Towards sub-milliarcsecond astrometric precision using seeing-limited imaging
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arXiv
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| Format: | Preprint |
| Publié: |
2025
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| _version_ | 1866914219585175552 |
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| author | Segev, Noam Ofek, Eran O. Shvartzvald, Yossi Rybicki, Krzysztof A. Lee, Chung-Uk Kim, Dong-Jin Yee, Jennifer C. Albrow, Michael D. Chung, Sun-Ju Gould, Andrew Han, Cheongho Hwang, Kyu-Ha Jung, Youn Kil Shin, In-Gu Yang, Hongjing Zang, Weicheng Cha, Sang-Mok Kim, Hyoun-Woo Kim, Seung-Lee Ryu, Yoon-Hyun Lee, Dong-Joo Lee, Yongseok Park, Byeong-Gon Pogge, Richard W. |
| author_facet | Segev, Noam Ofek, Eran O. Shvartzvald, Yossi Rybicki, Krzysztof A. Lee, Chung-Uk Kim, Dong-Jin Yee, Jennifer C. Albrow, Michael D. Chung, Sun-Ju Gould, Andrew Han, Cheongho Hwang, Kyu-Ha Jung, Youn Kil Shin, In-Gu Yang, Hongjing Zang, Weicheng Cha, Sang-Mok Kim, Hyoun-Woo Kim, Seung-Lee Ryu, Yoon-Hyun Lee, Dong-Joo Lee, Yongseok Park, Byeong-Gon Pogge, Richard W. |
| contents | The Earth's atmospheric turbulence degrades the precision of ground-based astrometry. Here, we discuss these limitations and propose that, with proper treatment of systematics and by leveraging the many epochs available from the Korean Microlensing Telescope Network (KMTNet), seeing-limited observations can reach sub-milliarcsecond precision. Such observations may be instrumental for the detection of Galactic black holes via microlensing. We present our methodology and pipeline for precise astrometric measurements using seeing-limited observations. The method is a variant of Gaia's Astrometric Global Iterative Solution (AGIS) that includes several detrending steps. Tests on 6,500 images of the same field, obtained by KMTNet with typical seeing condition of 1 arcsecond and pixel scale of 0.4 arcsecond, suggest that we can achieve, at the bright end (mag<17), per-epoch relative astrometric precision of ~5 and relative proper motion precision of 0.1-0.2 mas/yr over a baseline of approximately five years, using data from the Cerro Tololo Inter-American Observatory (CTIO) site. Time binning on 5--20 day cadences improves the bright-source precision to ~2 mas per coordinate on astrometric microlensing-relevant timescales. The precision is estimated using bootstrap simulations and further validated by comparing results from two independent KMTNet telescopes. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2507_11615 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | Towards sub-milliarcsecond astrometric precision using seeing-limited imaging Segev, Noam Ofek, Eran O. Shvartzvald, Yossi Rybicki, Krzysztof A. Lee, Chung-Uk Kim, Dong-Jin Yee, Jennifer C. Albrow, Michael D. Chung, Sun-Ju Gould, Andrew Han, Cheongho Hwang, Kyu-Ha Jung, Youn Kil Shin, In-Gu Yang, Hongjing Zang, Weicheng Cha, Sang-Mok Kim, Hyoun-Woo Kim, Seung-Lee Ryu, Yoon-Hyun Lee, Dong-Joo Lee, Yongseok Park, Byeong-Gon Pogge, Richard W. Instrumentation and Methods for Astrophysics Solar and Stellar Astrophysics The Earth's atmospheric turbulence degrades the precision of ground-based astrometry. Here, we discuss these limitations and propose that, with proper treatment of systematics and by leveraging the many epochs available from the Korean Microlensing Telescope Network (KMTNet), seeing-limited observations can reach sub-milliarcsecond precision. Such observations may be instrumental for the detection of Galactic black holes via microlensing. We present our methodology and pipeline for precise astrometric measurements using seeing-limited observations. The method is a variant of Gaia's Astrometric Global Iterative Solution (AGIS) that includes several detrending steps. Tests on 6,500 images of the same field, obtained by KMTNet with typical seeing condition of 1 arcsecond and pixel scale of 0.4 arcsecond, suggest that we can achieve, at the bright end (mag<17), per-epoch relative astrometric precision of ~5 and relative proper motion precision of 0.1-0.2 mas/yr over a baseline of approximately five years, using data from the Cerro Tololo Inter-American Observatory (CTIO) site. Time binning on 5--20 day cadences improves the bright-source precision to ~2 mas per coordinate on astrometric microlensing-relevant timescales. The precision is estimated using bootstrap simulations and further validated by comparing results from two independent KMTNet telescopes. |
| title | Towards sub-milliarcsecond astrometric precision using seeing-limited imaging |
| topic | Instrumentation and Methods for Astrophysics Solar and Stellar Astrophysics |
| url | https://arxiv.org/abs/2507.11615 |