Calibration of fish-eye lens and error estimation on fireball trajectories: application to the FRIPON network

International audienceContext. Fireball networks are developing over the whole planet, with the aim of recovering meteorites and at the same time determining their orbits. The ultimate goal of such networks is to identify the parent bodies of meteorite families to achieve this, orbit accuracy is critical. Yet, the determination of an orbit relies on a long and complex reduction process including: (1) astrometry, with heavy distortion for fish-eye lenses, (2) estimation of the external bias on the observation, (3) fit of the trajectory, (4) deceleration model, and (5) actual orbit computation.Aims. Our goal is to compute accurate trajectories with an estimate of internal and external errors as realistic as possible, taking advantage of the dense observation network FRIPON (Fireball Recovery and InterPlanetary Observation Network), which comprises more than 100 cameras in France and Europe. In particular, we pay special attention to the distortion of images due to fish-eye lenses. In the present paper, we describe the analytical protocol that allows us to compute trajectories and their uncertainties.Methods. We developed a general distortion model to be used on the FRIPON fish-eye cameras. Such a model needs to be accurate even at low elevation, as most fireball observations are performed low on the horizon. The radial distortion is modelled by a nine-degree odd polynomial, hence by five parameters. In addition, we used three parameters to describe the geometry of the camera and two for non-symmetrical distortion. Lastly, we used a new statistical method taking systematic errors into account, which allows us to compute realistic confidence intervals. We tested our method on a fireball that fell on 2017-08-94 UT 00:06.Results. The accuracy of our astrometrical model for each camera is 2 arcmin (1σ), but the internal error on the fireball of 2017-08-94 UT 00:06 measurement is 0.7 arcmin (better than 1/10 pixel). We developed a method to estimate the external error considering that each station is independent and found it equal to 0.8 arcmin. Real residuals are coherent with our estimation of internal and external error for each camera, which confirms the internal consistency of our method. We discuss the advantages and disadvantages of this protocol

FRIPON and IMPACT projects to pinpoint interplanetary matter in the centimetre -hundred meter range

International audienceInter planetaty Dus measurement from a few centimeter to 100 meter with FRIPON and IMPACT project

FRIPON and IMPACT projects to pinpoint interplanetary matter in the centimetre -hundred meter range

International audienceInter planetaty Dus measurement from a few centimeter to 100 meter with FRIPON and IMPACT project

FRIPON and IMPACT projects to pinpoint interplanetary matter in the centimetre -hundred meter range

International audienceInter planetaty Dus measurement from a few centimeter to 100 meter with FRIPON and IMPACT project

FRIPON and IMPACT projects to pinpoint interplanetary matter in the centimetre -hundred meter range

International audienceInter planetaty Dus measurement from a few centimeter to 100 meter with FRIPON and IMPACT project

Energy signature of ton TNT-class impacts: analysis of the 22 December 2018 fireball over Western Pyrenees

International audienceAbstract The increase in detector sensitivity and availability in the past three decades has allowed us to derive knowledge of the meteoroid flux and impact energy into the Earth’s atmosphere. We present the multi-instrument detected 22 December 2018 fireball over Western Pyrenees, and compare several techniques aiming to obtain a reliable method to be used when measuring impacts of similar scale. From trajectory data alone, we found a bulk density of 3.5 g/cm3 to be the most likely value for the Pyrenean meteoroid. This allowed to further constrain the dynamic mass, which translated into a kinetic energy of 1 ton TNT (4.184 · 109 J). For the second energy derivation, via the fireball’s corrected optical radiation, we obtained a more accurate empirical relation measuring well studied bolides . The result approximates to 1.1 ton TNT, which is notably close to the nominal dynamic result, and agrees with the lower margin of the seismic-based energy estimation, yet way lower than the infrasound estimate. Based on the relation derived in this study, we consider the nominal estimate from both the dynamic and photometric methods to be the most accurate value of deposited energy (1 ton TNT). We show that the combination of these two methods can be used to infer the meteoroid density. Among the methods presented in this paper, we found that the optical energy is the most reliable predictor of impact energy near the ton TNT-scale

FRIPON network status

International audienceThe FRIPON network (Fireball Recovery and Interplanetary observation Network) will be fully operational in 2016 (www.fripon.org). This "open source" project includes several new features that will be described in detail. We also discuss the opportunities for expansion outside France. The main innovation is the connectivity of cameras enabling better efficiency for meteors detection, and the possibility of computing orbits in real time to organize an observation campaign within 24 hours. Another innovation is the ability to daytime detections. Statistics show that there are more meteorites in late afternoon than during the rest of the day because of their low speed. As the project has been designed from the start to handle a large number of cameras it is easy to extend it to increase its effectiveness. I will show the next extension of the network and its operation

FRIPON network status

International audienceThe FRIPON network (Fireball Recovery and Interplanetary observation Network) will be fully operational in 2016 (www.fripon.org). This "open source" project includes several new features that will be described in detail. We also discuss the opportunities for expansion outside France. The main innovation is the connectivity of cameras enabling better efficiency for meteors detection, and the possibility of computing orbits in real time to organize an observation campaign within 24 hours. Another innovation is the ability to daytime detections. Statistics show that there are more meteorites in late afternoon than during the rest of the day because of their low speed. As the project has been designed from the start to handle a large number of cameras it is easy to extend it to increase its effectiveness. I will show the next extension of the network and its operation