Characterisation of the Perseid meteoroid stream through SPOSH observations between 2010–2016

We have characterised the Perseid meteoroid stream from data acquired in a series of observing campaigns between 2010 and 2016. The data presented in this work were obtained by the Smart Panoramic Optical Sensor Head (SPOSH), an all-sky camera system designed to image faint transient noctilucent phenomena on dark planetary hemispheres. For the data reduction, a sophisticated software package was developed that utilises the high geometric and photometric quality of images obtained by the camera system. We identify 934 meteors as Perseids, observed over a long period between late July (~124°) and mid-to-late August (~147°). The maximum meteor activity contributing to the annual shower was found at λ⊙ = 140°.08 ± 0°.07. The radiant of the shower was estimated at RA = 47°.2 and Dec = 57°.5 with a median error of 0°.6 and 0°.2, respectively. The mean population index of the shower between solar longitudes of 120°.68 and 145°.19 was r = 2.36 ± 0.05, showing strong temporal variation. A predicted outburst in shower activity for the night of August 11–12, 2016 was confirmed, with a peak observed 12.75 hr before the annual maximum at 23:30 ± 15′ UT. We measure a peak flux of 6.1 × 10−4 km−2 hr−1 for meteoroids of mass 1.6 × 10−2 g or more, appearing in the time period between 23:00 and 00:00 UT. We estimate the measured flux of the outburst meteoroids to be approximately twice as high as the annual meteoroid flux of the same mass. The population index of r = 2.19 ± 0.08, computed from the outburst Perseids in 2016, is higher than the value of r = 1.92 ± 0.06 derived from meteors observed in 2015 belonging to the annual Perseid shower which was active near the time of the outburst. A dust trail with an unusually high population index of r = 3.58 ± 0.24 was encountered in 2013 between solar longitudes 136°.261 and 137°.442. The relatively high r-value implies an encounter with a dust trail rich in low-mass particles

Vergleichende Evaluation bürgerwissenschaftlicher Co-Design-Prozesse im Projekt Nachtlicht-BüHNE

Idelaerweise arbeiten Bürger und teilnehmende Wissenschaftler schon bei der Konzeption, Gestaltung und Erprobung mobiler Softwareanwendungen für die Datenerhebung in Citizen-Science-Projekten zusammen (Co-Design). Auf diese Weise können beide Seiten ihre Erwartungen, Wünsche, Kenntnisse und ihr Engagement frühzeitig einbringen und so den Nutzen und die Akzeptanz der entstehenden Anwendungen verbessern. Wie ein solcher Co-Design-Prozess sinnvoll ausgestaltet werden muss und kann hängt sehr stark von (1) den Interessen, den Fähigkeiten und dem Hintergrundwissen der Projektteilnehmenden ab, (2) von der Komplexität und Art der Datenerhebungsmethodik, welche mit der späteren Anwendung umgesetzt werden soll, und (3) von den zeitlichen, finanziellen und rechtlichen Rahmenbedingungen unter denen die Software entwickelt wird. In unserem Beitrag stellen wir zwei Co-Design-Methodiken vor. Diese stellen ganz unterschiedliche Best Practice-Ansätze dar, welche bei der Entwicklung von mobilen Anwendungen zu den Themen Lichtverschmutzung und Meteorbeobachtung im Rahmen unseres Citizen-Science-Projektes Nachtlicht-BüHNE entstanden sind. Wir untersuchen und vergleichen die entstandenen Methoden hinsichtlich ihrer Eignung für den Einsatz unter verschiedenen Rahmenbedingungen und geben damit zukünftigen Citizen-Science-Projekten auf Basis von partizipativ entwickelten mobilen Anwendungen eine Entscheidungshilfe für die Ausgestaltung ihres Co-Design-Ansatzes an die Hand

Co-Designing Mobile Applications for Data Collection: A Comparative Evaluation of Co-Design Processes in the Project "Nachtlicht-BüHNE"

Data collection via mobile software applications is playing an increasingly important role in Citizen Science projects. When developing such applications, it is important to consider both the requirements of the scientists interested in data collection and the needs of the citizen scientists who contribute data. Citizens and participating scientists therefore ideally work together when conceptualizing, designing, and testing such applications (co-design). In this way, both sides - scientists and citizens - can contribute their expectations, desires, knowledge, and engagement at an early stage, thereby improving the utility and acceptance of the resulting applications. How such a co-design process must and can be meaningfully designed depends very much on (1) the interests, skills and background knowledge of the project participants, (2) the complexity and type of the data collection methodology to be implemented, and (3) the time, financial and legal conditions under which the software is developed. In our contribution, we address this point. We present two methodologies that enable the joint design and implementation of software applications for mobile data collection in citizen science projects. These represent quite different best practice approaches that emerged during the development of mobile applications on the topics of light pollution and meteor observation in our Citizen Science project Nachtlicht-BüHNE. We examine and compare the resulting methods with respect to their suitability for use under different conditions and thus provide future citizen science projects based on participatory developed mobile applications with decision support for the design of their co-design approach. We shed light on the two co-design methods with respect to the following criteria, among others: possible types of contributions by volunteers, requirements on expertise and knowledge of the contributors, flexibility of the method with respect to changing requirements, possibilities with respect to the design of complex data collection methods, costs incurred and time required for the implementation of the methodology

Erforschung von Kometen-Staub und -Schutt durch Meteorbeobachtungen und Modellierung

This work focuses on the cm-to-mm sized dust particles of the Perseid meteoroid stream, which is well known to originate from the parent comet 109P/Swift-Tuttle. The main objective of the thesis is the characterisation of the stream through dedicated observations of the Perseid meteor shower using the Smart Panoramic Optical Sensor Head (SPOSH) camera system. A series of observing campaigns have been carried out by the Technische Universität Berlin (TUB) and the German Aerospace Center (DLR) to monitor the Perseids activity from southern Greece in the years between 2010 and 2016. A data reduction software package (SPOSH-Red) was developed for double station meteor data obtained by SPOSH cameras. The software package consists of a number of modules for event detection, image geometric and radiometric calibration, radiant and speed estimates, trajectory and orbit determination, and meteor light curve recovery. The performance of the software was assessed by generating synthetic meteor images of known geometry and brightness, and comparing them with the estimated values. The estimated errors in radiant position had median deviations between 0◦.03 and 0◦.11, and the errors for the speeds had a median deviation between 0.40 and 0.45 km s−1 , while the brightness of the synthetic meteors was estimated to within +0.01 m. From 7 years of observations, a large dataset of images of high radiometric and geometric quality was acquired covering periods of a few days between late July and mid-to-late August, respectively. We identified 934 meteors as members of the Perseid meteoroid stream. The radiant positions, speeds and their errors were estimated for each meteor. Variations of the magnitude distribution index over the long observing period attest to the complex structure of the stream. Meteor fluxes and spatial number densities were estimated for each observing night from all years. From the reduced data, two features could be identified within the annual meteoroid stream: the predicted enhanced meteor activity of the shower on the night of Aug 11-12, 2016 and a hitherto unknown trail of the stream, encountered on Aug 8-10, 2013, dominated by sub-milimeter sized dust particles. Following the numerous studies of the Perseids published during the apparition of the parent comet in 1992, this work investigates the Perseid meteor shower from recent observations employing high-performance camera systems. The findings of this work will help to constrain models dealing with the evolution of dust trails through time and thus, understand the formation mechanisms of one of the oldest meteor showers observed on Earth.Diese Arbeit konzentriert sich auf die cm-bis-mm großen Staubpartikel des Perseidenmeteoridenstroms, der bekanntlich vom Kometen 109P/Swift-Tuttle ab- stammt. Das Hauptziel der Arbeit ist die Charakterisierung des Stroms durch spezielle Beobachtungen des Perseiden Meteorschauer mithilfe der Smart Panoramic Optical Sensor Head (SPOSH) Kamerasystem. Die Technische Universität Berlin (TUB) und das Deutsche Zentrum für Luft- und Raumfahrt (DLR) haben eine Reihe von Beobachtungskampagnen durchgeführt, um die Perseidenaktivität aus Südgriechenland in den Jahren zwischen 2010 und 2016 zu überwachen. Ein Softwarepaket zur Datenauswertung (SPOSH-Red) wurde für Doppelstationen-Meteordaten entwickelt, die mit SPOSH-Kameras gewonnen wurden. Das Softwarepaket besteht aus einer Reihe von Modulen für die Meteorerkennung, die geometrische und radiometrische Bildkalibrierung, Radiant- und Geschwindigkeitsschätzungen, die Trajektorien- und Bahnbestimmung, und die Rekonstruktion der Meteor-Lichtkurve. Die Leistung der Software wurde bewertet, indem synthetische Meteorbilder mit bekannter Geometrie und Helligkeit erzeugt, und mit den Schätzwerten verglichen wurden. Die Radiantposition hatten geschätzten Fehler mit mittleren Abweichungen zwischen 0◦.03 und 0◦.11, und die Fehler für die Geschwindigkeiten hatten eine mittlere Abweichung zwischen 0,40 und 0,45 km s−1 , während die Helligkeit der synthetischen Meteore auf +0,01 m geschätzt wurde. Aus 7 Jahren Beobachtungen wurde ein großer Bilddatensatz hoher radiometrischer und geometrischer Qualität, jeweils über Zeiträume von mehreren Tagen zwischen Ende Juli und Mitte bis Ende August, aufgenommen. Wir identifizierten 934 Meteore, die zum Perseiden Meteorstrom gehören. Die Radiantspositionen, Geschwindigkeiten und deren Fehler werden für jeden Meteor geschätzt. Variationen des Größenverteilungsindex über den langen Beobachtungszeitraum des Stroms belegen die komplexe Struktur des Meteoridenstromes. Meteorflüsse und räumliche Dichten wurden für jede Beobachtungsnacht aus allen Jahren geschätzt. Aus den reduzierten Daten konnten zwei Merkmale innerhalb des jährlichen Meteoritenstroms identifiziert werden: die vorhergesagte erhöhte Meteoraktivität des Schauerns in der Nacht vom 11. auf den 12. August 2016 und ein bisher unbekannter Zweig des Stromes, der am 8. auf den 10. August 2013 erfasst und von Staubpartikeln im Submilimeter dominiert wurde. Nach den zahlreichen Studien zu den Perseiden, die während der Erscheinung des Kometen und Mutterköper 1992 veröffentlicht wurden, untersucht diese Arbeit den Perseiden Schauer aus neueren Beobachtungen mithilfe von Hochleistungs-Kamerasystemen. Die Ergebnisse dieser Arbeit werden dazu beitragen, Modelle, die sich mit der Entwicklung von Staubspuren im Laufe der Zeit befassen, einzuschränken und so die Entstehungsmechanismen eines der ältesten auf der Erde beobachteten Meteorschauer zu verstehen

Telescopic Ground Observations for Lunar Impact Flash Detection using the SPOSH camera

We present first results from our observations carried out on the 28th of March for the detection of impact flashes on the lunar surface. The moon was monitored for 2 hours and more than 2000 images were acquired. The observations verified the ability of our observing system to image the dark side of the Moon for im- pact flashes benefitting from the high sensitivity of our camera. Most of the images obtained during our test observations are affected by motion blur due to the strong wind present at that time. Furthermore, strong reflections by the Moon can be seen in a few images. However, features of the lunar surface illuminated by earth- shine can be clearly seen in a number of images. Furthermore, faint stars up to +9 magnitude were identified in the images

Observations of the Perseids 2012 using SPOSH cameras

The Technical University of Berlin (TUB) and the German Aerospace Center (DLR) organize observing campaigns every summer monitoring the Perseids activity. The observations are carried out using the Smart Panoramic Optical Sensor Head (SPOSH) camera system. The SPOSH camera has been developed by DLR and Jena-Optronik GmbH under an ESA/ESTEC contract and it is designed to image faint, short-lived phenomena on dark planetary hemispheres. The camera features a highly sensitive back- illuminated 1024x1024 CCD chip and a high dynamic range of 14 bits. The custom-made fish-eye lens offers a 120◦x120◦ field-of-view (168◦ over the diagonal). The observations will be made on the Greek Peloponnese peninsula monitoring the post-peak activity of the Perseids during a one-week period around the August New Moon (14th to 21st). Two SPOSH cameras will be deployed in two remote sites in high altitudes for the triangulation of meteor trajectories captured at both stations simultaneously. The observations during this time interval will give us the possibility to study the poorly-observed postmaximum branch of the Perseid stream and compare the results with datasets from previous campaigns which covered different periods of this long-lived meteor shower. The acquired data will be processed using dedicated software for meteor data reduction developed at TUB and DLR. Assuming a successful campaign, statistics, trajectories and photometric properties of the processed double-station meteors will be presented at the conference. Furthermore, a first order statistical analysis of the meteors processed during the 2011 and the new 2012 campaigns will be presented

Simulations of Meteor Trajectories Observations from Orbiting Spacecraft

We have analyzed the possibilities of a spacecraft-based meteor search in the atmosphere of planets, focusing on Earth and Mars. This work concentrates on the geometrical conditions and prospects when using the wide-angle camera SPOSH (Smart Panoramic Optical Sensor Head) in varying heights above the surface and incident angles of meteor streams

Meteor observations of the Perseids 2014 using the SPOSH cameras

We will organize a meteor campaign in Greece focusing on the observation of the Perseid meteor shower. Double-station observations will be carried out from 30th of July until 3rd of August using SPOSH cameras. During this period, we anticipate rates of approximately 15 Perseids per hour. The participation of graduate students during the observations and the data reduction will strengthen the educational aspect of the campaign

Observations of the Perseids 2011 using SPOSH cameras

Photographic observations were carried out from two stations in Greece monitoring the early activity of the Perseids from 22nd to 30th of July. Two Smart Panoramic Optical Sensor Heads (SPOSH) were deployed on Mts Mainalon and Parnon. The radiants, velocites and trajectories of meteors captured simultaneously from both stations have been determined. Here we present the results of 107 meteors, a subset of the several thousands recorded during the observations

The fireball of 21/09/2017: A study of eyewitness reports

On September 21, 2017, a large fireball appeared over the Netherlands and vanished over the North Sea. Scores of eyewitness reports with descriptions of the phenomenon arrived through our notification e-mail address [email protected]. By studying these reports, given with varying level of details, and by comparing them with other trusted sources we may appreciate how reliable and complete the reported data are. This might be helpful for us to improve our notification system in the future. Also, reports sometimes include information not easily obtained by other observing techniques. On the other hand, the reporting system is useful to promote public awareness of Earth in the environment of space