Simulation of Light Naphtha Isomerization Process

An approach to modeling the isomerization process implemented in the technological scheme with the maximum normal paraffins conversion was described. The comprehensive mathematical model was designed as a powerful tool for optimization. It is based on the influence of the feedstock composition for assessment of the current catalyst activity. According to the calculations, the optimal operating parameters are determined by the refined feedstock composition

Prospect for VLBI Network Extension: the First Results of an Ad-hoc S2 Array Experiments

The Canadian S2 system gives a chance for Russian and some other radio telescopes in the world to be involved into international VLBI programs. Brief descriptions of previous S2 experiments and future possibilities are presented

Spin vector and shape of (6070) Rheinland and their implications

Main belt asteroids (6070) Rheinland and (54827) 2001NQ8 belong to a small population of couples of bodies which reside on very similar heliocentric orbits. Vokrouhlicky & Nesvorny (2008, AJ 136, 280) promoted a term "asteroid pairs", pointing out their common origin within the past tens to hundreds of ky. Previous attempts to reconstruct the initial configuration of Rheinland and 2001NQ8 at the time of their separation have led to the prediction that Rheinland's rotation should be retrograde. Here we report extensive photometric observations of this asteroid and use the lightcurve inversion technique to directly determine its rotation state and shape. We confirm the retrograde sense of rotation of Rheinland, with obliquity value constrained to be >= 140 deg. The ecliptic longitude of the pole position is not well constrained as yet. The asymmetric behavior of Rheinland's lightcurve reflects a sharp, near-planar edge in our convex shape representation of this asteroid. Our calibrated observations in the red filter also allow us to determine $H_R = 13.68\pm 0.05$ and $G = 0.31\pm 0.05$ values of the H-G system. With the characteristic color index $V-R = 0.49\pm 0.05$ for the S-type asteroids, we thus obtain $H = 14.17\pm 0.07$ for the absolute magnitude of (6070) Rheinland. This a significantly larger value than previously obtained from analysis of the astrometric survey observations. We next use the obliquity constraint for Rheinland to eliminate some degree of uncertainty in the past propagation of its orbit. This is because the sign of the past secular change of its semimajor axis due to the Yarkovsky effect is now constrained. Determination of the rotation state of the secondary component, asteroid (54827) 2001NQ8, is the key element in further constraining the age of the pair and its formation process.Comment: Published in AJ, 28 pages, 4 figures, 2 table

Implementing of the ISON project in Northern Mexico

ISON, being an open international project that collects and interprets data about space objects for scientific analysis and spacecraft operators, includes about 40 observational sites. An involvement of two Mexican sites participating in optical observations of geostationary and highly elliptical objects as a part of the ISON project is considered. A brief description of the facilities and their observation statistics are given. Prospects for the further development of sites for monitoring near-Earth objects in Mexico are presented, including data of astronomical observing conditions from field stations

Improving accuracy of LEO objects Two-Line Elements through optical measurements

Two-Line Elements (TLEs) of LEO objects, consisting in the object orbital parameters released by the North American Aerospace Defense Command (NORAD), are often characterized by low accuracy and short-term reliability. This is mostly due to sparse tracking data and relevant contribution of either unmodeled or poorly modelled perturbations of the orbital dynamics. Frequent updates of the dynamic state estimate are necessary for Space Situational Awareness (SSA) analyses and reliable orbit propagation. The optical Orbit Determination procedure represents a possible approach in order to increase TLE accuracy by processing ground-based optical measurements. In case of one-site observations, fast passes, together with possible bad weather conditions, can lead to a set of largely sparse measures, consequently leading to the impossibility of calculating consistent orbit determination solutions. The Sapienza Space Systems and Space Surveillance Laboratory (S5Lab) research team has developed an orbit determination algorithm aimed to improve TLEs accuracy by exploiting multiple-sites optical observations. The developed algorithm receives as input the astrometric solutions of different sites images, in order to integrate them to produce an improved orbit determination solution in TLE format. The considered observatories, which belong to the Sapienza Scientific Observatory Network (SSON) and to the International Scientific Optical Network (ISON), are MITO (Rome, Italy), RESDOS (Avezzano, Italy) and EQUO OG (Malindi, Kenya) with regards to Sapienza University of Rome, and MMT-9 (Nizhny Arkhyz, Russia) and PH-2A (Nauchny, Crimea) with regards to the ISON network. These telescopes locations allow to acquire less sparse data and increase the time spans, eventually allowing to track multiple arcs of the same orbit. Moreover, the observatories configuration provides redundancy to the data acquisition devices and it increases the optical data availability, even when coping with the different meteorological conditions of the observatories regions. Therefore, a higher accuracy in determining the target orbit is achievable. The developed software validation has been performed by analyzing pre-fit and post-fit residuals with respect to reference measures taken during Tiangong 1 re-entry monitoring campaign performed between February and March 2018. The analysis has demonstrated that the algorithm improves the state estimate accuracy on multiple test cases that will be described in detail. This paper will describe the developed algorithm for optical data integration and TLE improvement. In addition to the integration theoretical model, the validation campaigns and the used observatories features will be exposed

Kharkiv study of near-Earth asteroids

International audienc

Opposition effect of Trojan asteroids

International audienceCCD-photometry of three Jupiter Trojan asteroids were carried out to study their opposition effect. We obtained well-sampled magnitude-phase curves for (588) Achilles, (884) Priamus, and (1143) Odysseus in the maximal attainable phase angle range down to 0.1-0.2°. The magnitude-phase relations have a linear behavior in all observed range of phase angles and do not show any non-linear opposition brightening. We have not found any confident differences between phase slopes measured in B, V and R bands. The values of the measured phase slopes of Trojans are different from available data for Centaurs. They are within the range of phase slopes measured for some low-albedo main belt asteroids, also exhibit a linear behavior down to small phase angles. An absence of non-linear opposition brightening puts constraints on the surface properties of the studied objects, assuming very dark surfaces where single scattering plays dominating role. We also determined the rotation periods, amplitudes, the values of color indexes B-V and V-R, and the absolute magnitudes of these asteroids

Datura family: the 2009 update

International audienceContext: Research of asteroid families has been recently refreshed by the discovery of very young ones. These families are of great interest because they represent the product of their parent body fragmentation before orbital and physical evolutionary processes can change them. A cluster of seven objects around the largest body (1270) Datura is of particular interest because it has enough known members and resides in the inner part of the main asteroid belt, facilitating observations. Aims: We carried out photometric observations of the two largest members of the Datura family - asteroids (1270) Datura and (90265) 2003 CL5 - with the goal of inferring their physical parameters. We also used numerous astrometric observations of Datura-family members in the past few years to revisit the age of this cluster. Methods: We performed numerous photometric observations of (1270) Datura over several oppositions. We then used the lightcurve inversion method to determine the spin state and shape of this asteroid. In the case of (90265) 2003 CL5, for which only limited lightcurve data have been acquired so far, we used Fourier analysis to determine the synodic rotation period during the 2008 apparition. We also used backward numerical integration of the improved orbits of Datura family members to reduce uncertainty in its age. Results: We determined the rotation state of (1270) Datura, the largest member of its own family. Its major properties are a short rotation period of ~3.36 h and small obliquity, which, however, exhibits ~±15° excursions because of a forced Cassini state of the proper nodal frequency. Any possible initial non-principal rotation state has probably been damped and the asteroid rotates about the shortest axis of the inertia tensor. Its global shape, although convex in our representation, may reflect regions related to the excavation of the family members from the parent body surface. Interestingly, the second largest member of the Datura family - (90265) 2003 CL5 - appears to be very slow rotator with the rotation period ~24 h. The large amplitude of its rotation curve suggests that its shape is extremely elongated, possibly bi-lobed. Improved orbits of the family members allow us to re-determine the possible age of this family. We find an age that is slightly older than previously reported. Using a conservative approach, we obtain an age in the 450 to 600 kyr range. With strengthened, but plausible, conditions, we find that the current data may support an age of 530±20 kyr. Further astrometric and photometric observations of the Datura cluster members are needed to determine its age more accurately