- The paper highlights the successful use of twilight observations and the P48/ZTF system to detect near-sun objects with up to 80% efficiency for asteroids at r < 19–20 magnitudes.
- It reports the discovery of one Aylo asteroid, four Atiras, and multiple comets, including interstellar comet 2I/Borisov and comet C/2022 E3 (ZTF).
- The findings refine near-sun population models and inform future surveys like the Rubin Observatory’s LSST, enhancing strategies for planetary defense.
The Palomar Twilight Survey of Aylos, Atiras, and Comets: A Comprehensive Overview
This essay summarizes the objectives, methods, results, and future implications of the twilight survey conducted using the Palomar 48-inch telescope (P48) equipped with the Zwicky Transient Facility (ZTF) camera. The survey aimed to detect and characterize near-sun objects such as asteroids and comets that reside inside the orbits of Earth and Venus, notably the Aylos and Atiras. Spanning from September 2019 to September 2022, the survey achieved notable results, including the discovery of one Aylo, four Atiras, and several long and short-period comets.
Survey Overview
The twilight survey capitalized on observing the sky during evening and morning astronomical twilight, periods that allow for the detection of celestial objects close to the Sun. A total of 21,940 exposures in evening twilight and 24,370 exposures in morning twilight were captured. The limiting magnitudes for the r-band exposures ranged between 18.0 and 20.8, with slight improvements during the summer months.
Key Discoveries
Asteroids
- Aylos: The survey led to the discovery of one Aylo asteroid, (594913), inside the orbit of Venus with a semi-major axis of 0.56 au and an eccentricity of 0.18.
- Atiras: Four Atira asteroids were discovered with varying semi-major axes and eccentricities, offering valuable data to refine population models.
Comets
A total of six long-period and two short-period comets were identified using the Tails deep learning comet detection pipeline. Notable discoveries include interstellar comet 2I/Borisov and comet C/2022 E3 (ZTF), which exhibited near-naked-eye brightness.
Implications and Analysis
Observational Efficiency
The survey demonstrated the efficacy of twilight observations in detecting near-sun objects. The ZMODE Lite algorithm significantly increased detection efficiency, showcasing an 80% detection rate for asteroids with r < 19–20 magnitudes and a 43% efficiency for r < 20.5 magnitudes.
Population Models
Discoveries like (594913) suggest that the actual population of Aylos may be larger than current models predict. The survey's results provide empirical data to validate and refine models such as NEOMOD.
Seasonal Variations
The data indicate slight seasonal variations in limiting magnitude and sky coverage capabilities. The survey achieved optimal limiting magnitudes in the summer, benefiting from longer twilight duration and favorable atmospheric conditions.
Theoretical and Practical Implications
Future Surveys
The results of this twilight survey have significant implications for future observational efforts. The Rubin Observatory's Legacy Survey of Space and Time (LSST) will incorporate a twilight survey during its first year, expected to cover regions within 45 degrees from the Sun and reach much deeper limiting magnitudes (r > 23).
By comparing the average per-year sky coverage, the LSST twilight survey is expected to discover up to 50% of all Aylos with an absolute magnitude of H < 20 over its 10-year timeframe.
Speculative Outlook
The success of the Palomar twilight survey emphasizes the importance of near-sun observations for advancing our understanding of the inner Solar System. Future improvements in detection algorithms and deeper sky surveys will likely lead to the discovery of many more near-sun objects.
Moreover, the Rubin Observatory's twilight survey will dramatically extend our capability to detect faint Aylos, providing a more comprehensive grasp of their population dynamics. As twilight surveys evolve, they will undoubtedly continue to play a critical role in planetary defense and the characterization of near-Earth objects.
Conclusion
The Palomar twilight survey conducted using the P48/ZTF was a seminal effort in the detection and characterization of near-sun asteroids and comets. Its findings offer new insights into the populations of Aylos and Atiras, influencing future surveys like the Rubin Observatory's LSST. As twilight observation techniques continue to improve, they will remain indispensable tools in the ongoing exploration of our Solar System.
References
- B. T. Bolin et al., "The Palomar twilight survey of , Atiras, and comets," Chinese Journal of Astronomy and Astrophysics.
Appendices
Tables
Table 1: Aylo and Atira Asteroids, Long-Period, and Short-Period Comets Discovered by P48.
| Object | Date | Class | a/q | P | e | i | Q | H,M1 | p_v | D | Arc | AI | Ref. |
|-|--|--|||-|||--|--|--|-|--|--|
| (594913) | 2020-01-04 | Aylo | 0.56 au | 0.41 y | 0.18 | 15.87° | 0.65 au | 16.2 | 0.21 | 1670 m | 1351d | N/A | Bolin et al., 2022IVO |
Table 2: Observational Circumstances of Discovered Objects.
| Object | Date | Time | E | λ⊙ | β⊙ | α | R | Δ | X | δ_θ | m_lim | m_r |
|--|--|-|-||||-||-||||
| (594913) | 2020-01-04 | Evening | 39.5° | 37.0° | 8.6° | 86.4° | 0.6 au | 0.8 au | 2.3 | 1.7 | 19.2 | 18.0 |
Table 3: Aylo and Atira Asteroids, and Long-Period and Short-Period Comets Serendipitously Recovered by P48.
| Object | Date | Class | a/q | P | e | i | Q | H,M1 | p_v | D | Arc | AI | Ref. |
|-||-|--|--||||--|||-|-|--|
| 2I/Borsiov | 2019-10-15 | Interstellar | 2.00 | Undefined | 3.36 | 44.05° | Undefined | 13.7 | N/A | N/A | 311d | Yes| Bolin et al., 2019Borsiov |
Table 4: Observational Circumstances of Recovered Objects.
| Object | Date | Time | E | λ⊙ | β⊙ | α | R | Δ | X | δ_θ | m_lim | m_r |
|-||-|-||||-||-||||
| 2I/Borsiov | 2019-10-15 | Morning | 56.7° | 56.5° | 4.1° | 20.9° | 2.3 au | 2.7 au | 1.8 | 3.9 | 17.4 | 19.2 |
This compilation of observational data, combined with robust detection algorithms and pipeline processes, underscores the utility and potential of twilight surveys in modern astrophysics.
