Le projet MÉTÉORE
(The METEOR project)
A project which involves several amateur
astronomers
to determine the trajectory of shooting stars.
| Every amateur astronomers of Quebec and the world, are invited to take part in this original project. No experience is necessary. If you enjoy sky observation especially during meteor showers and you have access to a portable computer (PC), this project is addressed to you. Next meteor shower of importance: delta-Aquarids, July 28th 2000. "... an unquestionable advantage that I see with this project, and which was my motivation, is that it's amusing! The technique is very simple and allows a very large number of people to participate, even the public at large (with supervision) at times of the popular gatherings. All that is necessary, is a portable computer, your sense of the observation and a lawn chair! " If technicalities hardly interest you but you still wish to join the project, just read the introduction section, download the software and have a look at the section on How to take part and submit results. Good luck and don't hesitate to communicate with me.
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The purpose of the METEOR Project is to characterize meteors (shooting stars) of a particular meteor shower. The project makes it possible to determine meteor trajectories relative to the users, relative to Earth and relative to the stars (" absolute " trajectory). With phase II of the project, it will also be possible to determine the speed of the particles and their deceleration. The project requires the participation of amateur astronomers and is based on a statistical study by triangulation. Each participant must have a portable computer with him or her in order to run the METEOR software. The principles of triangulation, which will be further discussed later, is widespread but the approach used with the METEOR Project is, to my knowledge, unique. After a meteor shower and once the data analysis is complete, it will be possible, based on your good observations, to trace the point of origin of the particles responsible for the meteor showers (a comet tail for example). In the "absolute" reference frame, one expects the results to display the parallel trajectories of meteors. In the terrestrial reference frame, it will be possible to determine the beginning and end altitude of the meteors and the trace length. In observer reference frame, the study should clearly emphasize the radiant and it will be possible to generate three dimensionnal computarized images of a shower (and see a tunnel effect centered on the radiant).
The METEOR software is the key of this project. It is a real time planetarium software which is adjusted on the observer's position (at any given time, the sky generated by METEOR corresponds to the observed sky). Before any observation session, each user must synchronize his computer clock to within + / - 1s. of the local legal coordinated time. Each time a meteor is observed, the observer immediately signals it to the software. Then, the observer indicates on the planetarium the point of appearance in the sky of the meteor and the point where it died out. This procedure, which might appear dubious, gave favorable results during preliminary tests. Throughout the evening, the software provides the observer with statistics, as to the total number of shooting stars observed, the average rate per hour, the rate in the last ten minutes, the inflation of the rate, etc. The meteor traces can be displayed overlaying the sky, which allows for easy and early appearanceof the radiant. The software can also be used to record the statistics only; the user then does not have to enter the coordinates of the trajectory. As the night goes, the software constantly records the gathered information in a registry file (.log). This file contains the position of the observer as well as the coordinates and the time of each meteor observation. After the observing session, this file must be sent to me by e-mail. Analysis of the results begins when all observers have sent their registry file.
The analysis is possible since each user has a clock synchronized with the other participants and that each observation is noted immediately. All the registry files are combined and sorted in ascending order of time of appearance. Here for example three registry files (time of the observation only):
Sorting these nine observation in ascending order, we obtain the following list:
Considering that an observer takes a maximum of ten seconds to signal an observation to the software, we can infer that observation (1) and (2) correspond to the same shooting star since they are only 3 seconds apart. Observation (4),(5) and (6) would be also associated with the same event and similarly for observation (7) and (8). Only observation (3) seems to be unique to observer #3. And so on... This method relys on the fact that a given shooting star in the atmosphere is seen simultaneously by everybody. (Which is not true of meteors appearing near the horizon, but we will neglect this effect for now). The greater the number of observer of a given meteor, the better the precision of its trajectory. In fact, every observer commits a certain error in reporting the position of the meteor. However, every observers make a diferent error and it is reasonnable to think that, on average, observations will fluctuate about a true value. This is where a little bit of statistics is needed. Without yet being completely positive, I think that with about ten fairly spread out observers, we wil be able to determine the appearance point of a meteor within a sphere of 10-15 km diameter. the following illustration shows the spatial resolution (with a simplified 2D model) for two observers separated by 250 km. The meteor has a constant altitude of 60 km. We suppose here two good observers that can localize the meteor within a circle of 3 degrees in diameter, or +/- 1.5 degrees relative to the true value (For example, Dubhe and Merak of Ursa Major (the Big Dipper) are separated by approximately 5 degrees). The cones originating from each observation site are the error zones arround the reported position, i.e. that the region of space where it is most probable that the true position lies. When two observers see the same meteor, the true position is in the intersection of their error cones. The greater the distance between the observation site and the true position, the greater the error on the reported position.
On the illustration, we notice that the blue intersection give a much higher precision (~8km) than the red intersection(~25 km) which happens to be far from both observation sites. It is therefore very important to have a constellation of observer, not only numerous but very well spread out, in order to increase the chances that an observation is made inside the the network of observer..
Other methods exist to determine shooting star trajectories. Some methods also use photography based triangulations, which makes this technique much more precise. However, many pictures are needed and it is difficult for amateurs to cover the whole sky in one shot. Also, this later method is more expensive (films, development). Some very sensitive video systems allow quasi real-time visualisation of meteors when linked with other sites, but once again, this is not really accessible to the amateur astronomer. The same can be said of radio stuies of the ionization of the atmosphere produced by the passage of a meteor. An unquestionable advantage that I see with this project, and which was my motivation, is that it's amusing! The technique is very simple and allows a very large number of people to participate, even the public at large (with supervision) at times of the popular gatherings. All that is necessary, is a portable computer, your sense of the observation and a lawn chair!
Here are some links about shooting stars and meteor showers. I select only two for now, since they both regroup numerous links. Any of your suggestions are welcomed... International Meteor Organization
Sébastien Gauthier Back to CONTENTS of METEOR project NEXT section of METEOR project
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