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Abstract The relationship of an asteroid's reduced magnitude to its phase has a long history of study. Included in this history have been efforts to study the correlation between these parameters and spectral type. However, these efforts often suffer from the inclusion of only a few asteroids, missing phase curve data, uncorrected rotational or apparitional aberrations, and other issues. In this paper, we build upon previous approaches and address these issues. Broadly, this paper is split into two parts. The first is primarily concerned with carefully deriving phase curve parameters using a combined data set from several different sources, including observations from Gaia, the Transiting Exoplanet Survey Satellite, Palomar Transient Factory, Asteroid Terrestrial-impact Last Alert System, and Asteroid Lightcurve Data Exchange Format database using an ellipsoidal model that can correct for rotational and apparitional effects. The second concerns itself with making predictions on that data set and quantifying what can and cannot be inferred from phase parameters, both as a function of the phase curve parameterization chosen and as a function of the chosen model. We find that, while individual spectral classes remain hard to infer from the phase curves, broader statements on the presence of absorption features can dependably be made. 

Abstract Using Fisher information matrices, we forecast the uncertaintiesσ_Mon the measurement of a “Planet X” at heliocentric distanced_Xvia its tidal gravitational field’s action on the known planets. Using planetary measurements currently in hand, including ranging from the Juno, Cassini, and Mars-orbiting spacecraft, we forecast a median uncertainty (over all sky positions) of ${\sigma }_M=0.22M_{\oplus }{\left(d_x/400\mathrm{au}\right)}^3.$A 5σdetection of a 5M_⊕Planet X atd_X= 400 au should be possible over the full sky but over only 5% of the sky atd_X= 800 au. The gravity of an undiscovered Earth- or Mars-mass object should be detectable over 90% of the sky to a distance of 260 or 120 au, respectively. Upcoming Mars ranging improves these limits only slightly. We also investigate the power of high-precision astrometry of ≈8000 Jovian Trojans over the 2023–2035 period from the upcoming Legacy Survey of Space and Time (LSST). We find that the dominant systematic errors in optical Trojan astrometry (photocenter motion, nongravitational forces, and differential chromatic refraction) can be solved internally with minimal loss of information. The Trojan data allow cross-checks with Juno/Cassini/Mars ranging, but do not significantly improve the best achievableσ_Mvalues until they are ≳10× more accurate than expected from LSST. The ultimate limiting factor in searches for a Planet X tidal field is confusion with the tidal field created by the fluctuating quadrupole moment of the Kuiper Belt as its members orbit. This background will not, however, become the dominant source of uncertainty until the data get substantially better than they are today. 

Abstract Asteroid diameters are traditionally difficult to estimate. When a direct measurement of the diameter cannot be made through either occultation or direct radar observations, the most common method is to approximate the diameter from infrared observations. Once the diameter is known, a comparison with visible light observations can be used to find the visible geometric albedo of the body. One of the largest data sets of asteroid albedos comes from the NEOWISE mission, which measured asteroid albedos both in the visible and infrared. We model these albedos as a function of proper orbital elements available from the Asteroid Families Portal using an ensemble of neural networks. We find that both the visible and infrared geometric albedos are significantly correlated with asteroid position in the belt and occur in both asteroid families and in the background belt. We find that the ensemble’s prediction reduces the average error in the albedo by about 37% compared to a model that simply adopts an average albedo with no regard for the dynamical state of the body. We then use this model to predict albedos for the half million main belt asteroids with proper orbital elements available in the Asteroid Families Portal and provide the results in a catalog. Finally, we show that several presently categorized asteroid families exist within much larger groups of asteroids of similar albedos—this may suggest that further improvements in family identification can be made.