J/A+A/612/A85 AKARI IRC asteroid sample diameters & albedos (Ali-Lagoa+, 2018)
The AKARI IRC asteroid flux catalogue: updated diameters and albedos.
Ali-Lagoa V., Mueller T.G., Usui F., Hasegawa S.
<Astron. Astrophys. 612, A85 (2018)>
=2018A&A...612A..85A 2018A&A...612A..85A (SIMBAD/NED BibCode)
ADC_Keywords: Solar system ; Minor planets
Keywords: minor planets, asteroids: general - catalogs
Abstract:
The AKARI IRC all-sky survey provided more than twenty thousand
thermal infrared observations of over five thousand asteroids.
Diameters and albedos were obtained by fitting an empirically
calibrated version of the standard thermal model to these data. After
the publication of the flux catalogue in October 2016, our aim here is
to present the AKARI IRC all-sky survey data and discuss valuable
scientific applications in the field of small body physical properties
studies. As an example, we update the catalogue of asteroid diameters
and albedos based on AKARI using the near-Earth asteroid thermal model
(NEATM). We fit the NEATM to derive asteroid diameters and, whenever
possible, infrared beaming parameters. We fit groups of observations
taken for the same object at different epochs of the survey
separately, so we compute more than one diameter for approximately
half of the catalogue. We obtained a total of 8097 diameters and
albedos for 5170 asteroids, and we fitted the beaming parameter for
almost two thousand of them. When it was not possible to fit the
beaming parameter, we used a straight line fit to our sample's
beaming parameter-versus-phase angle plot to set the default value for
each fit individually instead of using a single average value. Our
diameters agree with stellar-occultation-based diameters well within
the accuracy expected for the model. They also match the previous
AKARI-based catalogue at phase angles lower than 50°, but we find
a systematic deviation at higher phase angles, at which near-Earth and
Mars-crossing asteroids were observed. The AKARI IRC All-sky survey is
an essential source of information about asteroids, especially the
large ones, since, it provides observations at different observation
geometries, rotational coverages and aspect angles. For example, by
comparing in more detail a few asteroids for which dimensions were
derived from occultations, we discuss how the multiple observations
per object may already provide three-dimensional information about
elongated objects even based on an idealised model like the NEATM.
Finally, we enumerate additional expected applications for more
complex models, especially in combination with other catalogues.
Description:
Table 1 contains the best-fitting values of size and beaming parameter
and corresponding visible geometric albedos for the full AKARI IRC
sample. We fitted the near-Earth asteroid thermal model (NEATM) of
Harris (1998Icar..131..291H 1998Icar..131..291H) to the AKARI IRC thermal infrared data
(Murakami et al., 2007PASJ...59S.369M 2007PASJ...59S.369M, Onaka et al.,
2007PASJ...59S.401O 2007PASJ...59S.401O, Ishihara et al., 2010A&A...514A...1I 2010A&A...514A...1I, Cat.
II/297, Usui et al., 2011PASJ...63.1117U 2011PASJ...63.1117U, Cat. J/PASJ/63/1117, Takita
et al., 2012PASJ...64..126T 2012PASJ...64..126T, Hasegawa et al., 2013PASJ...65...34H 2013PASJ...65...34H,
Cat. J/PASJ/65/34). The NEATM implementation is described in Ali-Lagoa
and Delbo' (2017A&A...603A..55A 2017A&A...603A..55A, cat. J/A+A/603/A55).
Minimum relative errors of 10, 15, and 20 percent are given for size,
beaming parameter and albedo in those cases where the beaming
parameter could be fitted. Otherwise, a default value of the beaming
parameter is assumed based on Eq. 1 in the article, and the minimum
relative errors in size and albedo increase to 20 and 40 percent (see
the discussions in Mainzer et al., 2011ApJ...736..100M 2011ApJ...736..100M, Ali-Lagoa et
al., 2016A&A...591A..14A 2016A&A...591A..14A, Cat. J/A+A/591/A14).
We also provide the asteroid absolute magnitudes and G12 slope
parameters retrieved from Oszkiewicz et al. (2012), the number of
observations used in each IRC band (S9W and L18W), plus the
heliocentric and geocentric distances and phase angle (r, Delta,
alpha) based on the ephemerides taken from the MIRIADE service
(http://vo.imcce.fr/webservices/miriade/?ephemph).
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 120 8097 Best-fitting values of size and infrared beaming
parameter and corresponding geometric visible
albedos for the AKARI IRC sample
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See also:
B/astorb : Orbits of Minor Planets (Bowell+ 2014)
II/297 : AKARI/IRC mid-IR all-sky Survey (ISAS/JAXA, 2010)
J/PASJ/63/1117 : Asteroid catalog using AKARI (AcuA). V1. (Usui+, 2011)
J/PASJ/65/34 : AKARI IRC slow-scan asteroid catalog AcuA-ISS (Hasegawa+ 2013)
J/A+A/591/A14 : PCF, SpecB or SDSSB asteroids parameters (Ali-Lagoa+, 2016)
J/A+A/603/A55 : WISE/NEOWISE Mars-crossing asteroids (Ali-Lagoa+, 2017)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 8 A8 --- d Asteroid designation (MPC-packed format)
10- 14 F5.2 --- H Asteroid absolute magnitude (MPC)
16- 20 F5.2 --- G Slope parameter (MPC)
22- 28 F7.2 km D Equivalent diameter
30- 36 F7.2 km e_D Equivalent diameter error bar
38- 44 F7.3 --- pV Visible geometric albedo
46- 52 F7.3 --- e_pV Visible geometric albedo error bar
54- 59 F6.2 --- eta Infrared beaming parameter
61- 66 F6.2 --- e_eta Infrared beaming parameter error bar
69- 73 A5 --- Fit [True False] Fit code:
"True" means eta was fitted
75- 80 I6 --- S9W Number of data fitted in the 9-micron band
82- 87 I6 --- L18W Number of data fitted in the 18-micron band
90- 96 F7.3 au r Average heliocentric distance
98-104 F7.3 au Delta Average geocentric distance
106-110 F5.2 deg alpha Average phase angle
112-120 F9.3 d MJD Modified Julian Date
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Acknowledgements:
Victor Ali-Lagoa, vali(at)mpe.mpg.de
(End) Patricia Vannier [CDS] 28-Dec-2017