The Wide-Field Infrared Transient Explorer (WINTER) is a new fully robotic infrared time-domain survey instrument at the Palomar Observatory, commissioned in June 2023. WINTER is performing a seeing-limited time domain survey of the infrared (IR) sky to detect, discover, and characterize astrophysical time-domain phenomena. As a dedicated observatory for real-time detection and rapid follow-up of infrared transient and variable targets, WINTER represents a new capability for multi-messenger astrophysics. We will describe the robotic software architecture of the WINTER Supervisor Program (WSP) which handles autonomous scheduling of both surveys and target-of-opportunity interrupts, as well as control and remote monitoring of the observatory, telescope, and cameras.
The Wide-Field Infrared Transient Explorer (WINTER) is a new near-infrared time-domain survey instrument installed on a dedicated 1-meter robotic telescope at Palomar Observatory in June of 2023. WINTER’s science goals include robotic follow-up of kilonovae from binary neutron star (BNS) and neutron-star black-hole (NSBH) mergers, surveys to study galactic and extragalactic transients and variables, along with building up a deep, coadded image of the near-infrared sky. The project also serves as a technology demonstration for new large-format Indium Gallium Arsenide (InGaAs) detectors for cost-effective near-infrared photometry without cryogenic cooling. WINTER’s custom camera combines six InGaAs detectors as a first run of a newly-designed 1920 x 1080 pixel read out integrated circuit (ROIC). It uses a novel tiled fly’s-eye optical design to cover a > 1 degree-squared field of view in Y-, J-, and shortened-H-band filters (0.9-1.7μm). The survey currently operates with a median limiting magnitude of JAB ≈ 18.5, running nightly robotic surveys and target of opportunity programs. In parallel to these science programs, there is ongoing work to improve WINTER’s performance, which shows a factor of ∼ 10 decreased instrument efficiency from the design. Laboratory and on-sky testing suggest the sensor’s InGaAs diode array is performing properly, but sensitivity is being lost during amplification in the ROIC’s pixel amplifier. We present the laboratory and on-sky performance newly-commissioned WINTER observatory along with ongoing and future efforts to improve performance.
The Wide-Field Infrared Transient Explorer (WINTER) is a new time-domain instrument which will perform a seeing-limited survey of the near-infrared sky. Deployed on a dedicated 1-meter robotic telescope at Palomar Observatory, WINTER is designed to study transients of particular interest in the near-infrared including kilo-novae from gravitational-wave sources, supernovae, tidal disruption events, and transiting exoplanets around low mass stars with surveys to a depth of J=21 magnitudes. WINTER’s custom camera combines six commercial large-format Indium Gallium Arsenide (InGaAs) sensors, observing in Y, J, and a short-H (Hs) band filters (0.9-1.7 microns), and employs a novel tiled optical design to cover a >1 degree squared field of view with 90% fill factor. Each wide-format (1920 x 1080 pixels) InGaAs sensor operates at T = -50°C with a thermoelectric cooler, achieving background-limited photometry without cryogenic cooling. The tiled InGaAs sensors result in a wide field-of-view instrument with significant cost savings when compared to HgCdTe sensors. We present WINTER’s novel readout scheme, which includes custom electronics, firmware, and software for low-noise, real-time readout of the InGaAs sensors, including up to a 30x speed up of data reduction using GPUs. This work also outlines the cooling design for warm (T = -50°C) operation of the sensors with a two-stage thermometric cooler, copper heat pipes, and liquid cooling. We conclude with updates on the alignment, integration, and test of the WINTER instrument with a projected first light in Fall 2022.
The Wide-Field Infrared Transient Explorer (WINTER) is a new infrared time-domain survey instrument which will be deployed on a dedicated 1 meter robotic telescope at Palomar Observatory. WINTER will perform a seeing-limited time domain survey of the infrared (IR) sky, with a particular emphasis on identifying r-process material in binary neutron star (BNS) merger remnants detected by LIGO. As a dedicated observatory for real-time detection and rapid follow-up of infrared transient events, WINTER represents a new capability for multi-messenger astrophysics. We present the status of the WINTER instrument, including laboratory characterization and initial results from commissioning at its robotic observatory.
The Wide-field Infrared Transient Explorer (WINTER) is a 1x1 degree infrared survey telescope under devel- opment at MIT and Caltech, and slated for commissioning at Palomar Observatory in 2021. WINTER is a seeing-limited infrared time-domain survey and has two main science goals: (1) the discovery of IR kilonovae and r-process materials from binary neutron star mergers and (2) the study of general IR transients, including supernovae, tidal disruption events, and transiting exoplanets around low mass stars. We plan to meet these science goals with technologies that are relatively new to astrophysical research: hybridized InGaAs sensors as an alternative to traditional, but expensive, HgCdTe arrays and an IR-optimized 1-meter COTS telescope. To mitigate risk, optimize development efforts, and ensure that WINTER meets its science objectives, we use model-based systems engineering (MBSE) techniques commonly featured in aerospace engineering projects. Even as ground-based instrumentation projects grow in complexity, they do not often have the budget for a full-time systems engineer. We present one example of systems engineering for the ground-based WINTER project, featuring software tools that allow students or staff to learn the fundamentals of MBSE and capture the results in a formalized software interface. We focus on the top-level science requirements with a detailed example of how the goal of detecting kilonovae flows down to WINTER’s optical design. In particular, we discuss new methods for tolerance simulations, eliminating stray light, and maximizing image quality of a fly’s-eye design that slices the telescope’s focus onto 6 non-buttable, IR detectors. We also include a discussion of safety constraints for a robotic telescope.
The Wide-Field Infrared Transient Explorer (WINTER) is a new infrared time-domain survey instrument which will be deployed on a dedicated 1 meter robotic telescope at the Palomar Observatory. WINTER will perform a seeing-limited time domain survey of the infrared (IR) sky, with a particular emphasis on identifying r -process material in binary neutron star (BNS) merger remnants detected by LIGO. We describe the scientific goals and survey design of the WINTER instrument. With a dedicated trigger and the ability to map the full LIGO O4 positional error contour in the IR to a distance of 190 Mpc within four hours, WINTER will be a powerful kilonova discovery engine and tool for multi-messenger astrophysics investigations. In addition to follow-up observations of merging binaries, WINTER will facilitate a wide range of time-domain astronomical observations, all the while building up a deep coadded image of the static infrared sky suitable for survey science. WINTER’s custom camera features six commercial large-format Indium Gallium Arsenide (InGaAs) sensors and a tiled optical system which covers a <1-square-degree field of view with 90% fill factor. The instrument observes in Y, J and a short-H (Hs) band tuned to the long-wave cutoff of the InGaAs sensors, covering a wavelength range from 0.9 – 1.7 microns. We present the design of the WINTER instrument and current progress towards final integration at the Palomar Observatory and commissioning planned for mid-2021.
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