J/A+A/712/A124 Binary asteroids candidates (Lallemand+, 2026)
Detection and characterisation of binary asteroids candidates through stellar
occultations.
Lallemand R., Desmars J., Sicardy B., Liu Z., Tanga P., Liberato L.,
Carry B., Leroy A., Kilic Y., Assafin M., Siakas A., Abe L., Mary D.,
Casarramona F., Smith D., Antuszewicz D., Dauvergne J.-L., Langin G.,
Henarejos P., Phan P.-L., Braga-Ribas F., Castro A., Pal A., Sodor A.,
Cano Ruiz A., Pratt A., Noschese A., Manna A., Eberle A., Schweizer A.,
Wendelborn A., Marciniak A., Ziolkowski B., Begicarslan B., Kattentidt B.,
Tezcan C.T., Weber C., Schnabel C., Domingues C.A., Ziolek C., Sartini C.,
Schaefer C.M., McPartlin C., Kiss Cs., Blazewicz D., Deneuchatel D.,
Herald D.., Dunham D.W., Sailing D., Fonseca Morato E., Fernandez-Garcia E.,
Smith E., Gradovski E., Donate Lucas E., Garcia Navarro E., Kaan Uelgen E.,
Garcia F., Genc F., Margoti G., Arraras G., Schmidt G., Privett G.,
Krannich G., Lyzenga G., de Groot H., Perez-Garcia I., Kelkitli I.Z.,
Manek J., Flores-Martin J., Prat J., Bardecker J., Siegert J., Dunham J.,
Moore J., Reyes J.A., Maestre J.L., Ortiz J.L., Perla J., Spagnotto J.,
Getrost K., Bath K.-L., Okasaki K., Bender K., OConnell M., Jennings M.,
Margoti M., Icen M., Acar M., Fidencio Neto M., Altan M., Rottenborn M.,
Turchenko M., Alava Amat M.A., Kretlow M., Tekkesinoglu M., Takacs N.,
Castro-Morales N., Morales N., Erece O., Canales Moreno O., Santos Sanz P.,
Fini P., Maley P.D., Teckenburg P., Walker P., Martorell P., Gilge P.,
Zeleny P., Stuart P., Ashimbekova A., Denyer P., Sfair R., Nolthenius R.,
Piety R., Liu R., Jones R., Szakats R., Goncalves R., Pastor S.,
Chairetas S., Kalkan S., Oezel S., Oetken S., Alis S., Tsavdaridis S.,
Meister S., Sposetti S., Conard S., Tirak S., Fisek S., Swift T., Haymes T.,
Janik T., Nikitin V., Hanna W., Dahoumane R., Ogloza W., Stewart W.,
Beisker W., Liu Y., Avcioglu Y., Quinet S., Counilh J.-F., Irzyk M.,
Marlot C., Keijzer A., Pinard Y., Salomon T., Mollier T., Valat S.,
Kindt S., Souchu J., Vasseur S., Dequinze R., Couvee P., Lemoine P.,
Barroy P., Mercier P.-J., Andre P., Le Guen P., Schreurs O., Boutet M.,
Giraud M., Lecossois M., Serrau M., Conjat M., Herrier L., Rousselot L.,
Delpau J., Bourgeois J., Dalouzy J.-C., Gout J.-F., Pittet J.-F.,
Coliac J.-F., Dumont J.-L., Nombret J.-P., Masini J.-P., Arnould J.-P.,
Marquette J.-B., Arlic G., Denjean F., Cavaille F., Barbotin E.,
Bourdens D., Walliang D., Auvray I., Latge C., Lavault C., Stachowicz A.,
Jacquet E., Rizand C., Raffard J., Saillenfest M., Hussein K., Montarges M.,
Robichon N., Renner S., Lapeyrere V., Thuillot W., Vachier F.,
Hestroffer D., Vienne A., Vaubaillon J., Bourdens C., Boninsegna R.,
Lin M.-C., Chen Y.-L., Tsai S.H., Lee C.-E., Lee Y.-N., Lin Z.-Y.,
Lin H.-C., Wang C.-H., Shen A.T.L., Chuang T.-H., Chang C.-C., Watanabe Ha.,
Ida M., Togashi H., Asai A., Nemoto T., Hosoi K., Watanabe Hi., Isobe K.,
Yoshihara H., Horikawa T., Kitazaki K., Takimoto M., Yamamura H.,
Yamashita M., Yoshida F., Gourdon F.
<Astron. Astrophys. 712, A124 (2026)>
=2026A&A...712A.124L 2026A&A...712A.124L (SIMBAD/NED BibCode)
ADC_Keywords: Minor planets ; Photometry ; Optical
Keywords: methods: observational - minor planets, asteroids: general -
planets and satellites: detection -
planets and satellites: fundamental parameters
Abstract:
Binary asteroids provide key access to fundamental parameters of Solar
System remnants and planetary formations. However, the current
knowledge of binary asteroids remains strongly biased by observational
limitations, and main belt binary systems are still poorly
characterised since current techniques preferentially detect either
widely separated binaries through direct imaging or close and bright
systems via photometry and radar for near-Earth asteroids. In this
context, the high-precision astrometry of the Gaia mission has
revealed a new population of candidate binaries exhibiting dynamical
signatures consistent with unresolved companions. Stellar occultations
have therefore emerged as one of the most effective methods to confirm
the binary nature of a candidate and improve the current census of
intermediate-size systems.
This work is part of the GaiaMoons program and aims to characterise a
sample of 357 potential binary asteroid targets and to confirm or
refute their binary nature. The properties of these candidates were
derived from the high-precision photometric and astrometric
observations provided by the Gaia satellite.
This work is part of the GaiaMoons program, and our aim with it was to
characterise a sample of 357 potential binary asteroid targets and
confirm or refute their binary nature. The properties of these
candidates were derived from the high-precision photometric and
astrometric observations provided by the Gaia satellite.
Out of 165 observations, 76 led at least to one positive observation.
Among them, 33 with at least 2 positives for 24 objects that have
undergone unprecedented occultation observation campaigns, with 4
objects showing indications of binary or contact binary features
namely (1127) Mimi, (35420) 1998 AG6, (206) Hersilia and (36882)
2000 SW155. The resulting dataset provides, for the vast majority of
these objects, unique physical and astrometric constraints, as they
had never been observed through stellar occultations before. 89
observations with only negatives allowed to probe the near environment
of the targets.
GaiaMoons illustrates how stellar occultation campaigns, associated to
Gaia observations, generate a self-improving cycle to find new binary
systems: probe size and shape to constrain future observations. By
standardising this approach, we deliver critical data in unexplored
parameter spaces, resolving long-standing observational ambiguities.
Description:
Through this work we have presented new physical and astrometric
constraints derived from stellar occultations for 101 target asteroid
systems observed between October 2023 and February 2026. This study
represents the first dedicated effort targeting intermediate-size
objects in the 5-100km range through a coordinated occultation
strategy, rather than isolated single-object campaigns. In particular,
the occultation of (5044) Shestaka on October 23, 2024, gathered an
unprecedented number of participants for an object of this size.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
stations.dat 266 523 Observing station informations corresponding to
each chord described in the paper
list.dat 60 224 List of ligth curves
lc/* . 224 Individual light curves
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Byte-by-byte Description of file: stations.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 31 A31 --- ID Chord designation ID (1)
33- 60 A28 --- Site Name of the observation site.
61- 69 F9.5 deg LAT ? Latitude of the observation site,
positive to the north
71- 80 F10.5 deg LON Longitude of the observation site,
positive to the east
82- 88 F7.2 m Alt Altitude of the observation site
90- 94 F5.1 cm TelSize Size of the telescope in centimeters.
96-108 A13 --- Method Observation method used, values can be
"IMG" or "image" for images, "VID" or
"video" for videos
110-136 A27 --- Camera Type of camera used for the observation.
138-153 A16 --- Result Observation status: "Positive", "Negative",
"Overcast", "Technical Failure"
155-162 A8 --- Timesrc Source of the time data
(e.g., "GPS", "NTP")
164-169 F6.2 s Exptime ? Exposure time .
171-182 A12 "h:m:s" Immersion Time of immersion (disappearance) in UTC
Format: "HH:MM:SS.sss".
184-187 F4.2 s e_Immersion ? Error in immersion time
189-200 A12 "h:m:s" Emersion Time of emersion (reappearance) in UTC
Format: "HH:MM:SS.sss" .
202-205 F4.2 s e_Emersion ? Error in emersion time
207-266 A60 --- Observers List of observer names, separated by commas
if multiple observers
(as "John Doe,Jane Smith")
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Note (1): Unique identifier for the a chords among all chords and occultation
events.
- Format: "{date}{bodyname}_{idx}" (e.g., "202601011Ceres_1").
The index (idx) is built as:
- For single chords: idx integer (e.g., "1", "2").
- For multiple drops (multi-chord observations): formatted as "{idx}.{sub_idx}"
(e.g., "1.1", "1.2").
- each ID corresponds to a chord as noted in lightcurves.dat
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Byte-by-byte Description of file: list.dat
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Bytes Format Units Label Explanations
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1- 9 A9 --- FileName Name of the light curve file in subdirectory lc
11- 41 A31 --- ID Chord designation ID (G1)
43- 60 A18 --- Note Note (No measured fluxes)
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Byte-by-byte Description of file: lc/*
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 31 A31 --- ID Chord designation ID (G1)
36- 53 F18.10 d JD Time in Julian Date (JD) (2)
56- 75 E20.18 --- Flux ? Flux value normalized around unity
76- 81 A6 d e_JD Julian Date uncertainty for non-detections
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Note (2): When the entire light curve is not available:
- For negative observations, initial and end times are given in Julian Date.
- For positive observations, initial and end times are given, followed by
immersion and emersion times in Julian Date with associates
uncertainties in second between parenthesis.
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Global notes:
Note (G1): Unique identifier:
- Format: "{date}{bodyname}_{idx}" (e.g., "202601011Ceres_1").
The index (idx) is built as:
- For single chords: idx integer (e.g., "1", "2").
- For multiple drops (multi-chord observations): formatted as
"{idx}.{sub_idx}" (e.g., "1.1", "1.2").
- each ID corresponds to a chord as noted in stations.dat
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Acknowledgements:
Raphael Lallemand, raphael.lallemand(at)obspm.fr
License: CC-BY-4.0
(End) Patricia Vannier [CDS] 08-Jun-2026