News
[2015-08-19]Manual counts during Perseids 2015
Using our online tool developed to draw rectangles around potential meteor echoes in spectrograms, manual counts between 18:00 UT on 12/08 and 14:00 on 13/08 were obtained.
The figure below shows an example of a spectrogram where red rectangles have been manually drawn around meteor echoes.
The 3 graphs below show successively :
The raw counts (obtained for each spectrogram every 5 minutes) including all meteor echoes (long and short). The peaks of the Perseids are nearly impossible to spot as the total number is a mix between Perseids and sporadics. The red curve is a moving average on 11 points (so more or less 1 hour) and shows some peaks but not very clearly.
Hourly raw counts including all meteor echoes (long and short), simply obtained from the first curve by adding individual counts for all spectrograms in one hour. The peaks of the Perseids become visible but again not very clear.
Hourly counts including only long meteor echoes. The definition of long is rather vague but includes basically all meteor echoes that have an horizontal extent in the spectrograms, indicating a long duration than typical short (underdense) meteor echoes that represent the bulk of the sporadic background. Then, in this plot, two peaks at ~ 5 UT and ~ 8 UT become visible. These are in agreement with meteor counts obtained by Felix Verbelen using the Ypres beacon at 49.99 MHz. It would be nice to compare these observations with visual observations (see e.g. this page at IMO).
The figure below shows an example of a spectrogram where red rectangles have been manually drawn around meteor echoes.
The 3 graphs below show successively :
The raw counts (obtained for each spectrogram every 5 minutes) including all meteor echoes (long and short). The peaks of the Perseids are nearly impossible to spot as the total number is a mix between Perseids and sporadics. The red curve is a moving average on 11 points (so more or less 1 hour) and shows some peaks but not very clearly.
Hourly raw counts including all meteor echoes (long and short), simply obtained from the first curve by adding individual counts for all spectrograms in one hour. The peaks of the Perseids become visible but again not very clear.
Hourly counts including only long meteor echoes. The definition of long is rather vague but includes basically all meteor echoes that have an horizontal extent in the spectrograms, indicating a long duration than typical short (underdense) meteor echoes that represent the bulk of the sporadic background. Then, in this plot, two peaks at ~ 5 UT and ~ 8 UT become visible. These are in agreement with meteor counts obtained by Felix Verbelen using the Ypres beacon at 49.99 MHz. It would be nice to compare these observations with visual observations (see e.g. this page at IMO).
[2015-08-17]Beacon switched off on 17/08/2015
Due to additional tests with the UAV equipped with a transmitter, the BRAMS beacon was temporarily switched off on 17/08 between 10:04 UT and 14:58 UT.
[2015-08-13]Perseids 2015 at ROB
On the night of 12 August 2015, the Planetarium and the Royal Observatory of Belgium (ROB) were organizing night-sky observations on the plateau of Uccle during the Perseids 2015. About 500 people visited the site between 10 PM and 1 AM. We ran a BRAMS demo as well which was very successful.
[2015-08-10]Beacon off on 07/08/2015
Due to lightnings near Dourbes, the beacon was temporarily off betwen 17h53 and 18h37 UT on 07/08/2015.
[2015-07-20]Beacon off during last week-end
Due to violent lightnings near Dourbes, the fuses in the house hosting our instruments were down and had to be manually switched on the next morning. The beacon was off between 23:12 UT on 18th July and 10:08 UT on 19th July.
[2015-07-03]Calibration tests in Dourbes done
The beacon in Dourbes has been switched on again. Tests with the drone are finished. The beacon was off from 1st of July around 11:55 UT until 14:10 UT on 3rd of July.
The drone was flying in the far-field of our antenna. The far field is approximately located at ~ 2 D^2/lambda with D being the largest size of the antenna. In our case, with a 8m x 8m grid, D is equal to the diagonal of the reflecting grid and therefore the far field is located at approximately 43m. The drone was flying in circles at a distance of 50 m from the bottom of the antenna. Each circle was carried out at a different elevation (between 30° and 80° with steps of 10°). 30° was the minimal elevation to be sure that the drone was flying way above the tallest trees nearby. For each circle, 36 positions were considered to span the whole azimuth angles with steps of 10°. The drone was staying 15 seconds at each position.
Below is a picture of the drone flying above the nearby trees.
The drone was flying in the far-field of our antenna. The far field is approximately located at ~ 2 D^2/lambda with D being the largest size of the antenna. In our case, with a 8m x 8m grid, D is equal to the diagonal of the reflecting grid and therefore the far field is located at approximately 43m. The drone was flying in circles at a distance of 50 m from the bottom of the antenna. Each circle was carried out at a different elevation (between 30° and 80° with steps of 10°). 30° was the minimal elevation to be sure that the drone was flying way above the tallest trees nearby. For each circle, 36 positions were considered to span the whole azimuth angles with steps of 10°. The drone was staying 15 seconds at each position.
Below is a picture of the drone flying above the nearby trees.
[2015-07-01]Calibration tests in Dourbes
Calibration tests are planned in Dourbes on July 2 & 3 to obtain the radiation pattern of our transmitter using our drone. Since the transmitter in this case is used as a receiver and the drone carries the transmitter (amplitude calibrator developed at BISA), we will have to switch off the beacon from time to time. Tests may continue on Friday if necessary.
[2015-06-29]BRAMS annual meeting at MIRA observatory on 27/06/2015
On 27/06/2015, we had our BRAMS annual meeting at the MIRA observatory in Grimbergen. Thank you to all the participants a nd to Philippe Mollet and the people at the observatory who welcomed us once again. You can find links to the presentations below :
- Recent advances in the BRAMS project - H. Lamy
- Amplitude calibrator for the BRAMS stations - M. Anciaux
- Power profiles of radio meteors - S. Calders
- Etude du profil d'un écho underdense - P. Ernotte
- Calibration measurements for the BRAMS network - S. Ranvier
- The BRAMS Zoo project
- Update of the FRIPON project and the determination of meteor trajectory - J. Vaubaillon
- Using the BRAMS beacon for studying meteor induced VLF propagation disturbances - J-L Rault
- Head echoes - F. Verbelen
[2015-04-08]New BRAMS station installed in Maasmechelen
On 28/04/2015, a new BRAMS station has been successfully installed in Maasmechelen. Thanks to Bjorn Di Paolo for helping us install and hosting the BRAMS station.
As can be seen, antennas will from now on be installed vertically. We have also installed the amplitude calibrator that will progressively be added to all BRAMS stations.
As can be seen, antennas will from now on be installed vertically. We have also installed the amplitude calibrator that will progressively be added to all BRAMS stations.
[2015-02-19]New antenna at BEUCCL
The antenna at the BEUCCL station has been replaced today at around 2 PM LT. The old antenna was there from the beginning and was built in-house. We have now replaced it with a commercial one. The quality of the signal is much better. Because commercial antennas use UHF connectors and not N connectors (like the older one), we temporarily use two adapters : a N-BNC connector followed by a BNC-UHF connector. A N-UHF connector has been ordered and will be added soon.