A data processing pipeline for the WINTER near-infrared surveyor using the $\texttt{mirar}$ framework

Viraj Karambelkar; Robert Stein; Danielle Frostig; Saarah Hall; Mansi M. Kasliwal; Tomás Ahumada; Michael W. Coughlin; Thomas Culino; Kishalay De; Sulekha Kishore; Theophile Jegou du Laz; Nathan P. Lourie; Geoffrey Mo; Tanishk Mohan; Sam Rose; Benjamin R. Roulston; Aditya Pawan Saikia; Mallika Sheshadri; Robert A. Simcoe; Jamie Soon; Aswin Suresh

arXiv · 2609.10675

A data processing pipeline for the WINTER near-infrared surveyor using the $\texttt{mirar}$ framework

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Abstract

We present the data reduction and transient detection pipeline for the Wide-field Infrared Transient Explorer (WINTER) surveyor and report its on-sky performance. The WINTER camera utilizes cost-effective InGaAs sensors as alternatives to traditional IR sensors, and is mounted on a dedicated 1-m robotic telescope at Palomar Observatory. The WINTER camera has six detectors producing a combined field-of-view of 1.2 sq. deg. equipped with y, J, and shortened-H bands. WINTER saw first light in June 2023 and has been operating robotically since. The WINTER data processing pipeline ($\texttt{winterdrp}$) has been implemented within the broader framework $\texttt{mirar}$: a modular, open-source $\texttt{python}$ package developed for realtime processing of images from time-domain surveys. $\texttt{winterdrp}$ performs end-to-end data processing implementing data reduction and image subtraction to go from raw dithered WINTER images to transient alerts in the $\texttt{avro}$ format, which are then sent to $\texttt{SkyPortal}$ for vetting and follow-up. During a year of observations in 2024, WINTER achieved J-band median 5-$σ$ depths ranging from $18.1-18.8$ mag (AB) on its six detectors in 960 second integrations as part of its survey, with an astrometric accuracy of $\approx0.2$ arcsec (a fifth of a pixel) and a detector-performance limited photometric accuracy ranging from $\approx0.09-0.18$ mag for its six detectors. We present early science results from WINTER, which include the identification of a stellar merger in M31, dust-enshrouded outbursting young stellar objects and classical novae in the Galactic plane, NIR followup of known supernovae, and multi-messenger follow-up of neutrinos, gravitational waves, fast X-ray transients and gamma-ray bursts.

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Viraj Karambelkar, Robert Stein, Danielle Frostig, Saarah Hall, Mansi M. Kasliwal, Tomás Ahumada, Michael W. Coughlin, Thomas Culino, Kishalay De, Sulekha Kishore, Theophile Jegou du Laz, Nathan P. Lourie, Geoffrey Mo, Tanishk Mohan, Sam Rose, Benjamin R. Roulston, Aditya Pawan Saikia, Mallika Sheshadri, Robert A. Simcoe, Jamie Soon, Aswin Suresh. 2026-09-09. A data processing pipeline for the WINTER near-infrared surveyor using the $\texttt{mirar}$ framework. https://arxiv.org/abs/2609.10675

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