Posts by Josef Durech
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21)
(Message 917)
Posted 25 Feb 2013 by Josef Durech Post: The numbers are 'standard' asteroid numbers, so no conversion/mapping is needed. |
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(Message 913)
Posted 24 Feb 2013 by Josef Durech Post: The first number is the date when the workunit was created (yymmdd) and the second is the number of the asteroid (1 Ceres, 2 Pallas, 3 Juno,...). Each asteroid is divided into several hundreds of workunits and that is the third number. |
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(Message 442)
Posted 12 Dec 2012 by Josef Durech Post: Are we going to perform calculations on data related to the near-earth fly of the asteroid Toutatis tomorrow at 7 million kilometers ? thank you No. Asteroid Toutatis is in so called "excited" rotation state, its spin axis is not fixed in space and its complex rotation can be described as free precession of an asymmetric top. The code we use assumes that the asteroid rotates around an axis fixed in space with a constant rotation period. Moreover, the shape and spin state of Toutatis is well known from radar measurements and should be confirmed by the Chang'E 2 space probe. |
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(Message 440)
Posted 11 Dec 2012 by Josef Durech Post: 2. Do you really work with photometric data from big surveys? We don't use all data from MPC, just a subset - outliers were removed and the data re-calibrated by Edward Bowell from Lowell Observatory. |
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(Message 432)
Posted 10 Dec 2012 by Josef Durech Post: 1. What lightcurves do you use? Do you use ALCDEF from MPC site? Now we use sparse-in-time photometry from astrometric surveys. For lightcurve inversion, we also use lightcurves from ALCDEF/MPC but they are processed at the computational cluster Tiger of the Astronomical Institute, Charles University in Prague, because their analysis is not so time-consuming. 2. Do you really work with photometric data from big surveys? Yes, we do. 3. How and where I can post my LC for your project? It will be useful or not? Post your lightcurves at ALCDEF/MPC. Sooner or later we will download them, combine them with other available data, and try to derive a model. If we succeed, the model will be posted on DAMIT http://astro.troja.mff.cuni.cz/projects/asteroids3D. |
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26)
(Message 100)
Posted 10 Jul 2012 by Josef Durech Post:
Some asteroids cross the orbit of the Earth and there is a non-zero probability of the collision. In such cases, it is very practical to be able to predict the trajectory of the asteroid for long time in the future (tens of years). For an accurate prediction of the trajectory, also non-gravitational forces have to be taken into account, namely the so-called Yarkovski effect (the net force caused by the thermal radiation of the surface changes the orbit). And this effect depends on the orientation of the spin axis of the asteroid and its shape.
Very little is known about the physical properties of the members of asteroid population. By deriving shapes and spins of a significant part of the population, we can learn a lot about the origin and evolution of the whole Solar System.
Definitely! Nobody would send a mission to an asteroid without knowing the basic physical properties of that asteroid.
We have contacts to other research groups, not to the space agencies directly. |
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(Message 99)
Posted 10 Jul 2012 by Josef Durech Post: I'm going to write more about the scientific background of the project and the algorithm soon. I'll post the text on the main page of the project. |
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28)
(Message 58)
Posted 25 Jun 2012 by Josef Durech Post: This project uses brightness measurements of known asteroids with accurate orbits to derive their shape and spin state. Trajectories have to be known in advance. Although asteroid's spin and shape might be important for its accurate ephemeris prediction, this is outside the scope of the project. |
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29)
(Message 30)
Posted 21 Jun 2012 by Josef Durech Post: Yes, it would be nice to have a GPU application but now it's on the bottom of the to-do list. |
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