Techniques d'observation spectroscopique d'astéroïdes

84 CHAPTER 5. M4AST - MODELING OF ASTEROIDS SPECTRA
1.2
1.15
1.15
Relative Reflectance
(a)
1.1
1.05
1
0.95
0.9
0.85
0.8
0.75
0.7
Apophis
Sq
S
Sr
0.5 1 1.5 2 2.5
Wavelength [um]
Relative Reflectance
(b)
1.1
1.05
1
0.95
0.9
0.85
0.8
0.75
1996 FG3
Ch
Cg
Xc
0.5 1 1.5 2 2.5
Wavelength [um]
Figure 5.6: Classification in Bus-DeMeo taxonomical system for: a)) (99942) Apophis, and b) (175706) 1996
FG3. All the spectra are normalized to 1.25 µm.
tel-00785991, version 1 - 7 Feb 2013
5.2.3 Updating the database
Permanent spectra can be added into the database via a dedicated interface - update database
(Fig. 5.2) - that requires administrative rights. The information needed to add a new permanent
file with spectral data are asteroid designations (an additional utility is provided to check the
designations), information about the observation (date, investigator, and IAU code of the observatory),
and information about the uploaded file containing the measurements. Each record
submitted to the database can be removed only from this interface.
5.3 Testing of M4AST
The functionality of M4AST is exemplified here by the analysis of two spectra available in
the database that were previously discussed by Binzel et al. [2009], and de León et al. [2011a].
Our selection here covers a wide variety of spectra, (99942) Apophis is an Sq type asteroid
with moderate features, and (175706) 1996 FG3 is a primitive type with featureless spectra.
My choice for these objects is not trivial. (99942) Apophis is a NEA which came very close to
the Earth. The next approach will occur in 2029 and its Minimum Orbital Intersection Distance
(MOID) is less than 40,000 km from the Earth surface. 1996 FG3 is the main target of the
future mission Marco-Polo-R. Ground based science is highly required for this object if the
mission will take place.
The discussion of the taxonomic type of each object is made with reference to both Fig. 5.6
for Bus-DeMeo taxonomy and Fig. 5.7 for G-mode taxonomies. Table 5.1 summarizes the
comparison of asteroid spectra with spectra from the Relab database. The corresponding plots
are given in Fig. 5.8.