J/A+A/687/A277 Asteroids Gaia DR3 photometric inversion results (Cellino+, 2024)
Asteroid spin and shape properties from DR3 photometry.
Cellino A., Tanga P., Muinonen K., Mignard F.
<Astron. Astrophys. 687, A277 (2024)>
=2024A&A...687A.277C 2024A&A...687A.277C (SIMBAD/NED BibCode)
ADC_Keywords: Solar system ; Minor planets
Keywords: methods: data analysis - techniques: photometric -
minor planets, asteroids: general
Abstract:
The third data release of Gaia, in June 2022, included the first large
sample of sparse photometric data for more than 150000 Solar System
objects (SSOs), mainly asteroids.
The SSO photometric data can be processed to derive information on the
physical properties for a large number of objects, including spin
properties, surface photometric behaviour in a variety of illumination
conditions, and overall shape.
After selecting a set of 22815 objects for which an adequate number
of accurate photometric measurements had been obtained by Gaia, we
applied the "genetic" algorithm of photometric inversion developed
by the Gaia Data Processing and Analysis Consortium to process SSO
photometric data. Given the need to minimise the required data
processing time, the algorithm was set to adopt a simple triaxial
ellipsoid shape model.
Our results show that in spite of the limited variety of observing
circumstances and the limited numbers of measurements per object at
present (in the majority of cases no greater than 40 and still far
from the number expected at the end of the mission of about 60-70),
the proportion of correct determinations for the spin period among the
observed targets is about 85%. This percentage is based on a
comparison with reliable literature data following a moderate
filtering procedure developed to remove dubious solutions.
The analysis performed in this paper is important in the context of
developing further improvements to the adopted data reduction
procedure. This includes the possible development of better solution
filtering procedures that take into account, for each object, the
possible presence of multiple, equivalent spin period solutions that
have not been systematically investigated in this preliminary
application.
Description:
The most important property of Gaia DR3 photometric data for SSOs is
that they are sparse and cover a long time span. In this respect, they
differ from the kind of data most frequently used in asteroid
photometry, namely, the analysis of measurements collected over
relatively short time spans (generally covering one or a few nights),
most often referred to as 'light curves'. Light curves are most
commonly used to obtain a reliable determination of the rotation
period for the target object, namely, this refers to the time needed
to complete a full rotational cycle.
table A.1 summarises the results of our photometric inversion study
for a tiny sub-sample of objects.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
tablea1.dat 78 8678 *Results of photometric inversion of Gaia DR3
data for the asteroids
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Note on tablea1.dat: Only inversion solutions passing the filter described in
the text of the above article are shown.
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See also:
B/astorb : Orbits of Minor Planets (Bowell+, 2014-)
I/359 : Gaia DR3 Part 5: Solar System
Byte-by-byte Description of file: tablea1.dat
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Bytes Format Units Label Explanations
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1- 6 I6 --- Name Asteroid identification number (MPC)
11- 12 I2 --- Nmeas Number of available photometric measurements
19- 24 F6.2 deg ELON Ecliptic longitude of the pole
27- 31 F5.2 deg ELAT Ecliptic latitude of the pole
34- 44 F11.5 h Prot Rotation Period
(a negative sign means retrograde rotation)
47- 50 F4.2 --- b/a Axial ratio b/a
(assuming a triaxial ellipsoid shape a>b>c)
52- 55 F4.2 --- c/a Axial ratio c/a
(assuming a triaxial ellipsoid shape a>b>c)
61- 66 F6.4 mag/deg Slope Slope of linear phase-magnitude relation
71- 78 F8.6 mag Res Residuals of the solution
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Acknowledgements:
Alberto Cellino, alberto.cellino(at)inaf.it
(End) Patricia Vannier [CDS] 09-May-2024