Shape and spin of asteroid 967 Helionape

AbstractKnowledge of the spin and shape parameters of the asteroids is very important for understanding of the conditions during the creation of our planetary system and formation of asteroid populations. The main belt asteroid and Flora family member 967 Helionape was observed during five apparitions. The observations were made at the Bulgarian National Astronomical Observatory (BNAO) Rozhen, since March 2006 to March 2016. Lihtcurve inversion method (Kaasalainen et al. (2001)), applied on 12 relative lightcurves obtained at various geometric conditions of the asteroid, reveals the spin vector, the sense of rotation and the preliminary shape model of the asteroid. Our aim is to contribute in increasing the set of asteroids with known spin and shape parameters. This could be done with dense lightcurves, obtained during small number of apparitions, in combination with sparse data produced by photometric asteroid surveys such as the Gaia satellite (Hanush (2011)).

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Photometry and shape modeling of Mars crosser asteroid (1011) Laodamia

Serbian Astronomical Journal ◽

10.2298/saj1489079a ◽

2014 ◽

pp. 79-85 ◽

Cited By ~ 1

Author(s):

G. Apostolovska ◽

Z. Donchev ◽

A. Kostov ◽

V. Ivanova ◽

G. Borisov ◽

...

Keyword(s):

Sparse Data ◽

Astronomical Observatory ◽

Shape Modeling ◽

Inversion Method ◽

Shape Parameters ◽

Spin Vector ◽

Shape Model ◽

Photometric Observations ◽

Vector Sense

An analysis of photometric observations of Mars crosser asteroid 1011 Laodamia conducted at Bulgarian National Astronomical Observatory Rozhen over a twelve year interval (2002, 2003, 2004, 2006, 2007, 2008, 2011, 2012 and 2013) is made. Based on the obtained lightcurves the spin vector, sense of rotation, and preliminary shape model of (1011) Laodamia have been determined using the lightcurve inversion method. The aim of this investigation is to increase the set of asteroids with known spin and shape parameters and to contribute in improving the model in combination with other techniques and sparse data produced by photometric asteroid surveys such as Pan-STARRS or GAIA.

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The physical and dynamical characteristics of the asteroid 4940 Polenov

Serbian Astronomical Journal ◽

10.2298/saj2102039v ◽

2021 ◽

pp. 39-49

Author(s):

E. Vchkova-Bebekovska ◽

N. Todorovic ◽

A. Kostov ◽

Z. Donchev ◽

G. Borisov ◽

...

Keyword(s):

Outer Part ◽

Astronomical Observatory ◽

Inversion Method ◽

Main Belt ◽

Dynamical Characteristics ◽

Photometric Observations ◽

Synodic Period ◽

Solar System Object ◽

Stability Time ◽

Astronomical Station

The asteroid (1986 QY4) 4940 Polenov is the first Solar system object whose 3D shape is determined using the observations from the newly built Astronomical Station Vidojevica (ASV). Here we present the results of photometric observations for Polenov, gathered from the ASV, and from the Bulgarian National Astronomical Observatory (BNAO) Rozhen, during 2014, 2019 and 2020 apparitions. Polenov is a 17.8km object located in the outer part of the main belt and belongs to the asteroid family Themis. We have determined the lightcurves, the synodic period of 4.161?0.001 h, as well as the solution for the shape and spin axis. Using the lightcurve inversion method, the combination of our lightcurves and the sparse data from ATLAS{HKO and ATLAS-MLO, we also found the sidereal period, indicating a retrograde rotation of the asteroid, with two possible mirrored pole solutions. The ratio of the largest to smallest reecting surface is about 1.4. In addition, we studied the dynamical properties of the asteroid and obtained a long stability time that exceeds 0.4 Gyrs.

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Asteroid collisions as origin of debris disks: Asteroid shape reconstruction from BNAO Rozhen photometry

Proceedings of the International Astronomical Union ◽

10.1017/s1743921319009426 ◽

2019 ◽

Vol 15 (S350) ◽

pp. 451-453

Author(s):

G. Apostolovska ◽

E. Vchkova Bebekovska ◽

A. Kostov ◽

Z. Donchev

Keyword(s):

Laboratory Experiments ◽

Extrasolar Planets ◽

Shape Reconstruction ◽

Inversion Method ◽

Debris Disks ◽

Shape Parameters ◽

Zodiacal Cloud ◽

Photometric Observations ◽

Different Shapes ◽

Asteroid Surface

AbstractAs a result of collisions during their lifetimes, asteroids have a large variety of different shapes. It is believed that high velocity collisions or rotational spin-up of asteroids continuously replenish the Sun’s zodiacal cloud and debris disks around extrasolar planets (Jewitt (2010)). Knowledge of the spin and shape parameters of the asteroids is very important for understanding collision asteroid processes. Lately photometric observations of asteroids showed that variations in brightness are not accompanied by variations in colour index which indicate that the shape of the lightcurve is caused by varying illuminations of the asteroid surface rather than albedo variations over the surface. This conclusion became possible when photometric investigations were combined with laboratory experiments (Dunlap (1971)). In this article using the convex lightcurve inversion method we obtained the sense of rotation, pole solutions and preliminary shape of 901 Brunsia.

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Optical observations of NEA 3200 Phaethon (1983 TB) during the 2017 apparition

Astronomy and Astrophysics ◽

10.1051/0004-6361/201833593 ◽

2018 ◽

Vol 619 ◽

pp. A123 ◽

Cited By ~ 7

Author(s):

M.-J. Kim ◽

H.-J. Lee ◽

S.-M. Lee ◽

D.-H. Kim ◽

F. Yoshida ◽

...

Keyword(s):

Optical Observations ◽

Inversion Method ◽

Observation Data ◽

Convex Model ◽

Convex Shape ◽

Axis Ratio ◽

Shape Model ◽

Spin Properties ◽

Pole Orientation ◽

Ecliptic Longitude

Context. The near-Earth asteroid 3200 Phaethon (1983 TB) is an attractive object not only from a scientific viewpoint but also because of JAXA’s DESTINY+ target. The rotational lightcurve and spin properties were investigated based on the data obtained in the ground-based observation campaign of Phaethon. Aims. We aim to refine the lightcurves and shape model of Phaethon using all available lightcurve datasets obtained via optical observation, as well as our time-series observation data from the 2017 apparition. Methods. Using eight 12-m telescopes and an optical imager, we acquired the optical lightcurves and derived the spin parameters of Phaethon. We applied the lightcurve inversion method and SAGE algorithm to deduce the convex and non-convex shape model and pole orientations. Results. We analysed the optical lightcurve of Phaethon and derived a synodic and a sidereal rotational periods of 3.6039 h, with an axis ratio of a∕b = 1.07. The ecliptic longitude (λp) and latitude (βp) of the pole orientation were determined as (308°, −52°) and (322°, −40°) via two independent methods. A non-convex model from the SAGE method, which exhibits a concavity feature, is also presented.

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Spins, shapes, and orbits for near-Earth objects by Nordic NEON

Proceedings of the International Astronomical Union ◽

10.1017/s1743921307003377 ◽

2006 ◽

Vol 2 (S236) ◽

pp. 309-320

Author(s):

Karri Muinonen ◽

Johanna Torppa ◽

Jenni Virtanen ◽

Jyri Näränen ◽

Jarkko Niemel ◽

...

Keyword(s):

Variation Method ◽

Inversion Method ◽

Shape Error ◽

The Novel ◽

Optical Telescope ◽

Shape Model ◽

Novel Approach ◽

Large Numbers ◽

Near Earth Objects ◽

Triaxial Shape

AbstractThe observing program of the Nordic Near-Earth-Object Network (NEON) accrues knowledge about the physical and dynamical properties of near-Earth objects (NEOs) using state-of-the-art inverse methods. Photometric and astrometric observations are being carried out at the Nordic Optical Telescope. Here, the NEON observations from June 2004–September 2006 are reviewed. Statistical orbital inversion is illustrated by the so-called Volume-of-Variation method. Statistical inversion for spins and shapes is carried using a simple triaxial shape model yielding analytical disk-integrated brightnesses for both Lommel-Seeliger and Lambert scattering laws. The novel approach allows spin-shape error analyses with the help of large numbers of sample solutions. Currently, such spin-shape solutions have been derived for 2002 FF12, 2003 MS2, 2003 RX7, and 2004 HW. For (1862) Apollo, an unambiguous spin-shape solution has been obtained using the conventional, convex inversion method and, for (1685) Toro and (1981) Midas, the conventional method has been applied repeatedly to map the regime of possible solutions.

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Photometric analysis for the spin and shape parameters of the C-type main-belt asteroids (171) Ophelia and (360) Carlova

Astronomy and Astrophysics ◽

10.1051/0004-6361/201526523 ◽

2015 ◽

Vol 581 ◽

pp. A55 ◽

Cited By ~ 4

Author(s):

Xiaobin Wang ◽

Karri Muinonen ◽

Yibo Wang ◽

Raoul Behrend ◽

Rui Goncalves ◽

...

Keyword(s):

Shape Parameters ◽

Main Belt ◽

Photometric Analysis

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A comparative analysis of the outer-belt primitive families

Astronomy and Astrophysics ◽

10.1051/0004-6361/202038536 ◽

2020 ◽

Vol 643 ◽

pp. A102

Author(s):

M. N. De Prá ◽

N. Pinilla-Alonso ◽

J. Carvano ◽

J. Licandro ◽

D. Morate ◽

...

Keyword(s):

Physical Properties ◽

Spectroscopic Data ◽

Planetary System ◽

Parent Body ◽

Comprehensive Analysis ◽

Asteroid Belt ◽

Main Belt ◽

Solar System Formation ◽

Visible Spectra ◽

Asteroid Families

Context. Asteroid families are witnesses to the intense collisional evolution that occurred on the asteroid belt. The study of the physical properties of family members can provide important information about the state of differentiation of the parent body and provide insights into how these objects were formed. Several of these asteroid families identified across the main belt are dominated by low-albedo, primitive asteroids. These objects are important for the study of Solar System formation because they were subject to weaker thermophysical processing and provide information about the early conditions of our planetary system. Aims. We aim to study the diversity of physical properties among the Themis, Hygiea, Ursula, Veritas, and Lixiaohua families. Methods. We present new spectroscopic data, combined with a comprehensive analysis using a variety of data available in the literature, such as albedo and rotational properties. Results. Our results show that Themis and Hygiea families, the largest families in the region, present similar levels of hydration. Ursula and Lixiaohua families are redder in comparison to the others and present no sign of hydrated members based on the analysis of visible spectra. Conversely, Veritas presents the highest fraction of hydrated members. Conclusions. This work demonstrates a diverse scenario in terms of the physical properties of primitive outer-belt families, which could be associated with dynamical mixing of asteroid populations and the level of differentiation of the parental body.

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Modeling asteroid shapes using BNAO Rozhen photometric data in combination with sparse data

10.5194/epsc2021-792 ◽

2021 ◽

Author(s):

Gordana Apostolovska ◽

Elena Vchkova Bebekovska ◽

Galin Borisov ◽

Andon Kostov ◽

Zahary Donchev

Keyword(s):

Weather Conditions ◽

Sparse Data ◽

Space Mission ◽

Physical Characteristics ◽

Photometric Data ◽

Inversion Method ◽

Physical Parameters ◽

Minor Planets ◽

Photometric Observations ◽

Dense Data

Our work aims to demonstrate how the use of our dense lightcurves in combination with sparse data from diverse sources will affect the results for obtaining the sidereal period, shape models, and ecliptic pole solution for a chosen asteroid. Photometric observations of minor planets are traditional at the Bulgarian National Astronomical observatory (BNAO) Rozhen. They started with photoelectric observations in 1991, and later have been continued as CCD photometric observations on all three telescopes: 2m Ritchey-Chreti&#233;n-Coud&#233;, 50cm/70cm, and 60cm Cassegrain. We hope that the new 1.5 m robotic telescope planned to be operational next year will be also partly devoted to the study of minor planets. Our target, 339 Dorothea, is a main-belt asteroid, a large member of the Eos dynamical family. For the last 8 years, between 2013 and 2021, the asteroid 339 Dorothea was observed at BNAO Rozhen during six apparitions and several dense lightcurve were obtained. We used these dense photometric data in lightcurve inversion method and reconstruct the model of the asteroid, determining its sidereal period, shape, and pole orientation. Afterward, using sparse data from the AstDys database with an accuracy of 0.01 mag in combination with the obtained dense data, new trials for calculating and improving the physical characteristics of the asteroid 339 Dorothea were made. Unlike very low photometric accuracy in ground-based sparse photometry, space missions have provided astronomers with sparse photometry with extremely high accuracy, for example, the ESA GAIA mission. The NEOWISE mission has observations only for a limited number of asteroids. Fortunately, we were able to find some sparse data for our target and use this accurate photometry in combination with our dense lightcurves for the reconstruction of the asteroid spin state and shape model. Due to bad weather conditions and limited allocation of observing time at the BNAO Rozhen dedicated to our project, we have at our disposal full and partial dense lightcurves obtained for several more asteroids in few different apparitions. Combining these dense data with ground-based or space mission sparse data will contribute to enlarging the database of asteroids with known physical characteristics. Enriching the number of asteroids with known physical parameters would provide more data for future statistical analysis and could help in answering the questions for the evolution of our Solar System.&#160;

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An iterative inversion method using transient electromagnetic data to predict water-filled caves during the excavation of a tunnel

Geophysics ◽

10.1190/geo2018-0253.1 ◽

2019 ◽

Vol 84 (2) ◽

pp. E89-E103 ◽

Cited By ~ 4

Author(s):

Yan Li ◽

Taiyue Qi ◽

Bo Lei ◽

Zongyang Li ◽

Wangping Qian

Keyword(s):

Warning System ◽

Inversion Method ◽

Tunnel Face ◽

Detection Techniques ◽

Electromagnetic Data ◽

Transient Electromagnetic ◽

Geometric Conditions ◽

Calculation Results ◽

Iterative Inversion ◽

Forward Calculation

The correct interpretation of full-space transient electromagnetic data has always constituted a critical safety problem during tunnel excavation projects. Targeting the interpretation of water-filled caves under narrow tunnel conditions, we have developed an iterative inversion method based on 3D finite-difference time-domain (FDTD) forward calculations and a direction algorithm. In total, 125 groups of 3D FDTD forward calculation results are analyzed to identify the correlations between the response data and the geometric conditions of the cave. A direction algorithm is established based on the correlations, thereby increasing the iterative inversion convergence speed. Using the proposed iterative inversion method, the location and volume of the water-filled cave in front of the tunnel face are successfully inverted. Through an iterative program, the inversion results of simulations involving the detection of water-filled caves under tunnel conditions are accurately analyzed, and the relative error is less than 10%. The application of the iterative inversion method to the Mingyue Mountain Tunnel project suggests that this method is capable of interpreting the size of water-filled caves and it is valid for a narrow tunnel face with only a single available measurement point. The proposed iterative inversion method can be used alone or in combination with other detection techniques, thereby providing engineers with a better early warning system for detecting water-filled caves in tunnels.

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V band photometry of asteroids from the All-Sky Automated Survey for Supernovae

10.5194/epsc2020-585 ◽

2020 ◽

Author(s):

Josef Hanus ◽

Ondrej Pejcha ◽

Ben Shappee

Keyword(s):

Physical Properties ◽

Photometric Data ◽

Spin Axis ◽

Inversion Method ◽

Small Aperture ◽

Shape Model ◽

V Band ◽

Rotation Periods ◽

Model Determination

The All-Sky Automated Survey for Supernovae (ASAS-SN) currently operates 24 small-aperture telescopes distributed around the globe to automatically survey the entire visible sky every night down to about g~18 mag. Between 2013 and 2018, the survey used a V filter with limiting magnitude V~17. Although primarily hunting for supernovae and other transients, asteroids are common intruders in the ASAS-SN's images. Here we present efforts to analyze the sparsely sampled V-band photometry extracted from the ASAS-SN images for >10,000 asteroids that get brighter than V~17 mag. The data span years 2013-2018 and sample up to 7 consequent apparitions for each asteroid. We provide details about the photometry extraction and calibration, photometry accuracy, and various statistics such as the typical number of data points per asteroid as a function of the brightness. Finally, we analyze the photometric data with the lightcurve inversion method and derive rotation periods, spin axis directions, and shapes for a sample of studied asteroids. We discuss the typical amount of data sufficient for a successful shape model determination. We compare derived physical properties with those available in the literature to illustrate the reliability of the ASAS-SN photometry.

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