The Asteroid Ephemeris 1900 to 2050

Product Information

terrestrial frames used with maps and GPS to specify surface locations. Universal Time (TDB -> UT Conversion)

Hamilton, V. E., Simon, A. A., Christensen, P. R., Reuter, D. C., Clark, B. E., Barucci, M. A., Bowles, N. E., Boynton, W. V., Brucato, J. R., Cloutis, E. A., Connolly, H. C. Jr., Hanna, K. L. D., Emery, J. P., Enos, H. L., Fornasier, S., Haberle, C. W., Hanna, R. D., Howell, E. S., Kaplan, H. H., Keller, L. P., Lantz, C., Li, J.-Y., Lim, L. F., McCoy, T. J., Merlin, F., Nolan, M. C., Praet, A., Rozitis, B., Sandford, S. A., Schrader, D. L., Thomas, C. A., Zou, X.-D., Lauretta, D. S., &

We use two methods to obtain estimates of the uncertainty of the particle ejection event location and time. A least squares estimation is performed with each measurement weighting appropriately scaled to the expected errors in the OpNav astrometric processing and potential errors in the conic trajectory fit compared to a high-fidelity dynamical model. The a posteriori covariance is directly obtained from the estimation process. The least squares estimation has the potential to latch onto a local minima and overoptimistic uncertainties associated with the a posteriori state estimate. An alternate uncertainty quantification method is used to determine if the least squares estimation solution and associated uncertainty is appropriate. Namely, a Markov chain Monte Carlo analysis is performed for each of the data sets to provide insight into the a posteriori distribution of the system. Asteroids are small Solar System objects that originate from times preceding planet formation. Typically, when rotating about its principal axis of inertia, an asteroid exhibits a periodic change of brightness caused by the varying part of its surface being both illuminated by the Sun and visible to the observer. On one hand, a photometric lightcurve is the result of photometric observations extending over a time span covering a substantial part of the rotation period or more. On the other hand, a photometric phase curve is the result of observations of the change in an asteroid’s apparent brightness obtained at different epochs during a single apparition, corresponding to a slowly changing Sun-observer-object geometry. In earlier work ( Muinonen et al., 2020), models of observational uncertainties were developed for dense relative photometry and sparse relative photometry. The former entailed ground-based lightcurves that were treated, in lightcurve inversion, on a relative magnitude scale. The latter comprised lightcurves of sparse Gaia photometry that were incorporated on a relative magnitude scale, too. Martikainen et al. (2021) then treated the Gaia photometry in the absolute sense, deriving absolute magnitudes for a large number of asteroids. In the present work, we provide a complete set of four models for observational uncertainties, including models for dense relative, sparse relative, dense absolute, and sparse absolute lightcurves.

The inverse methods are here applied to the ∼500 asteroids with ground-based and Gaia DR2 lightcurve data and to the simulated lightcurve data of the GS-asteroid. 4.1 Asteroids of Gaia Data Release 2 The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest. The use of optical images for angles-only IOD is widely applied in the determination of celestial orbits as well as in the space situation awareness (SSA) community (Gauss, 1963; Gibbs, 1889; Schaeperkoetter & Mortari, 2011; Taff, 1984). Short-arc IOD techniques have successfully been utilized in the determination of asteroid ephemerides (Bowell et al., 2002; Chesley, 2004; Gronchi, 2004). These techniques have been expanded from traditional angles-only IOD to include admissible region constraints on the orbit solution due to limited amounts of information from short-arc data sets (Gronchi, 2004; Milani et al., 2004, 2005; Spoto et al., 2018). Short-arc angles-only asteroid orbit determination utilizes ground-based measurements. The SSA community has expanded IOD techniques to the use of space-based imaging platforms (DeMars et al., 2009; Hussein et al., 2014; Kaya & Snow, 1991; Snow & Kaya, 1992). Charlier( 1910, 1911) postulated four potential solutions to the IOD problem using angles-only observations regardless of the location of the observer. Wie and Ahn( 2017) expanded upon Charlier's postulations to provide guidelines concerning the multiple solutions of angles-only orbit solutions. General angles-only orbit solutions disregard the uncertainties associated with the orbital solution. This limitation has been investigated through Gauss's solution via Binz and Healy( 2017) utilizing sigma points to ascertain more representative uncertainties when compared to traditional least squares-based solutions. Display the orbits of all the planets, planetary satellites, and optionally one or more small bodies.In the lower right table of the ephemeris under the title, “Lunar Phases & Eclipses,” lists the lunar phases (New, First Quarter, Full, and Last Quarter) dates, times, and zodiacal positions. If there is a Solar or Lunar eclipse in that particular month, you’ll find its date and positions in this table, below the lunar phases. Otherwise, you can assume there isn’t an eclipse that month (eclipses occur in sets approximately every 5-6 months). can be created in the Ephemeris section of Extended Chart Selection, and any year between 13'000 BCE and 17'000 CE can be chosen. The reflection coefficient in Eq. 5 belongs to a class of photometric models consisting of a Lommel-Seeliger-type volume-element part and a part describing scattering among volume elements in a particulate medium (e.g., Lumme and Bowell, 1981; Muinonen and Lumme, 1991). Provides access to key solar system data and flexible production of highly accurate ephemerides for solar system objects.

Note that the four major asteroids, included in the monthly ephemerides above for the year 2023, are Ceres, Juno, Vesta, and Pallas. Also added are Eros, Sappho, Psyche, and Chiron. This was a custom ephemeris built using the excellent and highly recommended software program, Sirius 3.0. Tools for Greater Understanding & Fulfillment Where Sappho is, there is greater vulnerability, yearning, desire for poetry and transcendence, and love.Chiron in our natal charts points to where we have healing powers as the result of our own deep spiritual wounds. We may over-compensate in these areas of life. Chiron, as a wounded healer, first must face issues of low self-worth and feelings of inadequacy and learn to rise above them. Because the wound goes deep, and we may work hard to overcome the wound, healing powers are potent. The following ephemerides are for the following selected asteroids: Eros, Psyche, Sappho, Ceres, Pallas, Juno, Vesta, and Chiron. or uncertainties for an object with no covariance in the database. Specific Quantities 1. Astrometric RA & DEC Time. A -7 would provide Pacific Daylight Time (or MST, if it is winter). Gregorian and Julian Calendar Dates The ephemerides above show the daily positions, month to month in the year 2023, of the four major asteroids, Chiron, and select minor asteroids.

Sign changes in the top ephemeris are displayed in the table under the ephemeris under the title “Ingresses.” Due to the quantity of particles detected and initial event reconstruction of their origin, a few assumptions can be made about the location of the origin of the particles. If one assumes that each individual particle leaves the surface independently of the others, then the traditional angles-only orbit determination should be used. However, another possibility is that an ejection event occurs when particles leave the same region simultaneously. In the supplementary materials of Lauretta et al.( 2019), the assumption of simultaneous particle release is evaluated for the 19 January and 11 February events. That analysis removes the assumption of simultaneous ejection but assumes that the particles ejected from the same location. The resulting distributions of possible event times largely fall within the time frames estimated by assuming simultaneous ejection. Thus, the assumption of simultaneously release is reasonable within the expected ejection time uncertainties. The ephemerides above display each planet, asteroid, or point by degree and sign (longitude) at Midnight in the Eastern time zone at a daily rate. With an ephemeris, we can follow their daily progress/movement and get a good understanding of sign change dates. where the index i describes the dense relative ( i= 1), sparse relative ( i= 2), dense absolute ( i= 3), and sparse absolute photometry ( i= 4). For dense and sparse relative lightcurves, the relative brightnesses ℓ obs, ikj and ℓ ikj( P) are computed using the mean-magnitude brightnesses of each lightcurve. However, for dense and sparse absolute lightcurves, they are computed using the mean magnitude of the entire absolute lightcurve data. Note that the sparse relative lightcurves are weighted equally to the absolute photometric data but they enter the inverse problem separately with no regard to the absolute level of brightness. 3.2 Absolute Magnitudes and Phase Functions

ORIGINAL RESEARCH article

Another constraint that we applied when estimating an ejection event was assuming that the event originated on the surface of the asteroid. We used the Bennu shape model (Barnouin et al., 2019) to create a constraint between the event location in latitude and longitude and the position at that location, reducing the number of unknowns by one. A benefit is that the estimation of the ejection location will naturally follow the topography, producing a more consistent solution and realization of the uncertainty in the location of the event. The disadvantage of this approach is that it produces a correlated solution between all of the particle trajectories and the time at which the event occurs. 4 Particle Event Reconstruction