Recording a stellar occultation is one powerful method that gives direct information about the physical properties of the occulting Solar system object. In order to obtain reliable and accurate results, simultaneous observations from... more
Recording a stellar occultation is one powerful method that gives direct information about the physical properties of the occulting Solar system object. In order to obtain reliable and accurate results, simultaneous observations from different locations across-track of the projected path are of great importance. However, organizing all the observing stations, aggregating, and analysing the data is time-consuming and not that easy. We have developed a web portal named Occultation Portal (OP) to manage all those occultation observation campaigns from a central server. With this portal, the instrumental and observational information of all observers participating in a stellar occultation campaign and the concerned data are archived systematically in a standard format. The researchers can then visualize the archived data on an event basis. The investigators can also extract the light curve for each data set with the added reduction pipeline to the portal base. This paper describes in de...
Context. The close approach of the near-Earth asteroid (99942) Apophis to Earth in 2029 will provide a unique opportunity to examine how the physical properties of the asteroid could be changed due to the Earth’s gravitational... more
Context. The close approach of the near-Earth asteroid (99942) Apophis to Earth in 2029 will provide a unique opportunity to examine how the physical properties of the asteroid could be changed due to the Earth’s gravitational perturbation. As a result, the Republic of Korea is planning a rendezvous mission to Apophis. Aims. Our aim was to use photometric data from the apparitions in 2020−2021 to refine the shape model and spin state of Apophis. Methods. Using thirty-six 1- to 2-meter-class ground-based telescopes and the Transiting Exoplanet Survey Satellite, we carried out a photometric observation campaign throughout the 2020−2021 apparition. The convex shape model and spin state were refined using the light-curve inversion method. Results. According to our best-fit model, Apophis is rotating in a short-axis mode with rotation and precession periods of 264.178 h and 27.38547 h, respectively. The angular momentum vector orientation of Apophis was found to be (275°, −85°) in the ec...
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Context: Gaia16aye was a binary microlensing event, the first such event ever discovered in the direction towards the Northern Galactic Disk and one of the first microlensing events detected and alerted by the Gaia space mission. Its... more
Context: Gaia16aye was a binary microlensing event, the first such event ever discovered in the direction towards the Northern Galactic Disk and one of the first microlensing events detected and alerted by the Gaia space mission. Its light curve exhibited five distinct brightening episodes, reaching up to 11 mag, and was covered in great detail with almost 25,000 data points gathered by a network of telescopes. Aims: We present the photometric and spectroscopic follow-up covering 500 days of the event evolution and search for a possible microlensing model in order to derive the parameters of the lensing binary system. Methods: For Gaia16aye event we employed a full Keplerian binary orbit microlensing model combined with the Earth and Gaia motion around the Sun, to reproduce the complex light curve. Results: The photometric data allowed us to solve the microlensing events entirely and to derive the complete and unique set of orbital parameters of the binary lensing system. We also re...
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Context. The so-called Barbarian asteroids share peculiar, but common polarimetric properties, probably related to both their shape and composition. They are named after (234) Barbara, the first on which such properties were identified.... more
Context. The so-called Barbarian asteroids share peculiar, but common polarimetric properties, probably related to both their shape and composition. They are named after (234) Barbara, the first on which such properties were identified. As has been suggested, large scale topographic features could play a role in the polarimetric response, if the shapes of Barbarians are particularly irregular and present a variety of scattering/incidence angles. This idea is supported by the shape of (234) Barbara, that appears to be deeply excavated by wide concave areas revealed by photometry and stellar occultations. Aims. With these motivations, we started an observation campaign to characterise the shape and rotation properties of Small Main-Belt Asteroid Spectroscopic Survey (SMASS) type L and Ld asteroids. As many of them show long rotation periods, we activated a worldwide network of observers to obtain a dense temporal coverage. Methods. We used light-curve inversion technique in order to d...