Advancing Small-Body Detection and Spectral Classification with Wide-Field Schmidt Imaging and Synthetic Tracking at Baldone Observatory

Advancing Small-Body Detection and Spectral Classification with Wide-Field Schmidt Imaging and Synthetic Tracking at Baldone Observatory

• Zariņš, E. Dovgaļuka, M. Kogane, J. Blahins, V. Silamiķelis, I. Eglītis, K. Nagainis

Asteroids hold a dual significance for modern astronomy and planetary science. On one hand, near Earth asteroids (NEAs) pose a measurable impact hazard that requires continuous monitoring, orbit refinement, and early detection to mitigate potential threats to Earth. On the other hand, small bodies are increasingly recognized as reservoirs of metals, water, and rare-earth elements, making them attractive targets for industrial utilization and in-situ resource extraction. Reliable physical and orbital characterization is therefore essential not only for planetary defense but also for understanding the evolutionary processes of the Solar System and supporting future space-resource strategies.

Baldone Observatory (MPC code 069) operates with the 1.2-m class Schmidt telescope, used historically for wide-field photographic surveys and now adapted for CCD-based astrometry, photometry, and slitless spectroscopy. Many asteroid discoveries and a substantial number of astrometric follow-ups have been made using this instrument and its archival plate collection.

The telescope’s optical system features an 0.83-m entrance aperture and an approximately 2.5-m focal length (f/3). The wide field of view makes it particularly well suited to survey work and small-body detection. Additionally, the telescope can be equipped with a 4-degree objective prism, enabling slitless spectral dispersal across the entire field and allowing simultaneous low-resolution spectroscopy of multiple objects.

To improve faint-object detection, especially for fast-moving NEAs, Baldone Observatory conducted initial tests of the Tycho Tracker software suite, which implements modern synthetic tracking algorithms. Unlike traditional long exposures - where moving objects appear smeared - synthetic tracking aligns and stacks sequences of short images along trial motion vectors. This process suppresses sky noise, preserves the signal of moving targets, and effectively increases limiting magnitude.

Test sequences obtained with the Schmidt telescope demonstrate that synthetic tracking enables reliable identification of moving objects fainter than magnitude 21, surpassing the conventional detection threshold previously achievable at Baldone. These results show that synthetic tracking, combined with the telescope’s wide-field capability, meaningfully enhances the observatory’s contribution to NEA surveys and faint object astrometry.

In addition to detection efforts, we obtained a slitless spectrum of the main-belt asteroid (471) Papagena using the Schmidt telescope equipped with the 4° objective prism. Although originally optimised for stellar spectroscopy, the system proved sufficiently sensitive for bright asteroid targets. The resulting reflectance spectrum, after extraction and calibration, agrees well with published datasets and aligns with the Bus-DeMeo taxonomic classification for Papagena. This confirms that objective-prism spectroscopy is feasible for asteroid mineralogical studies at Baldone and suggests a pathway for expanding the observatory’s role in spectral classification.

The combined success of synthetic tracking and slitless spectroscopy demonstrates that the Baldone Schmidt telescope remains a competitive wide-field instrument for asteroid research. Future improvements in detector sensitivity, spectral calibration, and automation of data pipelines are expected to enhance both the depth and the scientific value of observations conducted at MPC 069.