Physical Properties of Very Small Near-Earth Asteroids 2015 RN35 and 2013 YA14

Very small Near-Earth asteroids (diameter less than 200 m), due to their size, can usually be observed for a short time during close approaches to the Earth, after which it is often necessary to wait several or dozens years for another approach. Therefore, not many of these objects are well characterized, for example, only about 1% of them have a designated taxonomic type [1].

Since 2015, we have been conducting campaigns of photometric observations of very small NEAs with a very long observation arc in order to determine their physical properties from a single near-Earth flyby. We determine the rotation periods, colour indices, taxonomic types, absolute brightnesses from the phase curves, effective diameters, and spin axes. So far, we have organized four observation campaigns involving many observatories around the world. We observed 2015 AZ43 in February 2015 [2], 2021 DW1 in March 2021 [3][4][5] and 2022 AB in January 2022.[6][7][8]. Our last campaign in December 2022 targeted two objects 2013 YA14 and 2015 RN35[11].

2015 RN35 and 2013 YA14 are very small NEAs. Their estimated absolute magnitudes H =23.23 and H=23.80, respectively [9]. The asteroids were discovered on 9 January 2015 by PanSTARRS 1 and on 26 December 2013, respectively [10]. We observed these asteroids between 12 and 27 December 2022 and it coincided with the closest approach of these asteroids to Earth this century (nominal distances for 2015 RN35 on 15 December 2022: 1.79 Earth-Moon distance, and for 2013 YA14 on 25 December 2022: 2.66 Earth-Moon distance), giving us a unique opportunity to study the physical properties of these objects.

At the conference, we are going to report the results of the rotation periods, colour indices, taxonomic classes and estimated effective diameters of these asteroids.

Acknowledgments: This research was funded in whole or in part by the National Science Centre, Poland, Grant No. 2021/41/N/ST9/04259

References:

[1] Perna et al. (2018) P&SS, 157, 82-95

[2] Kwiatkowski et al. (2017) EPSC 2017, EPSC2017-874

[3] Kwiatkowski et al. (2021) A&A 656, A126

[4] Kwiatkowski et al. (2021) EPSC 2021, EPSC2021-840

[5] Koleńczuk et al. (2021) EPSC 2021, EPSC2021-758

[6] Koleńczuk et al. (2022) EPSC 2022, EPSC2022-1161

[7] Kwiatkowski et al. (2022) EPSC 2022, EPSC2022-1073

[8] Kwiatkowski et al. (2023) Photometry and model of near-Earth asteroid 2022 AB from one apparition, ACM 2023, Flagstaff, USA

[9] https://ssd.jpl.nasa.gov/

[10] https://minorplanetcenter.net

[11] Koleńczuk et al. (2023) Colour Indices and Taxonomy of Super-Fast Rotating Very Small Near-Earth Asteroid 2015 RN35, ACM 2023, Flagstaff,USA