypotheses of interest: possible associations, or demographic properties of a cosmic population that depend on identifying associations. Many cross-identification tasks can be formulated within a hierarchical Bayesian partition model framework, with components that explicitly account for astrophysical effects (e.g., source brightness vs. wavelength, source motion, or source extent), selection effects, and measurement error. We survey recent developments, and highlight important open areas for future research., Comment: 21 pages, 9 figures

One of the challenges faced within the astronomical X-ray community is how to produce lightweight high angular resolution optics for a future X-ray mission capable of probing the early X-ray universe. To this end, the differential deposition project at NASA Marshall Space flight Center (MSFC) is looking to improve current X-ray optic technology by applying a corrective coating with a goal of achieving arc-second-level resolution. This paper will focus on the correction of segmented glass optics fabricated at NASA Goddard Space Flight Center (GSFC) and the paper will highlight: the design of the vacuum chamber and internal mechanics; the algorithm used to perform the correction; metrology of the glass segments; and the improvement post correction that has been achieved to date.

A demonstration at iGRID 2005 used dynamic, deterministic, and dedicated LightPath network services to link radio telescopes from around the world with computational facilities at the MIT Haystack Observatory to create a single coherent instrument for real-time astronomical and geodetic research. The "electronic Very Long Baseline Interferometry" (e-VLBI) application provides ultra-high resolution images of very faint and very distant objects in the universe. The application-specific network topology carried 2 Gbps of VLBI data from radio telescopes in Europe, North America, and Japan to Haystack for real-time correlation processing. This paper describes the application, the network technologies employed for the demonstration, the results, challenges and future work.

The James Webb Space Telescope Near-Infrared Spectrograph (NIRSpec) instrument will offer a powerful multi-object spectroscopic capability enabled by the micro-shutter arrays (MSAs). The MSAs are fixed grids of configurable shutters that can be opened and closed on astronomical scenes. With this mode, the NIRSpec instrument can observe more than 100 targets simultaneously. The NIRSpec team and software developers at the Space Telescope Science Institute (STScI) have been implementing specialized algorithms in an MSA Planning Tool (MPT) to facilitate the complex observation planning process. Two main algorithms, the “Fixed Dithers” and “Flexible Dithers” algorithms, have been defined to achieve optimal multiplexing results with different observing strategies. The MPT is available to the astronomical community as part of the ASTRONOMER’S PROPOSAL TOOL (APT), an integrated software package for the preparation of observing proposals developed by STScI.

The Owens Valley Radio Observatory 40 meter telescope is currently monitoring a sample of about 1700 blazars every three days at 15 GHz, with the main scientific goal of determining the relation between the variability of blazars at radio and gamma-rays as observed with the Fermi Gamma-ray Space Telescope. The time domain relation between radio and gamma-ray emission, in particular its correlation and time lag, can help us determine the location of the high-energy emission site in blazars, a current open question in blazar research. To achieve this goal, continuous observation of a large sample of blazars in a time scale of less than a week is indispensable. Since we only look at bright targets, the time available for target observations is mostly limited by source observability, calibration requirements and slewing of the telescope. Here I describe the implementation of a practical solution to this scheduling, calibration, and slewing time minimization problem. This solution combines ideas from optimization, in particular the traveling salesman problem, with astronomical and instrumental constraints. A heuristic solution using well stablished optimization techniques and astronomical insights particular to this situation, allow us to observe all the sources in the required three days cadence while obtaining reliable calibration of the radio flux densities. Problems of this nature will only be more common in the future and the ideas presented here can be relevant for other observing programs., Published in Proc. SPIE. 9149, Observatory Operations: Strategies, Processes, and Systems V, 914925

We report on laboratory demonstrations of a vision-based sensor to aid in the formation flying of suborbital vehicles. Precision formation flying of such vehicles will allow us to hold a starshade external occulter in the line of sight between a telescope and star at large separations. This will enable us to perform the first astronomical demonstrations of starshades as we attempt high-contrast imaging of the outer planetary systems of nearby stars. In this report, we identify two sensor architectures and detail the equations for a closed loop visual feedback system to be used for precision formation flying. We investigate the sensor's expected performance through a suite of Monte Carlo simulations and system-level demonstrations in the lab. We also report on the development and demonstration of a means for visual attitude and position determination.

Over a 10-month period during 2013 and early 2014, development of the Neutron star Interior Composition Explorer (NICER) mission [1] proceeded through Phase B, Mission Definition. An external attached payload on the International Space Station (ISS), NICER is scheduled to launch in 2016 for an 18-month baseline mission. Its prime scientific focus is an in-depth investigation of neutron stars—objects that compress up to two Solar masses into a volume the size of a city—accomplished through observations in 0.2–12 keV X-rays, the electromagnetic band into which the stars radiate significant fractions of their thermal, magnetic, and rotational energy stores. Additionally, NICER enables the Station Explorer for X-ray Timing and Navigation Technology (SEXTANT) demonstration of spacecraft navigation using pulsars as beacons. During Phase B, substantive refinements were made to the mission-level requirements, concept of operations, and payload and instrument design. Fabrication and testing of engineering-model components improved the fidelity of the anticipated scientific performance of NICER’s X-ray Timing Instrument (XTI), as well as of the payload’s pointing system, which enables tracking of science targets from the ISS platform. We briefly summarize advances in the mission’s formulation that, together with strong programmatic performance in project management, culminated in NICER’s confirmation by NASA into Phase C, Design and Development, in March 2014.

We present a new type of R-θ fiber actuator named PotsPos for multi-object astronomical spectroscopy. It was initially intended to use as an alternative positioner design for the 4-meter Multi-Object Spectroscopic Telescope (4MOST). Although another tilting spine technology developed by the Australian Astronomical Observatory (AAO) is currently chosen for the 4MOST, PotsPos design has some technical advantages over other positioning technologies and might therefore be an attractive choice for future spectrographs. The design would be similar in positioning capabilities to the tilting spine design but would not suffer from telecentricity and defocus errors. The mechanical design, suitable motors, computational results from dynamic simulations and finite element analyses are presented.