16:15 〜 16:30
[PPS03-21] Spectroscopic and photometric properties of (98943) 2001 CC21, the target of Hayabusa2# space mission
キーワード：Hayabusa2, near-Earth asteroids, (98943) 2001 CC21, telescope observations, spectro-photometry, spectroscopy
The Hayabusa2 spacecraft completed the nominal mission that returned samples from the asteroid (162173) Ryugu. The near-Earth asteroid (98943) 2001 CC21 is the Hayabusa2 extended mission (nicknamed Hayabusa2#) flyby target in 2026 (Hirabayashi et al. 2021). Observations with ground-based telescopes are a key science input for the scientific investigation of this object.They will allow a direct comparison between ground-based telescopic observations and in-situ measurements by the instruments on board Hayabusa2 (the multi-band imager ONC-T and the near-infrared spectrometer). The data from pre-flyby observations will be useful for designing the engineering approach of the spacecraft to this near-Earth object.
The visible spectrum of 2001 CC21 was first reported in 2004 by Binzel et al. (2004). This initial spectral curve was classified as L-type (using Bus taxonomy), and it is characterized by a red slope and relatively flat around 1 µm. During the same observational window, Lazzarin, M. et al. (2005) reported a visible to near-infrared spectrum of this asteroid. Based on their spectral curve, they also classified it as an Sk-type with a less red spectral slope and a stronger 1-µm absorption band characteristic of olivine-pyroxene compositions.
Our first observations of 2001 CC21 were made during February-March 2022 using the 1.5 m Carlos Sánchez telescope (TCS) at Tenerife, Spain equipped with the MuSCAT2 instrument which acquirers data in three broad band filters, g (400-500 nm), r (550-720 nm), and zs (820-900 nm). The average colors: (g-r) = 0.713 +/- 0.037 mag, (r-z) = 0.125 +/- 0.02 mag are compatible with an S-type asteroid. We also determined the B-V =1.142 mag, and V-R = 0.461 mag by using 2.5m Isaac Newton Telescope at La Palma, Spain. During this favorable observation window we also obtain several light-curves of it. Our data confirms a rotation period of 5.02 hrs (estimated by using the best fit) and a light-curve amplitude of 0.85 +/- 0.1 mag Which suggest an elongated object.
We obtained new spectral observations using the OSIRIS instrument mounted on 10.4m Gran Telescopio Canarias (GTC). The spectral curves covered the 0.5 – 0.92 µm wavelengths and allowed to classify it as an S/Sq spectral type. The curve matching method with the Relab database indicated spectral similarities with irradiated pellets of L / LL ordinary chondrite meteorites. This suggests a space-weathered surface.
Detailed characterizations of the photometric and spectroscopic properties can be obtained during the beginning of 2023, when the asteroid will reach an apparent magnitude of 16.5 and a favorable geometry for observations. We will run an observing campaign to characterize (98943) 2001 CC21. Our objectives are 1) to estimate the surface composition, 2) to characterize the space-weathering effects on its surface, 3) to check for possible large-scale inhomogeneity, 4) to find a possible correlation between the slope of the spectra and the phase angle, and 5) to determine its rotational properties. Both photometric and spectroscopic observation will be performed using various telescopes from Observatorio del Roque de los Muchachos and the Infrared Telescope Facility (IRTF) from Mauna Kea, Hawaii. During the talk we will present the preliminary results of these observations.
The visible spectrum of 2001 CC21 was first reported in 2004 by Binzel et al. (2004). This initial spectral curve was classified as L-type (using Bus taxonomy), and it is characterized by a red slope and relatively flat around 1 µm. During the same observational window, Lazzarin, M. et al. (2005) reported a visible to near-infrared spectrum of this asteroid. Based on their spectral curve, they also classified it as an Sk-type with a less red spectral slope and a stronger 1-µm absorption band characteristic of olivine-pyroxene compositions.
Our first observations of 2001 CC21 were made during February-March 2022 using the 1.5 m Carlos Sánchez telescope (TCS) at Tenerife, Spain equipped with the MuSCAT2 instrument which acquirers data in three broad band filters, g (400-500 nm), r (550-720 nm), and zs (820-900 nm). The average colors: (g-r) = 0.713 +/- 0.037 mag, (r-z) = 0.125 +/- 0.02 mag are compatible with an S-type asteroid. We also determined the B-V =1.142 mag, and V-R = 0.461 mag by using 2.5m Isaac Newton Telescope at La Palma, Spain. During this favorable observation window we also obtain several light-curves of it. Our data confirms a rotation period of 5.02 hrs (estimated by using the best fit) and a light-curve amplitude of 0.85 +/- 0.1 mag Which suggest an elongated object.
We obtained new spectral observations using the OSIRIS instrument mounted on 10.4m Gran Telescopio Canarias (GTC). The spectral curves covered the 0.5 – 0.92 µm wavelengths and allowed to classify it as an S/Sq spectral type. The curve matching method with the Relab database indicated spectral similarities with irradiated pellets of L / LL ordinary chondrite meteorites. This suggests a space-weathered surface.
Detailed characterizations of the photometric and spectroscopic properties can be obtained during the beginning of 2023, when the asteroid will reach an apparent magnitude of 16.5 and a favorable geometry for observations. We will run an observing campaign to characterize (98943) 2001 CC21. Our objectives are 1) to estimate the surface composition, 2) to characterize the space-weathering effects on its surface, 3) to check for possible large-scale inhomogeneity, 4) to find a possible correlation between the slope of the spectra and the phase angle, and 5) to determine its rotational properties. Both photometric and spectroscopic observation will be performed using various telescopes from Observatorio del Roque de los Muchachos and the Infrared Telescope Facility (IRTF) from Mauna Kea, Hawaii. During the talk we will present the preliminary results of these observations.