[30/08/2017]Calibration of the radio interferometer in Humain
On 29 August we went to Humain to measure very accurately the electric length of the RF cables from the antennas to the receivers. Since the interferometer works by measuring phase differences between antennas, systematic errors may occur due to the fact that the radio waves still need to travel along the cables. In these cables, the speed of propagation is only 2/3 of the speed of light and the wavelength is then of 4 meters. An error in the length of one cable of 20 cm would then introduce a systematic error on the phase of (20/400)*360 = 18 degrees. Since the antennas are located at different distances to the location with all receivers the length of the cables are naturally different. To compensate we have added an extra-length of cable at the bottom of the antennas when necessary. However, the accuracy cannot be better than 10-20 cm and therefore we needed to make these tests.
The electric length of the cables is basically measured by generating a square signal, taking its approximate derivative which has a very fast rising flank. This signal is sent into the cable, reflected at the end, and we measure the delay needed to travel the cable (twice) by detecting the same (delayed) rising flank. This was done using a counter, a generator and two directional couplers. The principle is sketched below.
By repeating the measure on a very large number of flanks and integrating the results, the accuracy on the average delay is of the order of 4 picoseconds. The time delays measured between the rising flanks of the direct and reflected signals are typically of 250-252 nanoseconds. 250 nanoseconds corresponds to a length of around 50 meters. What matters are the small differences between the time delays measured between 2 antennas. These are systematic errors on phase delays that we need to take into account.
[21/08/2017]New fireball detected by the FRIPON camera in Uccle
On 19 August, another fireball was detected by the FRIPON network including the camera in Uccle.
[16/08/2017]First fireball detected by the FRIPON camera in Uccle
As part of the METRO project and an on-going international collaboration with IMCCE, we have installed a FRIPON camera on the roof of the institute in Uccle.
Last night, the very first detection of a fireball occured, also detected by the camera located at ESTEC in Noordwijk.
[11/08/2017]The Radio Meteor Zoo (and the Perseids) in the Flamish press
[11/08/2017]The Perseids are back and we need your help for the Radio Meteor Zoo
The Perseids are already coming back! The maximum of activity of the meteor shower is planned for 12-13 of August. The full Moon is on 7 August so conditions will not be optimal for visual observations. In this case radio observations are even more important.
This year we would like to be able to produce an activity curve for one station by August 15. This is very challenging and for that we will need the help of many of you!
One day of data consists of approximately 300 images. Each of them needs to be analyzed by 10 different users. We will provide images from 11 to 13 of August, one day at a time. So to obtain an activity curve on August 15, we will need about 9000 classifications in 3 days. If e.g. 1000 users are participating, that will be 9 classifications per user on average, or 3 images classified per day. Of course the more users the better!
Data will be released on 12, 13 and 14 of August as we need to collect and prepare them for upload to the RMZ website. Meanwhile you can also help us by analyzing data from the same station obtained on 22 and 23 of July, during days when the Perseids were not active at all. If these data are fully processed before the meteor shower, we will then be able to also subtract the background from the total activity. That is the ultimate goal for August 15.
We hope to "see" as many of you as possible on August 12-14 and that between two classifications, you might also be able to spot a few shooting stars at your location.
Get involved again at the Radio Meteor Zoo
Thank you in advance!
[08/05/2017]Internal seminar on the Radio Meteor Zoo
Last Friday, Hervé Lamy gave an internal seminar about the Radio Meteor Zoo. The presentation included the reasons why we started a Citizen Science project, how we collaborated with Zooniverse, how we deal with individual contributions from Zooniverse users and finally some preliminary results. The presentation is available here.
[18/10/2016]BRAMS annual meeting at Euro Space Center in Redu on 15/10/2016
On 15/10/2016, we had our BRAMS annual meeting at the Euro Space Center in Redu. Thank you to all the participants and to Dominique Gering and the people at the ESC who welcomed us for the first time. You can find links to the presentations below :
- Automatic detection of meteor echoes in BRAMS data : status - H. Lamy & P. Ernotte
- Retrieving meteoroids trajectories using BRAMS data : preliminary simulations - H. Lamy & C. Tétard
- The Radio Meteor Zoo - a citizen science project - H. Lamy & S. Calders
- The interferometer in Humain - H. Lamy & C. Tétard
- Forward Scattering : calcul de la vitesse d'un météoroïde qui génère un head Echo - P. Ernotte
- Update of the FRIPON project and the determination of meteor trajectory - F. Colas
- Correlating BRAMS radio and FRIPON video data - J-L Rault