The [PY]mpact Team scientific production

Since 2013, when the Chelyabinsk impact event literally hit the meteoritical and asteroidal community with the first impact event observed in the era of internet and pervasive observing networks, our group started to investigate these phenomena. In the list below you will find the peer-review papers and gray literature some of the members of our team has published during these years. Click here if you want to reveal the abstract of all papers.

	Conditions for visual and high-resolution bistatic radar observations of Apophis in 2029. Agustín Vallejo, Jorge I. Zuluaga, Germán Chaparro Monthly Notices of the Royal Astronomical Society, 518(3), 4438-4448. DOI: 10.1093/mnras/stac3046 arXiv: 2201.12205 On April 13, 2029, asteroid Apophis will pass within six Earth radii (∼31000 km above surface), in the closest approach of this asteroid in recorded history. This event provides unique scientific opportunities to study the asteroid, its orbit, and surface characteristics at an exceptionally close distance. In this paper we perform a synthetic geometrical, geographical and temporal analysis of the conditions under which the asteroid can be observed from Earth, with a particular emphasis on the conditions and scientific opportunities for bistatic radar observations, the most feasible radar technique applicable during such a close approach. For this purpose, we compile a list of present and future radio observatories around the globe which could participate in bistatic radar observation campaigns during the closest approach of Apophis. We estimate signal-to-noise ratios, apparent sky rotation, surface coverage and other observing conditions. We find that a global collaboration of observatories across Australia, Africa, Europe and America will produce high-resolution delay-Doppler radar images with signal-to-noise ratios above 108, while covering ∼85\% of the asteroid surface. Moreover, if properly coordinated, the extreme approach of the asteroid might allow for radio amateur detection of the signals sent by large radio observatories and citizen science projects could then be organized. We also find that for visual observations, the Canary Islands will offer the best observing conditions during the closest approach, both for professionals as well as for amateurs. The apparent size of Apophis will be 2-3 times larger than typical seeing, allowing for resolved images of the surface.
	Location, orbit and energy of a meteoroid impacting the moon during the Lunar Eclipse of January 21, 2019. Jorge I. Zuluaga (SEAP/IF/UdeA), Matipon Tangmatitham (MTU), Pablo A. Cuartas-Restrepo (SEAP/IF/UdeA), Jonathan Ospina (CAMO/SAA), Fritz Pichardo (ASTRODOM), Sergio A. Lopez (Astrosur/Orion/SAA), Karls Pena (ASTRODOM), J. Mauricio Gaviria-Posada (Obs.LaLoma) Monthly Notices of the Royal Astronomical Society, Volume 492, Issue 3, March 2020, Pages 3666–3673 DOI: 10.1093/mnras/stz3531 arXiv: 1901.09573 During lunar eclipse of 2019 January 21, a meteoroid impacted the Moon producing a visible light flash. The impact was witnessed by casual observers offering an opportunity to study the phenomenon from multiple geographical locations. We use images and videos collected by observers in seven countries to estimate the location, impact parameters (speed and incoming direction), and energy of the meteoroid. Using parallax, we achieve determining the impact location at lat. ⁠, lon. ⁠, and geocentric distance as 356 553 km. After devising and applying a photometric procedure for measuring flash standard magnitudes in multiple RGB images having different exposure times, we found that the flash, had an average G-magnitude 〈G〉 = 6.7 ± 0.3. We use gravitational ray tracing (GRT) to estimate the orbital properties and likely radiant of the impactor. We find that the meteoroid impacted the moon with a speed of km s−1 (70 per cent C.L.) and at a shallow angle, θ < 38.2 deg. Assuming a normal error for our estimated flash brightness, educated priors for the luminous efficiency and object density, and using the GRT-computed probability distributions of impact speed and incoming directions, we calculate posterior probability distributions for the kinetic energy (median Kmed = 0.8 kton), body mass (Mmed = 27 kg) and diameter (dmed = 29 cm), and crater size (Dmed = 9 m). If our assumptions are correct, the crater left by the impact could be detectable by prospecting lunar probes. These results arose from a timely collaboration between professional and amateur astronomers that highlight the potential importance of citizen science in astronomy.
	Can we predict the impact conditions of metre-sized meteoroids?. Jorge I. Zuluaga (SEAP/IF/UdeA), Pablo A. Cuartas-Restrepo (SEAP/IF/UdeA), Jhonatan Ospina (SAA/CAMO), Mario Sucerquia (SEAP/IF/UdeA) Monthly Notices of the Royal Astronomical Society: Letters, 486(1), L69-L73. DOI: 10.1093/mnrasl/slz060 arXiv: 1904.12807 Every year, a few metre-sized meteoroids impact the atmosphere of the Earth. Most (if not all) of them are undetectable before the impact. Therefore, predicting where and how they will fall seems to be an impossible task. In this letter we show compelling evidence that we can constrain in advance, the dynamical and geometrical conditions of an impact. For this purpose, we analyse the well-documented case of the Chelyabinsk (Russia) impact and the more recent and smaller Viñales (Cuba) event, whose conditions we estimate and provide here. After using the {m Gravitational Ray Tracing} algorithm (GRT) to "predict" the impact conditions of the aforementioned events, we find that the speed, incoming direction and (marginally) the orbital elements of the corresponding meteoroids could be constrained in advance, starting only on one hand, with the geographical location and time of the impact, and on the other hand, with the distribution in configuration space of Near Earth Objects (NEOs). Any improvement in our capability to predict or at least to constrain impact properties of medium-sized and large meteoroids, will help us to be better prepared for its potentially damaging effects.
	Speed Thresholds for Hyperbolic Meteors: The Case of the 2014 January 8 CNEOS Meteor. Jorge I. Zuluaga (SEAP/IF/UdeA) Research Notes of the AAS, 3(5), 68.. DOI: 10.3847/2515-5172/ab1de3
	Towards a theoretical determination of the geographical probability distribution of meteoroid impacts on Earth. Jorge I. Zuluaga (SEAP/FACom/IF/UdeA), Mario Sucerquia (SEAP/FACom/IF/UdeA) Monthly Notices of the Royal Astronomical Society, 477(2), 1970-1983.. DOI: 10.1093/mnras/sty702 arXiv: 1801.05720 Tunguska and Chelyabinsk impact events occurred inside a geographical area of only 3.4\% of the Earth's surface. Although two events hardly constitute a statistically significant demonstration of a geographical pattern of impacts, their spatial coincidence is at least tantalizing. To understand if this concurrence reflects an underlying geographical and/or temporal pattern, we must aim at predicting the spatio-temporal distribution of meteoroid impacts on Earth. For this purpose we designed, implemented and tested a novel numerical technique, the "Gravitational Ray Tracing" (GRT) designed to compute the relative impact probability (RIP) on the surface of any planet. GRT is inspired by the so-called ray-casting techniques used to render realistic images of complex 3D scenes. In this paper we describe the method and the results of testing it at the time of large impact events. Our findings suggest a non-trivial pattern of impact probabilities at any given time on Earth. Locations at 60−90° from the apex are more prone to impacts, especially at midnight. Counterintuitively, sites close to apex direction have the lowest RIP, while in the antapex RIP are slightly larger than average. We present here preliminary maps of RIP at the time of Tunguska and Chelyabinsk events and found no evidence of a spatial or temporal pattern, suggesting that their coincidence was fortuitous. We apply the GRT method to compute theoretical RIP at the location and time of 394 large fireballs. Although the predicted spatio-temporal impact distribution matches marginally the observed events, we successfully predict their impact speed distribution.
	A General Method for Assessing the Origin of Interstellar Small Bodies: The Case of 1I/2017 U1 ('Oumuamua). Jorge I. Zuluaga (SEAP/FACom/IF/UdeA), Oscar Sanchez-Hernandez (SEAP/FACom/IF/UdeA), Mario Sucerquia (SEAP/FACom/IF/UdeA), Ignacio Ferrin (SEAP/FACom/IF/UdeA) The Astronomical Journal, 155(6), 236.. DOI: 10.3847/1538-3881/aabd7c arXiv: 1711.09397 With the advent of more and deeper sky surveys, the discovery of interstellar small objects entering into the Solar System has been finally possible. In October 19, 2017, using observations of the Pan-STARRS survey, a fast moving object, now officially named 1I/2017 U1 ('Oumuamua), was discovered in a heliocentric unbound trajectory suggesting an interstellar origin. Assessing the provenance of interstellar small objects is key for understanding their distribution, spatial density and the processes responsible for their ejection from planetary systems. However, their peculiar trajectories place a limit on the number of observations available to determine a precise orbit. As a result, when its position is propagated ∼105−106 years backward in time, small errors in orbital elements become large uncertainties in position in the interstellar space. In this paper we present a general method for assigning probabilities to nearby stars of being the parent system of an observed interstellar object. We describe the method in detail and apply it for assessing the origin of 'Oumuamua. A preliminary list of potential progenitors and their corresponding probabilities is provided. In the future, when further information about the object and/or the nearby stars be refined, the probabilities computed with our method can be updated. We provide all the data and codes we developed for this purpose in the form of an open source { t C/C++/Python package}, {\bf t iWander} which is publicly available at this http URL.
	The orbit of the Chelyabinsk event impactor as reconstructed from amateur and public footage. Jorge I. Zuluaga (IF/FCEN, UdeA), Ignacio Ferrin (IF/FCEN, UdeA), Stefan Geens (Ogle Earth) arXiv Repository DOI: arXiv.1303.1796 arXiv: 1303.1796 A ballistic reconstruction of a meteoroid orbit can be made if enough information is available about its trajectory inside the atmosphere. A few methods have been devised in the past and used in several cases to trace back the origin of small impactors. On February 15, 2013, a medium-sized meteoroid hit the atmosphere in the Chelyabinsk region of Russia, causing damage in several large cities. The incident, the largest registered since the Tunguska event, was witnessed by many thousands and recorded by hundreds of amateur and public video recording systems. The amount and quality of the information gathered by those systems is sufficient to attempt a reconstruction of the trajectory of the impactor body in the atmosphere, and from this the orbit of the body with respect to the Sun. Using amateur and public footage taken in four different places close to the event, we have determined precisely the properties of the entrance trajectory and the orbit of the Chelyabinsk event impactor. We found that the object entered the atmosphere at a velocity ranging from 16.0 to 17.4 km/s in a grazing trajectory, almost directly from the east, with an azimuth of velocity vector of 285o, and with an elevation of 15.8o with respect to the local horizon. The orbit that best fits the observations has, at a 95% confidence level, a semi-major axis a = 1.26±0.05 AU, eccentricity e = 0.44±0.03, argument of perihelion ω=95.5o±2o and longitude of ascending node Ω= 326.5o±0.3o. Using these properties the object can be classified as belonging to the Apollo family of asteroids. The absolute magnitude of the meteoroid was H= 25.8, well below the threshold for its detection and identification as a Potential Hazardous Asteroid (PHA). This result would imply that present efforts intended to detect and characterize PHAs are incomplete.
	A preliminary reconstruction of the orbit of the Chelyabinsk Meteoroid. Jorge I. Zuluaga (SEAP/FACom/IF/UdeA), Ignacio Ferrin (SEAP/FACom/IF/UdeA) arXiv Repository DOI: 10.48550/arXiv.1302.5377 arXiv: 1302.5377 In February 15 2013 a medium-sized meteoroid impacted the atmosphere in the region of Chelyabinsk, Russia. After its entrance to the atmosphere and after travel by several hun- dred of kilometers the body exploded in a powerful event responsible for physical damages and injured people spread over a region enclosing several large cities. We present in this letter the results of a preliminary reconstruction of the orbit of the Chelyabinsk meteoroid. Using evidence gathered by one camera at the Revolution Square in the city of Chelyabinsk and other videos recorded by witnesses in the close city of Korkino, we calculate the trajectory of the body in the atmosphere and use it to reconstruct the orbit in space of the meteoroid previous to the violent encounter with our planet. In order to account for the uncertainties implicit in the determination of the trajectory of the body in the atmosphere, we use Monte Carlo methods to calculate the most probable orbital parameters. We use this result to classify the meteoroid among the near Earth asteroid families finding that the parent body belonged to the Apollo asteroids. Although semimajor axis and inclination of the preliminary orbit computed by us are uncertain, the rest of orbital elements are well constrained in this preliminary reconstruction.