# The Discovery and Characterization of Earth-crossing Asteroid 2024 YR4

Bryce T. Bolin, Josef Hanuš, Larry Denneau, Roberto Bonamico, Laura-May

Abron, Marco Delbo, Josef Ďurech, Robert Jedicke, Leo Y. Alcorn, Aleksandar Cikota, et al.

► To cite this version:

Bryce T. Bolin, Josef Hanuš, Larry Denneau, Roberto Bonamico, Laura-May Abron, et al. The Discovery and Characterization of Earth-crossing Asteroid 2024 YR4. The Astrophysical Journal Letters, 2025, 984, 10.3847/2041-8213/adc910. insu-05099870

HAL Id: insu-05099870

https://insu.hal.science/insu-05099870v1

Submitted on 6 Jun 2025

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<figure><img src="image_1.png" /></figure>

Distributed under a Creative Commons Attribution 4.0 International License
# The Discovery and Characterization of Earth-crossing Asteroid 2024 YR₄

Bryce T. Bolin<sup>1,10</sup>①, Josef Hanuš<sup>2,10</sup>①, Larry Denneau<sup>3,10</sup>①, Roberto Bonamico<sup>4</sup>①, Laura-May Abron<sup>5</sup>①, Marco Delbo<sup>6,7</sup>①, Josef Đurech<sup>2</sup>①, Robert Jedicke<sup>3</sup>①, Leo Y. Alcorn<sup>8</sup>①, Aleksandar Cikota<sup>9</sup>①, Swayamtrupta Panda<sup>9</sup>①, and Henrique Reggiani<sup>9</sup>①

Received 2025 March 7; revised 2025 April 1; accepted 2025 April 4; published 2025 April 24

## Abstract

We describe observations and physical characteristics of Earth-crossing asteroid 2024 YR₄, discovered on 2024 December 27 by the Asteroid Terrestrial-impact Last Alert System. The asteroid has semimajor axis *a* = 2.52 au, eccentricity *e* = 0.66, inclination *i* = 3.41, and a ~0.003 au Earth minimum orbit intersection distance. We obtained *g*-, *r*-, *i*-, and Z-imaging with the Gemini South/Gemini Multi-Object Spectrograph on 2025 February 7 and *Y* and *J* imaging with the Keck/Multi-Object Spectrometer for Infrared Exploration on 2025 February 12. We measured a *g* – *i* spectral slope of 13% ± 3%/100 nm and color indices *g* – *r* = 0.70 ± 0.10, *r* – *i* = 0.25 ± 0.06, *i* – *Z* = -0.27 ± 0.10, and *Y* – *J* = 0.41 ± 0.10. 2024 YR₄ has a spectrum that best matches R-type and Sa-type asteroids and a diameter of ~30–65 m using our measured absolute magnitude of 23.9 ± 0.3 mag and assuming an albedo of 0.15–0.4. The lightcurve of 2024 YR₄ shows ~0.4 mag variations with a rotation period of ~1170 s. We use photometry of 2024 YR₄ from Gemini and other sources taken between 2024 December to 2025 February to determine the asteroid’s spin vector and shape, finding that it has an oblate, ~3:1 axial ratio and a pole direction of *λ*, *β* = ~42°, ~25°. Finally, we compare the orbital elements of 2024 YR₄ with the near-Earth object population model and find that its most likely sources are resonances between the inner and central Main Belt.

*Unified Astronomy Thesaurus concepts: Apollo group (58); Near-Earth objects (1092); Asteroid rotation (2211); Asteroid surfaces (2209)*

## 1. Introduction

Earth-crossing asteroids (ECAs) are asteroids whose orbital trajectories cross the Earth’s, coming within its 0.983 au perihelion, *q*, and 1.017 au aphelion, *Q*, distances. By definition, ECAs belong to the Apollo near-Earth object (NEO) class with semimajor axes, *a* > 1 au and *q* < 1.017 au, and the Aten NEO class with *a* < 1 au and *Q* > 0.983 au. ECAs present scientific opportunities for detailed study of close-approaching NEOs, e.g., M. Granvik et al. (2013) and R. P. Binzel et al. (2015). Interactions with the Earth’s tides during close-approaching asteroids can affect the structural integrity of asteroids, causing changes in their surface material properties (R. P. Binzel et al. 2010) or completely disrupt them, making Earth encounters a source of some NEOs (M. Granvik & K. J. Walsh 2024; D. Nesvorný et al. 2024). Additionally, a portion of ECAs are a source of impacts on the Earth and the Moon affecting their total impact flux (S. Mazrouei et al. 2019; B. A. Cohen et al. 2023). Thus, ECAs provide examples of useful study on the effect of close approaches on the physical properties of asteroids and the impact chronology of the Earth and Moon.

The majority of ECAs originate from sources in the inner Main Belt between 2.2 au and 2.5 au (M. Granvik et al. 2018). Asteroids leave the Main Belt due to the Yarkovsky effect causing their semimajor axes to evolve, increasing for prograde-spinning asteroids and decreasing for asteroids that are spinning retrograde (D. Vokrouhlický et al. 2015). As asteroids evolve in their semimajor axis due to the Yarkovskyy effect, they cross resonances such as the *ν*₆ resonance that defines the inner border of the Main Belt at 2.2 au, the 3:1 mean motion resonance (MMR) with Jupiter at 2.5 au, and various weaker resonances located between 2.2 au and 2.5 au (M. Granvik et al. 2017). The interaction between the orbits of these asteroids and the resonances causes their orbits to chaotically evolve, sending them on trajectories where they can encounter the Earth (J. Wisdom 1983; P. Farinella et al. 1993).

While the majority of inner Main Belt asteroids belong to the siliceous S complex, ~20% of inner Main Belt asteroids belong to the more primitive and carbonaceous C complex (F. E. DeMeo & B. Carry 2013). This results in the majority of C-complex NEOs originating from the inner region of the Main Belt (R. P. Binzel et al. 2019). Additionally, a considerable portion of NEOs can also belong to the X complex, whose compositions span enstatite chondrites and achondrite, metallic and stony iron compositions (E. A. Cloutis et al. 1990; S. J. Bus & R. P. Binzel 2002; P. Vernazza et al. 2009; F. E. DeMeo et al. 2015; C. Avdellidou et al. 2022). While the orbits of NEOs and their likely sources within the Main Belt can provide constraints on their composition (R. Jedicke et al. 2022), the information on

<figure><img src="image_2.png" /></figure>

<footnote n="1">¹Eureka Scientific, Oakland, CA 94602, USA</footnote>

<footnote n="2">²Charles University, Faculty of Mathematics and Physics, Institute of Astronomy, 180 00 Prague, Czech Republic</footnote>

<footnote n="3">³Institute for Astronomy, University of Hawai'i at Mānoa, Honolulu, HI 96822, USA</footnote>

<footnote n="4">⁴BSA Osservatorio (K76), 12038 Savigliano, Cuneo, Italy</footnote>

<footnote n="5">⁵Griffith Observatory, Los Angeles, CA 90027, USA</footnote>

<footnote n="6">⁶Université Côte d'Azur, CNRS Lagrange, Observatoire de la Côte d'Azur, F 06304, Nice, France</footnote>

<footnote n="7">⁷University of Leicester, School of Physics and Astronomy, Leicester, LE1 7RH, UK</footnote>

<footnote n="8">⁸W. M. Keck Observatory, Waimea, HI 96743, USA</footnote>

<footnote n="9">⁹International Gemini Observatory/NSF NOIRLab, Casilla 603, La Serena, Chile</footnote>

<footnote n="10">¹⁰These authors contributed equally to this work.</footnote>
<figure><img src="image_3.png" /><figcaption>**Figure 1.** Panel (a): the first of four *o*-band ATLAS, Rio Hurtardo telescope discovery images of 2024 YR₄ from 2024 December 27 05:42:49 UTC. The asteroid moved at a rate of 22.8 per hour (9.11 per day) in the northwest direction. The asteroid makes a ~6 pixel trail (~11") in the 30 s ATLAS exposures, indicated by the red circle. Panel (b): the same as panel (a) but shows the image after subtracting static sources. Despite the presence of nearby stars, the asteroid is detected cleanly in the subtracted images. Panel (c): the same as panel (a), but the second of four *o*-band images containing 2024 YR₄ taken on 2024 December 27 05:46:04 UTC. Panel (d): the same as panel (c) but shows the image after subtracting static sources. The asteroid was detected with an apparent magnitude of *o* = 16.54 in panel (a) and *o* = 15.80 in panel (c). The large black areas in the subtracted images are regions of saturated pixels from bright stars. The direction of the asteroid and cardinal directions are indicated in each figure.</figcaption></figure>

the composition of NEOs is determined directly through observations covering visible and near-infrared wavelengths (F. E. DeMeo et al. 2009).

This Letter discusses the discovery of ECA 2024 YR₄ by the Asteroid Terrestrial-impact Last Alert System (ATLAS; J. L. Tonry et al. 2018) telescope and observations taken at Gemini South and the determination of its physical shape model. We also adapt the techniques described by B. T. Bolin et al. (2020, 2021, 2025) of using multiband photometry to constrain the physical and taxonomic properties of 2024 YR₄. Finally, we will use the lightcurve inversion techniques established by J. Hanuš et al. (2011, 2018a) on publicly sparse and dense data to determine the spin vector and shape of 2024 YR₄ and test its likely source within the Main Belt using the NEO population model (A. Morbidelli et al. 2020; D. Nesvorný et al. 2023, 2024).

## 2. Observations

The ATLAS Rio Hurtado telescope in Chile, with Minor Planet Center (MPC) observing code W68, made the first discovery observations of 2024 YR₄ on 2024 December 27 05:42:49 UTC, as seen in panels (a)–(d) of Figure 1. The asteroid was discovered at R.A. and decl. of 08:56:40.97, −00:16:11.93 and was located 0.996 au from the Sun, 0.017 au from the Earth, and at a phase angle of 43.2 and an apparent

magnitude of ~16.17 in the ATLAS *o*-band filter (L. Denneau et al. 2024). The ATLAS camera has a pixel scale of 186, an “orange” *o*-band custom filter providing wavelength coverage between 560 nm and 820 nm, and an effective wavelength of 663 nm (J. L. Tonry et al. 2018). The asteroid was detected in all four *o*-band images taken in a 3160 s interval from 2024 December 27 05:42:49 UTC to 2024 December 27 06:35:30 UTC. The asteroid was moving northwest at ~22" minute⁻¹, resulting in the detections forming a trail ~11" long (panels (a)–(d), Figure 1).

A director’s discretionary time request (DDT) was granted at Gemini South to observe 2024 YR₄ on 2025 February 7 02:23:46 UTC under program GS-2025A-DD-102 (PI: Bolin). The asteroid was located at R.A., decl. = 08:04:08.66, +13:33:24.31, 1.367 au from the Sun and 0.399 au from the Earth and had a phase angle of 14.8 during the 2025 February 7 UTC observations. The Gemini Multi-Object Spectrograph (GMOS) instrument (I. M. Hook et al. 2004) was used in imaging mode to observe 2024 YR₄ in *g*, *r*, *I*, and *Z* filters. The GMOS camera comprises a 5.5 × 5.5 field-of-view Hamamatsu array with an effective pixel scale of 0.08. The camera was used in 2 × 2 binning mode, giving an effective pixel scale of 0.16. The GMOS *g*, *r*, and *i* filters are equivalent to Sloan Digital Sky Survey (SDSS) *g*, *r*, and *i* filters with effective wavelengths of 475 nm, 630 nm, and 780 nm (M. Fukugita et al. 1996).
<figure><img src="image_4.png" /><figcaption>**Figure 2.** Top left panel: a coadd stack of 11 × 200 s g-filter images of 2024 YR₄ with a red 5" wide double arrow for scale. The cardinal directions are shown with yellow arrows. Top right panel: a coadd stack of 12 × 200 s *r* filter images of 2024 YR₄. Bottom left panel: a coadd stack of 8 × 200 s *i* filter images of 2024 YR₄. Bottom right panel: a coadd stack of 8 × 60 s Z filter images of 2024 YR₄. The scale and orientation of the *r*-, *i*-, and Z-band panels are the same as in the g-band panel.</figcaption></figure>

A filter was used for coverage past 800 nm equivalent to the WFCAM Z with an effective wavelength of 880 nm (M. Casali et al. 2007). This filter has the advantage of being equivalent to the SDSS *z* filter but avoids telluric absorption features near 950 nm (S. T. Hodgkin et al. 2009). Observations of 2024 YR₄ were also taken on 2025 February 23 02:13:17 UTC when the asteroid was located at R.A., decl. = 08:04:08.66, 13:33:24.31, 1.520 au from the Sun and 0.598 au from the Earth and had a phase angle of 21.7, but only exposures in *i* band were taken. During both the 2025 February 7 UTC and 2025 February 23 UTC observing dates, 200 s exposures were used for all filters, and the telescope was tracked at the rate of motion of 2024 YR₄.

During the 2025 February 7 UTC Gemini S observations, the measured seeing in the *r* band was ~0.8 and the air mass ranged from 1.43 to 1.50 during the ~2 hr 35 minute observing sequence. We acquired 11 g-band images, 12 *r*-band images, 8 *i*-band images, and 8 Z-band images. The *g*, *r*, *i*, and Z filters changed between exposures in an *rgiZrgriZgr* sequence to smear out the brightness variations in the asteroid's lightcurve and limit its effect on the color measurements. The *DRAGONS* image pipeline was used with bias and flat-field calibration frames to detrend the data (K. Labrie et al. 2023). Images of 2024 YR₄ when it intersected a background star were discarded. A mosaic showing 2024 YR₄ in the coadded *g*, *r*, *i*, and Z frames is shown in Figure 2.

Additionally, we obtained observations of 2024 YR₄ with Keck I on 2025 February 12 07:26:30 UTC using the Multi-Object Spectrometer for Infrared Exploration (MOSFIRE) under program R379 (PI: Bolin). On 2025 February 12 UTC, 2024 YR₄ had a heliocentric distance of 1.417 au, a geocentric distance of 0.461 au, and a phase angle of 17.4. MOSFIRE has a plate scale of 0.18 pixel⁻¹ and was used in imaging mode (I. S. McLean et al. 2012). Observations of 2024 YR₄ were taken with the *Y* filter (possessing a central wavelength of 1048 nm and FWHM of 152 nm) and the *J* filter (possessing a central wavelength of 1253 nm and of FWHM 200 nm). Seeing measured for stars in fields near the asteroid in *J* band was ~0.8. The telescope was tracked at the nonsidereal motion of 2024 YR₄, and an exposure time of 180 s was used. A nearby solar analog star was also observed to provide a calibration reference.

# 3. Results

## 3.1. Orbit and Source Population

Astrometry of 2024 YR₄ from observing dates was reported to the MPC (G. V. Williams 2025a, 2025b). Additional astrometry was reported by ~440 observations of 2024 YR₄ between 2024 December 25 UTC and 2025 March 1 UTC.<fnref n="11" /> Table 1 shows the six orbital element solution computed by

<footnote n="11">¹¹ https://minorplanetcenter.net/db_search/show_object?utf8=%E2%9C%93&object_id=2024+YR4</footnote>
<figure><img src="image_5.png" /><figcaption>**Figure 3.** Top panel: edge-on ecliptic view of the orbits and positions of 2024 YR₄ (black), Mercury (red), Venus (blue), Earth (purple), and Mars (green) at the time of the discovery of 2024 YR₄ on 2024 December 27 05:42:49. Bottom panel: the same as the top panel, except from the ecliptic pole. A close-up of the positions of 2024 YR₄ and the Earth is shown in an inset. This orbital diagram was generated using REBOUND (H. Rein & S.-F. Liu 2012; H. Rein & D. S. Spiegel 2015).</figcaption></figure>

<table><caption>**Table 1**
Orbital Elements of 2024 YR₄ Taken from JPL HORIZONS (Accessed on 2025 March 4 UTC) Based on ~440 Observations Submitted to the MPC Between 2024 December 25 UTC and 2025 March 1 UTC</caption><thead><tr><th colspan="2">Heliocentric Elements</th></tr><tr><th>Epoch<br>(JD)</th><th>2460800.5</th></tr></thead><tbody><tr><td>Time of perihelion, T<sub>p</sub> (JD)</td><td>2460636.9175586 ± (3.76 × 10<sup>-5</sup>)</td></tr><tr><td>Semimajor axis, a (au)</td><td>2.5158656 ± (2.35 × 10<sup>-5</sup>)</td></tr><tr><td>Eccentricity, e</td><td>0.66154790 ± (3.35 × 10<sup>-6</sup>)</td></tr><tr><td>Perihelion, q (au)</td><td>0.851499970 ± (4.87 × 10<sup>-7</sup>)</td></tr><tr><td>Aphelion, Q (au)</td><td>4.1802311 ± (3.90 × 10<sup>-5</sup>)</td></tr><tr><td>Inclination, i (deg)</td><td>3.4081731 ± (1.22 × 10<sup>-5</sup>)</td></tr><tr><td>Ascending node, Ω (deg)</td><td>271.36561725 ± (8.89 × 10<sup>-6</sup>)</td></tr><tr><td>Argument of perihelion, ω (deg)</td><td>134.3613663 ± (1.54 × 10<sup>-5</sup>)</td></tr><tr><td>Mean Anomaly, M (deg)</td><td>40.402628 ± (5.7 × 10<sup>-4</sup>)</td></tr></tbody></table>

**Note.** The osculating orbital elements are shown for the Julian date (JD) epoch 2460800.5. The 1σ uncertainties are given in parentheses.

JPL HORIZONS using these observations.<fnref n="12" /> The asteroid has an Apollo-type orbit with $a > 1$ au, and a perihelion takes it inside the orbit of the Earth. The Earth minimum orbit

intersection distance according to JPL HORIZONS is $2.82 \times 10^{-3}$ au.

The orbital and location of 2024 YR₄ at the time of its discovery on 2024 December 27 UTC are shown in Figure 3 based on values from JPL Horizons.<fnref n="13" /> We compared the orbit elements, *a*, *e*, *i*, and absolute magnitude *H* (see following Section 3.2) of 2024 YR₄ with the NEOMOD3 population model (D. Nesvorný et al. 2024), suggesting its most likely source is the 3:1 MMR with Jupiter resonance located in between the inner and central Main Belt regions at 2.5 au with a 73.9% probability. The next most likely location, with a 9.8% chance is the $ν_6$ resonance located at the inner edge of the Main Belt at 2.2 au. We combine our source probabilities for 2024 YR₄ with the NEO albedo model of A. Morbidelli et al. (2020) to estimate its albedo, $p_v$, finding a predicted value of ~0.18.

## 3.2. Color Photometry and Spectral Classification

We measured the photometry of 2024 YR₄ in the Gemini *g*, *r*, *i*, and *Z* images using a 1.12 aperture and a sky-median subtraction annulus with an inner and outer radius of 2.08 and 2.88. Local solar analog stars from the Pan-STARRS catalog (K. C. Chambers et al. 2016) were used to calibrate the

<footnote n="12">¹² https://ssd.jpl.nasa.gov/tools/sbdb_lookup.html#/?sstr=2024%20YR4, solution date 2025 March 1 UTC, accessed on 2025 March 4 UTC.</footnote>

<footnote n="13">¹³ https://ssd.jpl.nasa.gov/horizons/app.html#/</footnote>
<figure><img src="image_6.png" /><figcaption>**Figure 4.** The $a^*$ parameter vs. $i-z(Z)$ colors of 2024 $YR_4$ from our measurements and the $a^*$ and $i-z(Z)$ of C-, S-, and V-complex asteroids from Ž. Ivezić et al. (2001) and M. Jurić et al. (2002). We use the scheme of Ž. Ivezić et al. (2002) that sets the color of data points as a function of $a^*$ and $i-z$, where blue symbol colors correspond to C-complex asteroids, red symbol colors correspond to S-complex asteroids, and green symbol colors correspond to V-complex asteroids. We note we use the Z magnitude of 2024 $YR_4$ in place of its Z magnitude for its $i-z$ color calculation used in this plot. We also include the $a^*$ and $i-z$ determined with the mean S-, V-, and C-complex spectra taken from F. E. DeMeo et al. (2009) and the $a^*$ and $i-z$ determined from the Sun's colors (C. N. A. Willmer 2018).</figcaption></figure>

photometry according to the transformations described by J. L. Tonry et al. (2012). The brightnesses per bandpass of our measured photometry are $g=24.01 \pm 0.09$, $r=23.31 \pm 0.04$, $i=23.06 \pm 0.04$, and $Z=23.34 \pm 0.09$. The asteroid's $g-i$ color and spectral gradient are $g-i=0.95 \pm 0.10$ and 13% $\pm 33\%$ / 100 nm. The other multiband color indices of 2024 $YR_4$ are $g-r=0.70 \pm 0.10$, $r-i=0.25 \pm 0.06$, $i-Z=-0.27 \pm 0.10$, $r-Z=-0.02 \pm 0.10$, and the $a^*$ parameter, an indicator of spectral slope defined by Ž. Ivezić et al. (2001) as $a^*=(0.89 (g-r)+(0.45 (r-i))-0.57$ is $a^*=0.16 \pm 0.09$. We also measured the 2025 February 12 UTC Keck/MOSFIRE J and K photometry of both 2024 $YR_4$ and the solar analog using a 0.9 aperture and an inner and outer radius of 1.44 and 2.16. The per-bandpass brightness of our measured photometry is $Y=23.56 \pm 0.07$ and $J=23.15 \pm 0.07$, resulting in a color index of $Y-J=0.41 \pm 0.10$.

The $a^*$ and $i-Z(Z)$ of 2024 $YR_4$ are plotted in Figure 4, which has $a^*$ and $i-z(Z)$ on the border between the S-complex asteroids, which have on average $a^*=0.12 \pm 0.03$ and $i-z=-0.08 \pm 0.07$, and the V-complex asteroids, which have on average $a^*=0.15 \pm 0.11$ and $i-z=-0.46 \pm 0.04$ (F. E. DeMeo et al. 2009). However, this is still redder compared to the Sun, which has $a^*=-0.13$ and $i-z=0.03$ (C. N. A. Willmer 2018), and C-complex asteroids, which have on average $a^*=-0.09 \pm 0.02$ and $i-z=0.02 \pm 0.03$ (F. E. DeMeo et al. 2009). Additionally, the equivalent V-band brightness of 2024 $YR_4$ is $V=23.92 \pm 0.10$ determined by combining our g- and r-band measurements of the asteroid and the color transformation from K. Jordi et al. (2006). The $Y-J$ color of $0.41 \pm 0.10$ measured from our MOSFIRE photometry

is broadly consistent with the $Y-J$ colors of S-complex asteroids (M. Popescu et al. 2018).

We estimate the $H$ magnitude of 2024 $YR_4$ using our estimated $V$ magnitude and the HG phase function (E. Bowell et al. 1988):

$$H = V - 5 \log_{10}(r_h \Delta) + 2.5 \log_{10}[(1 - G) \Phi_1(\alpha) + G \Phi_2(\alpha)], \quad (1)$$

where $r_h$ is the 1.367 au heliocentric distance of 2024 $YR_4$, $\Delta$ is its geocentric distance of 0.399 au, and $\alpha$ is its phase angle of 14.8 of 2024 $YR_4$ on 2025 February 7 UTC. $G$ is the phase coefficient that we use for the value of 0.23, the average value for S-complex asteroids (P. Pravec et al. 2012; P. Vereš et al. 2015). $\Phi_1(\alpha)$ and $\Phi_2(\alpha)$ are the basis functions normalized at $\alpha=0^\circ$ described in E. Bowell et al. (1988). We obtain $H=23.91 \pm 0.10$ in agreement from the value calculated from JPL HORIZONS of $H=23.96 \pm 0.28$ but caution that the uncertainty on estimate of $H$ is underestimated due to the lack of information about the phase function (e.g., B. T. Bolin et al. 2022). Therefore, we adopt the larger uncertainty on $H$ taken from JPL HORIZONS of $\sim 0.3$.

For each g, r, i, and Z filter, we compute the spectral reflectance of 2024 $YR_4$, dividing its measured flux by the flux of a solar analog star. The reflectivity spectrum of 2024 $YR_4$ normalized to a wavelength of 550 nm is shown in Figure 5 and features a red slope from 470 nm to 770 nm, and absorption at 880 nm. We take the approach of B. T. Bolin et al. (2023) by comparing the spectrum of 2024 $YR_4$ with the Bus–DeMeo asteroid spectral catalog (F. E. DeMeo et al. 2009) as a test of its taxonomic spectral type. We determine the reduced-$\chi^2$
<figure><img src="image_7.png" /><figcaption>**Figure 5.** Reflectance photometric spectrum of 2024 YR₄ consisting of *g*, *r*, *i*, and *Z* observations of 2024 YR₄ on 2024 September 27 UTC. The λ<sub>eff</sub> locations of the *g*, *r*, *i*, and *Z* filters have been plotted as vertical dashed lines. The data points for the normalized reflectivity of 2024 YR₄ have been offset slightly from their location in the wavelength direction. The error bars on the spectrum data points correspond to 1σ uncertainty. The red cross indicates the spectrum has been normalized to unity at 550 nm. The spectral range of R-, Sr-, Sa-, and C-type asteroids from the Bus–DeMeo asteroid taxonomic catalog (F. E. DeMeo et al. 2009) are overplotted with the R-type spectrum most closely resembling the spectra of 2024 YR₄. The flat C-type spectrum serves as a baseline to contrast with the other asteroid spectra.</figcaption></figure>

statistic between the reflectance of 2024 YR₄ and S-complex asteroids (S, Sq, Sv, Q), C-complex (B, C, Cg, Cgh), X-complex (X, Xc, Xe, Xk, Xn), and assorted other asteroids (A, D, K, L, O, R, V). The closest match with the spectrum of 2024 YR₄ is to the R-type and Sa-type spectral classes with a reduced χ² of ~0.9 and 1.1. The next closest match after R-type and Sa-type asteroids is with Sr-type asteroids with a reduced χ² of 1.7. By comparison, the reduced χ² for the spectrum of 2024 YR₄ with V types and C types are ~2.5 and 11.8.

As a rough estimate of 2024 YR₄'s size, we estimate its visible albedo, $p_v$, assuming it has similar albedo properties as other small S-complex and R-type NEOs of ~0.15–0.40 (M. Delbo et al. 2017). This range contains the independent albedo estimate for 2024 YR₄ that we obtained by using with the NEO albedo model (A. Morbidelli et al. 2020) of 0.18 when considering the ~0.1 spread in albedos of small NEOs (M. Delbo et al. 2003). We use the albedo estimate and *H* magnitude of 2024 YR₄ to determine the diameter, *D*, of 2024 YR₄ using the equation $D = \frac{1329}{\sqrt{p_v}} 10^{-\frac{H}{5}}$ from A. W. Harris & J. S. V. Lagerros (2002), arriving at $D = 30–65$ m.

### 3.3. Lightcurve Photometry and Shape Model

The *g*, *r*, *i*, and *Z* GMOS photometry data of 2024 YR₄ from 2025 February 7 UTC were used to search for periodic variations in its brightness. The *g*–*r*, *r*–*i*, and *r*–*Z* colors computed from Section 3.2 were used to convert the *g*, *i*, and *Z* data into equivalent *r*-band magnitudes. The combined *r*-band-equivalent *g*–,*r*–,*i*–, and *Z*-time-series lightcurves are plotted in the top panel of Figure 6. The lightcurve shows evidence of variations larger than the ~0.1 mag 1σ photometric uncertainties of the individual data points in the lightcurve.

We take a similar approach as described by B. T. Bolin et al. (2024) to estimating the lightcurve period of the *r*-band

equivalent data by applying a Lomb–Scargle periodogram (LS; N. R. Lomb 1976; J. D. Scargle 1982) algorithm and a phase-dispersion minimization (PDM; R. F. Stellingwerf 1978) algorithm to the data. The LS and PDM algorithms result in finding an estimated lightcurve period of ~587–590 s as seen in the top and bottom panels of Figure 7. We use the approach of J. N. Purdum et al. (2021) to estimate the uncertainty on the determined period by removing $\sqrt{N}$ data points from the time-series lightcurve and repeating our periodogram estimation of the lightcurve period ~1000 times, resulting in a central value of ~586 s and a 1σ uncertainty estimate of ~142 s. These period estimates imply that 2024 YR₄ has a double-peaked synodic rotation period of ~1172 ± 284 s.

The central panel of Figure 6 shows the *r*-band equivalent lightcurve of 2024 YR₄ folded by the double-peaked rotation period of 1172 s. The result shows almost complete coverage in the lightcurve of 2024 YR₄ over its 1172 s rotation. We rebin the phased lightcurve of 2024 YR₄ into 0.075 wide bins in phase-dimensional space as seen in the bottom panel of Figure 6. We note that estimating an asteroid’s shape from a single lightcurve observation is affected by the degeneracy between viewing angle and axial ratio (e.g., B. T. Bolin et al. 2018b); therefore, we will take a multi-epoch approach to estimating the asteroid’s shape as described below.

To estimate a more accurate shape for 2024 YR₄, we use the lightcurve inversion method (M. Kaasalainen & J. Torppa 2001; M. Kaasalainen et al. 2001), which has been widely applied to derive the physical properties of small bodies, including near-Earth asteroids (NEAs). A similar approach was successfully used in the case of (3200) Phaethon, where photometric data from multiple observing geometries determined its rotational state and shape (J. Hanuš et al. 2018b).

For 2024 YR₄, we used a combination of dense lightcurves obtained from Gemini (MPC observatory code I11). We used only data in the *r* and *g* filters that are the most accurate, public data taken by the Very Large Telescope (VLT; MPC
<figure><img src="image_8.png" /></figure>

<figure><img src="image_9.png" /></figure>

<figure><img src="image_10.png" /><figcaption>**Figure 6.** Top panel: the *r*-band-filter-equivalent time-series lightcurve *g*, *r*, *i*, and *Z* observations of 2024 YR₄ taken by GMOS on 2025 February 7 UTC. The *g*, *i*, and *Z* data were converted to an equivalent *r*-band brightness by using the colors *g* − *r* = 0.70 ± 0.10, *r* − *i* = 0.25 ± 0.06, *r* − *Z* = −0.02 ± 0.10. The error bars on the data points equal their 1σ photometric uncertainties. Center panel: the same as in the top panel, but the data have been phased by a double-peaked rotation period of 1172 s. A sinusoidal lightcurve model with a double-peaked period of ~1172 s and amplitude of 0.40 mag is plotted in black. Bottom panel: the same as in the center panel, except that the data have been rebinned with 0.075 wide bins in phase-dimensional space.</figcaption></figure>

observatory code 309), and sparse photometry reported to the MPC that provided sufficient coverage of observing geometries. The modeling procedure followed the methodology outlined in our previous studies (D. Athanasopoulos et al. 2022; J. Hanuš et al. 2023).

We used photometric observations reported to the MPC, selecting data from observatories providing magnitude measurements with at least two decimal places, to ensure the highest possible accuracy. After initial modeling attempts, we further filtered out the MPC photometry, ending with three data sets. Namely, observations from multiple ATLAS (J. L. Tonry et al. 2018) stations (MPC observatory codes T05, T08, and W68) were combined into a single data set in the *o* filter, consisting of 25 individual measurements. Additional observations from the Catalina Sky Survey (S. Larson et al. 2003; MPC observatory code 703) and Pan-STARRS2 (K. C. Chambers et al. 2016; MPC observatory code F52) stations combined in the *G*-filter finalized the sparse data set.

The photometric data were processed following the methodology outlined in J. Hanuš et al. (2011) to prepare them for lightcurve inversion. This procedure included transformation to fluxes, epoch light-travel time correction, flux normalization to unit distance to the Sun and the observer, and unity. Any outliers or measurements affected by systematic errors were identified and removed.

The additional dense photometric observations of 2024 YR₄ were obtained from the European Southern Observatory (ESO) Science Archive as part of a long-term monitoring program (ESO Program ID 113.2690.002, PI Hainaut). The program, conducted in Service Mode at VLT UT1-Antu, supports the ESA Space Situational Awareness Near-Earth Objects Protection Program, which aims to characterize the physical properties of potentially hazardous asteroids. The observations were taken with the FORS2 instrument on 2025 January 21 UTC.

The VLT data are publicly available, and we retrieved them from the ESO database as raw images. The data were processed using the Minor Planet Observations (MPO) Canopus software package, following standard photometric reduction procedures (B. D. Warner et al. 2009). Bias and flat-field corrections were applied to all frames, followed by aperture photometry extraction, calibrated against known field stars to ensure accurate magnitude measurements.

The available photometric data set spans 42 days of observations, covering a range of phase angles from 45.7 to 14.8, which is critical for constraining the shape model. Table A1 summarizes the complete list of photometric measurements, including observation epochs, filter bands, and sources.

We conducted a broad period search within the range of 0.15–0.50 hr, encompassing the suspected synodic period of approximately ~0.32 hr derived from the photometric data set. A well-defined minimum was identified in the periodogram at *P*<sub>sid</sub> = 0.32439 hr (1168 s) (Figure 8). This solution remains stable against variations in the relative weighting of the individual data sets, confirming its robustness.

Adopting this sidereal period, we explored possible spin-vector orientations by testing a wide range of initial values isotropically distributed on a sphere. The results indicate a degree of sensitivity to the chosen data weighting. Several pole solutions were tested using different relative weight
<figure><img src="image_11.png" /><figcaption>**Figure 7.** Left panel: LS of lightcurve period vs. spectral power (N. R. Lomb 1976) for the *g*-filter data from the 2024 September 27 UTC Gemini N/GMOS observations. A peak in power is located at a single-peaked lightcurve period of 587 s. Right panel: phase-dispersion minimization analysis of lightcurve rotation period vs. Θ metric (R. F. Stellingwerf 1978). The Θ metric is minimized at single-peaked rotation periods of 1150 s, similar to the 1320 ± 227 s period found with the LS.</figcaption></figure>

<figure><img src="image_12.png" /><figcaption>**Figure 8.** The periodogram of 2024 YR4, computed near the suspected synodic period. The minimum at $P_{\text{sid}}$ = 0.32439 hr, indicated by the vertical line, corresponds to the global minimum. The horizontal line represents the rms threshold, indicating the statistical significance of the minimum.</figcaption></figure>

configurations, with the most prominent solution found at an ecliptic longitude and latitude of approximately $\lambda = 42^\circ$ and $\beta = -25^\circ$, respectively. This particular solution satisfies physical constraints, ensuring that the derived shape model rotates around its principal axis with maximum momentum of inertia. While alternative pole solutions cannot be entirely excluded, this solution appears to be the most plausible. This solution will be included in the Database of Asteroid Models from Inversion Techniques lightcurve inversion software package (J. Durech et al. 2015).

Figure 9 presents the fit to the photometric data, incorporating dense lightcurves obtained from VLT and Gemini in the *r* and *g* filters, along with sparse photometric measurements from ATLAS, the Catalina Sky Survey, and Pan-STARRS. The derived shape of 2024 YR4 is notably peculiar, resembling a highly flattened spheroid with nearly equal equatorial dimensions (Figure 10).

## 4. Discussion and Conclusions

The properties of 2024 YR₄ are similar to other small NEOs, has an R-type/S-complex composition, most likely originated from a resonances located inner Main Belt, and likely has moderate reflective properties implying a size of ~42 m. The exact origin within the Main Belt seems less clear though a clue may lie in its spin-vector orientation. As recent asteroid lightcurve spin-vector studies have shown, the spin direction of an asteroid can affect the way an asteroid's orbit evolves due to the thermal recoil Yarkovsky effect, with prograde asteroids drifting outward and retrograde asteroids drifting inwards (B. T. Bolin et al. 2018a; J. Hanuš et al. 2018a; D. Athanasopoulos et al. 2022). Since the spin direction of 2024 YR₄ is retrograde with its -39° ecliptic latitude, an origin from the inner Main Belt since its retrograde spin would cause it to drift inwards away from the 3:1 MMR at 2.5 au, its most likely escape path into the NEO population.
<figure><img src="image_13.png" /><figcaption>**Figure 9.** Lightcurve fit of 2024 YR4, showing dense photometric observations from VLT and Gemini in the *r* and *g* filters (top panels) and sparse data sets from ATLAS, Catalina Sky Survey, and Pan-STARRS (bottom three panels). The best-fit model is overlaid.</figcaption></figure>

Therefore, 2024 YR₄'s suspected retrograde spin may imply that its original location was the central Main Belt, located at 2.52 au–2.82 au from the Sun (D. Nesvorný et al. 2015). This would take 2024 YR₄'s origins away from the inner Main Belt, where S-complex asteroids dominate, to the central Main Belt, where C-complex asteroids are more plentiful, seemingly in tension with its taxonomic type (F. E. DeMeo & B. Carry 2014). However, we caution that several S-complex families

are located near the 3:1 MMR in the central Main Belt, such as the Rafita family located at 2.58 au, which could be a candidate source family for 2024 YR₄. In addition, recent lightcurve studies of asteroid families show that some asteroids can be located on the exterior side of an asteroid family's V shape and still have a retrograde spin (D. Athanasopoulos et al. 2024). We expect more ECAs to be found in the future by surveys targeting NEAs (e.g., S. Larson et al. 1998; J. L. Tonry et al. 2018) or
<figure><img src="image_14.png" /><figcaption>**Figure 10.** Convex shape model of 2024 YR₄ in three orthogonal views obtained using publicly available photometry of 2024 YR₄ from the MPS archive, VLT archive, and Gemini. The X-vs.-Z and Y-vs.-Z views show the edge-on view of the asteroid with the spin axis pointing in the Z-direction (ecliptic longitude and latitude equal to 42° and -25°). The asteroid is viewed from a pole-on view in the X-vs.-Y view.</figcaption></figure>

in large all-sky surveys (e.g., P. J. Whidden et al. 2019; M. E. Schwamb et al. 2023; J. R. Masiero et al. 2024).

## Acknowledgments

This study is based on observations obtained at the international Gemini Observatory, a program of NSF's NOIRLab, which is managed by the Association of Universities for Research in Astronomy (AURA) under a cooperative agreement with the National Science Foundation on behalf of the Gemini Observatory partnership.

Keck Observatory is located on Maunakea, land of the Kānaka Maoli people, and a mountain of considerable cultural, natural, and ecological significance to the indigenous Hawaiian people. The authors wish to acknowledge the importance and reverence of Maunakea and express gratitude for the opportunity to conduct observations from the mountain.

This work has been supported by the grant 25-16789S of the Czech Science Foundation.

The authors wish to thank Matthew Belyakov for help with the observations of 2024 YR₄, and Mauro Barbieri for help with searching the VLT data archive. The authors also wish to thank K. Wierzchos and C. Fuls for their help with measuring the astrometry from the Gemini images and submitting it to the MPC. The authors also wish to thank the team members of the Catalina Sky Survey, the Panoramic Survey Telescope and Rapid Response System, an ATLAS for submitting observations of 2024 YR₄ to the MPC that were used in this work.

This research has made use of data and/or services provided by the International Astronomical Union, Minor Planet Center.

Facilities: ATLAS, Gemini:South, Keck:I, VLT:Antu.

## Appendix

Table A1 includes a list of the photometry used in Section 3.3.

<table><caption>Table A1</caption><caption>Summary of 2024 YR<sub>4</sub> Photometry between 2024 December 27 and 2025 February 7 UTC</caption><thead><tr><th>Date<br>(MJD UTC)<br>(1)</th><th>Mag<br>(2)</th><th>Mag Unc.<br>(s)<br>(3)</th><th>Obs. Code<br>(4)</th></tr></thead><tbody><tr><td>60671.23807315</td><td>16.54</td><td>0.03</td><td>W68</td></tr><tr><td>60671.24033426</td><td>15.80</td><td>0.03</td><td>W68</td></tr><tr><td>60671.26732187</td><td>16.28</td><td>0.03</td><td>W68</td></tr><tr><td>60671.27464815</td><td>16.12</td><td>0.03</td><td>W68</td></tr><tr><td>60672.34588600</td><td>17.31</td><td>0.10</td><td>703</td></tr><tr><td>60672.35043700</td><td>17.12</td><td>0.10</td><td>703</td></tr><tr><td>60672.35271000</td><td>17.26</td><td>0.10</td><td>703</td></tr><tr><td>60672.48815185</td><td>17.10</td><td>0.05</td><td>T05</td></tr><tr><td>60672.48996875</td><td>17.30</td><td>0.05</td><td>T05</td></tr><tr><td>60672.49358611</td><td>17.14</td><td>0.03</td><td>T05</td></tr><tr><td>60672.49902662</td><td>16.98</td><td>0.03</td><td>T05</td></tr><tr><td>60673.52814200</td><td>17.49</td><td>0.13</td><td>F52</td></tr><tr><td>60673.54101000</td><td>17.13</td><td>0.13</td><td>F52</td></tr><tr><td>60673.55386300</td><td>17.35</td><td>0.13</td><td>F52</td></tr><tr><td>60673.56663600</td><td>17.37</td><td>0.13</td><td>F52</td></tr><tr><td>60674.40934711</td><td>18.05</td><td>0.07</td><td>T08</td></tr><tr><td>60674.41258137</td><td>18.07</td><td>0.07</td><td>T08</td></tr><tr><td>60674.41536956</td><td>18.00</td><td>0.05</td><td>T08</td></tr><tr><td>60674.44491667</td><td>17.72</td><td>0.04</td><td>T08</td></tr><tr><td>60675.28366667</td><td>18.04</td><td>0.09</td><td>W68</td></tr><tr><td>60675.28781644</td><td>18.45</td><td>0.09</td><td>W68</td></tr><tr><td>60675.30947500</td><td>18.27</td><td>0.27</td><td>703</td></tr><tr><td>60675.31180000</td><td>18.38</td><td>0.27</td><td>703</td></tr><tr><td>60675.31644000</td><td>18.90</td><td>0.27</td><td>703</td></tr><tr><td>60675.32319479</td><td>18.04</td><td>0.07</td><td>W68</td></tr><tr><td>60675.34909931</td><td>18.11</td><td>0.12</td><td>W68</td></tr><tr><td>60676.55924286</td><td>18.80</td><td>0.11</td><td>T05</td></tr><tr><td>60676.56982976</td><td>18.68</td><td>0.09</td><td>T05</td></tr><tr><td>60676.57969515</td><td>18.55</td><td>0.11</td><td>T05</td></tr><tr><td>60677.43338700</td><td>18.72</td><td>0.11</td><td>F52</td></tr><tr><td>60677.44491300</td><td>18.82</td><td>0.11</td><td>F52</td></tr><tr><td>60677.45652500</td><td>19.02</td><td>0.11</td><td>F52</td></tr><tr><td>60677.46819900</td><td>18.87</td><td>0.11</td><td>F52</td></tr><tr><td>60678.32803200</td><td>19.25</td><td>0.18</td><td>703</td></tr><tr><td>60678.33011000</td><td>19.60</td><td>0.18</td><td>703</td></tr></tbody></table>
<table><caption>**Table A1**
(Continued)</caption><thead><tr><th>Date<br>(MJD UTC)<br>(1)</th><th>Mag<br>(2)</th><th>Mag Unc.<br>(s)<br>(3)</th><th>Obs. Code<br>(4)</th></tr></thead><tbody><tr><td>60678.33218800</td><td>19.29</td><td>0.18</td><td>703</td></tr><tr><td>60678.33426500</td><td>19.09</td><td>0.18</td><td>703</td></tr><tr><td>60678.45297894</td><td>19.23</td><td>0.15</td><td>T08</td></tr><tr><td>60678.45618218</td><td>19.24</td><td>0.15</td><td>T08</td></tr><tr><td>60678.45939005</td><td>19.00</td><td>0.13</td><td>T08</td></tr><tr><td>60678.48978009</td><td>19.00</td><td>0.12</td><td>T08</td></tr><tr><td>60680.33804700</td><td>19.22</td><td>0.17</td><td>703</td></tr><tr><td>60680.34013000</td><td>19.37</td><td>0.17</td><td>703</td></tr><tr><td>60680.34428800</td><td>19.63</td><td>0.17</td><td>703</td></tr><tr><td>60680.39489045</td><td>19.24</td><td>0.17</td><td>T05</td></tr><tr><td>60680.44102885</td><td>19.38</td><td>0.19</td><td>T05</td></tr><tr><td>60696.11607700</td><td>21.55</td><td>0.05</td><td>309</td></tr><tr><td>60696.11669800</td><td>21.54</td><td>0.05</td><td>309</td></tr><tr><td>60696.11851100</td><td>21.55</td><td>0.05</td><td>309</td></tr><tr><td>60696.11911300</td><td>21.42</td><td>0.04</td><td>309</td></tr><tr><td>60696.12032800</td><td>21.43</td><td>0.04</td><td>309</td></tr><tr><td>60696.12093800</td><td>21.52</td><td>0.05</td><td>309</td></tr><tr><td>60696.12155200</td><td>21.53</td><td>0.05</td><td>309</td></tr><tr><td>60696.12215700</td><td>21.57</td><td>0.05</td><td>309</td></tr><tr><td>60696.12275900</td><td>21.57</td><td>0.05</td><td>309</td></tr><tr><td>60696.12337200</td><td>21.55</td><td>0.05</td><td>309</td></tr><tr><td>60696.12398200</td><td>21.42</td><td>0.04</td><td>309</td></tr><tr><td>60696.12458800</td><td>21.34</td><td>0.04</td><td>309</td></tr><tr><td>60696.12520900</td><td>21.34</td><td>0.04</td><td>309</td></tr><tr><td>60696.12581400</td><td>21.22</td><td>0.04</td><td>309</td></tr><tr><td>60696.12642500</td><td>21.15</td><td>0.03</td><td>309</td></tr><tr><td>60696.12703500</td><td>21.23</td><td>0.04</td><td>309</td></tr><tr><td>60696.12764300</td><td>21.24</td><td>0.04</td><td>309</td></tr><tr><td>60696.12826200</td><td>21.22</td><td>0.04</td><td>309</td></tr><tr><td>60696.12887900</td><td>21.39</td><td>0.04</td><td>309</td></tr><tr><td>60696.12948400</td><td>21.53</td><td>0.05</td><td>309</td></tr><tr><td>60696.13008500</td><td>21.65</td><td>0.05</td><td>309</td></tr><tr><td>60696.13069600</td><td>21.73</td><td>0.05</td><td>309</td></tr><tr><td>60696.13130900</td><td>21.69</td><td>0.05</td><td>309</td></tr><tr><td>60696.13191400</td><td>21.49</td><td>0.04</td><td>309</td></tr><tr><td>60696.13253600</td><td>21.46</td><td>0.04</td><td>309</td></tr><tr><td>60696.13314100</td><td>21.51</td><td>0.04</td><td>309</td></tr><tr><td>60696.13375100</td><td>21.51</td><td>0.05</td><td>309</td></tr><tr><td>60696.13619300</td><td>21.48</td><td>0.04</td><td>309</td></tr><tr><td>60696.13679900</td><td>21.51</td><td>0.04</td><td>309</td></tr><tr><td>60696.13740900</td><td>21.36</td><td>0.04</td><td>309</td></tr><tr><td>60696.13801400</td><td>21.32</td><td>0.04</td><td>309</td></tr><tr><td>60696.13862800</td><td>21.24</td><td>0.04</td><td>309</td></tr><tr><td>60696.13923000</td><td>21.18</td><td>0.03</td><td>309</td></tr><tr><td>60696.13984300</td><td>21.21</td><td>0.04</td><td>309</td></tr><tr><td>60696.14045700</td><td>21.18</td><td>0.03</td><td>309</td></tr><tr><td>60696.14107800</td><td>21.17</td><td>0.03</td><td>309</td></tr><tr><td>60697.33390700</td><td>22.01</td><td>0.20</td><td>F52</td></tr><tr><td>60697.34534000</td><td>21.92</td><td>0.20</td><td>F52</td></tr><tr><td>60697.35679700</td><td>21.51</td><td>0.20</td><td>F52</td></tr><tr><td>60697.36823700</td><td>21.64</td><td>0.20</td><td>F52</td></tr><tr><td>60713.10456210</td><td>23.38</td><td>0.22</td><td>I11</td></tr><tr><td>60713.12729625</td><td>23.63</td><td>0.29</td><td>I11</td></tr><tr><td>60713.13864208</td><td>23.38</td><td>0.19</td><td>I11</td></tr><tr><td>60713.14415887</td><td>23.35</td><td>0.19</td><td>I11</td></tr><tr><td>60713.15552038</td><td>23.51</td><td>0.23</td><td>I11</td></tr><tr><td>60713.16686808</td><td>23.29</td><td>0.17</td><td>I11</td></tr><tr><td>60713.19509238</td><td>23.48</td><td>0.18</td><td>I11</td></tr><tr><td>60713.20646260</td><td>23.21</td><td>0.14</td><td>I11</td></tr><tr><td>60713.10180008</td><td>23.24</td><td>0.11</td><td>I11</td></tr><tr><td>60713.11316511</td><td>23.56</td><td>0.14</td><td>I11</td></tr><tr><td>60713.14139774</td><td>23.44</td><td>0.12</td><td>I11</td></tr><tr><td>60713.15275886</td><td>23.35</td><td>0.12</td><td>I11</td></tr></tbody></table>

<table><caption>**Table A1**
(Continued)</caption><thead><tr><th>Date<br>(MJD UTC)<br>(1)</th><th>Mag<br>(2)</th><th>Mag Unc.<br>(s)<br>(3)</th><th>Obs. Code<br>(4)</th></tr></thead><tbody><tr><td>60713.15827524</td><td>23.11</td><td>0.08</td><td>I11</td></tr><tr><td>60713.16962233</td><td>23.21</td><td>0.09</td><td>I11</td></tr><tr><td>60713.18097070</td><td>23.42</td><td>0.10</td><td>I11</td></tr><tr><td>60713.19232942</td><td>23.38</td><td>0.10</td><td>I11</td></tr><tr><td>60713.10734983</td><td>23.63</td><td>0.12</td><td>I11</td></tr><tr><td>60713.12143592</td><td>23.73</td><td>0.14</td><td>I11</td></tr><tr><td>60713.13280506</td><td>23.38</td><td>0.09</td><td>I11</td></tr><tr><td>60713.14694628</td><td>23.40</td><td>0.09</td><td>I11</td></tr><tr><td>60713.17237680</td><td>23.33</td><td>0.09</td><td>I11</td></tr><tr><td>60713.18652172</td><td>23.35</td><td>0.09</td><td>I11</td></tr><tr><td>60713.20061316</td><td>23.32</td><td>0.09</td><td>I11</td></tr><tr><td>60713.11023326</td><td>23.32</td><td>0.22</td><td>I11</td></tr><tr><td>60713.13568818</td><td>23.52</td><td>0.26</td><td>I11</td></tr><tr><td>60713.14983347</td><td>23.31</td><td>0.22</td><td>I11</td></tr><tr><td>60713.16391275</td><td>23.39</td><td>0.25</td><td>I11</td></tr><tr><td>60713.18940483</td><td>23.54</td><td>0.26</td><td>I11</td></tr><tr><td>60713.20350766</td><td>23.37</td><td>0.29</td><td>I11</td></tr></tbody></table>

**Note.** Columns (1): observation date; column (2): r-band equivalent magnitude; column (3): $1\sigma$ magnitude uncertainty; column (4): observatory code.

ORCID iDs

Bryce T. Bolin https://orcid.org/0000-0002-4950-6323

Josef Hanuš https://orcid.org/0000-0002-2934-3723

Larry Denneau https://orcid.org/0000-0002-7034-148X

Roberto Bonamico https://orcid.org/0009-0001-6475-144X

Laura-May Abron https://orcid.org/0009-0000-8709-5273

Marco Delbo https://orcid.org/0000-0002-8963-2404

Josef Dřech https://orcid.org/0000-0003-4914-3646

Robert Jedicke https://orcid.org/0000-0001-7830-028X

Leo Y. Alcorn https://orcid.org/0000-0002-2250-8687

Aleksandar Cikota https://orcid.org/0000-0001-7101-9831

Swayamtrupta Panda https://orcid.org/0000-0002-5854-7426

Henrique Reggiani https://orcid.org/0000-0001-6533-6179

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