Antarctic TianMu Staring Observation Project II: Data reduction and preliminary results

TL;DR

The paper presents the Antarctic TianMu Staring Observation Program's 18-cm prototype (AT-Proto), deployed at Zhongshan Station to enable high-cadence, wide-field time-domain optical surveys in Antarctica. It details a four-stage data reduction pipeline—preprocessing, artifact correction, astrometry, and photometry—and reports robust astrometric (~1.7–1.9 arcsec) and photometric (<0.1 mag for G<14, approaching 0.01 mag for bright stars) performance on 30 s G-band exposures, with a 1.5 mag detection limit at G≈15. The authors release the 2023 data products, including reduced images and photometric catalogs, and outline the pipeline's capabilities, validation metrics, and data-quality controls. They also discuss future plans to extend flux calibration, de-trend light curves, and expand the instrument network to broaden sky coverage for time-domain astronomy in the southern hemisphere.

Abstract

The Antarctic TianMu Staring Observation Program is a time-domain optical sky survey project carried out in Antarctica, capable of large sky coverage, high-cadence sampling, and long-period staring. It utilizes the exceptional observing conditions in Antarctica to conduct high-cadence time-domain sky surveys. At present, we have successfully developed an 18-cm aperture Antarctic TianMu prototype, which has been deployed at Zhongshan Station in Antarctica for two consecutive years of trouble-free observations, during which more than 300,000 original images were obtained. This paper systematically outlines the commissioning data of the prototype telescope in 2023, the primary data processing pipeline, and the preliminary data products. The core pipeline encompasses four key stages: Data preprocessing, instrumental effect correction, astrometric solution, and full-field stellar photometry. Here, we release the 2023 data products, which specifically include reduced image data and a photometric catalog, for which, preliminary analyses demonstrate robust performance. Using Gaia Data Release 3 as a reference catalog, the astrometric precision, quantified by the root mean square of positional errors, is determined to be better than approximately 2 arcseconds, validating the observational capabilities of the system. For a 30-second exposure, the detection limit in the G-band is achieved at 15.00~mag, with a detection threshold of 1.5~$σ$. The photometric errors are below 0.1~mag for the majority of stars brighter than 14.00~mag. Furthermore, it improves significantly, reaching better than 0.01~mag for most stars brighter than 11.00~mag and 12.00~mag when employing the adaptive aperture photometry and point spread function photometry methods, respectively.

Figures (12)

• Figure 1: Days with ATSOP observation data in 2023. The dark blue areas show the number of days observed.
• Figure 2: Data reduction flowchart, showing the key processing steps from raw observations to final science-ready products. The pipeline incorporates parallel processing branches with quality control checks at each critical transition point.
• Figure 3: The original image and the region to be cropped, with the valid data area indicated by the red rectangular box.
• Figure 4: Mask of bad pixels, derived from different epochs of super master sky flats.
• Figure 5: Characterization of a saturated star’s profile with charge bleeding artifacts. Left panel: Three-dimensional surface plot showing the star’s PSF with a prominent vertical trench (columns 2893-2899) caused by charge blooming. Right panel: Two-dimensional intensity profile, showing the dark bleeding trail extending from the saturated core.