A fast rotation period and large amplitude for PHA 2021 NY1

We report optical light curve observations of the near earth asteroid 2021 NY1. It was first observed with Pan-STARRS 1, Haleakala, on 2021, July 7 and has been classified by the Minor Planet Center as a potentially hazardous asteroid

Radar Shape Modeling of Binary Near-Earth Asteroid (385186) 1994 AW1

(385186) 1994 AW1 is a potentially hazardous asteroid and the first near-Earth asteroid suspected to be a binary [1,2]. It made a close approach to Earth in July 2015 getting as close as 25 lunar distances on the 15th. This flyby was a great opportunity for observations in photometry [3] and radar. Continuous-wave (CW) and Delay-Doppler imaging modes were used, first at Goldstone for the 14-19 July period (0.066-0.700 au), and then by Arecibo for 20-30 July (0.075-0.126 au). A range resolution of 150 m was achieved at Goldstone in bistatic configuration with Green Bank Telescope, while monostatic observations in S-band (2380 MHz, 12.6 cm) at Arecibo were obtained at resolutions of 30 m and 75 m. The rotation period of the primary (2.52 h) and orbital period of the secondary (22 h) derived from optical light curves were confirmed by these observations. The primary is about 600 m in diameter and the secondary is about half of the primary's size. A more recent but relatively distant approach (July 8, 2022; 0.11 au) allowed CW spectra to be obtained at Goldstone [4]. We also obtained new light curves on 2023 January 13-24 while it was at V ~16-17 mag. We used the TRAPPIST-South (I40, Chile) and -North (Z53, Morocco) [5] to gather 10 light curves in total. For four of them, brightness drops indicate mutual events between 1994 AW1 and its satellite. We then used our radar and optical datasets with SHAPE [6] to perform shape modeling of the primary component. We will present our preliminary 3D shape model, pole coordinates and system density. References: [1] Pravec, P. and Hahn, G. (1997) Icarus, 127 [2] Mottola, S. et al. (1995) LPIC, 26 [3] Warner D. B. (2016) MPB, 43 [4] Brozovic, M. et al. (2022) DPS 54. [5] Jehin, E. et al. (2011) The Messenger 145, 2–6. [6] Magri, C. et al. (2007) Icarus 186, 152-177

398P/Boattini a new JFC carbon-chain poor comet

E. Jehin, Y. Moulane, J. Manfroid, F. Pozuelos, M. Ferrais, D. Hutsemekers (STAR Institute, University of Liege, Belgium) report that they obtained with TRAPPIST-North (code=Z53, at Oukaimeden Observatory, Morocco) 0.6-m robotic telescope, three sets of observations of the recently recovered comet 398P/Boattini (= 2009 Q4 = 2020 P2, CBET 4829) on November 10, 15 and 20 UT under photometric conditions using HB cometary narrowband filters (Farnham et al. 2000)

TRAPPIST comet production rates: 19P/Borrelly, 67P/C-G, 104P/Kowal 2, C/2019 L3 (ATLAS), and C/2021 A1 (Leonard)

E. Jehin, Y. Moulane, J. Manfroid, M. Vander Donckt, F. Pozuelos, M. Ferrais, and D. Hutsemekers (STAR Institute, University of Liege) report that they obtained from TRAPPIST-North (code=Z53, Morocco) and TRAPPIST-South (code=I40, Chile) robotic telescopes (Jehin el al. 2011) recent observations using cometary HB narrowband filters (Farnham et al. 2000) for the following comets and computed preliminary production rates at 10.000 km using a Haser Model (Vp=Vd=1km/s) (Haser 1957)

Outburst of comet C/2021 A1 (Leonard) on January 7, 2021

We report about an outburst of comet C/2021 A1 (Leonard) that happened between January 6 and 8, 00:00 UT 2021. Observations were carried on with TRAPPIST-South (code=I40, Chile) robotic telescopes about every night since Dec 20 until Jan 25, using broad band and cometary HB narrowband filters (Jehin el al. 2011)

Shape Modeling of 1036 Ganymed from Radar and Lightcurve Data

Asteroid (1036) Ganymed was discovered in 1924 by Walter Baade. This asteroid is considered the largest Near-Earth object; however, its orbit is completely exterior to Earth's orbit, with a perihelion distance of 1.24 au. Many observations of this asteroid have been made, and for this research we used Arecibo and Goldstone radar data from 1998 and 2011, and lightcurves from numerous apparitions, including new lightcurves from TRAPPIST in early 2023. The Arecibo delay-Doppler images from four nights during Ganymed's 2011 apparition (0.36 au from Earth, its closest approach since discovery) are particularly helpful in revealing surface features. Taking the shape model of Hanuš et al. (2015, Icarus 256) as a starting point, we used SHAPE (Magri et al. 2007, Icarus 186) to develop a three-dimensional physical model of Ganymed. We find Ganymed to be approximately ellipsoidal with some bumps, with dimensions of about 42 × 41 × 39 km and a volume-equivalent diameter of 38 km. We confirm that Ganymed has a rotation period of 10.31 hours, with a pole direction near ecliptic (180, -75)

Radar shape modeling and physical characterization of the PHA 1998 OR2

On April 29th 2020, the potentially hazardous asteroid (52768) 1998 OR2 (herafter OR2) flew-by the Earth at a distance of 16.4 Lunar distances. OR2 is a near-Earth object of absolute magnitude H = 16 that can experience close approaches to Earth as close as 6 Lunar distances. During this fly-by we obtained high SNR Arecibo S-band (2380 MHz; 12.6 cm) radar delay-Doppler images between Apr 13-23. We also obtained polarimetric observations with the ToPol polarimeter [1] mounted on the Omicron-West 1-m telescope from the Calern Observatory, Nice, France. These polarimetric observations span a range of phase angles from 30° to 77° allowing detailed characterization of the positive branch of 1998 OR2 phase-polarization curve. We also obtained new photometric observations with the Trappist-North telescope [2] located at the Oukaimeden Observatory in Morroco. Using the radar delay-Doppler and the lightcurve observations, we derived a non-convex shape model of 1998 OR2. This model displays a typical top-shape (diamond-like) model with an equivalent diameter of 1.6 km. The spin axis solution is oriented toward 330° +- 10° of ecliptic longitude and 23° +- 10° of ecliptic latitude with a rotation period of 4.1084 +- 0.0001 hours. Top-shape asteroids are typical for near-Earth objects as it had been observed for the asteroids Bennu [3], Ryugu [4], or Moshup [5]. Radar shape modeling has already been proven to be effective in modeling these type of asteroid as the radar shape model of Bennu [3], that was obtained before the Osiris-Rex mission, proved to be highly accurate.OR2 delay-Doppler images are characterized by the presence of a large feature visible on the leading edge of the echo. The shape model shows that this feature is a crater located near the equator. The shape model also shows that there are other craters/concavities formations mostly located on one-side of OR2 while the other side is lacking large scale structures. The polarimetric observations of OR2 displays a phase-polarization curve typical of moderate albedo objects with a polarization of 8.3% at a phase angle of 77.5°. The degree of linear polarization (especially at large phase angles) of an asteroid is directly correlated with its albedo. At a similar phase angle, the low albedo asteroid (3200) Phaethon (pv = 0.107 +- 0.011 [6]) is displaying a polarization of 27.3% [7] while the high albedo object E-type 1998 WT24 (pv = 0.654 +- 0.13 [8]) only displays a polarization around 1.5% [9]. Polarimetric observations were also collected over several hours during the same nights in order to obtain time-series. Folding the polarimetric data according to the rotation period of OR2, we observed that the degree of linear polarization is dependant on the rotation phase angle. Such variation means that the surface of OR2 displays heterogeneities that can be either due to a variation of albedo or grain size over the surface. We also observe that the maximum of the polarization occurs when crater is facing the observer. In conclusion, we obtained new radar, polarimetric, and photometric data of 1998 OR2 during its close approach to Earth on April 2020. These observations allowed us to obtain a non-convex shape model displaying a spin axis orientation of (330°,23°) with a rotation period of P = 4.1084 +- 0.0001 hours. The shape model displays large scale structures like concavities and craters. The polarimetric observations display variation of the polarization locked with the rotation phase angle of 1998 OR2 that seems to be correlated with the large structures observed on the shape model

Photometry of 25 Large Main-belt Asteroids with TRAPPIST-North and -South

editorial reviewedDensely sampled lightcurves of 25 large main-belt asteroids were obtained with the TRAPPIST-South (TS) and TRAPPIST-North (TN) telescopes from 2017 to 2021. Those observations took place in support of an ESO large program aiming at observing a representative sample of large asteroids with the ESO VLT for precise shape determination from adaptive optics high-resolution imaging. Synodic rotation periods and lightcurve amplitudes have been determined for all but one target. Six asteroids were observed during two different apparitions. The data have been submitted to the ALCDEF database

Lightcurve Based Determination of 10 Hygiea'S Rotational Period With Trappist-North and -South

peer reviewedA densely-sampled lightcurve of the large main-belt asteroid 10 Hygiea was obtained with the TRAPPISTSouth (TS) and TRAPPIST-North (TN) telescopes in 2018 September and October. We found its synodic rotation period and amplitude to be 13.8224 ± 0.0005 h and 0.27 mag. The data have been submitted to the ALCDEF database

(65) Cybele is the smallest asteroid at hydrostatic equilibrium, why?

Context - Cybele asteroids constitute an appealing reservoir of primitive material genetically linked to the outer Solar system. The physical properties (size, shape) of the largest members can be directly measured with high-angular resolution imagers mounted on large (8-m class) telescopes.Aim - We took advantage of the bright apparition of the most iconic member of the Cybele population, (65) Cybele, in July and August 2021 to acquire high angular resolution images and optical light curves of the asteroid that were used to analyze its shape, topography and bulk properties (volume, density).Methods - Eight series of images were acquired with SPHERE+ZIMPOL on the Very Large Telescope (ESO Program ID 107.22QN.001; PI: Marsset) and combined with optical light curves to reconstruct the shape of the asteroid using the ADAM (Viikinkoski et al. 2015), MPCD (Capanna et al. 2013) and SAGE (Bartczak & Dudziński 2018) algorithms.Results - We will present Cybele's bulk properties, including its volume-equivalent diameter and average density, in the context of other low-albedo P-type asteroids. We will show that Cybele's shape and rotation state are entirely compatible to those of a Maclaurin equilibrium figure, opening up the possibility that D≥260 km (M≥1.4x10^19 kg) small bodies from the outer Solar System formed at equilibrium. We will further present the results of N-body simulations used to explore whether the equilibrium shape of Cybele is the result of a large resetting impact (similarly to the case of Hygiea; Vernazza et al. 2020), or if it is primordial (i.e., the result of early internal heating due to the radioactive decay of short- and long-lived radionuclides)