This is a list of reviewers who served JATIS in 2018.

Our contribution presents a high bandwidth platform that implements traffic aggregation and switching capabilities for the Cherenkov telescope array (CTA) cameras. Our proposed system integrates two different data flows: a unidirectional one from the cameras to an external server and a second one, fully configurable dedicated to configuration and control traffic for the camera management. The former requires high bandwidth mechanisms to be able to aggregate several 1 gigabit Ethernet links into one high speed 10 gigabit Ethernet port. The latter is responsible for providing routing components to allow a control and management path for all the elements of the cameras. Hence, a simple, efficient, and flexible routing mechanism has been implemented avoiding complex circuitry that impacts in the system performance. As a consequence, an asymmetric network topology allows high bandwidth communication and, at the same time, a flexible and cost-effective implementation. In our contribution, we analyze the camera requirements and present the proposed architecture. Moreover, we have designed several evaluation tests to demonstrate that our solution fulfills the CTA project needs. Finally, we illustrate the general possibilities of the proposed solution for other data acquisition applications and the most promising futures lines of research are discussed.

The reflectivity of a telescope primary mirror is one of the fundamental parameters that determines the telescope performance. Due to a lack of suitable instruments, however, measuring the absolute value of the reflectivity, in particular wide spectral measurements in-situ, has been almost impossible. To solve this problem, we developed a portable spectrophotometer called the Subaru Portable Spectrophotometer (SPS). SPS covers a spectral range between 380 and 1000 nm with a resolution of 2 nm. Its dimension and weight enable in-situ measurement on the primary mirror. A modified V-N method is applied to SPS for obtaining the absolute reflectivity. A sequential measurement makes SPS compensate the instrumental drift. The great advantage of SPS is its capability of getting absolute spectral reflectivity in-situ, even after the primary mirror is mounted on a telescope. In the case of Subaru Telescope, SPS clarified the reflectivity of the primary mirror coated with aluminum 4 years ago. Periodic measurements have been on-going since the primary mirror recoating in 2017. It is now possible to study the telescope reflectivity degradation with SPS.

The Dark Energy Spectroscopic Instrument (DESI) is under construction to measure the expansion history of the universe using the Baryon Acoustic Oscillation technique. The spectra of 35 million galaxies and quasars spanning over 14,000  deg² are measured during the life of the experiment. A prime focus corrector for the Kitt Peak National Observatory Mayall telescope delivers light to 5000 robotically positioned optic fibers. The fibers in turn feed 10 broadband spectrographs. Proper alignment of the focal plate structure, mainly consisting of a focal plate ring and 10 focal plate petals, is crucial in ensuring minimal loss of light in the focal plane. A coordinate measurement machine (CMM) metrology-based approach to alignment requires comprehensive characterization of critical dimensions of the petals and the ring, all of which are 100% inspected. The metrology data not only serve for quality assurance but also, with careful modeling of geometric transformations, inform the initial choice of integration accessories, such as gauge blocks, pads, and shims. The integrated focal plate structure is inspected again on a CMM, and each petal is adjusted individually according to the updated focal plate metrology data until all datums are extremely close to nominal positions and optical throughput nearly reached the theoretically best possible value. We present our metrology and alignment methodology and complete results for 12 official DESI petals. The as-aligned, total RMS optical throughput for 6168 positioner holes of 12 production petals is indirectly measured to be 99.88  %    ±  0.12  %  , well above the 99.5% project requirement. The successful alignment fully demonstrated the wealth of data, reproducibility, and micron-level precision made available by our CMM metrology-based approach.

Conical Wolter-I geometry is employed for many x-ray telescopes to lower their cost and fabrication difficulty at the expense of angular resolution. Owing to the conic error, the angular resolution of conical Wolter-I geometry is much worse than that of Wolter-I geometry, especially for the telescopes with large diameter. We optimized the conical Wolter-I geometry to significantly improve the angular resolution. We designed a conical Wolter-I geometry with sectioned secondary mirrors. Based on the normal conical Wolter-I geometry, we divided the secondary mirror into two equal sections along the optical axis. In this case, the collecting area was reduced by 5% because of the interval between the two sections. Meanwhile, the conic error was reduced by about 50%, indicating a great improvement in angular resolution. Regarding our improvement in the thermal slumping technique, it is feasible to fabricate sectioned mirrors, thus improving the angular resolution by 50% at the cost of a 5%-reduction in collecting area. In addition, a hybrid geometry, comprising the sectioned and nonsectioned geometries, is proposed as an alternative for x-ray telescopes with a large amount of nested shells, to obtain both a large collecting area and decent angular resolution.

A light-weighted primary mirror is the most important optical element for a large ground-based solar telescope. It receives solar radiation of more than 1000  W  /  m², of which about 10% is converted into heat energy, bringing in mirror seeing effect and surface shape distortion. Thus, a thermal control system (TCS) is necessary and important. Many studies have discussed the factors that influence the temperature difference between mirror surface and ambient air, but few refer to TCS modeling and optimization for the sake of parameter estimation. A thermal control model for the parameter estimation is proposed. The analytical process and the numerical analysis results of the model on the Chinese large ground-based solar telescope are given. A 60-cm prototype of open solar telescope (POST) is developed, on which practical experiment is taken place. According to the parameters estimated results, we select devices for the TCS of the POST. The experiment results show that the maximum temperature difference was restricted within ±0.5  °  C, despite the temperature variation of the ambient air, whereas without TCS, the maximum temperature difference rises up to 6.5°C. That validates the feasibility and effectiveness of the proposed model, and it can be referred for other large ground-based solar telescopes.

Remote-sensing observations of Solar System objects with a space telescope offer a key method of understanding celestial bodies and contributing to planetary formation and evolution theories. The capabilities of Twinkle, a space telescope in a low Earth orbit with a 0.45-m mirror, to acquire spectroscopic data of Solar System targets in the visible and infrared are assessed. Twinkle is a general observatory that provides on-demand observations of a wide variety of targets within wavelength ranges that are currently not accessible using other space telescopes or that are accessible only to oversubscribed observatories in the short-term future. We determine the periods for which numerous Solar System objects could be observed and find that Solar System objects are regularly observable. The photon flux of major bodies is determined for comparison to the sensitivity and saturation limits of Twinkle’s instrumentation and we find that the satellite’s capability varies across the three spectral bands (0.4 to 1, 1.3 to 2.42, and 2.42 to 4.5  μm). We find that for a number of targets, including the outer planets, their large moons, and bright asteroids, the model created predicts that with short exposure times, high-resolution spectra (R  ∼  250, λ  <  2.42  μm; R  ∼  60, λ  >  2.42  μm) could be obtained with signal-to-noise ratio (SNR) of   >  100 with exposure times of <300  s. For other targets (e.g., Phobos), an SNR  >  10 would be achievable in 300 s (or less) for spectra at Twinkle’s native resolution. Fainter or smaller targets (e.g., Pluto) may require multiple observations if resolution or data quality cannot be sacrificed. Objects such as the outer dwarf planet Eris are deemed too small, faint or distant for Twinkle to obtain photometric or spectroscopic data of reasonable quality (SNR  >  10) without requiring large amounts of observation time. Despite this, the Solar System is found to be permeated with targets that could be readily observed by Twinkle.

The communication architecture required to provide a bidirectional communication between a central command node and a full set of fiber positioners feeding a spectrograph is studied. Six different architectures have been analyzed in terms of communication time and power consumption. These architectures are the result of the combination of three different communication protocols: transmission control protocol/internet protocol (TCP/IP) over ethernet, interintegrated circuit (I²C), and controller area network. The design of communication architecture must prioritize between communication time and power consumption. The fastest architecture is the hybrid TCP/IP over ethernet-I²C. This architecture requires the least time to provide a full set of coordinates to every fiber positioner less than 50 ms. The most power efficient solution is the I²C—I²C with demultiplexers. This architecture solves a bidirectional communication between a central node and a full set of fiber positioners requiring only an addition of 27 mW.

We report the development of a four-color simultaneous camera for the 1.52-m Telescopio Carlos Sánchez in the Teide Observatory, Canaries, Spain. The instrument, named MuSCAT2, has a capability of four-color simultaneous imaging in g (400 to 550 nm), r (550 to 700 nm), i (700 to 820 nm), and z_s (820 to 920 nm) bands. MuSCAT2 equips four 1024  ×  1024  pixel CCDs, having a field of view of 7.4  ×  7.4  arc min² with a pixel scale of 0.44 arc sec per pixel. The principal purpose of MuSCAT2 is to perform high-precision multicolor exoplanet transit photometry. We demonstrate photometric precisions of 0.057%, 0.050%, 0.060%, and 0.076% as root-mean-square residuals of 60 s binning in g, r, i, and z_s bands, respectively, for a G0 V star WASP-12 (V  =  11.57  ±  0.16). MuSCAT2 has started science operations since January 2018, with over 250 telescope nights per year. MuSCAT2 is expected to become a reference tool for exoplanet transit observations and substantially contributes to the follow-up of the Transiting Exoplanet Survey Satellite and Planetary Transits and Oscillations of stars space missions.

We present an innovative imaging Stokes polarimeter. The main unit of the polarimeter is an integral polarization-holographic diffraction element, which enables the instant complete analysis of the polarization state of light in real time. An element is recorded by a special holographic schema using circularly and linearly polarized beams. As a result, it decomposes an incoming light into orthogonal circular and linear diffraction orders. We then capture diffraction orders using a CCD and transform the measured intensities into the Stokes images through the calibration parameters. The Stokes images are used to determine polarization state of a point or an extended space object in different spectral ranges. The operating spectral range of the polarimeter is 500 to 1600 nm with diffraction efficiency equal to 50% at 532 nm, 30% at 635 nm, and 5% at 1550 nm. The theoretical model of relations between measured intensities in different diffraction orders and Stokes parameters was used to calibrate the polarimeter. The calibration observations of day time sky show that the resulting errors are near of ^{10  −  3} order.

Two key areas of emphasis in contemporary experimental exoplanet science are the detailed characterization of transiting terrestrial planets and the search for Earth analog planets to be targeted by future imaging missions. Both of these pursuits are dependent on an order-of-magnitude improvement in the measurement of stellar radial velocities (RV), setting a requirement on single-measurement instrumental uncertainty of order 10  cm  /  s. Achieving such extraordinary precision on a high-resolution spectrometer requires thermomechanically stabilizing the instrument to unprecedented levels. We describe the environment control system (ECS) of the NEID spectrometer, which will be commissioned on the 3.5-m WIYN Telescope at Kitt Peak National Observatory in 2019, and has a performance specification of on-sky RV precision &lt;50  cm  /  s. Because NEID’s optical table and mounts are made from aluminum, which has a high coefficient of thermal expansion, sub-milliKelvin temperature control is especially critical. NEID inherits its ECS from that of the Habitable-Zone Planet Finder (HPF), but with modifications for improved performance and operation near room temperature. Our full-system stability test shows the NEID system exceeds the already impressive performance of HPF, maintaining vacuum pressures below 10^−  6  Torr and a root mean square (RMS) temperature stability better than 0.4 mK over 30 days. Our ECS design is fully open-source; the design of our temperature-controlled vacuum chamber has already been made public, and here we release the electrical schematics for our custom temperature monitoring and control system.

We explore the use of scintillation detectors coupled with silicon photomultipliers (SiPMs) as position sensitive hard x-ray spectroscopic detectors for potential applications in the field of high-energy astrophysics. X-ray photons on interaction with scintillation crystals generate optical photons and the distribution of these scintillation light photons is captured with the array of SiPM pixels, providing the spectral and spatial information of the incident x-ray photons. As the position is estimated by fitting the distribution of optical photons, it should be possible to achieve spatial resolution lesser than the pixel size. Development of two detector modules with CsI (Tl) and CeBr₃ scintillators coupled with different sets of array of SiPM pixels is presented here. Spectral and spatial resolutions of both detector modules are characterized with experiments using x-ray lines from laboratory radioactive sources. It is shown that a faster scintillator with an array of low-noise SiPM pixels provides better spectral and spatial resolution and it is possible to achieve subpixel spatial resolution with such a detector module.

The limitations of adaptive optics and coronagraph performance make exoplanet detection close to λ  /  D extremely difficult with conventional imaging methods. The technique of nonredundant masking (NRM), which turns a filled aperture into an interferometric array, has pushed the planet detection parameter space to within λ  /  D. For high Strehl, the related filled-aperture kernel phase technique can achieve resolution comparable to NRM, without the associated dramatic decrease in throughput. We present NRM and kernel phase contrast curves generated for ground- and space-based instruments. We use both real and simulated observations to assess the performance of each technique, and discuss their capabilities for different exoplanet science goals such as broadband detection and spectral characterization.

SPHiNX is a proposed gamma-ray burst (GRB) polarimeter mission operating in the energy range 50 to 600 keV with the aim of studying the prompt emission phase. The polarization sensitivity of SPHiNX reduces as the uncertainty on the GRB sky position increases. The stand-alone ability of the SPHiNX design to localize GRB positions is explored via Geant4 simulations. Localization at the level of a few degrees is possible using three different routines. This results in a large fraction (&gt;80  %  ) of observed GRBs having a negligible (&lt;5  %  ) reduction in polarization sensitivity due to the uncertainty in localization.

Pulsar-based navigation for spacecraft is a revolutionary technology that has been researched for several decades. To validate it, China launched a small experimental satellite, the x-ray pulsar navigation-I (XPNAV-1), whose main payload was the first Chinese on-orbit grazing incidence focusing x-ray telescope, called the time-resolved soft x-ray spectrometer (TSXS). XPNAV-1/TSXS observes the x-ray pulsar at the 0.5- to 10-keV band. Based on 85-day observation data of the pulsar B0531+21 (Crab), a ground pulsar-based navigation experiment is conducted. The pulsar timing is performed to determine Crab’s spin parameters at the x-ray band. A pulse phase estimation method is designed that eliminates the influence of the Doppler effect and generates ranging measurements from 25 observations. The ranging measurements are introduced as control points into the orbit propagation of XPNAV-1. The result indicates that, in nearly three months, by observing Crab only, XPNAV-1 can locate itself with an average navigation error of 38.4 km at the control points.

The Colorado Ultraviolet Transit Experiment (CUTE) is a 6U NASA CubeSat carrying on board a low-resolution (R  ∼  2000 to 3000), near-UV (2500 to 3300 Å) spectrograph. It has a rectangular primary Cassegrain telescope to maximize the collecting area. CUTE, which is planned for launch in spring 2020, is designed to monitor transiting extra-solar planets orbiting bright, nearby stars, aiming at improving our understanding of planet atmospheric escape and star–planet interaction processes. We present here the CUTE data simulator, which we complemented with a basic data reduction pipeline. This pipeline will be then updated once the final CUTE data reduction pipeline is developed. We show here the application of the simulator to the HD209458 system and a first estimate of the precision on the measurement of the transit depth as a function of temperature and magnitude of the host star. We also present estimates of the effect of spacecraft jitter on the final spectral resolution. The simulator has been developed considering also scalability and adaptability to other missions carrying on board a long-slit spectrograph. The data simulator will be used to inform the CUTE target selection, choose the spacecraft and instrument settings for each observation, and construct synthetic CUTE wavelength-dependent transit light curves on which to develop the CUTE data reduction pipeline.

Adaptive optics (AO) instruments for the future extremely large telescopes (ELTs) are characterized by advanced optical systems with diffraction-limited optical quality. Low geometric distortion is also crucial for high accuracy astrometric applications. Optical alignment of such systems is a crucial step of the instrument integration. Due to relative inaccessibility of these giant instruments, automatic alignment methods are also favored to improve the instrument availability after major events, such as extraordinary maintenance. The proposed alignment concept for these systems is described: the notable example which is analyzed here is the case of the multiconjugate AO relay for the future ELT. The results of ray-tracing simulations carried out to validate the method are discussed in detail, covering the error sources, which could degrade the alignment performance.

FRIDA (inFRared Imager and Dissector for Adaptive optics) is a near-infrared integral-field spectrograph operating at the wavelength range of 0.9 to 2.5  μm for use at the Nasmyth B platform of the Gran Telescopio de Canarias (GTC). FRIDA is a collaborative project led by the Instituto de Astronomía Universidad Nacional Autónoma de México (IA-UNAM, México) with the collaboration of the Instituto de Astrofísica de Canarias (IAC, Spain), Centro de Ingeniería y Desarrollo Industrial (CIDESI, México), the University of Florida (UF, USA), and the Universidad Complutense de Madrid (UCM, Spain). In imaging mode, FRIDA will provide scales of 0.010, 0.020, and 0.040  arc sec  /  pixel and, in IFS mode, spectral resolutions of R  ∼  1000, 4500, and 30,000. FRIDA is the first GTC instrument to use the telescope’s adaptive optics (GTCAO) system and is rescheduled to be delivered to the GTC shortly in 2020. This paper not only provides a starting point for possible future developers of GTC instruments but also presents a generic solution that we adopted in FRIDA to manage the sequences of operations and science observations. Specifically, this paper gives an overview of the high-level control software components of FRIDA. The main components are the mechanisms control system, whose primary task is to control the mechanisms of FRIDA, the data acquisition system, which interacts with the detector to take images, the data factory system, whose main tasks are to perform the reduction, storage and also to provide quality control for both engineering and scientific data, the Instrument Library (IL) component responsible for operating the devices associated with FRIDA, and the sequencer manager component responsible for the execution of both the operational sequencing of the telescope’s instruments and the observing sequences of FRIDA in close co-ordination with the GTCAO system. In other GCS instruments, the responsibilities of the sequencer manager are inside the IL representing an overload on this component with the added problems of extensibility and reusability.

We investigate the use of ultra-narrow band interference filters to enable daytime use of sodium laser guide star (LGS) adaptive optics systems. Filter performance is explored using theoretical and vendor supplied filter transmission profiles, a modeled daylight sky background, broadband measurements of the daytime sky brightness on Maunakea, and an assumed photon return from the sodium LGS and read noise for the wavefront sensor (WFS) detector. The critical parameters are the bandpass of the filter, the out-of-band rejection, and the peak throughput at the wavelength of the LGS light. Importantly, a systematic trade between these parameters leads to potentially simple solutions enabling daytime observations. Finally, we simulated the Mid-Infrared Adaptive Optics (MIRAO) system planned for the Thirty Meter Telescope with an end-to-end simulation, folding in daytime sky counts. We find that MIRAO with five sodium LGSs, commercial off-the-shelf filters to suppress the sky background in the LGS WFSs, and a near-infrared natural guide star (K  ≤  13) tip/tilt/focus WFS can attain daytime Strehl ratio values comparable to those at night.

A table-top soft x-ray polarimetry setup has been developed at the Institute of Precision Optical Engineering for characterizing the polarization properties of mirrors designed for the lightweight asymmetry and magnetism probe project. Based on a Co/C multilayer polarizer mirror, linearly polarized soft x-rays were generated at a wavelength of 4.48 nm, which could be rotated around the beam-propagation direction by using a differentially pumped rotary feedthrough. The setup design and the alignment method are described in detail. The capabilities of this spectrometer were demonstrated through a polarization test on a twin Co/C multilayer polarizer sample, and the results agree well with the expected sine wave.

Linking a coronagraph instrument to a spectrograph via a single-mode optical fiber is a pathway toward detailed characterization of exoplanet atmospheres with current and future ground- and space-based telescopes. However, given the extreme brightness ratio and small angular separation between planets and their host stars, the planet signal-to-noise ratio will likely be limited by the unwanted coupling of starlight into the fiber. To address this issue, we utilize a wavefront control loop and a deformable mirror to systematically reject starlight from the fiber by measuring what is transmitted through the fiber. The wavefront control algorithm is based on the formalism of electric field conjugation (EFC), which in our case accounts for the spatial mode selectivity of the fiber. This is achieved by using a control output that is the overlap integral of the electric field with the fundamental mode of a single-mode fiber. This quantity can be estimated by pairwise image plane probes injected using a deformable mirror. We present simulation and laboratory results that demonstrate our approach offers a significant improvement in starlight suppression through the fiber relative to a conventional EFC controller. With our experimental setup, which provides an initial normalized intensity of 3  ×  ^{10  −  4} in the fiber at an angular separation of 4λ  /  D, we obtain a final normalized intensity of 3  ×  ^{10  −  6} in monochromatic light at λ  =  635  nm through the fiber (100  ×   suppression factor) and 2  ×  ^{10  −  5} in Δλ  /  λ  =  8  %   broadband light about λ  =  625  nm (10  ×   suppression factor). The fiber-based approach improves the sensitivity of spectral measurements at high contrast and may serve as an integral part of future space-based exoplanet imaging missions as well as ground-based instruments.

This erratum corrects an error in Eq. 39.