- ID:
- ivo://CDS.VizieR/J/AJ/155/213
- Title:
- Absolute reflectance & new calibration site of the Moon
- Short Name:
- J/AJ/155/213
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- How bright the Moon is forms a simple but fundamental and important question. Although numerous efforts have been made to answer this question such as use of sophisticated electro-optical measurements and suggestions for calibration sites, the answer is still debated. An in situ measurement with a calibration panel on the surface of the Moon is crucial for obtaining the accurate absolute reflectance and resolving the debate. China's Chang'E-3 (CE-3) "Yutu" rover accomplished this type of measurement using the Visible-Near Infrared Spectrometer (VNIS). The measurements of the VNIS, which were at large emission and phase angles, complement existing measurements for the range of photometric geometry. The in situ reflectance shows that the CE-3 landing site is very dark with an average reflectance of 3.86% in the visible bands. The results are compared with recent mission instruments: the Lunar Reconnaissance Orbiter Camera (LROC) Wide Angle Camera (WAC), the Spectral Profiler (SP) on board the SELENE, the Moon Mineralogy Mapper (M^3^) on board the Chandrayaan-1, and the Chang'E-1 Interference Imaging Spectrometer (IIM). The differences in the measurements of these instruments are very large and indicate inherent differences in their absolute calibration. The M^3^ and IIM measurements are smaller than LROC WAC and SP, and the VNIS measurement falls between these two pairs. When using the Moon as a radiance source for the on-orbit calibration of spacecraft instruments, one should be cautious about the data. We propose that the CE-3 landing site, a young and homogeneous surface, should serve as the new calibration site.
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- ID:
- ivo://CDS.VizieR/J/A+A/607/A72
- Title:
- Absolute Refletivity of Jupiter and Saturn
- Short Name:
- J/A+A/607/A72
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We provide measurements of the absolute reflectivity of Jupiter and Saturn along their central meridians in filters covering a wide range of visible and near-infrared wavelengths (from 0.38 to 1.7um) that are not often presented in the literature. We also give measurements of the geometric albedo of both planets and discuss the limb-darkening behavior and temporal variability of their reflectivity values for a period of four years (2012-2016). This work is based on observations with the PlanetCam-UPV/EHU instrument at the 1.23m and 2.2m telescopes in Calar Alto Observatory (Spain). The instrument simultaneously observes in two channels: visible (VIS; 0.38-1.0um) and short-wave infrared (SWIR; 1.0-1.7um). We obtained high-resolution observations via the lucky-imaging method. We show that our calibration is consistent with previous independent determinations of reflectivity values of these planets and, for future reference, provide new data extended in the wavelength range and in the time. Our results have an uncertainty in absolute calibration of 10-20%. We show that under the hypothesis of constant geometric albedo, we are able to detect absolute reflectivity changes related to planetary temporal evolution of about 5-10%.
- ID:
- ivo://CDS.VizieR/J/MNRAS/505/5253
- Title:
- A comparison of centering in ISS astrometry
- Short Name:
- J/MNRAS/505/5253
- Date:
- 22 Feb 2022
- Publisher:
- CDS
- Description:
- In the caviar software package, a standard tool for astrometry of images from the Cassini imaging science subsystem (ISS), Gaussian fitting is used to measure the centre of point-like objects, achieving a typical precision of about 0.2 pixels. In this work, we consider how alternative methods may improve on this. We compare three traditional centroiding methods: two-dimensional Gaussian fitting, median, and modified moment. Results using 56 selected images show that the centroiding precision of the modified moment method is significantly better than the other two methods, with standard deviations for all residuals in sample and line of 0.065 and 0.063 pixels, respectively, representing a factor of over 2 improvement compared to Gaussian fitting. Secondly, a comparison of observations using Cassini ISS images of Anthe is performed. Anthe results show a similar improvement. The modified moment method is then used to reduce all ISS images of Anthe during the period 2008-2017. The observed-minus-calculated residuals relative to the JPL SAT393 ephemeris are calculated. In terms of {alpha}xcos({delta}) and {delta} in the Cassini-centred international celestial reference frame, mean values of all residuals are close to 0km, and their standard deviations are less than 1km for narrow angle camera images, and about 4km for wide angle camera images.
- ID:
- ivo://CDS.VizieR/J/A+A/612/A85
- Title:
- AKARI IRC asteroid sample diameters & albedos
- Short Name:
- J/A+A/612/A85
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- 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{deg}, 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.
- ID:
- ivo://CDS.VizieR/J/PASJ/65/34
- Title:
- AKARI IRC slow-scan asteroid catalog, AcuA-ISS
- Short Name:
- J/PASJ/65/34
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present an asteroidal catalog from the mid-infrared wavelength region using the slow-scan observation mode obtained by the Infrared Camera (IRC) on-board the Japanese infrared satellite AKARI. An archive of IRC slow-scan observations comprising about 1000 images was used to search for serendipitous encounters of known asteroids. We have determined the geometric albedos and diameters for 88 main-belt asteroids, including two asteroids in the Hilda region, and compared these, where possible, with previously published values. Approximately one-third of the acquired data reflects new asteroidal information. Some bodies classified as C or D-type with high albedo were also identified in the catalog.
- ID:
- ivo://CDS.VizieR/J/PASJ/71/1
- Title:
- AKARI Near Infrared Asteroid Spectral Catalog V1
- Short Name:
- J/PASJ/71/1
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Knowledge of water in the solar system is important for the understanding of a wide range of evolutionary processes and the thermal history of the solar system. To explore the existence of water in the solar system, it is indispensable to investigate hydrated minerals and/or water ice on asteroids. These water-related materials show absorption features in the 3um band (wavelengths from 2.7 to 3.1um). We conducted a spectroscopic survey of asteroids in the 3um band using the Infrared Camera (IRC) on board the Japanese infrared satellite AKARI. In the warm mission period of AKARI, 147 pointed observations were performed for 66 asteroids in the grism mode for wavelengths from 2.5 to 5um. According to these observations, most C-complex asteroids have clear absorption features (>10% with respect to the continuum) related to hydrated minerals at a peak wavelength of approximately 2.75um, while S-complex asteroids have no significant features in this wavelength range. The present data are released to the public as the Asteroid Catalog using AKARI Spectroscopic Observations (AcuA-spec).
- ID:
- ivo://CDS.VizieR/J/AJ/161/112
- Title:
- 2012 and 2017 light curves of asteroid 2012 TC4
- Short Name:
- J/AJ/161/112
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Asteroid 2012TC4 is a small (~10m) near-Earth object that was observed during its Earth close approaches in 2012 and 2017. Earlier analyses of light curves revealed its excited rotation state. We collected all available photometric data from the two apparitions to reconstruct its rotation state and convex shape model. We show that light curves from 2012 and 2017 cannot be fitted with a single set of model parameters; the rotation and precession periods are significantly different for these two data sets, and they must have changed between or during the two apparitions. Nevertheless, we could fit all light curves with a dynamically self-consistent model assuming that the spin states of 2012TC4 in 2012 and 2017 were different. To interpret our results, we developed a numerical model of its spin evolution in which we included two potentially relevant perturbations: (I) gravitational torque due to the Sun and Earth and (II) radiation torque, known as the Yarkovsky-O'Keefe-Radzievskii-Paddack (YORP) effect. Despite our model simplicity, we found that the role of gravitational torques is negligible. Instead, we argue that the observed change of its spin state may be plausibly explained as a result of the YORP torque. To strengthen this interpretation, we verify that (I) the internal energy dissipation due to material inelasticity and (II) an impact with a sufficiently large interplanetary particle are both highly unlikely causes of its observed spin state change. If true, this is the first case where the YORP effect has been detected for a tumbling body.
- ID:
- ivo://CDS.VizieR/J/AJ/161/187
- Title:
- A new martian crater chronology
- Short Name:
- J/AJ/161/187
- Date:
- 16 Mar 2022 11:45:44
- Publisher:
- CDS
- Description:
- Crater chronologies are a fundamental tool to assess the relative and absolute ages of planetary surfaces when direct radiometric dating is not available. Martian crater chronologies are derived from lunar crater spatial densities on terrains with known radiometric ages, and thus they critically depend on the Moon-to-Mars extrapolation. This extrapolation requires knowledge of the time evolution of the impact flux, including contributions from various impactor populations, factors that are not trivially connected to the dynamical evolution of the early Solar System. In this paper, we will present a new Martian crater chronology based on current dynamical models, and consider the main sources of uncertainties (e.g., impactor size-frequency distribution; dynamical models with late and early instabilities, etc.). The resulting "envelope" of Martian crater chronologies significantly differs from previous chronologies. The new Martian crater chronology is discussed using two interesting applications: Jezero crater's dark terrain (relevant to the NASA Mars 2020 mission) and the southern heavily cratered highlands. Our results indicate that Jezero's dark terrain may have formed ~3.1Ga, i.e., up to 0.5Gyr older than previously thought. In addition, available crater chronologies (including our own) overestimate the number of craters larger than 150km on the southern highlands, suggesting either that large craters have been efficiently erased over Martian history or that dynamical models need further refinement. Further, our chronology constrains the age of Isidis basin to be 4.05-4.2Ga and that of the Borealis basin to be 4.35-4.40Ga; these are predictions that can be tested with future sample and return missions.
- ID:
- ivo://CDS.VizieR/J/A+A/658/A158
- Title:
- A polarimetric study of ACOs
- Short Name:
- J/A+A/658/A158
- Date:
- 22 Feb 2022 15:07:47
- Publisher:
- CDS
- Description:
- Asteroids in comet-like orbits (ACOs) consist of asteroids and dormant comets. Due to their similar appearance, it is challenging to distinguish dormant comets from ACOs via general telescopic observations. Surveys for discriminating dormant comets from the ACO population have been conducted via spectroscopy or optical and mid-infrared photometry. However, they have not been conducted through polarimetry. We conducted the first polarimetric research of ACOs. We conducted a linear polarimetric pilot survey for three ACOs: (944) Hidalgo, (3552) Don Quixote, and (331471) 1984 QY1. These objects are unambiguously classified into ACOs in terms of their orbital elements (i.e., the Tisserand parameters with respect to Jupiter TJ significantly less than 3). Three ACOs were observed by the 1.6-m Pirka Telescope from UT 2016 May 25 to UT 2019 July 22 (13 nights). We found that two ACOs, Don Quixote and Hidalgo, have polarimetric properties similar to comet nuclei and D-type asteroids (optical analogs of comet nuclei. However, 1984 QY1 exhibited a polarimetric property consistent with S-type asteroids. We conducted a backward orbital integration to determine the origin of 1984 QY1 and found that this object was transported from the main belt into the current comet-like orbit via the 3:1 mean motion resonance with Jupiter. We conclude that the origins of ACOs can be more reliably identified by adding polarimetric data to the color and spectral information. This study would be valuable for investigating how the ice-bearing small bodies distribute in the inner solar system.
- ID:
- ivo://CDS.VizieR/J/PASJ/63/1117
- Title:
- Asteroid catalog using AKARI (AcuA). V1.
- Short Name:
- J/PASJ/63/1117
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The AKARI Infrared Astronomical Satellite observed the whole sky in the far infrared (50-180{mu}m) and the mid-infrared (9 and 18{mu}m) between May 2006 and August 2007 (Murakami et al. 2007PASJ...59S.369M). The Asteroid catalog using AKARI (AcuA) version 1.0 is the first asteroid catalog produced based on the AKARI/IRC Mid-Infrared Survey. The catalog provides the size and albedo of 5120 asteroids.
