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.
There have been a dramatic increase in the number of optical and radio transient surveys due to astronomical transients such as gravitational waves and gamma ray bursts, however, there have been a limited number of wide-field infrared surveys due to narrow field-of-view and high cost of infrared cameras, we present two new wide-field near-infrared fully automated surveyors; Palomar Gattini-IR and the Dynamic REd All-sky Monitoring Survey (DREAMS). Palomar Gattini-IR, a 25 square degree J-band imager that begun science operations at Palomar Observatory, USA in October 2018; we report on survey strategy as well as telescope and observatory operations and will also providing initial science results. DREAMS is a 3.75 square degree wide-field imager that is planned for Siding Spring Observatory, Australia; we report on the current optical and mechanical design and plans to achieve on-sky results in 2020. DREAMS is on-track to be one of the first astronomical telescopes to use an Indium Galium Arsenide (InGaAs) detector and we report initial on-sky testing results for the selected detector package. DREAMS is also well placed to take advantage and provide near-infrared follow-up of the LSST.
While optical and radio transient surveys have enjoyed a renaissance over the past decade, the dynamic infrared sky remains virtually unexplored from the ground. The infrared is a powerful tool for probing transient events in dusty regions that have high optical extinction, and for detecting the coolest of stars that are bright only at these wavelengths. The fundamental roadblocks in studying the infrared time-domain have been the overwhelmingly bright sky background (250 times brighter than optical) and the narrow field-of-view of infrared cameras (largest is VISTA at 0.6 sq deg). To address these challenges, Palomar Gattini-IR is currently under construction at Palomar Observatory and we propose a further low risk, economical, and agile instrument to be located at Siding Spring Observatory, as well as further instruments which will be located at the high polar regions to take advantage of the low thermal sky emission, particularly in the 2.5 micron region.
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