The Japan Aerospace Exploration Agency (JAXA) Hayabusa2# mission will perform a high-speed flyby of near-Earth asteroid (98943) Torifune on 5 July 2026, offering a rare opportunity to compare a pre-encounter spin and shape model derived from convex light-curve inversion with spacecraft imaging. We refined Torifune’s rotational state and convex shape model using previously published dense light curves, new photometry data obtained in late 2025, and selected sparse photometry data from the Asteroid Terrestrial-impact Last Alert System (ATLAS). A key methodological contribution is a per-measurement weighting scheme that accounts for heterogeneous data quality and cadence through light-curve scatter, rotational-phase-dependent brightness, and correlation-time downweighting of closely spaced measurements. We also estimated uncertainties with an apparition-constrained block bootstrap, resampling complete light curves while preserving the dense/sparse composition of the dataset and retaining coverage of each apparition. This procedure provides realistic uncertainties for the determined sidereal period, pole direction, and shape parameters. We refine the sidereal period to Psid=5.0215221−0.0000007+0.0000011 h and confirm a prograde spin state with the axis near the north ecliptic pole. The nominal pole solution is (λ,β)=(314°,+84°), with a 5.4° angular uncertainty. The dynamically equivalent ellipsoid has a/b=1.66−0.07+0.03, whereas its polar axis remains less well constrained, with b/c=1.49−0.29+0.44. All quoted uncertainties correspond to the two-sided 95% intervals of the block-bootstrap distributions. The forthcoming Hayabusa2# flyby should enable direct evaluation of which elements of this pre-encounter convex inversion model are robust, particularly the pole orientation and global silhouette, and may help constrain the remaining uncertainty in the polar dimension of the body.

The potentially hazardous asteroid (153814) 2001 WN_5 will pass inside the lunar distance on June 26, 2028, offering a rare opportunity to characterize a kilometer-scale near-Earth asteroid at high angular resolution. We aim to constrain the rotation state, shape, visible colors, geometric albedo, and taxonomy of 2001 WN_5 before its 2028 close approach. We combined new photometry from the 1.54 m Danish Telescope (DK154) with archival and survey observations from the Transiting Exoplanet Survey Satellite (TESS), Dark Energy Camera (DECam), Zwicky Transient Facility (ZTF), and the Asteroid Terrestrial-impact Last Alert System (ATLAS). These data were used to refine the rotation period, investigate the spin-shape solution space, derive visible colors, and estimate the geometric albedo from phase curve slopes. The available lightcurves do not uniquely constrain the sidereal rotation period, but the preferred pole solutions lie in the southern hemisphere in ecliptic coordinates. Visible colors from multiple independent datasets are consistent with the C-complex, while the TESS phase curve slopes give p_ V = 0.13±0.04, consistent with previous thermal-infrared albedo estimates. Combining the visible colors, albedo, and published near-infrared spectra, we classify 2001 WN_5 as most likely a B-type asteroid. The effective diameter is estimated to be D = 0.81 ± 0.13 km using the H-G model, while the linear model yields a slightly smaller value of 0.74 ± 0.11 km. During the 2028 encounter, 2001 WN_5 should reach an apparent diameter of about 0.5 arcsec, making it an excellent target for coordinated photometric, spectroscopic, and high-angular-resolution observations. Observations during the 2026-2027 apparition will be essential for improving its spin and shape model before its 2028 close approach.

On 27 December 2024, near-Earth object (NEO) 2024 YR_4 was discovered by the ATLAS survey and identified as a virtual impactor. A few weeks later, it eventually reached level 3 on the Torino Scale and was the first and only asteroid to be ever classified at that level. Here we report an intensive observational campaign combining time-series photometry in the visible, broadband visible and near-infrared colors, and low-resolution visible reflectance spectroscopy to assess its physical properties. Fourier analysis of the lightcurves yields a synodic rotation period of P = 19.46341 ± 0.00008 min, placing 2024 YR_4 among the fast rotators, even if such rotation is common for objects of similar H magnitude. Its visible and near-infrared colors and spectra are most consistent with an Sq or K taxonomic classification, though some ambiguity remains. Finally, its phase curve exhibits a notably shallow slope (G = 0.51 ± 0.11), from which we derive an absolute magnitude of H_R = 23.82±0.09 mag. After color correction and taking into account other models for the phase function, we report an absolute magnitude of H_V = 24.14±0.25 mag. These characterizations, rotation period, taxonomy, and surface properties, would have been crucial for risk assessment and mitigation planning had the initially high impact probability scenario been confirmed, underscoring the importance for planetary defense of a rapid, coordinated international response.

Contact binaries are found throughout the Solar System. The recent discovery of Selam, the satellite of main-belt asteroid (152830) Dinkinesh, by the NASA Lucy mission has made it clear that the term 'contact binary' covers a variety of different types of bimodal mass distributions and formation mechanisms. Only by modelling more contact binaries can this population be properly understood. We determined a spin state and shape model for the Apollo group contact binary asteroid (388188) 2006 DP14 using ground-based optical and radar observations collected between 2014 and 2023. Radar delay-Doppler images and continuous-wave spectra were collected over 2 d in February 2014, while 16 light curves in the Cousins R and SDSS-r filters were collected in 2014, 2022, and 2023. We modelled the spin state using convex inversion before using the shape modelling software to include the radar observations in modelling concavities and the distinctive neck structure connecting the two lobes. We find a spin state with a period of (5.7860 +/- 0.0001) h and pole solution of lambda=(180 +/- 121)degrees and beta=(-80 +/- 7)degrees with morphology indicating a 520 m long bilobed shape. The model's asymmetrical bimodal mass distribution resembles other small near-Earth asteroid contact binaries such as (85990) 1999 JV6 or (8567) 1996 HW1, which also feature a smaller 'head' attached to a larger 'body'. The final model features a crater on the larger lobe, similar to several other modelled contact binaries. The model's resolution is 25 m, comparable to that of the radar images used

The results of a two decade long R-band photometric survey of novae in M31 are presented. From these data, R-band light curves have been determined for 180 novae with data sufficient for estimating peak brightness and subsequent rate of decline. The data show a weak correlation of peak brightness with fade rate consistent with the well-known Maximum Magnitude versus Rate of Decline (MMRD) relation. As generally appreciated for Galactic novae, the large scatter in the MMRD relation precludes its use in determining distances to individual novae. The novae at maximum light are distributed with standard deviation σ=0.89 mag about a mean R-band absolute magnitude given by ⟨ M_R ⟩=-7.57±0.07. The overall M31 luminosity distribution is in excellent agreement with that found for Galactic novae suggesting that the nova populations in M31 and the Galaxy are quite similar. The notion that all novae can be characterized by a standard luminosity 15 d after maximum light (M_15) is also explored. Surprisingly, the distribution of M_15 values is characterized by a standard deviation only slightly smaller than that for novae at maximum light and thus offers little promise for precise extragalactic distance determinations. A dozen faint and fast novae that are likely to be previously unidentified recurrent novae have been identified from their position in the MMRD plot and in the M_15 distribution.

On 26 September 2022, the Double Asteroid Redirection Test (DART) spacecraft impacted Dimorphos, the satellite of binary near-Earth asteroid (65803) Didymos. This demonstrated the efficacy of a kinetic impactor for planetary defense by changing the orbital period of Dimorphos by 33 minutes (Thomas et al. 2023). Measuring the period change relied heavily on a coordinated campaign of lightcurve photometry designed to detect mutual events (occultations and eclipses) as a direct probe of the satellite's orbital period. A total of 28 telescopes contributed 224 individual lightcurves during the impact apparition from July 2022 to February 2023. We focus here on decomposable lightcurves, i.e. those from which mutual events could be extracted. We describe our process of lightcurve decomposition and use that to release the full data set for future analysis. We leverage these data to place constraints on the post-impact evolution of ejecta. The measured depths of mutual events relative to models showed that the ejecta became optically thin within the first ~1 day after impact, and then faded with a decay time of about 25 days. The bulk magnitude of the system showed that ejecta no longer contributed measurable brightness enhancement after about 20 days post-impact. This bulk photometric behavior was not well represented by an HG photometric model. An HG1G2 model did fit the data well across a wide range of phase angles. Lastly, we note the presence of an ejecta tail through at least March 2023. Its persistence implied ongoing escape of ejecta from the system many months after DART impact.

The results of a two-decade-long R -band photometric survey of novae in M31 are presented. From these data, R -band light curves have been determined for 180 novae with data sufficient for estimating the peak brightness and subsequent rate of decline. The data show a weak correlation of peak brightness with fade rate consistent with the well-known maximum magnitude versus rate of decline (MMRD) relation. As generally appreciated for Galactic novae, the large scatter in the MMRD relation precludes its use in determining distances to individual novae. The novae at maximum light are distributed with standard deviation σ = 0.89 mag about a mean R -band absolute magnitude given by 〈 M _R 〉 = −7.57 ± 0.07. The overall M31 luminosity distribution is in excellent agreement with that found for Galactic novae suggesting that the nova populations in M31 and the Galaxy are quite similar. The notion that all novae can be characterized by a standard luminosity 15 days after maximum light ( M _15 ) is also explored. Surprisingly, the distribution of M _15 values is characterized by a standard deviation only slightly smaller than that for novae at maximum light and thus offers little promise for precise extragalactic distance determinations. A dozen faint and fast novae that are likely to be previously unidentified recurrent novae have been identified from their position in the MMRD plot and in the M _15 distribution.

We present the results of a fourth planetary defense exercise, focused this time on the small near-Earth asteroid (NEA) 2023 DZ2 and conducted during its close approach to the Earth in 2023 March. The International Asteroid Warning Network (IAWN), with support from NASA's Planetary Defense Coordination Office (PDCO), has been coordinating planetary defense observational campaigns since 2017 to test the operational readiness of the global planetary defense capabilities. The last campaign focused on the NEA Apophis, and an outcome of that exercise was the need for a short burst campaign to replicate a real-life near-Earth object impact hazard scenario. The goal of the 2023 DZ2 campaign was to characterize the small NEA as a potential impactor and exercise the planetary defense system including observations, hypothetical risk assessment and risk prediction, and hazard communication with a short notice of just 24 hr. The entire campaign lasted about 10 days. The campaign team was divided into several working groups based on the characterization method: photometry, spectroscopy, thermal IR photometry and optical polarimetry, radar, and risk assessment. Science results from the campaign show that 2023 DZ2 has a rotation period of 6.2745 ± 0.0030 minutes; visible wavelength color photometry/spectroscopy/polarimetry and near-IR spectroscopy all point to an E-type taxonomic classification with surface composition analogous to aubrite meteorites; and radar observations show that the object has a diameter of 30 ± 10 m, consistent with the high albedo (0.49) derived from polarimetric and thermal IR observations.

The excited non-principal axis rotation state of asteroid Apophis can be described by two periods - rotation and precession. These periods (263 h and 27.38 h, respectively), together with other spin parameters and a convex shape model, were derived by [1] from photometric observations in 2012/13. Radar observations from the same apparition are consistent with the spin state derived from light curves and suggest that the shape of Apophis might be bifurcated [2]. During another favorable apparition in 2020/21, Apophis was observed extensively, and an updated shape and spin model was derived [3].We carried out photometric observations of Apophis between November 2020 and May 2021 with the Danish 1.5m telescope at La Silla, ESO. This data set consists of 1280 calibrated photometric measurements in Cousins R filter distributed over 67 individual nights.We used all available photometric data from 2012/13 and 2020/21 to determine Apophis's spin state and convex shape with the light curve inversion method [4]. Due to the large gap of eight years between observations, the rotation parameters cannot be determined uniquely. However, all acceptable models have about the same orientation in 2029 due to the same separation of eight years between 2021 and 2029. This enables us to reliably predict Apophis attitude during the close approach in 2029 and estimate the change of its spin state caused by the Earth's gravitation torque during the encounter.Acknowledgments: This work was supported by the grant 23-04946S of the Czech Science Foundation.References: [1] Pravec P. et al. (2014) Icarus, 233, 48. [2] Brozovic M. et al. (2018) Icarus, 300, 115. [3] Lee H.-J. et al. (2022) A&A, 661, L3. [4] Kaasalainen M. (2001) A&A, 376, 302.

We report physical and mutual orbit characteristics of near-Earth binary asteroid (163693) Atira. Using S-band (2380 MHz, 12.6 cm) radar observations from the Arecibo Observatory and several epochs of lightcurve observations from 2003 to 2019 with SHAPE modeling software, we determine the shape, size, rotational period, and mutual orbit of the primary and secondary components and the density of the primary component. We confirm the primary's sidereal rotation period to be 3.398521 +/- 0.000003 hr, and we find a likely spin axis orientation of ecliptic longitude and latitude (187 degrees, -53 degrees) +/- 12 degrees. We find the primary's volume-equivalent diameter to be 4.92 +/- 0.95 km and the secondary's volume-equivalent diameter to be 0.80 +/- 0.30 km. We find the primary component's density to be 1.43 +/- 0.87 g cm-3. We also find that the secondary has a semimajor axis of 7.8 +/- 0.5 km and a sidereal orbital period of 15.577 +/- 0.003 hr based on orbital calculations using delay and Doppler offsets between the primary and secondary and the timing of mutual events observed in lightcurve data. This work represents the first detailed analysis of the shape of an Atira-class asteroid.

The Double Asteroid Redirection Test (DART) spacecraft successfully performed the first test of a kinetic impactor for asteroid deflection by impacting Dimorphos, the secondary of near-Earth binary asteroid (65803) Didymos, and changing the orbital period of Dimorphos. A change in orbital period of approximately 7 min was expected if the incident momentum from the DART spacecraft was directly transferred to the asteroid target in a perfectly inelastic collision 1 , but studies of the probable impact conditions and asteroid properties indicated that a considerable momentum enhancement ( β ) was possible 2 , 3 . In the years before impact, we used lightcurve observations to accurately determine the pre-impact orbit parameters of Dimorphos with respect to Didymos 4 – 6 . Here we report the change in the orbital period of Dimorphos as a result of the DART kinetic impact to be −33.0 ± 1.0 (3 σ ) min. Using new Earth-based lightcurve and radar observations, two independent approaches determined identical values for the change in the orbital period. This large orbit period change suggests that ejecta contributed a substantial amount of momentum to the asteroid beyond what the DART spacecraft carried.

(155140) 2005 UD has a similar orbit to (3200) Phaethon, an active asteroid in a highly eccentric orbit thought to be the source of the Geminid meteor shower. Evidence points to a genetic relationship between these two objects, but we have yet to fully understand how 2005 UD and Phaethon could have separated into this associated pair. Presented herein are new observations of 2005 UD from five observatories that were carried out during the 2018, 2019, and 2021 apparitions. We implemented light curve inversion using our new data, as well as dense and sparse archival data from epochs in 2005–2021 to better constrain the rotational period and derive a convex shape model of 2005 UD. We discuss two equally well-fitting pole solutions (λ = 116.6^∘, β = -53.6^∘) and (λ = 300.3^∘, β = -55.4^∘), the former largely in agreement with previous thermophysical analyses and the latter interesting due to its proximity to Phaethon's pole orientation. We also present a refined sidereal period of P_sid = 5.234246 ± 0.000097 hr. A search for surface color heterogeneity showed no significant rotational variation. An activity search using the deepest stacked image available of 2005 UD near aphelion did not reveal a coma or tail but allowed modeling of an upper limit of 0.04 to 0.37 kg s^-1 for dust production. We then leveraged our spin solutions to help limit the range of formation scenarios and the link to Phaethon in the context of nongravitational forces and timescales associated with the physical evolution of the system.

(155140) 2005 UD has a similar orbit to (3200) Phaethon, an active asteroid in a highly eccentric orbit thought to be the source of the Geminid meteor shower. Evidence points to a genetic relationship between these two objects, but we have yet to fully understand how 2005 UD and Phaethon could have separated into this associated pair. Presented herein are new observations of 2005 UD from five observatories that were carried out during the 2018, 2019, and 2021 apparitions. We implemented light curve inversion using our new data, as well as dense and sparse archival data from epochs in 2005–2021, to better constrain the rotational period and derive a convex shape model of 2005 UD. We discuss two equally well-fitting pole solutions (λ = 116.°6, β = −53.°6) and (λ = 300.°3, β = −55.°4), the former largely in agreement with previous thermophysical analyses and the latter interesting due to its proximity to Phaethon’s pole orientation. We also present a refined sidereal period of P sid = 5.234246 ± 0.000097 hr. A search for surface color heterogeneity showed no significant rotational variation. An activity search using the deepest stacked image available of 2005 UD near aphelion did not reveal a coma or tail but allowed modeling of an upper limit of 0.04–0.37 kg s−1 for dust production. We then leveraged our spin solutions to help limit the range of formation scenarios and the link to Phaethon in the context of nongravitational forces and timescales associated with the physical evolution of the system.

Asteroid pairs are genetically related asteroids that recently separated (< few million years), but still reside on similar heliocentric orbits. A few hundred of these systems have been identified, primarily in the asteroid main belt. Here, we studied a newly discovered pair of near-Earth objects (NEOs): 2019 PR2 and 2019 QR6. Based on broad-band photometry, we found these asteroids to be spectrally similar to D-types, a type rare amongst NEOs. We recovered astrometric observations for both asteroids from the Catalina Sky Survey from 2005, which significantly improved their fitted orbits. With these refinements we ran backwards orbital integrations to study formation and evolutionary history. We found that neither a pure gravitational model nor a model with the Yarkovsky effect could explain their current orbits. We thus implemented two models of comet-like non-gravitational forces based on water or CO sublimation. The first model assumed quasi-continuous, comet-like activity after separation, which suggested a formation time of the asteroid pair 300(-70)(+120) yr ago. The second model assumed short-term activity for up to one heliocentric orbit (similar to 13.9 yr) after separation, which suggested that the pair formed 272 +/- 7 yr ago. Image stacks showed no activity for 2019 PR2 during its last perihelion passage. These results strongly argue for a common origin that makes these objects the youngest asteroid pair known to date. Questions remain regarding whether these objects derived from a parent comet or asteroid, and how activity may have evolved since their separation.

(99942) Apophis is a near-Earth asteroid that will closely approach to Earth in 2029; the minimum geocentric distance will be about 38,000 km. During the approach, the spin state of Apophis is expected to be altered by Earth's gravitation torque. The exact change depends on the orientation of Apophis during the close approach. Although the shape and spin-state model of Apophis was reconstructed from 2012/13 observations by Pravec et al. (2014, Icarus 233, 48), the precision of rotation parameters they derived was not sufficient to predict the orientation for 2029. We will present our analysis of photometric observations of Apophis that we carried out from 2020-11-16 to 2021-05-06 with the 1.54-m Danish telescope at La Silla. By applying the lightcurve inversion technique of Kaasalainen (2001, A&A 376, 302), we reconstructed the spin state and shape of Apophis. This new model agrees with the one reconstructed by Pravec et al. (2014) and with an updated model published by Lee et al. (2022, arXiv:2204.02540). We aimed to invert both the 2012-2013 and 2020-2021 data together and reconstruct the Apophis spin state with high precision. The long interval of observations would enable us to precisely determine the rotation and precession periods and thus reliably predict the orientation of Apophis during its 2029 flyby, calculate a change of its spin state, and predict how the Yarkovsky effect will influence the post-encounter orbit of Apophis, which is crucial for its post-2029 impact predictions.

The existence of asteroid pairs, two bodies on similar heliocentric orbits, reveals an. ongoing process of rotational fission among asteroids. This newly found class of objects has not been studied in detail yet. Here we choose asteroids (6070) Rheinland and (54827) 2001 NQ8, the most suitable pair for an in-depth analysis. First, we use available optical photometry to determine their rotational state and convex shapes. Rotational pole of Rheinland is very near the south ecliptic pole with a latitude uncertainty of about 10 degrees. There are two equivalent solutions for the pole of 2001 NQ8, either (72 degrees, -49 degrees) or (242 degrees, -46 degrees) (ecliptic longitude and latitude). In both cases, the longitude values have about 10 degrees uncertainty and the latitude values have about 15 degrees uncertainty (both 3 sigma uncertainties). The sidereal rotation period of 2001 NQ8 is 5.877186 +/- 0.000002. hr. Second, we construct a precise numerical integrator to determine the past state vectors of the pair's components, namely their heliocentric positions and velocities, and orientation of their spin vectors. Using this new tool, we investigate the origin of the (6070) Rheinland and (54827) 2001 NQ8 pair. We find a formal age solution of 16.34 +/- 0.04 kyr. This includes effects of the most massive objects in the asteroid belt (Ceres, Pallas, and Vesta), but the unaccounted gravitational perturbations from other asteroids may imply that the realistic age uncertainty is slightly larger than its formal value. Analyzing results from our numerical simulation to 250 kya, we argue against a possibility that this pair would allow an older age. Initial spin vectors of the two asteroids, at the moment of their separation, were not collinear, but tilted by 38 degrees +/- 12 degrees.

Observations of three near-Earth asteroids (NEAs) were made between 1993 and 2016. The resulting data were used to find preliminary pole and shape models for 1863 Antinous, (5836) 1993 MF, and (154244) 2002 KL6.

The Schulhof family, a tight cluster of small asteroids around the central main belt body (2384). Schulhof, belongs to a so far rare class of very young families (estimated ages less than 1 Myr). Characterization of these asteroid clusters may provide important insights into the physics of the catastrophic disruption of their parent body. The case of the Schulhof family has been up to now complicated by the existence of two proposed epochs of its origin. In this paper, we first use our own photometric observations, as well as archival data, to determine the rotation rate and spin axis orientation of the largest fragment (2384). Schulhof. Our data also allow us to better constrain the absolute magnitude of this asteroid, and thus also improve the determination of its geometric albedo. Next, using the up-to-date catalog of asteroid orbits, we perform a new search of smaller members in the Schulhof family, increasing their number by 50%. Finally, the available data are used to access Schulhof's family age anew. We now find that the younger of the previously proposed two ages of this family is not correct, resulting from a large orbital uncertainty of single-opposition members. Our new runs reveal a single age solution of about 800 kyr with a realistic uncertainty of 200 kyr.

We explored the statistical and compositional link between Chelyabinsk meteoroid and potentially hazardous asteroid (86039) 1999 NC43 to investigate their proposed relation proposed by Borovi\v{c}ka et al. (2013). Using detailed computation we confirm that the orbit of the Chelyabinsk impactor is anomalously close to 1999 NC43. We find about (1-3) x 10-4 likelihood of that to happen by chance. Taking the standpoint that the Chelyabinsk impactor indeed separated from 1999 NC43 by a cratering or rotational fission event, we run a forward probability calculation, which is an independent statistical test. However, we find this scenario is unlikely at the about (10-3 -10-2) level. We also verified compositional link between Chelyabinska and 1999NC43. Mineralogical analysis of Chelyabinsk (LL chondrite) and (8) Flora (the largest member of the presumed LL chondrite parent family) shows that their olivine and pyroxene chemistries are similar to LL chondrites. Similar analysis of 1999 NC43 shows that its olivine and pyroxene chemistries are more similar to L chondrites than LL chondrites (like Chelyabinsk). We also took photometric observations of 1999 NC43 over 54 nights during two apparitions (2000, 2014). The lightcurve of 1999 NC43 resembles simulated lightcurves of tumblers in Short-Axis Mode with the mean wobbling angle 20-30 deg. While, a mechanism of the non-principal axis rotation excitation is unclear, we can rule out the formation of asteroid in disruption of its parent body as a plausible cause, as it is unlikely that the rotation of an asteroid fragment from catastrophic disruption would be nearly completely halted. Considering all these facts, we find the proposed link between the Chelyabinsk meteoroid and the asteroid 1999 NC43 to be unlikely.