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1. Pipeline for the Antarctic Survey Telescope 3-3 in Yaoan, Yunnan

   https://doi.org/10.3389/fspas.2022.897100  

   Sun, Tianrui; Hu, Lei; Zhang, Songbo; Li, Xiaoyan; Meng, Kelai; Wu, Xuefeng; Wang, Lifan; Castro-Tirado, A. J. (July 2022, Frontiers in Astronomy and Space Sciences)

   AST3-3 is the third robotic facility of the Antarctic Survey Telescopes (AST3) for transient surveys to be deployed at Dome A, Antarctica. Due to the current pandemic, the telescope has been currently deployed at the Yaoan Observation Station in China, starting the commissioning observation and a transient survey. This article presented a fully automatic data processing system for AST3-3 observations. The transient detection pipeline uses state-of-the-art image subtraction techniques optimized for GPU devices. Image reduction and transient photometry are accelerated by concurrent task methods. Our Python-based system allows for transient detection from wide-field data in a real-time and accurate way. A ResNet-based rotational-invariant neural network was employed to classify the transient candidates. As a result, the system enables the auto-generation of transients and their light curves. 

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2. Alignment of the optical system of the 9.7-m prototype Schwarzchild-Coulder Telescope

   https://doi.org/10.1117/12.2564653  

   Adams, C.~B.~; Alfaro, R.~; G.~Ambrosi, Ambrosi; Ambrosio, M.~; Aramo, C.~; Benbow, W.~; Bertucci, B.~; Bissaldi, E.~; Bitossi, M.~; Boiano, A.~; et al (December 2020, Proceedings Volume 11445, Ground-based and Airborne Telescopes VIII;)

   Marshall, Heather K.; Spyromilio, Jason; Usuda, Tomonori (Ed.)

   The novel 9.7m Schwarzschild-Couder Telescope (SCT), utilizing aspheric dual-mirror optical system, has been constructed as a prototype medium size x-ray telescope for the Cherenkov Telescope Array (CTA) observatory. The prototype SCT (pSCT) is designed to achieve simultaneously the wide (≥ 8°) field of view and the superior imaging resolution (0.067 per pixel) to significantly improve scientific capabilities of the observatory in conducting the sky surveys, the follow-up observations of multi-messenger transients with poorly known initial localization and the morphology studies of x-ray sources with angular extent. In this submission, we describe the hardware and software implementations of the telescope optical system as well as the methods specifically developed to align its complex optical system, in which both primary and secondary mirrors are segmented. The pSCT has detected Crab Nebula in June 2020 during ongoing commissioning, which was delayed due to worldwide pandemic and is not yet completed. Verification of pSCT performance is continuing and further improvement of optical alignment is anticipated. 

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3. NSF-DOE Vera C. Rubin Observatory Observations of Interstellar Comet 3I/ATLAS (C/2025 N1)

   https://doi.org/10.3847/2041-8213/ae4b3a  

   Chandler, Colin Orion; Bernardinelli, Pedro H; Jurić, Mario; Singh, Devanshi; Hsieh, Henry H; Sullivan, Ian; Jones, R Lynne; Kurlander, Jacob A; Vavilov, Dmitrii; Eggl, Siegfried; et al (April 2026, The Astrophysical Journal Letters)

   Abstract We report on the observation and measurement of astrometry, photometry, morphology, and activity of the interstellar object 3I/ATLAS, also designated C/2025 N1 (ATLAS) with the NSF-DOE Vera C. Rubin Observatory. Comet 3I/ATLAS, the third known interstellar object, was discovered on UT 2025 July 1. Rubin Observatory had coincidentally collected images of the object’s region of the sky during routine commissioning. Facilitated by Rubin’s high resolution and large aperture, we successfully recovered object detections from Rubin observations spanning UT 2025 June 21 (10 days before discovery, when 3I/ATLAS was 4.5 au from the Sun) through the date of discovery, and we acquired additional images through UT 2025 July 20 as part of commissioning. We measure on-sky locations of 3I/ATLAS in Rubinugrizybands, with a typical precision of ∼70 mas, and briefly describe the reason this is coarser than our measured static source astrometric precision of ∼3 mas in Rubin images. We measuregrizymagnitudes of 3I/ATLAS photometry at ∼0.01 mag precision, detecting no short-term photometric variability above 0.01 mag. We derive an estimated near-nucleus dust-to-nucleus scattering cross-sectional ratio ofη ≳ 13 on UT 2025 July 2 based on Rubin photometry and an upper limit nucleus size computed from Hubble Space Telescope observations. We find Rubin colors ofg − r =  (0.657 ± 0.013) mag,r − i =  (0.235 ± 0.018) mag,i − z = (0.147 ±  0.042) mag, andz − y =  (0.047 ± 0.052) mag. These data represent the earliest observations of this object by a large (≳8 m class) telescope and illustrate the type of measurements (and discoveries) Rubin’s Legacy Survey of Space and Time will provide after it begins in early 2026. 

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4. Resolving the Young 2 Cygni Runaway Star into a Binary Using iLocater

   https://doi.org/10.3847/1538-3881/ad9b1d  

   Crepp, Justin R; Crass, Jonathan; Bechter, Andrew J; Sands, Brian L; Ketterer, Ryan; King, David; Kopon, Derek; Hamper, Randall; Engstrom, Matthew; Smous, James E; et al (December 2024, The Astronomical Journal)

   Precision radial velocity spectrographs that use adaptive optics (AO) show promise to advance telescope observing capabilities beyond those of seeing-limited designs. We are building a spectrograph for the Large Binocular Telescope (LBT) named iLocater that uses AO to inject starlight directly into single mode fibers. iLocater's first acquisition camera system (the SX camera), which receives light from one of the 8.4 m diameter primary mirrors of the LBT, was initially installed in summer 2019 and has since been used for several commissioning runs. We present results from first-light observations that include on-sky measurements as part of commissioning activities. Imaging measurements of the bright B3IV star 2 Cygni (V= 4.98) resulted in the direct detection of a candidate companion star at an angular separation of onlyθ = 70 mas. Follow-up AO measurements using Keck/NIRC2 recover the candidate companion in multiple filters. AnR ≈ 1500 miniature spectrograph recently installed at the LBT named Lili provides spatially resolved spectra of each binary component, indicating similar spectral types and strengthening the case for companionship. Studying the multiplicity of young runaway star systems like 2 Cygni (36.6 ± 0.5 Myr) can help to understand formation mechanisms for stars that exhibit anomalous velocities through the Galaxy. This on-sky demonstration illustrates the spatial resolution of the iLocater SX acquisition camera working in tandem with the LBT AO system; it further derisks a number of technical hurdles involved in combining AO with Doppler spectroscopy. 

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5. The wide-field infrared transient explorer (WINTER)

   https://doi.org/10.1117/12.2561210  

   Lourie, Nathan P.; Baker, John W.; Burruss, Richard S.; Egan, Mark D.; Furész, Gábor; Frostig, Danielle; Garcia-Zych, Allan A.; Ganciu, Nicolae; Haworth, Kari; Hinrichsen, Erik; et al (December 2020, X-Ray, Optical, and Infrared Detectors for Astronomy IX)

   Evans, Christopher J.; Bryant, Julia J.; Motohara, Kentaro (Ed.)

   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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