University of Calgary PRISM: University of Calgary's Digital Repository

Graduate Studies Legacy Theses

2010 Physical Properties of Fireball-Producing Earth-Impacting Meteoroids and Orbit Determination through Shadow Calibration of the Buzzard Coulee Meteorite Fall

Milley, Ellen Palesa

Milley, E. P. (2010). Physical Properties of Fireball-Producing Earth-Impacting Meteoroids and Orbit Determination through Shadow Calibration of the Buzzard Coulee Meteorite Fall (Unpublished master's thesis). University of Calgary, Calgary, AB. doi:10.11575/PRISM/17766 http://hdl.handle.net/1880/47937 master thesis

University of Calgary graduate students retain copyright ownership and moral rights for their thesis. You may use this material in any way that is permitted by the Copyright Act or through licensing that has been assigned to the document. For uses that are not allowable under copyright legislation or licensing, you are required to seek permission. Downloaded from PRISM: https://prism.ucalgary.ca UNIVERSITY OF CALGARY

Physical Properties of Fireball-Producing Earth-Impacting Meteoroids and Orbit

Determination through Shadow Calibration of the Buzzard Coulee Meteorite Fall

by

Ellen Palesa Milley

A THESIS

SUBMITTED TO THE FACULTY OF GRADUATE STUDIES

IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE

DEGREE OF MASTER OF SCIENCE

DEPARTMENT OF GEOSCIENCE

CALGARY, ALBERTA

April, 2010

©c Ellen Palesa Milley 2010

The author of this thesis has granted the University of Calgary a non-exclusive license to reproduce and distribute copies of this thesis to users of the University of Calgary Archives.

Copyright remains with the author.

Theses and dissertations available in the University of Calgary Institutional Repository are solely for the purpose of private study and research. They may not be copied or reproduced, except as permitted by copyright laws, without written authority of the copyright owner. Any commercial use or re-publication is strictly prohibited.

The original Partial Copyright License attesting to these terms and signed by the author of this thesis may be found in the original print version of the thesis, held by the University of Calgary Archives.

Please contact the University of Calgary Archives for further information: E-mail: [email protected] Telephone: (403) 220-7271 Website: http://archives.ucalgary.ca

Abstract

The physical properties of the meteoroid population were investigated through combining data from a number of fireball camera networks. PE values, as a measure of meteoroid strength, were calculated and linked with other observational criteria (Tisserand param­ eter, meteor shower identification). The historic divisions for fireball types based on the

PE criterion were not observed in the large data set, but a correlation with source re­ gion was recognized. Meteor showers demonstrated different amounts of variation in PE values potentially related to the materials found in each parent comet.

The trajectory and pre-fall orbit for the Buzzard Coulee meteoroid were determined through the calibration of shadows cast by the fireball. The method of using shadows to triangulate a trajectory was developed and evaluated. The best fit trajectory was coupled with an initial velocity of 18.0 km/s to compute the heliocentric orbit. Buzzard Coulee fell from a modestly inclined near-Earth Apollo orbit. It is the 12th fallen meteorite to be associated with an orbit.

ii Acknowledgements

First and foremost I would like to thank Dr. Alan Hildebrand for his experience, guidance and financial support throughout the course of this project. He has given me an incredible number of learning opportunities from the classroom in Geology 699: Meteorites and

Asteroids, to travelling the world and meeting other scientists in Prague, Czech Republic.

He has been pivotal in the progress of my research project, has extended me invitations for speaking engagements, given me experience working with the media and allowed me to lead some of the meteorite search efforts. It has been an adventure.

I am grateful to Dr. Margaret Campbell-Brown for her time and patience working with me throughout the past years. She has provided me with continuous support and supervision throughout my project. She was a wonderful host during my two visits to the University of Western Ontario.

I would like to acknowledge Dr. Peter Brown for his time and consistent support throughout my project. In particular, I would like to thank him for the work he did in calibrating Gordon Sarty’s all-sky camera to work out an initial velocity for Buzzard

Coulee, and in adapting code and running numerous simulations to determine the un­ certainties in the trajectory solution. Your knowledge in meteor science is an immense resource, thank you for sharing it with me.

Thank you to my examination committee members for taking the time out of their busy schedules to read and review my work. Additionally I would like to thank a number of people for their contributions and guidance. In the Meteor Physics Group at the Uni­ versity of Western Ontario: Dr. Wayne Edwards, Sean Kohut and Zbigniew Krzeminski.

At Portland State University: Drs. Alex Ruzicka and Melinda Hutson. Thanks to Mike

Noble for the effort in taking crucial measurements for the site surveys at camera loca­ tions. Rob Cardinal for computer assistance, creating orbit plots and predicting Buzzard

iii iv

Coulee’s position prior to falling. Jeff Kriz, for driving long hours and staying up late to help take pictures of stars. A special thank you to Lynne Maillet for her computer software assistance, her expertise in mapping and for lending me her camera to take stellar shots.

There are hundreds of people who have had an influence over my project, many may not even realize it. Thank you to the landowners, search volunteers, business owners and camera operators in Buzzard Coulee and beyond. I would like to extend my gratitude to video owners for kindly granting me the use of their records: Adam Baxter and the town of Devon, Glenn Lypkie, Alister Ling, Rod and Diana Meger, Ali and Fara Rahmanian,

Gordon Sarty, and Rob Tait. Thank you to the landowners, in particular to Al and Jan

Mitchell, Ellen and Ian Mitchell, Barb and Elwood Ferguson, for allowing us to trample through their fields in the name of science. A special thank you to Ellen and Ian for their gracious hospitality in hosting our search headquarters and for giving me two rocks that hold a special place in my heart.

I am grateful to a number of funding institutions for their support throughout my graduate work: NSERC for a Canada Graduate Scholarship, Alberta Ingenuity Fund for an Incentive Award, the Department of Graduate Studies for two Graduate Research

Scholarships, the Canadian Space Agency for a Space Awareness & Learning Grant and to the Graduate Student Association (University of Calgary) for a Conference Grant.

Friends and family often seem to be left until the end of the acknowledgements, of course without them I would not be where I am today. Samantha Jones, thank you for showing me how it is all done, you are a role model and a great friend. Thank you to my family for their unwavering support. Bobby, your continuity in my life is a foundation, thank you for your patience. “Equipped with his five senses, man explores the universe around him and calls the adventure Science.” — Edwin Hubble, 1889-1953

For my Family.

v vi

Table of Contents

Abstract ...... ii Acknowledgements ...... iii Table of Contents ...... vi List of Tables ...... vii List of Figures ...... viii List of Units and Symbols ...... ix List of Acronyms and Abbreviations ...... xi 1 Introduction ...... 1 1.1 Comets, Asteroids and Meteors ...... 1 1.2 Linking Origin and Material ...... 7 1.2.1 The PE Criterion ...... 7 1.2.2 The Tisserand Parameter ...... 9 1.2.3 Meteorites Associated with an Orbit ...... 9 1.3 The Buzzard Coulee Fall ...... 15 1.4 Research Project Outline ...... 15 2 Fireball Network Events ...... 17 2.1 Historical Overview of Fireball Networks ...... 17 2.2 Methodology ...... 21 2.2.1 Calibration, Trajectory and Orbit Derivation ...... 21 2.2.2 Determining Mass and Calculating the PE Criterion ...... 23 2.2.3 Combining and Correcting Data from Fireball Networks . . . . . 27 2.3 Results and Discussion ...... 30 2.3.1 PE Value Distributions by Fireball Network ...... 30 2.3.2 Fireball Strength and Source Region ...... 34 2.3.3 PE Values of Shower Events ...... 38 2.3.4 Distribution of Orbital Elements ...... 41 2.4 Summary and Conclusions ...... 48 3 The Buzzard Coulee Meteorite Fall ...... 51 3.1 Introduction to the Buzzard Coulee Event ...... 51 3.1.1 Naming and Typing of the Meteorite ...... 54 3.2 Atmospheric Trajectory ...... 60 3.2.1 Shadow Calibrations ...... 60 3.2.2 Video Calibrations ...... 70 3.2.3 Trajectory Results and Discussion ...... 74 3.2.4 Velocity Results and Discussion ...... 84 3.3 Pre-Fall Orbit ...... 89 3.3.1 Discussion ...... 89 3.4 Summary and Conclusions ...... 99 Bibliography ...... 102 A Fireball Networks ...... 112 B Site Survey Schematics ...... 115 C Trailside Inn Derivation of Altitude and Azimuth ...... 119 D MILIG Files ...... 125 E MORB Files ...... 150 F Flux of Instrumentally Recorded Meteorite Falls ...... 153

vii List of Tables

1.1 Meteorites associated with a derived orbit ...... 12

2.1 Luminous efficiencies published by Ceplecha & McCrosky (1976) . . . . . 25 2.2 Luminous efficiencies published by Halliday et al. (1996) ...... 25 2.3 Breakdown by raw number and raw mass of meteoroid strengths by source region ...... 37 2.4 Average PE values for meteor shower events ...... 40

3.1 Buzzard Coulee trajectory solution ...... 77 3.2 Orbital parameters for the Buzzard Coulee meteoroid ...... 89

A.1 List of published works used to assemble a data set comprised of MORP, PN and EN events ...... 112 A.2 Summary of parameters required for the calculation of PE value, Tisserand parameter and the orbital elements ...... 114

viii ix

List of Figures

1.1 Kirkwood gaps in the Asteroid Belt ...... 2 1.2 Artist’s rendition of the Oort Cloud and Kuiper Belt ...... 4 1.3 Flow chart demonstrating the dynamic groups of comets and their assumed source region ...... 5 1.4 Terminology and durations associated with a meteor event ...... 6 1.5 Distribution of PE values for Prairie Network fireballs used to determine divisions of meteoroid material ...... 7 1.6 Plot of all comets and asteroids known in 2002 with magnitudes brighter than 18 ...... 10

2.1 Map of the European Network ...... 18 2.2 Map of the Prairie Network ...... 19 2.3 Map of the Meteorite Observation and Recovery Project ...... 20 2.4 Histogram of PE values for events captured by the Prairie Network . . . 31 2.5 Histogram of PE values for events captured by the European Network . . 31 2.6 Histogram of PE values for events captured by the Meteorite Observation and Recovery Project ...... 32 2.7 Histogram of PE values for events captured by the Southern Ontario Me­ teor Network ...... 32 2.8 Histogram plotting all PE values for events captured by the EN, PN and MORP ...... 33 2.9 Histogram of PE values from the MORP Clear-Sky Survey ...... 34 2.10 MORP Clear-Sky Survey events in Tisserand parameter and PE criterion space ...... 35 2.11 Percentages of raw numbers of MORP Clear-Sky Survey objects from Fig­ ure ?? falling into each region of the plot ...... 35 2.12 Percentages of raw observed masses of MORP Clear-Sky Survey objects from Figure ?? falling into each region of the plot ...... 36 2.13 Distribution of weighting factors applied to events ...... 41 2.14 a: Collision probability and mass distribution corrected values of eccen­ tricity for events larger than 100 g. b: Similar to (a) but plotted on a logarithmic scale. c: Eccentricity values of the uncorrected events . . . . 43 2.15 a: Collision probability and mass distribution corrected values of incli­ nation for events larger than 100 g. b: Similar to (a) but plotted on a logarithmic scale. c: Inclination values of the uncorrected events . . . . . 44 2.16 a: Collision probability and mass distribution corrected values of perihe­ lion distance for events larger than 100 g. b: Similar to (a) but plotted on a logarithmic scale. c: Perihelion distances of the uncorrected events . . . 45 2.17 a: Collision probability and mass distribution corrected values of geocen­ tric speed for events larger than 100 g. b: Similar to (a) but plotted on a logarithmic scale. c: Geocentric speeds of the uncorrected events . . . . . 46 x

2.18 Orbital element distributions obtained by Galligan & Baggaley (2004) for an unbiased distribution of ∼5 ×105 radar meteors ...... 47

3.1 Infrared satellite image of Western Canada showing the weather at the time of the Buzzard Coulee fall ...... 52 3.2 Composite image showing a video frame of the fireball from a number of locations ...... 53 3.3 Uncalibrated radiometer measurement of light output by the Buzzard Coulee fireball ...... 53 3.4 Illustration of the ordinary chondrite clans ...... 56 3.5 Petrologic types of chondrites ...... 57 3.6 Diagram illustrating the olivine and pyroxene compositions observed in Buzzard Coulee ...... 58 3.7 Ferrosilite of low-Ca pyroxene with fayalite content of olivine for equili­ brated ordinary chondrites ...... 59 3.8 Photograph of the back of the Trailside Inn highlighting the uneven roof geometry ...... 61 3.9 Calibration image taken through the security camera at the Trailside Inn 62 3.10 Left: A bright frame of the NW pump at the Lashburn Esso Station showing the shadows of the light fixtures. Right: Security camera frame near the end of the fireball emphasizing the three fragments reflected in the truck windshield ...... 66 3.11 Left: Calibration image for the SE pump taken through the Lashburn Esso security system. Right: Calibration image taken for the NW pump . . . 66 3.12 Left: Security camera image from Tait’s Liquor Store of the cloth deploy­ ment. Right: Security camera image of the shadows cast by the fireball . 70 3.13 Image demonstrating the fit between the Biggar security camera frame and the stellar calibration shot ...... 72 3.14 Image showing the fit between the Devon police dashboard camera frame and the stellar calibration shot ...... 73 3.15 Fireball positions from the Trailside Inn in Lloydminster taken through the calibration and measurement of the shadows cast ...... 75 3.16 Fireball positions measured through shadow calibrations at the Esso Sta­ tion in Lashburn ...... 75 3.17 Fireball positions measured through shadow calibrations at Tait’s Liquor Store in Lloydminster ...... 76 3.18 Positions measured from Biggar, Saskatchewan of four large fragmentation events and the three final glowing fragments ...... 77 3.19 Map of the atmospheric trajectory of Buzzard Coulee ...... 79 3.20 Total distance each point is away from the best fit solution ...... 80 3.21 Vertical deviations from the best fit trajectory ...... 81 3.22 Horizontal deviations from the best fit trajectory ...... 81 3.23 Comparison of the vertical and horizontal deviations ...... 82 3.24 Start of the fireball measured from Devon, Alberta ...... 86 3.25 Best fit line giving an initial velocity from the Devon, AB measurements. 86 3.26 Deviations of each point from the MILIG best fit solution including the Sarty all-sky video in Saskatoon ...... 88 3.27 Heliocentric orbit of the Buzzard Coulee meteoroid looking at the ecliptic plane ...... 90 3.28 Heliocentric orbit of the Buzzard Coulee meteoroid looking from the First Point of Ares toward the ecliptic plane ...... 90 3.29 The debiased orbital distribution of Apollo objects predicted by Bottke et al. (2002) ...... 92 3.30 Orbits of meteorites plotted together for comparison ...... 94 3.31 Meteorite orbits from a side view of the ecliptic plane ...... 95 3.32 Timeline of meteorite falls for which orbits have been derived ...... 96 3.33 Plot of the sky coverage achieved by asteroid search telescopes for the period of January 20-27, 2010 ...... 98

B.1 Schematic view from above the Trailside Inn ...... 115 B.2 Schematic showing the z-axis of the Trailside Inn ...... 115 B.3 Schematic showing the x-axis of the Trailside Inn ...... 116 B.4 Left: Rotation of the coordinate system relative to North. Right: Detailed measurements of the gutter ...... 116 B.5 Schematic overhead view of the Lashburn Esso ...... 117 B.6 Schematic showing the x-axis of the Lashburn Esso ...... 117 B.7 Schematic overhead view of Tait’s Liquor Store ...... 118 B.8 Schematic showing the x-axis of Tait’s Liquor Store ...... 118

C.1 Relevant parameters to define a plane in space ...... 119

xi List of Units and Symbols

◦ degree ’ arcminute

” arcsecond AU astronomical unit (1.5 × 1011 m)

α cumulative mass index a semi-major axis aJ semi-major axis of Jupiter Cextinction extinction correction

Crange range correction Δ difference or change in DEC declination e eccentricity g grams kg kilograms

Hz hertz i inclination

I intensity Iinst instrumental intensity J Julian date k extinction co-effiecient

K Kelvin m meter

µm micrometer mm millimeter cm centimeter km kilometer m mass m∞ initial mass mE end or terminal mass ma air mass co-efficient

M magnitude Mabs absolute magnitude

Mapp apparent magnitude Minst instrumental magnitude

Mpan panchromatic magnitude ν true anomaly

xii xiii

N frequency nc collision probability correction nm mass correction ω argument of perihelion Ω longitude of ascending node φ angle of rotation

PE PE criterion q perihelion distance

Q aphelion distance ρE air density at end height R Distance (km) RA right ascension

σ standard deviation s seconds t time T Tisserand parameter

τ luminous efficiency factor τR effective target radius v velocity v∞ initial velocity ve escape velocity VvE Earth orbital velocity

VvG geocentric velocity VvH heliocentric velocity

ZR zenith distance List of Acronyms and Abbreviations

AB Alberta AVI audio video interweave

CCD charge-coupled device cpx clinopyroxene

DVR digital video recorder EN European Network

En enstatite Fa fayalite

Fs ferrosilite HTC Halley-type comet

JFC Jupiter-family comet JPEG image compression format

LINEAR Lincoln Near Earth LP long-period comet Asteroid Research

LCD liquid crystal display MORP Meteorite Observation and Recovery Project

MST Mountain Standard Time NEA near-Eath asteroid

NEO near-Earth object NIC nearly isotropic comet

NTSC standard video rate opx orthopyroxene (29.97 frames/s)

PMD percent mean deviation PN Prairie Network

RASC Royal Astronomical RCMP Royal Canadian Society of Canada Mounted Police

SK Saskatchewan SOMN Southern Ontario Meteor Network

SP short-period comet UT Universal Time

Wo wollastonite

xiv 1

Chapter 1

Introduction

1.1 Comets, Asteroids and Meteors

Understanding the processes that shape the Solar System enables scientists to assemble a timeline of the Solar System’s history and make predictions. One piece of this story involves understanding the initial distribution of physical and chemical conditions of the

Solar System at the time of planet formation. Today, these historical conditions are preserved within the small primitive Solar System planetesimals, comets and asteroids.

Two main reservoirs for these planetesimals have remained in their original locations and essentially drive the observational definitions of what is an asteroid and what is a comet.

The Asteroid Belt (or Main Belt) is located between 2.06 and 3.65 AU (Lewis, 1997).

Objects that formed in this region of the Solar System are thought to be made mostly of rocky silicate material and are called asteroids. The current distribution and population of the Main Belt is the result of a complex dynamical evolution largely driven by the gravitational perturbations of Jupiter and Saturn. Vivid structure exists in the pattern of observed orbits within the Main Belt (Figure 1.1). Gaps in semi-major axes are caused by orbital or mean motion resonances, those orbits with simple ratios of Jupiter’s orbital period. These spaces in the Main Belt were first recognized in 1867 by Daniel Kirkwood, and now bear his name: Kirkwood gaps (Lewis, 1997). Structure is also given to the

Main Belt by secular resonances, a synchronous orbital precession with a major planet.

In particular, the ν6 secular resonance with Saturn defines the inner edge of the Main Belt at 2.06 AU. Bodies that are either collisionally or dynamically (i.e. by the Yarkovsky effect or Poynting-Robertson drag) altered into an orbit that falls in a resonance region 2 are quickly removed from the Main Belt (de El´ıa & Brunini, 2007) within millions of years (Gladman et al., 1997). An object leaving the Main Belt then meets one of three fates, being ejected from the Solar System, being sent on a crash course into the Sun, or being altered into a stable inner Solar System orbit (i.e. near-Earth orbits: Aten, Amor,

Apollo) where it has an increased chance of colliding with one of the inner terrestrial planets.

Figure 1.1: Strong dynamical structure is visible in this distribution of 10 592 asteroids plotted in osculating inclination and semi-major axis space (from Ivezi´c et al., 2002). Strong mean motion resonances with Jupiter can been seen as Kirkwood gaps at 2.5AU (3:1 resonance), 2.8 AU (5:2 resonance), 2.9 AU (7:3 resonance) and 3.3 AU (2:1 reso­ nance).

The other planetesimal reservoir more or less in its original location is the Kuiper

Belt, a region extending beyond the orbit of Neptune from roughly 35 to several hundred

AU (Weissman et al., 2002). This region of the Solar System represents the tail-end of the proto-planetary disk where there was insufficient mass to accrete another major planet (Malhotra et al., 2000). The planetestimals that formed here are known as comets, 3 thought to be composed of a substantial proportion of icy, volatile material capable of forming a gaseous envelop or coma when the comet nucleus is heated. Traditionally, the ‘snow-line’ division for the formation of asteroids (rocky bodies) versus comets (icy bodies) is approximately at the orbit of Jupiter, however, there is some evidence that this boundary may have been closer to the Sun at ∼4 AU (Weissman et al., 2002). The comets that originally formed amongst the major planets (Jupiter to Neptune) became scattered under gravitational perturbations as the large planets grew. Many of these objects ended up in the Oort Cloud, a spherical volume bounded by galactic tides, found outside the planet region extending between 103 – 105 AU (Figure 1.2). At these vast distances from the Sun, galactic and stellar perturbations play a large role in the orbits of these objects. Some comets in the Uranus-Neptune region were scattered so that their semi-major axes increased but did not become large enough to join the Oort Cloud.

These bodies remain in orbits with perihelia near Neptune but with semi-major axes in the Kuiper Belt. Comets in such orbits are known to inhabit the scattered disk which is near the Kuiper Belt but dynamically distinct (Malhotra et al., 2000).

Observationally comets are divided into two groups: long-period comets (LP) and short-period comets (SP). Long-period comets are randomly distributed in inclination

(therefore can be prograde or retrograde) with large eccentricities and semi-major axes, as well as, long orbital periods (> 200 years) . Short-period comets lie closer to the ecliptic plane in prograde orbits and have shorter semi-major axes and orbital periods

(< 200 years). Short-period comets are further divided into two groups: Jupiter-family comets (JFC) and Halley-type comets (HTC). Jupiter-family comets display orbital pe­ riods less than 20 years and a median inclination of 11◦, while Halley-type comets have periods between 20 and 200 years with a median inclination of 45◦ (Weissman et al., 2002).

These three groups (LP, JFC and HTC) represent the comets that have been gravita­ tionally perturbed out of one of the three comet reservoirs. Based on the assumed initial 4

Figure 1.2: Artist’s rendition of the comet reservoirs, the large spherically shaped Oort Cloud and the smaller disk-like Kuiper Belt (Yeoman, 2003). holding reservoir the dynamic groups of comets can be re-classified. Long-period comets and Halley-type comets are thought to originate in the Oort Cloud and are together called nearly isotropic comets (NIC). Jupiter-family comets are thought to originate in either the Kuiper Belt or the scattered disk (which become indistinguishable after being dynamically altered into a Jupiter-family orbit) and are called ecliptic comets (Figure

1.3) (Weissman et al., 2002).

Comets and asteroids represent the initial distribution of physical and chemical condi­ tions during the planet-forming period in the early Solar System. A relatively inexpensive way for scientists to study these primitive bodies is through the free sampling that Earth’s orbit collects and its atmosphere detects. The Earth collides frequently with meteoroids ranging from microscopic dust to bodies tens of meters in diameter. Ceplecha et al.

(1998) determined that on average 8 × 105 kg are accreted to Earth each year for masses ranging from 10−7 to 102 kg. As a body travels through the Earth’s atmosphere, colli­ 5

Figure 1.3: Flow chart demonstrating the dynamic groups of comets and their assumed source region. sions between the meteoroid and the atmospheric particles cause its surface temperature to rise quickly to evaporation at approximately 2500 K (Opik, 1958). Meteoroids larger than a few tenths of a millimeter are unable to conduct this heat efficiently away from its surface and ablation results (Ceplecha et al., 1998). Ablation is a process through which meteoroid mass is lost and can occur through a number of mechanisms: vaporization, fragmentation, sputtering. Vaporization of a meteoroid produces the light phenomenon known as a meteor. Sufficiently large and strong meteoroids do not completely ablate during their journey through the atmosphere; they are decelerated below a critical ve­ locity (∼3 or 4 km/s) where light production no longer occurs and they enter what is known as dark flight. During dark flight the surface of the body is cooled into a glassy fusion crust before falling to the ground as a meteorite. Meteors brighter than Venus

(-5 magnitude) that potentially drop meteorites are known as fireballs (Figure 1.4). 6

Figure 1.4: Terminology and durations associated with a meteor event (from Ceplecha et al., 1998)

Naturally, the Earth only impacts meteoroids found in near-Earth space, be those of asteroidal or cometary origin. Asteroidal meteoroids in near-Earth space represent objects that are likely collisional fragments whose orbits have been dynamically altered through resonance interactions with the large Jovian planets. A meteor of asteroidal origin is expected to demonstrate more rugged physical properties being able to penetrate further into the atmosphere due to its stronger rocky composition. A meteor of cometary origin is expected to ablate higher in the atmosphere due to its weaker icy composition.

Many cometary meteor events can be traced directly to a parent comet by their orbital elements. Streams of material are left behind as a comet travels through the inner Solar

System and meteor showers occur when the Earth passes through the debris stream.

While many showers have been linked to a parent body, others still lack an associated parent object. 7

1.2 Linking Origin and Material

1.2.1 The PE Criterion

Meteor scientists attempt to categorize meteoroid material by considering the nature of the meteor event. Criteria have been proposed based on different observational parame­ ters for various sizes of events and then linked with orbits and other considerations.

Figure 1.5: Distribution of PE values for Prairie Network fireballs used to determine divisions of meteoroid material. Type I is associated with stony material, type II with carbonaceous material and type III with icy cometary material (from Ceplecha & Mc- Crosky, 1976).

The PE criterion1 is an empirical definition (Figure 1.5) based upon a least-squares

fit with 156 Prairie Network meteors (Ceplecha & McCrosky, 1976). It was inspired by the idea that fireballs of different composition are able to penetrate a depth into the atmosphere related to their strength. Considering the initial mass (m∞), speed (initial velocity, v∞), trajectory orientation (zenith distance, ZR) and the atmospheric air density

1 The name PE is in reference to ρE , the air density at end height, the criterion’s defining characteristic for classifying fireballs. 8

(ρE ) at end height, the PE value relates to the body’s strength (Equation 1.1).

PE = log (ρE) − 0.42 · log (m∞) + 1.49 · log (v∞) − 1.29 · log (cos (ZR)) (1.1)

Ceplecha & McCrosky (1976) made three assumptions about meteoroids when consider­ ing the PE values obtained from Prairie Network meteors:

1. Discrete classes of meteoroid structures exist.

2. Carbonaceous material is more abundant in the fireball population than indicated

by the meteorite collection (more comparable in population to ordinary chondrites).

3. A relationship exists between a meteoroid’s strength and its density.

They defined the fireball groups by the following divisions (although they noted that the division between groups I and II could not be thoroughly defended statistically):

I −4.60 < PE

II −5.25 < PE ≤ −4.60

IIIa −5.70 < PE ≤ −5.25

IIIb PE ≤ −5.70

Each fireball group has been connected with a meteoroid composition type. Type I

fireballs are associated with stony asteroidal material as demonstrated by the three pho­ tographed meteorite falls at the time: Pˇr´ıbram, Lost City and Innisfree. Type II fireballs are associated with carbonaceous material of either asteroidal or cometary origin; the argument for this association is strengthened by the presence of carbon in the spectra of several events of this type. Types IIIa and IIIb are both assumed to be cometary in origin having numerous associations with shower events (Ceplecha, 1994). 9

1.2.2 The Tisserand Parameter

The mathematics describing a small body gravitationally bound to the Sun becomes complicated with the introduced gravity of another large body. In classical mechanics the Jacobi integral is used to describe the circular restricted three-body problem, it has no analytic solution, and so the Tisserand parameter (Equation 1.2) is employed as an approximation to the Jacobi constant (Weissman et al., 2002). When the small tertiary body (comet or asteroid) is influenced by the secondary body (e.g. Jupiter with semi- major axis aJ ) it experiences a change in semi-major axis (a) that is correlated with a change in eccentricity (e) and inclination (i) while the Tisserand parameter is quasi- conserved (Morbidelli et al., 2002).

a a T = J + 2 (1 − e2) cos (i) (1.2) a aJ

Objects with T > 3 are not Jupiter-crossing and are therefore associated with asteroids.

The Tisserand parameter may also be used to distinguish between types of comets as they have vastly different orbital parameters related to their source regions (Weissman et al., 2002). Nearly isotropic comets (LP and HTC) have T < 2, while ecliptic comets

(JFC) have T > 2 (Figure 1.6).

1.2.3 Meteorites Associated with an Orbit

The PE criterion can be used to determine the physical properties of a meteoroid, and used in conjunction with the Tisserand parameter to determine where the material orig­ inated. This is a simple way to study the distribution of material in the Solar System, simply taking advantage of the free delivery of material to Earth and the natural sensor that is the Earth’s atmosphere. Calibrating the results with ground truth is of utmost importance. This calibration can come in the form of fallen meteorites with computed orbits, recovered samples that can be directly associated with a precisely calculated orbit 10

Figure 1.6: Plot from Weissman et al. (2002) of all comets and asteroids known in 2002 with magnitudes brighter than 18. Asteroids are plotted with closed circles, comets with open circles. Dashed lines show the Tisserand parameter boundary between comets and asteroids at T = 3 and between types of comets (ecliptic and nearly isotropic) at T =2. Additionally, objects within the q < 1.017 AU and Q > 0.983 AU are Earth-crossing, and the q = 1.3 AU line denotes the Earth-approaching boundary for Amor-type orbits. 11 as triangulated from two or more locations. Worldwide, only a dozen or so fallen mete­ orites can be associated with an orbit, having varying precision based on the method of orbit determination. Imaging an object in space prior to fall gives the most accurately determined orbit. In practice, this is statistically improbable considering the size and albedo of objects being discussed (tens to hundreds of centimetres). Precisely calibrated, dedicated systems are more likely to image the fall of a meteorite and from these images it is possible to compute a precise orbit. However, with the spread of technology, fireballs are more often being captured serendipitously by non-dedicated systems (security cam­ eras, personal video cameras or photographs) that require careful and extensive effort to calibrate after the fall, usually resulting in less precise orbital parameters. Eye witnesses, though still valuable, give relatively imprecise constraints. Finding credible sources from local observers can be difficult as memories quickly fade and details are jumbled in the excitement of a large, unexpected and brief display in the sky.

Table 1.1 shows instrumentally recorded meteorite falls for which orbits have been derived. Five of these (Pˇr´ıbram, Lost City, Innisfree, Neuschwanstein and Bunburra

Rockhole) were imaged by dedicated systems and have accurately determined orbits.

Almahata Sitta was particularly exciting, as it was first imaged as asteroid 2008 TC3 and predicted to impact the Earth. It has the most accurate orbit of any meteorite, note the precision quoted in Table 1.1. This object achieves the ultimate goal in calibrating models, allowing for a direct association between meteorite type and origin, but also as the

first ground truth for the asteroid classification system (Jenniskens et al., 2009). All other events detailed in Table 1.1 were observed by non-dedicated methods (satellite systems, videos and eye witnesses) which typically lead to less precision in orbital parameters but these methods should not be overlooked as they account for ∼50% of the determined orbits. As well, with the spread of technology worldwide, observing a fall instrumentally through one of these means is becoming more and more probable. 12

Table 1.1: Meteorites associated with a derived orbit. The location abbreviations are: AUS– Australia, CAN– Canada, CSR– Czechoslovakia, CZE– Czech Republic, GER– Germany, ESP– Spain, SUD– Sudan and USA– United States of America. The observed abbreviations correspond to: DS– dedicated system, VC– video cameras, EW– eye wit­ nesses, S– satellites, SS– space survey. Event

Date (m/d/y) Time Location Recovered Type Observed Reference Mass (kg) Orbit a (AU) e i (◦) q (AU) Q (AU) ω (◦) Ω (◦)

Pˇr´ıbram J2000.0: 4/7/1959 19:30:21 UT CSR 5.8 H5 DS Ceplecha, 1977

Orbit: 2.402 0.6712 12.481 0.7894 4.012 241.75 17.110

Lost City J1950.0: 1/4/1970 02:14 UT USA 17.2 H5 DS McCrosky et al., 1971 Orbit: 1.66 0.417 12.0 0.967 2.35 161.0 283.0

Innisfree J1950.0: 2/6/1977 02:17:38 UT CAN 4.58 L5 DS Halliday et al., 1978 Orbit: 1.872 0.4732 12.27 0.986 2.758 177.97 316.80

Peekskill J2000.0: 10/9/1992 23:48 UT USA 12.57 H6 VC Brown et al., 1994 Orbit: 1.49 0.41 4.9 0.886 2.10 308 17.030 Continued... 13

Event

Date (m/d/y) Time Location Recovered Type Observed Reference Mass (kg) Orbit a (AU) e i (◦) q (AU) Q (AU) ω (◦) Ω (◦)

St-Robert J2000.0: 5/15/1994 00:02 UT CAN 25.4 H5 EW/S Brown et al., 1996 Orbit: 1.9 0.48 0.7 1.0158 2.86 179 83.746

Tagish Lake J2000.0: 1/18/2000 16:43:43 UT CAN 5-10 CI VC/EW/S Hildebrand et al., 2006 Orbit: 1.98 0.55 2 0.884 3.08 224.4 197.901

Mor´avka J2000.0: 5/6/2000 11:52 UT CZE 1.4 H5 VC Boroviˇcka et al., 2003 Orbit: 1.85 0.47 32.2 0.9823 2.71 203.5 46.258

Neusch­ wanstein J2000.0: 4/6/2002 20:20:17.7 UT GER 6.2 EL6 DS Spurn´y et al., 2003 Orbit: 2.40 0.670 11.41 0.7929 4.01 241.20 16.82264 Continued... 14

Event

Date (m/d/y) Time Location Recovered Type Observed Reference Mass (kg) Orbit a e i q Q ω Ω

Park Forest J2000.0: 3/27/2003 05:50 UT USA 18 L5 VC/S Brown et al., 2004 Orbit: 2.53 0.68 3.2 0.811 4.26 237.5 6.1156

Villalbeto de la Pe˜na J2004.01: 1/4/2004 16:46:45 UT ESP 5 L6 VC Trigo-Rodr´ıguez et al., 2006 Orbit: 2.3 0.63 0 0.86 3.7 132.3 283.6712

Bunburra Rockhole J2000.0: 7/20/2007 19:13:53.2 UT AUS 0.324 Eucrite DS Spurn´y et al., 2009 Orbit: 0.851 0.245 9.07 0.643 1.05997 209.9 297.5953

Almahata Sitta J2000.0: 10/7/2008 02:45:40 UT SUD 3.95 Ureilite SS Jenniskens et al., 2009 Orbit: 1.308201 0.312065 2.5422 0.899957 1.716445 234.449 194.1011 15

1.3 The Buzzard Coulee Fall

On November 20, 2008 a large bright fireball was observed by tens of thousands of people in Alberta, Saskatchewan, Manitoba and Montana. A vast number of people were witness to this event due to its large size and brightness but also partly due to the time of day, falling during ‘rush hour’ at approximately 5:30 MST. Eye witness accounts as well as crude security camera calibrations led to meteorites being recovered one week after the fall in Buzzard Coulee, Saskatchewan. The fresh newly fallen meteorites were accompanied by sufficient instrumental data to derive an atmospheric trajectory and pre-fall orbit. That is to say, enough data was available to allow the Buzzard Coulee meteorite to join the small but growing family of meteorites associated with an orbit. A number of dedicated all-sky cameras imaged the fall of Buzzard Coulee but all were quite distant from the fireball and were not calibrated at the time of the fall. For the first time, careful measurements of the shadows cast by the event provided the best instrumental records to derive an atmospheric trajectory.

1.4 Research Project Outline

This research project seeks to gain a better understanding of the history and current environment of the Solar System through the study of Earth-impacting meteoroids. The research has been split into two distinct studies divided into chapters, each containing relevant background information, description of methods, results and concluding discus­ sions.

The first part of this thesis studied the events captured by dedicated fireball networks.

The objectives for Chapter 2 include: (1) combining data from several networks to im­ prove statistics, (2) re-evaluating the historic divisions of PE values, (3) comparing the strengths of objects with source region, (4) investigating the use of PE values of meteor 16 showers as fiducial points to compare events between networks, and (5) investigating the orbital parameters of meteoroids in the fireball size range.

The second part of this thesis studied the Buzzard Coulee meteorite fall summarizing the meteorite typing and camera calibration efforts. The objectives of Chapter 3 were to: (1) determine a trajectory for Buzzard Coulee, (2) derive a velocity and determine its orbit, (3) search for the Buzzard Coulee meteoroid in space survey images, and (4) evaluate the novel method calculating a trajectory by calibrating the shadows cast. 17

Chapter 2

Fireball Network Events

2.1 Historical Overview of Fireball Networks

A small system of dedicated fireball cameras was started in 1951 at the Ondˇrejov Observa­ tory in Czechoslovakia. After eight years of operation, multiple stations photographically recorded the fall of a meteorite. The four recovered Pˇr´ıbram meteorites were the first ever to be instrumentally recorded so that an orbit could be derived. Inspired by this event, the coverage of the network and the number of cameras expanded. By the end of 1963 five stations were already in operation with plans for a further 15 stations to be built in Czechoslovakia and Germany (Ceplecha & Rajchl, 1965). This system of cam­ eras became known as the European Fireball Network (EN). Each EN site employs an all-sky camera which takes long exposure images of a 36 mm parabolic mirror. In order to obtain timing (and hence velocity) information for meteor events, a 12.5 Hz rotating shutter is used to break the path of the fireball into well-timed intervals.

Incredibly after almost sixty years, the European Network is still in operation today

(Figure 2.1). A total of 12 stations are spread across the Czech and Slovak Republics with a further 22 sites in Germany, Belgium, Switzerland and Austria, covering approximately

106 km2 . While the technology used to image fireballs has remained largely unchanged, the cameras in the Czech Republic and Slovakia have been upgraded several times and now use Zeiss Distagon fish-eye lens cameras pointed toward the zenith (Oberst et al.,

1998). Despite the flood of CCD technology into the world of astronomy, the EN cameras continue to operate with conventional photographic film due to its wide dynamic range and high resolution. This system is restricted to imaging at night during clear, dark times 18

Figure 2.1: Map of the current European Fireball Network (EN) with stations in Belgium, Germany, Switzerland, Austria, Czech Republic and Slovakia (Oberst et al., 1998).

(no Moon). Oberst et al. (1998) estimate that an average of 3 – 3.5 hours of imaging occurs nightly throughout the year, with as much as sixty percent of the yearly imaging occurring during the winter months. The network sees over 50 fireballs brighter than

-6 magnitude each year (∼50% of these events are observed simultaneously by two or more stations). They estimate, based on a meteorite flux rate, that ∼15% of meteorites falling in the EN area are photographed. To date, two meteorite dropping events have been imaged and subsequently recovered, Pˇr´ıbram which fell in 1959 and Neuschwanstein which fell in 2002 (Spurn´y et al., 2003).

McCrosky & Boeschenstein (1965) describe the establishment of a fireball network in the midwest United States. The Prairie Meteorite Network (PN) operated for a decade and consisted of 16 stations covering approximately 7.5 × 105 km2 across seven States,

South Dakota to Oklahoma, Nebraska to Illinois (Figure 2.2). Each station employed four wide-field T-11 aerial mapping cameras with a Metrogon lens taking long exposure photographs similar to the European Network. A shutter rotating at 20 Hz created 19 breaks in the meteor trajectory used to obtain velocity information for events (McCrosky

& Ceplecha, 1968). The stations were sufficiently automated to remain unmanned for several weeks at a time, needing the film to be changed by an attendant every three to six weeks, but in practice were routinely inspected every few days. On January 3,

1970 the Prairie Network successfully photographed the fall of a meteorite, predicted the fall location, and recovered the Lost City meteorites (McCrosky et al., 1971). These meteorites became the second to have an associated orbit but were the only meteorites recovered by the Prairie Network.

Figure 2.2: Map of the Prairie Fireball Network (PN) with stations in the midwest United States (McCrosky & Boeschenstein, 1965).

A third fireball network began operation during the time of the European and Prairie

Networks. The Canadian network, maintained by the National Research Council (Figure

2.3), started full operation in 1971 and ran until 1985. The Meteorite Observation and

Recovery Project (MORP) consisted of 12 stations spread throughout the three Prairie

Provinces — Alberta, Saskatchewan and Manitoba (Halliday et al., 1978). Similar in 20 design to the Prairie Network, instead of using all-sky cameras, MORP covered nearly the entire sky using five 50◦ field of view cameras pointed 72◦ apart at each location

(Campbell-Brown & Hildebrand, 2004). Shutters rotating at 4 Hz were used to determine event velocities. This network was responsible for observing, recovering and deriving an orbit for one meteorite, Innisfree, which fell February 5, 1977.

Figure 2.3: Map of the Meteorite Observation and Recovery Project (MORP) with sta­ tions in the Canadian Prairie Provinces (Halliday et al., 1978).

The University of Western Ontario has developed a small camera network as part of the Southern Ontario Meteor Network (SOMN) since 2004. It currently consists of seven stations throughout Ontario. The system is fully automated running small calibrated all-sky CCD cameras. Meteor events are automatically detected by software and checked against events recorded at the other stations. Trajectory and orbit solutions are then automatically calculated for multistation detections (Weryk et al., 2008). While CCD systems like this one do not have the dynamic range or resolution of the photographic cameras of the European Network, they do gain the benefit of being fully digital and automated. One meteorite fall on September 25, 2009 in Grimsby, Ontario has recently 21 been observed by this network (McCausland et al., 2010).

Fireball networks have operated with some success at achieving a primary goal of imaging and recovering fallen meteorites. These systems have also given insight into the distribution of orbital elements of large meteors, helped to develop an understanding of the interaction between meteoroids and the atmosphere (Ceplecha & McCrosky, 1976), and have provided estimates of flux values of meteoroids onto the Earth (Halliday et al., 1996). This thesis project explores the properties of the Earth-impacting meteoroid population through the fireball data recorded by camera networks. For the first time, this study combines the data from four camera networks to create one large data set. The

PE values (related to meteoroid strength) and Tisserand parameters (commonly used to distinguish source region) were calculated for all sufficiently well-characterized events and were explored along with the orbital elements of the fireball events.

2.2 Methodology

Each fireball camera network calibrated and derived orbit solutions independently, choos­ ing which events to reduce depending on selection criteria dictated by the objectives set for each project. It would be impractical, and in some cases impossible, to re-calculate the orbits from each camera network, therefore it must be assumed that calibration work was done with a sufficiently high standard to result in correct orbit solutions which are used in this project. While none of the orbit solutions are reduced through this project, the overall method for deriving the necessary parameters is described in the following sections.

2.2.1 Calibration, Trajectory and Orbit Derivation

Once images of a meteor event are captured, either photographically or digitally on a CCD, positions can be measured to determine an initial velocity and to triangulate 22 an atmospheric trajectory. Deriving an atmospheric trajectory gives insight into the phenomena arising from the interaction of a meteoroid with the atmosphere (ablation, fragmentation, deceleration, etc.), as well as the information needed to calculate an orbit.

Obtaining a heliocentric orbit for a given meteoroid increases the understanding of the meteoroid’s origins, as well as the dynamical environment of the Solar System. A meteor trajectory is triangulated through observations taken at two or more locations. Firstly, images must be calibrated so that positions may be mapped to a coordinate system in the sky. For this, typically images of the sky are taken at known times, individual stars are identified within the images and their known right ascension and declination are converted to an altitude and azimuth for the camera location at the given time. The star positions are used to build a plate solution for the camera, so that any position in the sky can be accurately determined. The altitude and azimuth of a meteor are measured in each frame for all cameras imaging the event. A single camera is able to define a plane in space along which the meteor travelled; it is the intersection of planes from each camera that gives the meteor trajectory through the atmosphere. The intersection of three or more planes is unlikely to be perfect due to the uncertainties associated with measurements, however, a weighted average can be calculated to derive an average meteor trajectory (Ceplecha, 1987). Code called MILIG (Boroviˇcka, 1990) takes altitude and azimuth observations from each camera site and calculates a least squares fit for a trajectory solution incorporating subtle effects such as the curvature of the Earth.

Velocity and position information are required to obtain a heliocentric orbit for a meteoroid. The initial velocity before atmospheric deceleration, v∞, can be measured from the start of the trajectory using timing information. The geocentric velocity ( vVG) is obtained by correcting the initial observed velocity for Earth’s gravitation (escape velocity ve). The heliocentric velocity ( vVH ) is then found by subtracting the Earth’s orbital velocity (vV E) (Equation 2.1). Details of the equations used to determine the 23 heliocentric orbital parameters using a geocentric position and velocity are reviewed by

Ceplecha (1987). In practice, a program called MORB (Ceplecha et al., 2000) inputs initial velocity and position of a meteor then computes the orbital parameters of the meteoroid.

VvH = VvG − VvE (2.1)

where:

� 2 2 vG = v∞ − ve

The steps and the specific computer programs involved in determining the trajectories and orbits of events captured by the SOMN are briefly outlined in Appendix A. The orbital parameters of MORP, EN and PN events used in this study are taken from the list of published papers presented in Table A.1 of Appendix A.

2.2.2 Determining Mass and Calculating the PE Criterion

The PE criterion (Equation 1.1) derived by Ceplecha & McCrosky (1976) weights all meteors for mass, velocity and zenith angle, then compares the end height (or equivalently the atmospheric density at end height) as a measure of the body’s strength. The end height, velocity and zenith angle are obtained by finding the trajectory solution using

MILIG. The end height is converted to an atmospheric density through the MSIS-E­

90 atmosphere model (Hedin, 1990). MSIS-E-90 requires the latitude, longitude, date and time to model atmospheric density at various heights. Finally, the only remaining parameter necessary to determine a PE value is the mass of the ablating object.

The intensity of light produced by a meteor can be used to estimate the mass of the meteoroid, known as the photometric mass. A light curve plots the intensity (I, where

I = 1 for 0 magnitude) of a meteor over time (t), and the initial mass of the meteoroid may be determined by integrating this curve and making a few assumptions about the 24 nature of the meteor. Equation 2.2 shows the integration of a light curve to calculate a photometric mass (Ceplecha, 1988).

� tE Idt m = 2 + m (2.2) ∞ 2 E tB τv

Equation 2.2 adds the ablated mass and the terminal or end mass (mE ) to determine the initial mass (m∞). The luminous efficiency factor (τ) is the total kinetic energy that is converted to electromagnetic radiation; it exhibits a velocity dependence (v). The light producing processes that occur as a meteoroid enters the atmosphere are not well understood and considerable uncertainty remains in the luminous efficiency factor and its dependence on velocity. Experimentally it is not possible to recreate meteor conditions in the laboratory for objects larger than microns in diameter. Spacecraft re-entries also make poor meteor analogs due to their inappropriate composition and structure, as well as comparably low velocities. Table 2.1 taken from Ceplecha & McCrosky (1976) shows the values of luminous efficiency adopted for given velocities used for EN, PN and SOMN events. Table 2.2 shows the luminous efficiency values used for MORP events by Halliday et al. (1996). The values presented in Table 2.2 have been corrected by a factor of

1.8 × 10−10 s/erg for 0-mag (Halliday, 1988) so that panchromatic meteor intensities are expressed similarly to Ceplecha & McCrosky (1976) and can be compared more directly with Table 2.1.

The photometry of a system must be carefully calibrated to obtain accurate measure­ ments of the initial mass. Simply measuring the pixel values of the meteor in each frame gives an instrumental intensity (which can be converted to the logarithmic instrumental magnitude scale via Equation 2.3).

Minst = −2.5 · log (Iinst) (2.3)

The goal in calibrating the photometry of a system is to be able to measure an instru­ mental intensity or magnitude and convert it to a value independent of the system, an 25 absolute panchromatic value. The absolute panchromatic (‘all colours’) intensity is cor­ rected to be equivalent to the brightness of an event measured at zenith, 100 km away in the colour response of panchromatic film. A number of corrections are needed for the conversion from instrumental to absolute intensity.

Table 2.1: Luminous efficiencies (0-mag s/erg) published by Ceplecha & McCrosky (1976) used to determine photometric masses of events recorded by the PN, EN and SOMN. Velocity (km/s) log (τ)

≤ 9.3 −12.75

9.3 – 12.5 −15.60 + 2.92 · log (v)

12.5 – 17.0 −13.24 + 0.77 · log (v)

17.0 – 27.0 −12.50 + 0.17 · log (v)

> 27.0 −13.69 + log (v)

Table 2.2: Luminous efficiencies published by Halliday et al. (1996) used to determine photometric masses of events recorded by MORP. A factor of 1.8 × 10−10 s/erg for 0-mag (Halliday, 1988) has been applied so that panchromatic meteor intensities are expressed with respect to the magnitude system (τ is in units of 0-mag s/erg) and can be more readily compared with the luminous efficiencies of Ceplecha & McCrosky (1976). Velocity (km/s) log (τ)

< 10 negligible

10 – 36 -11.65

36 -11.42

> 36 −8.30 − 2 · log (v)

The measured instrumental magnitude is affected by the quantum efficiency and wave­ lengths of light to which the system is sensitive. In order to convert to an apparent 26 magnitude (independent of the camera), various instrumental magnitudes of stars are measured and compared against their known values to obtain a mathematical conver­ sion between the instrumental magnitudes of meteors and their apparent magnitudes.

Meteors display a wide range of spectra due to the variety in composition, so there is significant uncertainty introduced in this conversion without meteor spectra. The next step is to convert the apparent magnitude into an absolute magnitude, which the object would have if it were a standard distance of 100 kilometres away overhead at zenith

(Nudds, 2007). This conversion is done by correcting for the extinction and range of the event (Equation 2.4). The extinction correction (Equation 2.5) is found using the ex­ tinction coefficient (k), which describes the quantity of light dispersed travelling through a standard amount of air, and the air mass (ma), a dimensionless parameter describing how much atmosphere lies between the camera and the meteor.

Mabs = Mapp − Cextinction − Crange (2.4)

Cextinction = k · ma (2.5) 100 km C = −5 · log (2.6) range R The light intensity of a point source geometrically falls off by the inverse square of the distance. The range correction (Equation 2.6) maintains this proportionality through the logarithmic magnitude scale and evaluates the difference between the meteor’s intensity at distance R (in kilometres) and at the standard 100 km away. Finally, the absolute magnitude is adjusted to a panchromatic magnitude by a quantity specific to the sys­ tem’s method of observation. For example, as mentioned before, the SOMN uses CCD cameras rather than panchromatic film for imaging meteors. It has been estimated that the spectral response of a CCD gives photometry that is two magnitudes dimmer than panchromatic film, therefore Mpan = Mabs − 2 for SOMN events (Nudds, 2007). 27

2.2.3 Combining and Correcting Data from Fireball Networks

The relevant parameters required to calculate the PE value and Tisserand parameter as well as the orbital elements are summarized in Table A.2 of Appendix A. Table A.2 also indicates how each parameter is obtained through the various stages of data reduction.

The event solutions for this project were taken from the previously published papers listed in Table A.1. Due to the fact that each network calibrated and reduced solutions independently, a correction must be applied before combining the data. The most signifi­ cant difference in the data reduction process between networks is in the determination of photometric masses, for example through assumptions made for the luminous efficiency factor. For this reason a mass correction must be applied so that direct comparisons between network events can be made. Ceplecha (1988) determined a mass scaling factor

(Equation 2.7) that can be used to convert between different mass scales adopted by each network.

log (mCeplecha88) = log (mMORP) + 0.2 = log (mEN/PN) − 0.3 (2.7)

MORP events were mass scaled by a factor of 100.5 so that PE values determined for

MORP events may be directly compared with those calculated for the EN and PN. An equivalent mass scaling factor has not yet been determined for the SOMN, therefore a direct comparison between PE values of SOMN events can not be made against other networks.

A number of shower associations were made in the original published papers (Table

A.1). In this study additional associations have been made by comparing orbital elements, velocity and date against known meteoroid streams. Often one or more orbital elements appear to be off from the catalog shower value. In particular, the Perseid events published by Halliday et al. (1996) were often out in semi-major axis and/or eccentricity. This is likely due to the fact that the Perseids have a very large semi-major axis for which large 28 errors can be expected as a result of small uncertainties in the derived velocity. Published shower associations were assumed to be valid, any newly associated events made during this study were rigid in only accepting orbital elements matching closely with the known meteoroid stream values.

PE values and Tisserand parameters were calculated for events of the EN, PN, MORP and SOMN networks. Comparisons between object source region, shower associations and meteoroid ‘strength’ have been made. The divisions between fireball types developed by

Ceplecha & McCrosky in 1976 (Section 1.2.1) were re-evaluated using the much larger data set combined from events of the EN, PN and MORP. As fireball networks operated with a primary goal of observing meteorite falls, many events selected for reduction are highly biased toward large, strong events. Halliday et al. (1996) published orbital solutions for 213 meteors assigned to the Clear-Sky Survey, an unbiased sub-set of the

MORP data. The Clear-Sky Survey is possibly the most representative data set for considering the true distribution of meteoroid physical properties.

In addition to observing and recovering fallen meteorites, fireball networks offer the chance to study the orbital dynamics of the inner Solar System. Naturally the fact that the Earth must collide with an object in order for it to be observed places a bias on the data. To help compensate for Earth’s bias on the data, a collision probability factor in terms of an object’s orbital elements is used to correct the data. The correction factor

(nc) adopted by Galligan & Baggaley (2004) has been applied to adjust the data from all networks for collision probability (Equation 2.8). The collision probability correction uses an object’s orbital elements: semi-major axis (a), inclination (i), eccentricity (e) and a factor representing the effective target radius of the Earth (τR). The target radius 29

1 is the ratio between the initial speed (v∞) and the geocentric speed (vG).

τ 2 3 − a−1 − 2� a(1 − e2) · cos i n ≈ R (2.8) c a1.5 sin i 2 − a−1 − a(1 − e2)

v∞ where: τR = vG

There are limitations associated with the collision probability correction factor de­ scribed by Galligan & Baggaley (2004). Equation 2.8 assigns a very large correction for semi-major axes larger than 4 AU and for this reason all semi-major axes were restricted to a = 4 AU for the calculation of the correction factor. Another limitation is that the derivation of Equation 2.8 assumes the Earth to have a circular orbit, potentially leading to some objects having a distorted correction factor.

A second correction factor has been applied to the raw data which re-weights events based on the mass distribution of objects observed in the Solar System. The Solar System has a far greater number of small stones than large minor planets. The shape of the power law distribution is governed by the exponent α, known as the cumulative mass index.

Halliday et al. (1984) determined a value for the cumulative mass index of -0.69 for objects with sizes corresponding to meteorite falls.

mass −0.69 n = (2.9) m 1 kg

This project adopts a reference mass of 1 kg and a cumulative mass index α = −0.69 for the mass correction factor (Equation 2.9). Due to the nature of this correction factor, small objects receive large weightings to reflect the real distribution of Solar System objects observed. Fireball networks are capable of observing a wide range of object masses from bodies weighing thousands of kilograms to sub-grams, depending on their sensitivity to a limiting magnitude. To make the data more manageable and to help

1 � 2 2 Note that: vG = v∞ − ve , where ve is the Earth’s escape velocity. 30 restrict the size of the correction factor, only objects with masses larger than 100 g are included in the investigation of the orbital elements of meteoroids from the fireball data

(found in plots in Section 2.3.4).

The total weight assigned to each event is a ratio of the two correction factors de­ scribed above, namely nm/nc. Each event has been counted by its assigned weight. This is important for studying the distributions and statistics of all the events combined from each fireball network.

2.3 Results and Discussion

2.3.1 PE Value Distributions by Fireball Network

In this study the PE values were calculated for events from each fireball network and distributions of the results were plotted. The PE value divisions found by Ceplecha &

McCrosky (1976), as shown in Figure 1.5, have been used to compare with the results obtained in this study. At the top of each histogram, the original divisions of PE values corresponding to different object material are indicated.

Figure 2.4 shows a plot of PE values for the Prairie Network based on events published in Ceplecha & McCrosky (1976) and McCrosky et al. (1976). This plot has 57 more events than the original study (Ceplecha & McCrosky, 1976). The general shape remains quite similar and the original divisions are as recognizable as they had appeared in the original paper. On the other hand, divisions in the PE values from a histrogram of the European

Network events, found in Figure 2.5, do not match the results of Ceplecha & McCrosky

(1976). The EN data set used in this study contains considerably fewer events (N = 93) compared to either the PN or MORP, and may not show the same PE divisions due to the statistics of the small sampling numbers. Figure 2.6 plots PE values for the Meteorite

Observation and Recovery Project (N = 263). This plot does not follow the divisions 31

Figure 2.4: Histogram of PE values for events captured by the Prairie Network. These PE values were taken from or calculated using data published in: Ceplecha & McCrosky (1976), McCrosky et al. (1976).

Figure 2.5: Histogram of PE values for events captured by the European Network. These PE values were taken from or calculated using the data published in a number of papers: Ceplecha (1971), Ceplecha et al. (1976), Ceplecha (1977), Ceplecha et al. (1979), Ce­ plecha et al. (1980), Ceplecha et al. (1983), Spurn´y (1994), Spurn´y et al. (2001), Spurn´y et al. (2002). 32

Figure 2.6: Histogram of PE values for events captured by the Meteorite Observation and Recovery Project. These PE values were calculated based on data published in: Halliday et al. (1989), Halliday et al. (1990), Halliday et al. (1996). Mass scale corrections recommended by Ceplecha (1988) were made. Latitude and longitude of the end position for input into the MSIS-E-90 model were taken from the original computed solutions on file at the University of Calgary.

Figure 2.7: Histogram of PE values for events captured by the Southern Ontario Meteor Network. These events do not have a mass scale correction and therefore cannot be directly compared with the results from the other networks. 33

Figure 2.8: Histogram combining all PE values for events captured by the EN, PN and MORP, 638 events in total. The distribution appears quite continuous, individual discrete groups are not readily apparent. of fireball types as found by Ceplecha & McCrosky (1976). There appears to be some structure in the distribution of PE values but divisions in the plot do not resemble the historical boundaries indicated in Figure 1.5. Figure 2.7 shows the PE values calculated for the Southern Ontario Meteor Network events. To date no mass scale correction factor has been determined for this network, so these results can not be directly compared to the other networks.

All PE values from PN, MORP and EN events have been combined to produce a histogram found in Figure 2.8. This plot, based on 638 events (282 PN, 263 MORP and 93 EN), shows a much more continuous distribution in PE values than discrete sub- populations. This plot appears heavily skewed with many more events having larger PE values, a result of networks preferentially selecting deeply penetrating, probable meteorite dropping events for analysis. Halliday et al. (1996) published 213 unbiased events as part of MORP’s Clear-Sky Survey which are assumed to be a truely representative sample of 34

Figure 2.9: Histogram of PE values from the MORP Clear-Sky Survey. These events represent an unbiased sample of the Earth-impacting population. This distribution is less skewed toward larger PE values than those in Figure 2.8. the Earth-impacting population. Figure 2.9 shows a histogram of PE values calculated from the MORP Clear-Sky Survey. The distribution appears to have some structure, a roughly bimodal distribution, but once again the historical divisions do not agree with these results. The divisions between types I and II, and between II and III correspond to peaks rather than breaks in the overall distribution.

2.3.2 Fireball Strength and Source Region

The Tisserand parameter has been plotted against the PE criterion to produce Figure

2.10 for events included in the unbiased MORP Clear-Sky Survey.2 The vertical lines divide object material by PE value (types I through III) and the horizontal lines divide source region by Tisserand parameter (Asteroid Belt, Kuiper Belt or scattered disk for ecliptic comets and Oort Cloud for nearly isotropic comets). These divisions create nine

2All statistics quoted for Figure 2.10 are based on raw numbers representing a limiting magnitude, not a limiting mass. 35

Figure 2.10: Plot of MORP Clear-Sky Survey events in Tisserand parameter and PE criterion space which helps to link object strength with source region. Meteoroid masses are binned by a logarithmic scale and plotted with varying size of circle. Of particular interest is the very weak material originating in the Asteroid Belt and the very strong nearly isotropic comet material coming from the Oort Cloud.

Figure 2.11: Percentages of the raw numbers of MORP Clear-Sky Survey objects falling into each region of Figure 2.10. 36

Figure 2.12: Percentages of the raw observed masses of MORP Clear-Sky Survey objects falling into each region of Figure 2.10. regions in the plot, each corresponding to material strength within a source region. The size of the symbol relates to the object mass with the smallest symbols representing the bin 0–1 kg, the intermediate size 1–10 kg and the largest size 10–100 kg. Of the number of events included here, 71% fall into the 0-1 kg bin (representing only 6% of the raw observed mass), 20% fall into the 1–10 kg bin (representing 24% of the observed mass) and 9% fall into the 10–100 kg bin (representing 70% of the observed mass). The largest event included in the plot is 41 kg.

Percentages within each region of Figure 2.10, determined by raw number (N) and by raw observed mass, are shown in Figures 2.11 and 2.12, respectively. The proportions of material strength by source region are presented in Table 2.3. Traditionally, asteroidal material is thought to be strongest, made of stones and some carbonaceous material.

Whereas comets are made of weaker, more fragile icy material. In general, the trends between material type and source region agree in that material from the Asteroid Belt is stronger, penetrates more deeply into the atmosphere and corresponds to types I and

II fireballs, while cometary material is weaker, less penetrating and corresponds to types 37

II and III fireballs. It is somewhat surprising to find that this analysis shows so much weak asteroidal material, 20% of the mass originating in the Asteroid Belt was observed as type III fireballs. This result indicates that there is a considerable quantity of weak material found in the Asteroid Belt. Indeed a considerable proportion of the outer Main

Table 2.3: Breakdown by raw number and by raw mass of meteoroid strength within Tisserand parameter determined source regions. An unexpectedly high percentage of weak asteroidal material and strong Oort Cloud (nearly isotropic comet) material is observed. Tisserand Parameter PE Value: III II I Total Asteroid N 29% 35% 35% 99 Belt Mass 20% 35% 47% 485 kg

Ecliptic N 57% 26% 17% 46 Comet Mass 51% 11% 38% 133 kg

Nearly Isotropic N 79% 17% 4% 53 Comet Mass 83% 12% 6% 7 kg

Belt is composed of dark spectral classes C-, P- and D-type asteroids which have been linked to weak carbonaceous chondrites (McSween, 1999). The Tagish Lake meteorite, for example, is a carbonaceous chondrite and is one of the most primitive and weak meteorites recovered to date. Its powder shows reflectance spectra similar to D- and

P-type asteroids and its derived orbital parameters also make a strong argument for an outer Main Belt origin of this meteorite (Hildebrand et al., 2006). Stuart & Binzel (2004) modeled a bias-corrected distribution of the near-Earth population, they observed that

∼18% of the near-Earth population with T > 3 (implying an Asteroid Belt origin) is composed of C- and D-type asteroids which could be the source of the weak Asteroid

Belt material observed in this study. The percentage of potentially weak material within the near-Earth population would be even larger when the P-type asteroids are considered.

Stuart & Binzel (2004) predicted that ∼32% of the NEOs with T > 3 are X-complex asteroids, to which the P-type belongs. They did not specifically separate the P-type 38 objects from the X-complex, which also contains the M-type asteroids linked with iron meteorites and not likely to be the source of the weak type III fireballs.

Another surprising observation is that two nearly isotropic comet (NIC) events which apparently originated in the Oort Cloud ablated in the atmosphere like hard stones.

They were events: MORP 441 (41.1 g, v∞ = 70.3 km/s) and MORP 835 (379.5 g, v∞ = 24.2 km/s). These events are particularly exciting because they indicate that it may be possible to have Oort Cloud material survive atmospheric transit and result in meteorites. It is traditionally believed that cometary meteors do not result in meteorites, so having two type I events out of 53 NIC events is very surprising. It was, however, suggested by Weissman & Levison (1997) that a small proportion of the Oort Cloud

(∼0.8 – 2.3%) is in fact composed of asteroids that were ejected from the inner Solar

System late in the planetary-zone clearing stages. Alternatively, it is also thought that if a comet spends sufficient time in the inner Solar System near the Sun, it may loose much of its volatile material and develop a hard outer crust or rind made of the hardest cometary material. It is possible that the two small type I NICs could be sampling pieces of hard baked comet crust.

2.3.3 PE Values of Shower Events

A total of 118 objects from the four camera networks have been associated with meteor showers. Table 2.4 summarizes these shower events, including the total number of objects recognized for each shower and the average PE value calculated.

Using the events combined in this study, the best statistical observations can be made for the Perseids (N = 37) and the Taurids (Northern Taurids N = 17 and Southern Tau- rids N = 18). The average PE value calculated for the 37 Perseids is -5.43 corresponding to type IIIa fireballs. This value is consistent with the expectation of weak meteoroids resulting from their long period Oort Cloud parent, comet 109P/Swift-Tuttle. The distri­ 39 bution of PE values for this shower was quite tight with a standard deviation of 0.24. In contrast with this result, the 35 Taurid stream meteors had an average PE value of -5.22 corresponding to type II fireballs (very near the historically defined border with type

IIIa at -5.25). However, this stream varies quite widely with a standard deviation over twice as large as the result for the Perseids at 0.57. Shrben´y & Spurn´y (2009) calculated

PE values as part of their study on 54 Leonids. They concluded that the Leonid parent body 55P/Tempel-Tuttle was inhomogeneous due to the variation of PE values observed corresponding to types II, IIIa and IIIb. Their average PE value based on 54 Leonids was -5.74 (slightly larger than the value presented in Table 2.4 based on only 8 events) corresponding to type IIIb fireballs. They observed a fair amount of variation in the

Leonid PE values with a standard deviation of 0.33. The PE values obtained by Spurn´y

& Shrben´y (2008) for 10 Orionids gave an average of -5.43 (type IIIa) with a standard deviation of 0.28, slightly larger than the average found for only 3 events in Table 2.4.

Unfortunately, the sample size for each shower is too small to make specific conclusions about their PE values. One possible way to check the mass scale corrections between different networks would be to compare PE values of different showers captured by each network. Many more shower events than those identified in the current data set from each network would be needed to accomplish this task. There is variation of PE values within each shower with some showers showing a wide range while others have tight distributions of PE values. To make a mass scale correction based on meteor shower PE values, streams with tight distributions would be recommended to look at differences between networks.

The distribution of PE values within meteor showers offers a relatively inexpensive way to compare the strongest non-volatile materials that make up parent comets, and to provide information on the amount of compositional variation within each comet. 40

Table 2.4: Average PE values for meteor shower events. Parent bodies taken from The Meteoroid Stream Working List (Jenniskens, 2006)

Shower PE Value N Type Source Region Parent

Alpha Capricornid -5.24 8 II Kuiper Belt 169P/NEAT (= 2002 EX12) December Ursid -5.78 1 IIIb Oort Cloud 8P/Tuttle

Delta Cancrid -4.79 2 II

Geminid -4.61 7 I Asteroid Belt 3200 Phaethon

Quadrantid -4.52 2 I Kuiper Belt 2003 EH1

Kappa Cygnid -5.97 2 IIIb Kuiper Belt

Leonid -5.96 8 IIIb Oort Cloud 55P/Tempel-Tuttle

Mu Virginid -5.42 1 IIIa

North Delta Aquariid -4.73 2 II Oort Cloud

Northern Taurid -5.05 17 II Asteroid Belt 2004 TG10

October Draconid -5.15 7 II Kuiper Belt 21P/Giacobini-Zinner

Orionid -5.71 3 IIIb Oort Cloud 1P/Halley

Perseid -5.43 37 IIIa Oort Cloud 109P/Swift-Tuttle

Southern Chi Orionid -5.26 2 IIIa

Southern Taurid -5.39 18 IIIa Asteroid Belt 2P/Encke

South Iota Aquariid -4.86 1 II Kuiper Belt 41

2.3.4 Distribution of Orbital Elements

The orbital elements of the combined network events help to develop a picture of the dynamical environment of the inner Solar System for objects in the fireball size range.

The correction factors discussed in Section 2.2.3 for mass distribution (Equation 2.9) and collision probability (Equation 2.8) have been applied to all events. Identified meteor shower events have been removed from the data. The total weighting factors (nm/nc) applied to each event are plotted in the histogram in Figure 2.13. The majority of applied weighting factors are less than 2, although 12.8 was the largest weighting factor used.

Figure 2.13: Distribution of weighting factors applied to events in order to overcome biases due to collision probability and mass distribution. The vast majority of calculated weights are less than 2.

Figure 2.14a shows a plot of eccentricity values, corrected for collision probability and mass distribution from the EN, PN and MORP for objects larger than 100 g. Figure 2.14b shows the same plot on a logarithmic scale and Figure 2.14c shows the raw uncorrected number of events counted within each 0.05 bin. The large number of events in the bins between 0.6 and 0.75 are reduced by the correction factors, while the significance of a 42 small number of events in the 0.95 bin has been increased. As well, the importance of more circular, smaller eccentricity values (less than 0.5) have also been reduced. Corrected inclination values are plotted in Figure 2.15a and can be compared with the logarithmic scale and the uncorrected numbers found in Figures 2.15b and 2.15c, respectively. High inclination events are given extraordinarily high importance as most peaks over ∼50◦ correspond to only a few events. Most Asteroid Belt objects have lower inclinations up to ∼30◦ . Correcting the perihelion distances observed (Figure 2.16a) from the raw uncorrected numbers (Figure 2.16c) reduces the significance of orbits with a perihelion near 1 AU. Figure 2.17 shows the corrected geocentric speed, a logarithmic scale of the same plot and the uncorrected numbers of events. Greater emphasis has been placed on faster events in the corrected version of the plot, which is driven by only a few events. Many of the slower events would be asteroidal but cometary objects may also be included in this bulk. The fast objects, in retrograde orbits colliding with Earth in a head-on impact are attributable to cometary events. 43

Figure 2.14: a: Collision probability and mass distribution corrected values of eccentricity for events larger than 100 g. b: Similar to (a) but plotted on a logarithmic scale. c: Eccentricity values of the uncorrected observed events. 44

Figure 2.15: a: Collision probability and mass distribution corrected values of inclination for events larger than 100 g. b: Similar to (a) but plotted on a logarithmic scale. c: Inclination values of the uncorrected observed events. 45

Figure 2.16: a: Collision probability and mass distribution corrected values of perihelion distance for events larger than 100 g. b: Similar to (a) but plotted on a logarithmic scale. c: Perihelion distances of the uncorrected observed events. 46

Figure 2.17: a: Collision probability and mass distribution corrected values of geocentric speed for events larger than 100 g. b: Similar to (a) but plotted on a logarithmic scale. c: Geocentric speeds of the uncorrected observed events. 47

Galligan & Baggaley (2004) produced collision probability and mass distribution cor­ rected plots of orbital elements for ∼5 ×105 radar meteors corresponding to ‘dust-sized’ meteoroids. Figure 2.18 shows the plots of their results for comparison. Their curves are much smoother than the results found in this study, likely due to the considerably larger data set available in their study and to some extent the different dynamical environment experienced by dust-sized objects compared with fireball-sized objects.

Figure 2.18: Orbital element distributions obtained by Galligan & Baggaley (2004) for an unbiased distribution of ∼5 ×105 radar meteors. The radar-detected meteoroids used in their study correspond to ‘dust-sized’ grains. 48

2.4 Summary and Conclusions

In this study, after compiling all available data, it has been found that the distribution of PE values does not appear to have obvious discrete strength groups. The distribution appears to be more continuous than originally thought. The PE value does carry some significance as relating the PE value with the Tisserand parameter largely follows that strong material is of asteroidal origin and weak material is of cometary origin. The precise divisions in PE value, as determined by Ceplecha & McCrosky (1976), do not seem relevant when applied to fireballs from other networks, and therefore less importance should be assigned to the fireball type. The PE value is of more relevance when used in conjunction with the Tisserand parameter and can be used as a comparative tool between

fireballs. The first assumption made by Ceplecha & McCrosky (1976) was that “discrete classes of meteoroid structures exist.” This may be true to some extent when strictly observing rocks from the Asteroid Belt versus ‘snowballs’ from the Oort Cloud but it seems that there is a continuum in the strengths of meteoroids especially since materials may be mixed together in a single body (as demonstrated by the variation within a single meteor shower).

Figure 2.10 also showed two surprisingly strong type I NIC events. Weissman &

Levison (1997) predicted that between ∼0.8 – 2.3% of the Oort Cloud is composed of scattered asteroids from the planetary-zone clearing stages of the Solar System. However, these two events represent 6% of the uncorrected observed mass of NIC events. Another possible explanation is that these two events have spent a sufficient amount of time in the inner Solar System to lose all of the weak volatile material leaving behind only the hardest strongest cometary material. It would be of interest if other strong NIC events of varying sizes could be identified. It would be useful to understand if these bodies have spent a considerable amount of time in the inner Solar System. Their histories could be 49 explored by integrating their orbits back in time.

Table 2.4 summarizes the PE values calculated for all recognized meteor shower events from four fireball camera networks (EN, PN, MORP and SOMN). Some showers have produced wide distributions of PE values while others are more uniform. The Perseids demonstrate the tightest distribution with a standard deviation of 0.24, whereas the

Taurids show a very wide variation with a standard deviation of 0.57. It would be interesting to investigate whether systematic trends exist in the variation in strength of meteoroid streams by comet type, to consider the inhomogeneity in composition by source region. For example, the Perseids, Leonids and Orionids are from HTC-parents and demonstrate tighter distributions of PE values, whereas streams parented by Encke­ type comets (like the Taurids) may show more variation in PE values. The width of the

PE distribution for meteor showers may be related to the inhomogeneity of the parent comet, which in turn could be related to the variation of materials expected in each comet source region.

The dynamical environment of the inner Solar System was investigated through the distributions of the orbital parameters from all of the camera networks used in this study.

These distributions were corrected for several biases including the collision probability with the Earth and the mass distribution of Solar System objects observed in the rele­ vant size range (cumulative mass index -0.69). The results for eccentricity, inclination, perihelion distance and geocentric speed are given in Figures 2.14 through 2.17. The distributions of orbital elements for fireball-sized objects can be compared with the re­ sults of Galligan & Baggaley (2004) for tens of thousands of dust-sized radar-detected objects. The curve for eccentricity of dust-sized meteoroids shows a steady increase in the number of values between zero to one, whereas fireballs show almost no eccentricity values less than 0.5, but have substantial peaks in numbers around 0.7, 0.85 and 0.95.

Both size groups show a large peak at low inclinations, the radar data show the peak 50 of dust-sized grains at 20◦ whereas fireball-sized bodies show a lower peak around 10◦ .

Dust particles also have a minor wide peak around 140◦ inclination but the fireball data show several large spikes in retrograde orbits likely as a result of strong emphasis being placed on just a few retrograde events. The radar data show a peak in the perihelion distance at ∼0.1 AU and a fairly steady decrease to 1 AU. Fireball-sized objects appear to have a strong peak in perihelion distance near 0.95 AU, and a number of other peaks at 0.8 AU, 0.7 AU, small peaks at 0.55 AU and 0.4 AU, as well as a fairly large peak at

0.2AU. Dust-sized meteoroids demonstrate geocentric velocities in a somewhat skewed curve centered around 33 km/s and skewed toward fast events up to 72 km/s. The fire­ ball data shows a bumpy distribution with a large peak at 31 km/s, similar to the radar data, but the fireball data also show a number of high velocity spikes, the largest spike appearing at 43 km/s. Compiling an even larger data set of fireball events would act to smooth the curves of orbital elements and help build a more complete picture of the dynamical environment for fireball-producing meteoroids. 51

Chapter 3

The Buzzard Coulee Meteorite Fall

3.1 Introduction to the Buzzard Coulee Event

On the evening of November 20, 2008 the skies of Western Canada were explosively il­ luminated by a large bolide. The fireball occurred from 17:26:40 to 17:26:45 MST when many people were making their commute home from work, leading to tens of thou­ sands of eye witnesses (Hildebrand et al., 2009). The event was widely seen throughout

Saskatchewan, Alberta, Manitoba and Montana. The weather was mainly clear over the

Prairie Provinces with some cloud cover around northern and western Alberta, including

Calgary (Figure 3.1). Emergency services, media, radio outlets and the Canadian Fire­ ball Reporting Centre were flooded with witness accounts of the event. It was the most widely observed meteorite fall in recent Canadian history.

This event was also widely recorded instrumentally by a personal video camera (Ed­ monton, AB), a police dashboard camera (Devon, AB) and a number of security systems

(Saskatoon, Biggar, and Turtle Lake in Saskatchewan; Fort McMurray and Edmonton in Alberta, as well as Lloydminster and surrounding areas) which imaged the fireball and subsequent dust cloud or the shadows cast by the light (Figure 3.2). The event was captured by distant all-sky cameras in Saskatoon, Calgary and Edmonton, a radiometer operated by M. Beech at the University of Regina (Figure 3.3) and was detected by six infrasound stations (the furthest reported detection was recorded in Greenland).

A fall area was predicted and released to the public four days later by Dr. Alan

Hildebrand using crude camera measurements and accounts from proximal witnesses.

The first meteorites were recovered from a frozen pond in Buzzard Coulee, Saskatchewan 52

Figure 3.1: Infrared satellite image of Western Canada showing the weather at the time of the Buzzard Coulee fall. A large cloud bank covers British Columbia and much of Alberta but there were clear skies over Saskatchewan, Manitoba and central Alberta (Environment Canada Weather Office, 2008). 53

Figure 3.2: Composite image showing a video frame of the fireball from a number of locations. Images a, c and d were taken by security camera systems, whereas image b was captured by an RCMP dashboard camera while driving down the street. The shadows observed in c (the closest record to the fireball of the four shown here) were cast by the fireball, which is reflected in the window of the truck.

Figure 3.3: Radiometer measurement of light output by the Buzzard Coulee fireball recorded ∼475 km away in Regina, SK. The y-axis shows an uncalibrated relative mea­ surement of light intensity and the x-axis indicates an uncorrected time. The peaks in light output are associated with fragmentation events of the meteoroid (Beech, 2009). 54 on the evening of Thursday, November 27, 2008, almost precisely one week after the fall.

A total of ten fragments ranging between approximately 10 – 384 g were found on the ice of about a 1/2 hectare pond. Extrapolating this density one might expect approximately

2000 meteorites/km2 in this region of the strewn field. Search efforts over the following months recovered over 2500 fragments, breaking the Canadian record for the number of pieces collected from a single fall. The media attention following the recovery was immense with a press conference being held at the pond the following afternoon. The story of meteorites being recovered by the University of Calgary was featured prominently in national and international news. This is the second time in Canadian history that the location of fallen meteorites were predicted and first found by a scientific team (the other was the recovery of Innisfree in 1977 by a team led by Dr. Ian Halliday).

3.1.1 Naming and Typing of the Meteorite

Meteorites are named after the place where they are found. The Meteoritical Society maintains a record of all meteorites known on Earth and officially administers the naming of new meteorites. To grant a name to a new meteorite, the Meteoritical Society requires a written description of the rock, details about the meteor event (for witnessed falls), the total number of pieces and total mass recovered. As well, the submission must be accompanied by an authoritative classification of the rock, details on the shock stage, weathering grade and mineral compositions.

Meteorites are crudely classified into three main groups by bulk composition, namely stones, irons and stony-irons. Historically the most common finds are iron meteorites as they tend to be conspicuous compared to common Earth rocks, however, irons only represent ∼5% of the fall population (McSween, 1999). By far the most common type of meteorite to fall are stones of the ordinary chondrite clan. Chondrites are named as a reference to chondrules, the small round grains or inclusions which they contain. 55

Ordinary chondrites are divided into three groups: H, L and LL, depending upon their iron content (high, low and very low). A further division is made by petrologic type and assigned a number from one through six, 1-2 depending on the amount of aqueous alteration1 and 4-6 depending on the thermal metamorphism that the material has been subjected to since formation. Type 3 chondrites demonstrate the least amount of al­ teration, with increasing petrologic type above 3 showing increased metamorphism with higher temperatures (Figure 3.4). The processes through which chondrules formed in the early Solar System are not fully understood. Ordinary chondrites accreted early in the Solar System but were never part of a sufficiently large body for differentiation to occur. It is believed that some heating at the core of an asteroid led to varying degrees of metamorphism amongst the ordinary chondrites (McSween, 1999). This can be pictured as an ‘onion skin’ asteroid, with the most heated type 6 material located in the center varying through to the least heated type 3 material at the surface. Scientifically, type 3 meteorites are valuable since that represent the least changed record of the earliest Solar

System processes.

Determination of the petrologic type of a meteorite involves investigating the mineral­ ogy with a microscope and electron probe. Important indicators to classify the petrologic type include the dispersion of olivine and pyroxene compositions, the geometric shape of low calcium pyroxene (monoclinic versus orthorhombic), presence of secondary feldspar grains, presence of isotropic glass and weight percent of metallic minerals, water, carbon and sulfides. Crudely, the petrologic type of a meteorite may be estimated by how de­ lineated and obvious the chondrules appear. A greater occurrence of metamorphism and re-crystallization of chondrules makes them increasingly more difficult to observe with increasing petrologic type above type 3. The characteristics relevant for classifying the petrologic type of a chondrite are summarized in Figure 3.5.

1Petrologic types 1-2 are not relevant for ordinary chondrites. The aqueous alteration processes are associated with the carbonaceous chondrite clan (see Figure 3.4). 56

Figure 3.4: Illustration of the ordinary chondrite clans (from McSween, 1999). Ordinary chondrites are by far the most common of all meteorite falls, hence the term ‘ordinary’. The petrologic types, numbered 1-6, refer to the quantity of alteration away from type 3, lower numbers by aqueous processes and larger numbers by thermal metamorphism. The temperature scale along the bottom of the figure shows the heating associated with each petrologic type. The black and grey bars shown for the ordinary and enstatite chondrites refer to the relative proportion of falls by petrologic type for each chondrite group (i.e. far more L6 ordinary chondrites fall than any other petrologic type of L-ordinary chondrite). 57

Figure 3.5: Defining characteristics of chondrite petrologic types (adapted from Sears & Dodd, 1988). The dashed and solid lines reflect the distinctness of property transitions between petrologic types. 58

The classification of Buzzard Coulee was performed at Portland State University in collaboration with A. Ruzicka and M. Hutson (Cascadia Meteorite Laboratory). Two thin sections were analyzed using an electron probe to type the meteorite. The olivine composition was found to be Fa17.8 ± 0.3 (fayalite) with a percent mean deviation (PMD)

Fa = 1.22. The low-Ca orthopyroxene composition was found to be Fs16.1 ± 0.8 (ferrosilite) and Wo1.6 ± 1.0 (wollastonite) with a PMD Fs = 4.06 (Figure 3.6). Figure 3.7 adapted from

Figure 3.6: Diagram illustrating the olivine and pyroxene compositions observed in Buz­ zard Coulee (Hutson et al., 2009). Small dispersions (< 5%) in the compositions of olivine and orthopyroxene (opx) lend support for the type 4 classification. The circled points labelled cpx correspond to diopside, the data points falling in between opx and cpx likely result from small intergrown crystals of the two pyroxenes (lamellar structures and diopside rims) that are unresolved by the electron probe beam.

Sears & Dodd (1988) demonstrates that the mineralogy of Buzzard Coulee is consistent with an H chondrite. The petrologic type was determined to be type 4 considering the low dispersion of olivine and pyroxene, the presence of devitrified glass and the overall texture of the meteorite (re-crystallized matrix, readily delineated to well-defined chondrules). 59

However, this meteorite shows evidence that it could be in transition from type 3, as a small quantity of clear isotropic glass was also observed. The official name and type of Buzzard Coulee (H4) were accepted by the Meteoritical Society and printed in The

Meteoritical Bulletin, No. 95 (Weisberg et al., 2009).

Figure 3.7: Plot adapted from Sears & Dodd (1988) showing ferrosilite of low-Ca pyroxene with fayalite content of olivine for equilibrated ordinary chondrites. The mineralogy of Buzzard Coulee plots into the group of H chondrites.

Buzzard Coulee has another scientifically interesting feature, the presence of large

(up to a centimeter in the longest dimension) light-coloured igneous textured inclusions.

Examination using the electron probe found that these inclusions were made of both high- and low-calcium pyroxene and a polymorph of silica (Hutson et al., 2009). The presence of this unexpected material demonstrates the complexity of the early Solar

System history. Based on radiometric dating, chondrules are known to have formed early in the Solar System and were incorporated into the chondrites. After sufficiently large bodies had appeared, planetary differentiation and igneous processes began. The presence of igneous textured inclusions in a chondrite is a bit puzzling, and the processes involved in their formation and incorporation into chondrites are unknown at this time. Similar 60 igneous textured inclusions have been identified in other ordinary chondrites (Ruzicka et al., 1998). Due to the vast quantity of material recovered from the Buzzard Coulee fall, a great opportunity exists to study these inclusions more extensively.

3.2 Atmospheric Trajectory

3.2.1 Shadow Calibrations

A number of distant cameras directly imaged the passage of Buzzard Coulee through the atmosphere, and many nearby security systems fortuitously captured images of the shadows cast by the fireball. The three all-sky cameras that recorded the fall were uncal­ ibrated and located several hundred kilometers from the event. Since small uncertainties in angles are exaggerated over longer distances, uncertainties in measurements can be reduced by using the most proximal records. Other distant videos directly recorded the

fireball in the sky, but each had specific calibration and measurement difficulties. An Ed­ monton, AB video camera had no foreground reference objects in the frame. A Devon,

AB police dashboard camera recorded the fireball from a moving vehicle. For a secu­ rity camera record from Biggar, SK much of the fireball was off-screen, the image was over-saturated and cloud cover obscured part of the sky. For these reasons, the videos of shadows cast by Buzzard Coulee seemed to offer the closest, most easily calibrated records. Specific videos were selected if they contained an easily measured reference object that cast shadows and upon the camera location relative to the fireball. Never before had a trajectory been obtained through the calibration and measurement of the shadows cast by a fireball. This novel approach of shadow calibration was applied to the

Buzzard Coulee meteorite fall to explore whether a sufficiently accurate trajectory could be determined to derive a pre-fall orbit. 61

Trailside Inn Security Camera

The Trailside Inn is a motel located in Lloydminster, Saskatchewan (53◦16’40.8”N,

250◦00’9.0”W). The Inn is protected by a Lorex SG17LD800 integrated network LCD and digital video recorder. The shadows cast by the fireball were captured on four out­ door cameras; however one video sequence in particular provided optimal conditions for calibration and measurement. The video selected for calibration had a view of the back corner of the building facing away from the fireball. This video captured the corner shadow cast by the overhanging roofs which travelled along the sidewalk and up the wall of the building. The geometry of this situation was not completely straight-forward as the two roofs were at different heights, causing the roof position that cast the corner shadow to change with time (Figure 3.8).

Figure 3.8: Photograph of the back of the Trailside Inn highlighting the uneven roof geometry. The shadows of the roofs cast by the fireball travelled across the sidewalk and up the tiled wall. 62

For calibration of this video, it was necessary to have a well established layout of the building. The geometry was surveyed and various measurements were made, including heights of the roofs, width of the sidewalk, details of the gutter geometry, etc. The bearing of the walls were accurately measured using a theodolite by M. Noble (retired surveyor and RASC member). Site survey sketches of the Trailside Inn can be found in Appendix B (Figures B.1 - B.4). A large piece of fabric containing a regular grid pattern was placed on the sidewalk and imaged through the security camera (Figure 3.9) so that shadow positions could be accurately measured. The fabric was carefully aligned with the adjacent walls and the position of the fabric with respect to the sidewalk was carefully measured. The individual squares of the fabric measured 4.25 cm but were poorly resolved through the security camera. Overcast lighting conditions were found to provide the best resolution as direct sunlight washed out the frame and greatly reduced the contrast between the squares. Additional bold lines were added to the fabric using black tape at half meter intervals. A slight amount of material stretching was observed but errors associated with this were not significant compared with other sources of error.

Figure 3.9: Trailside Inn calibration image taken through the security camera showing the grid patterned fabric used to measure shadow positions. 63

Individual frames from the AVI video were extracted by exporting the image sequence into JPEGs using VirtualDub 1.8.8 (Lee, 2009). The pixel locations of the corner shadow position on the sidewalk and on the wall were measured using ImageJ (Rasband, 2009).

The most reproducible method for picking the shadow corner was to extend the proximal line of shadow cast by each roof, then pick the intersection of the two lines. The edge of the shadow was taken as the intermediate pixel brightness. Some uncertainty was introduced here as the shadows were observed to move at different rates depending upon their orientation with the fireball. One shadow edge appeared more diffuse than the other because it had moved more within the time of one frame, making it more difficult to pick the line of intermediate pixel brightness. That said, there was surprising consistency in picking the shadow corner, the position differed at most by 1-2 pixels when selected by different people. In the future, it may be possible to develop or adapt computer code to pick the shadow positions in each frame to streamline the process and to reduce the associated uncertainties.

The pixel positions of the shadow corner were located on the image of the calibration fabric. It is important to note that the camera had not been moved between the time of the fireball and the calibration shots. The distance from the edge of the relevant fabric square containing the shadow corner position was determined relative to the right-handed coordinate system. The shadow location within the fabric square was then proportionally measured to obtain the total distance from the origin for each shadow position. The shadow positions on the wall were similarly measured using the ∼20 cm tiles of the wall

(which were visible through the security images). The tiles were not evenly built, and the grout spacing was found to vary enough to have an effect on the results. For this reason, the edges of each relevant tile had to be measured during the site survey (see survey sketch in Figure B.3).

The altitude and azimuth of the fireball in the sky was determined based on the 64 measured positions of the shadows. Vector calculus was applied to deal with the geometry of the two roofs. One can imagine a plane of shadow that is created as light falls along the edge of a straight object. The coordinate system employed had an origin at sidewalk height directly beneath the two roofs. The y-axis was set to be the vertical direction, the x-axis ran nearly East/West along one wall and the z-axis ran nearly North/South along the other wall. The roof that lies parallel to the x-axis is referred to as the ‘x-roof’ and the roof parallel to the z-axis is referred to as the ‘z-roof’. For the Trailside Inn two planes have been defined, one for the shadow plane cast by the edge of the x-roof and one for the shadow plane cast by the edge of the z-roof. The intersection of these two planes gives a line pointing in elevation and direction to the fireball in the sky. A point

(Zx, Zy, Zz) can be defined as a position on the z-roof, similarly (Xx, Xy, Xz) as a point on the x-roof and (Cx, Cy, Cz) as the corner shadow position. Derived for the geometry of the Trailside Inn, the azimuth of the fireball is given by Equation 3.1, and the altitude of the fireball is given by Equation 3.2. Figure B.4 (in Appendix B) shows that there is a rotation of 33’ 39” between the coordinate system and the true cardinal directions.

Equation 3.3 makes a mathematical rotation from the applied coordinate system to the

/ cardinal directions with φ = −33 39”, where for example (Cx, Cy, Cz) ⇒ (Cx/ , Cy/ , Cz/ ) in the rotated system. These new coordinates are found in Equations 3.1 and 3.2, so the altitude and azimuth are measured relative to the cardinal directions rather than some arbitrary coordinate system. Details of deriving these equations can be found in

Appendix C. 65

(Z / − C / )(X / − C / ) azimuth = tan−1 y y z z + 90◦ (3.1) (−Zx/ + Cx/ )(−Xy/ + Cy/ )

(−Z / + C / )(−X / + C / ) altitude = 90◦ − cos− 1 y y y y (3.2) ||v||

where:

2 2 ||v|| = [(−Zx/ + Cx/ )(−Xy/ + Cy/ )] + [(−Zy/ + Cy/ )(−Xy/ + Cy/ )]

2 +[(Zy/ − Cy/ )(Xz/ − Cz/ )]

x/ = East = z sin φ + x cos φ (3.3)

y/ = Up = y (no tilting)

z/ = South = z cos φ − x sin φ

Lashburn Esso Security Camera

The Esso Station is located in Lashburn, Saskatchewan (53◦7’26.4” N, 250◦23’7.1” W).

Two outdoor security cameras captured images of shadows cast by the fireball with a

Samsung Real Time DVR SHR 2082 system. Both cameras showed shadows created by the square light fixtures mounted above the gasoline pumps which moved along the pavement as the fireball traversed through the sky. These square light fixtures made both videos prime candidates for calibration. VirtualDub 1.8.8 was used to extract individual frames from the AVI videos as JPEGs. One camera pointed at the NW pump and captured ∼20 frames of light and shadows associated with the fireball. Of particular interest in this video record are the reflections of individual fragments in a truck windshield as they continued to fall after the major light emission of the bolide

(Figure 3.10). The other camera pointed at the SE pump and captured ∼17 frames 66 showing shadows of the fireball. Many frames in this video record could not be calibrated because the shadow of the light fixture disappeared from the field early in the record. pro Fit TRIAL version

Figure 3.10: Left: A bright frame of the NW pump at the Lashburn Esso Station showing the shadows of the light fixtures cast by the fireball. Right: Security camera frame near the end of the fireball emphasizing the three fragments reflected in the truck windshield. The reflections in the rear car window are the lights mounted above the pump rather than the fireball.

Figure 3.11: Left: Calibration image for the SE pump taken through the Lashburn Esso security system. Right: Calibration image taken for the NW pump.

The same methods of calibration were used at the Lashburn Esso as the Trailside

Inn. Various measurements were made, including the heights and widths of the light

fixtures, and the bearings of each pump island (measured accurately by M. Noble). The grid patterned fabric with 4.25 cm squares was laid out on the pavement beside each pump and a series of images were taken through the security system (Figure 3.11). The 67 small squares of the fabric could not be resolved though the security images, but the black tape delineating one meter and half meter intervals was visible. One difficulty at this location was deploying the fabric square with the pump island. Small deviations could introduce systematic errors in the measurements that become larger with greater distance from the pump island. Orthogonality was obtained using string aligned with the edge of the pump island to project a line across the pavement. Chalk was used to trace the line of the string and served as a guide to deploy the fabric.

The shadow corners of the light fixtures were measured by taking the intersection of lines of intermediate pixel brightness. The pixel locations of the shadow corner were then located on the fabric grid pattern. The proportion across the large tape squares were measured and converted to a distance in the right-handed coordinate system. The coordinate system employed at this location had an origin located on the pavement at the NE corner of each pump island (see Appendix B, Figures B.5 and B.6). The x-axis ran along the front of the pump island at a bearing of 304.2178◦ for the NW pump and 304.0128◦ for the SE pump, the y-axis was the vertical direction and the z-axis perpendicular to the long axis of the pump island.

The geometry at this location was simpler than the Trailside Inn because the position of the light fixture that cast the shadow could be directly identified. The altitude and azimuth measurements were calculated using two points in space: the corner of the shadow on the pavement, C(x, 0, z), and the position of the light fixture casting the shadow, P (x, y, z). The azimuth measures the angle from the x-direction between the shadow corner C and the ground projection of point P (x, 0, z), and is adjusted by the bearing of the pump island (Equation 3.4). The altitude was simply the angle measured up from the ground using the length between the point C and the ground projection of

P (Equation 3.5). 68

|P − C | azimuth = bearing − tan−1 z z (3.4) |Px − Cx| � � P altitude = tan−1 y (3.5) � 2 2 (Px − Cx) + (Pz − Cz)

Equations 3.4 and 3.5 can only be used if the geometry is simple, namely, the position

on the light fixture that cast the shadow must be accurately known. The fireball was

located above and to the SW of the Esso, therefore the NE corners of the light fixtures

offer the simplest geometry because only the top edges of the light fixture were able to

create the shadow corner. For this reason, the NE corners of the light fixture shadows

were measured.

The NW and SE pumps were calibrated independently, providing a verification of the

results, allowing significant systematic errors between the two calibrations to be checked.

A substantial disagreement between the two cameras was resolved after it was discovered

that a small shift in the pointing direction of the SE pump camera had occurred between

the time of the fireball and the calibration shots.

ImageJ measures pixel locations in an image starting with position (x = 0, y = 0)

in the upper left-hand corner of the image. Pixel numbers increase in x moving right

along the image and increase in y moving down the image (for example a 100 x 100 pixel

image would have the coordinates (100, 0) in the upper right-hand corner and (0, 100)

in the lower left-hand corner). Pixel locations of several reference objects were measured

within a frame of the fireball video and compared with the same reference objects in

the calibration shot. In this manner, a shift of (x − 3, y − 1) was found so that shadow

locations measured in the fireball video were shifted by this amount before being located

on the calibration grid pattern. No such shift was deemed necessary for the camera

imaging the NW gas pump. 69

It was, however, observed that the pavement near the NW pump had a significant slant causing another systematic problem and giving increasing error at greater distances away from the pump. The pavement sloped up away from the pump about 3.5 cm over a distance of 9 m, giving a slope of approximately 0.22◦ . The height y between the light

fixture and the pavement position of the shadow was adjusted accordingly for this slope.

No significant pavement slope was observed for the SE pump.

An additional check of uncertainty was possible using Sun shadows captured through the NW pump camera. The altitude and azimuth of the Sun in a given location at a given time is known, calculating its position using the shadows cast by the light fixture illuminates on the accuracy of the measured positions of the fireball. Two Sun positions were measured through the shadows cast and their differences from the true Sun position at those times were found to be i) Δ0.2◦ azimuth and Δ0.0◦ altitude, and ii) Δ0.2◦ azimuth and Δ0.1◦ altitude.2 The Sun shadows were near the end of the cloth and the agreement was improved by including the pavement slant correction.

Tait’s Liquor Store Security Camera

Tait’s Liquor Store in Lloydminster, Alberta (53◦ 17’ 25.9” N, 110◦ 00’ 21.8” W), captured

∼40 frames of light and shadows from the fireball on the security camera which images the front door of the building. The camera was pointed away from the fireball, and imaged the shadows cast by a large sign as they travelled across the parking lot (Figure

3.12). The sign had a large pole fixed to the side which cast a shadow point, making it ideal for calibrating. A site survey was conducted with the help of M. Noble to obtain the relevant layout information (Appendix B, Figures B.7 and B.8). The grid patterned cloth was deployed and images were taken through the security system. The origin for

2There is an additional source of uncertainty that factors into the Sun comparison which is not involved in the fireball measurements, that is the measurement of an accurate time to determine the true Sun position. This however, was not considered to be significant in comparison with the other measurement uncertainties. 70 a right-handed coordinate system was taken as the ground position below the pole, with the y-axis as the vertical, the z-axis running parallel to the wall of the building and the x-axis running perpendicular out from the building. The geometry was similar to the

Lashburn Esso Station with the position of the object that cast the shadow known for all frames. Since a similar right-handed coordinate system could be used, Equations 3.5 and 3.4 derived for the altitude and azimuth measurements at Lashburn were also valid and applied for this site.

Figure 3.12: Left: Security camera image from Tait’s Liquor Store of the cloth deployment used for calibration. Right: Security camera image of the shadows cast by the fireball.

3.2.2 Video Calibrations

A number of video recordings directly imaged the passage of the fireball as it travelled through the sky. All were distant, ∼200 km away or more, and each had specific calibra­ tion issues. Nonetheless, two videos were deemed important enough to proceed with cal­ ibration. The first was a private security system in Biggar, Saskatchewan which directly imaged several of the large explosions although the system was highly over-saturated resulting in CCD blooming effects. However, a few frames were captured showing the persistent glowing where major fragmentations had occurred, making this video worthy of calibration efforts. The second significant video was the police dashboard camera in 71

Devon, Alberta which captured the very start of the fireball, important for an initial velocity determination. Since the police car was driving down the street at the time of the fireball, the video did not offer a simple and straight-forward calibration.

Biggar Security Camera

A video record was captured by a home security system in Biggar, Saskatchewan ap­ proximately 180 km (ground distance) from the start of the fireball. The video imaged the late stages of the fireball trajectory close to the end of the luminous portion when the fragments dropped behind some clouds. A number of late stage fragmentations were captured, as well as three large surviving fragments that continued to glow after the main ablation stage of the fireball. The video frame views the yard of a farmstead keeping watch over a garage and water tank, both offering good references to guide the overlay of a stellar calibration image.

Stellar calibration images were taken in both digital and film formats. The original security camera did not capture enough light to see stars. Stellar images were taken with cameras set to infinite focus and apertures opened wide to capture the maximum amount of light possible. The cameras were fixed one at a time to a tripod and positioned as near to the security camera as physically possible. A number of stellar shots of different exposure lengths were taken during a time of the night when a large number of bright stars were visible in the region of interest. A number of bright stars were required for the calibration because images were taken during the summer, facing a northerly direction, a region of the sky that never achieves total darkness at this latitude. A digital Canon

Rebel XSi/EOS 450D (12.2 megapixel) camera with a standard 18-55 mm lens and a

Minolta Maxxum 450si using Kodax 800 35 mm color film were used to capture stellar images. Most automatic features of the digital camera were disabled, except — unknown at the time — an optical image stabilizer which was still active. The stabilizer attempted 72 to correct for the trailing of stars over a long exposure, resulting in blobs of light rather than distinct star trails. The film images, however, were successful in capturing a number of clearly visible stars in the area of interest. The best image captured was the last photo taken by the film camera (30 second exposure), after the yard lights had been turned on and were starting to warm up casting some light onto the foreground. Without the foreground light it would not have been possible to link reference positions between the calibration image and the security camera frames.

Figure 3.13: Image demonstrating the fit between the Biggar security camera frame and the stellar calibration shot. The opacity of the stellar calibration has been reduced to show the overlay and for this reason the stars are not very apparent.

ArcGIS 9 ArcMap Version 9.3 was used to carefully match positions between the security frame and the stellar calibration image (Figure 3.13). Three points were used to accomplish a good fit with little distortion. Six stars near the fireball trajectory were identified. Their known positions at the time of the calibration image were used to mea­ sure the position of the fireball in the sky. Large fragmentation events saturated the dynamic range of the security camera so major fragmentation heights were measured by finding pixel locations in frames where persistent glowing continued after the fireball had passed. The fragmentation location in the sky was converted from a pixel value to the celestial horizontal coordinate system (altitude/azimuth) by comparing its position 73 relative to the identified stars. In this manner, it was possible to measure four frag­ mentation events from the Biggar video record (two large fragmentations and two lesser fragmentations). The light from the two large fragmentations persisted longer and were measured in four frames, whereas the lesser fragmentations were only found to persist for one or two frames. In addition to the four fragmentation events, the last positions of the three individual large glowing fragments were measured.

Devon RCMP Dashboard Camera

Figure 3.14: Image showing the fit between the Devon police dashboard camera frame and the stellar calibration shot. The opacity of the stellar calibration has been reduced for demonstration, so stars are not visible.

A video record was captured by a police dashboard camera in Devon, Alberta ∼250km ground distance from the start of the fireball. The video was taken at NTSC frame rate

(29.97 frames per second) as the police car drove down the street. It captured the start of the fireball before it travelled behind some clouds and close to the end when the fireball dropped behind some buildings. Since the frame rate was known and the start of the

fireball was captured, this video seemed ideally suited for determining an initial velocity.

A series of stellar calibration shots with varying lengths of exposure were taken from a tripod placed at five stages along the street where the police car had been driving at the time of the fireball. Two cameras were used to take stellar images, a digital Canon 74

PowerShot G6 and a Minolta Maxxum 450si using Kodax 800 35 mm color film. Once again, cameras were set to infinite focus, with apertures opened wide to capture the maximum amount of light possible. The street lies adjacent to a car dealership, whose lights were turned off for the duration of the calibration shots. Again, the images taken on

film were most successful at capturing the greatest number of stars in the area of interest.

Calibration shots were aligned with the video frames using ArcMap (Figure 3.14). The

first two stellar calibration shots in the series were used to measure the fireball’s position in the first 40 frames. Due to the movement of the police car, each frame had to be individually aligned and star positions re-measured for each frame of the video.

3.2.3 Trajectory Results and Discussion

The altitude and azimuth positions of the fireball obtained by measuring the shadows at the Trailside Inn are plotted in Figure 3.15. The plot appears to have two clumps of data which correspond to positions measured on the sidewalk (above 60◦ altitude) and the wall. The data show scatter of several tenths of degrees due to the accuracy with which the correct shadow corner pixel position could be identified, but more significantly through measuring its position on the grid pattern relative to the coordinate system.

Figure 3.16 shows the fireball positions obtained from the Esso Station in Lashburn,

Saskatchewan. The two gas pumps were independently calibrated to give consistent results. The measured and actual Sun positions are also included in Figure 3.16 and show excellent agreement, strengthening the certainty in the quality of the calibration for the NW pump. Jumps in the data at higher altitudes appear to correlate with fragmentation events visible as bright frames in the security video. Large fragmentation events caused persistent illumination of the atmosphere along the trail of the fireball which might smear the shadow, causing it to linger during one frame and jump ahead during the next. 75

Figure 3.15: Fireball positions from the Trailside Inn in Lloydminster taken through the calibration and measurement of the shadows cast. Note that the Trailside Inn is located west of the fireball so azimuth measurements are to the east, in contrast with Figure 3.16 showing observations from the Lashburn site which is located east of the fireball resulting in fireball azimuths to the west. These two sites offer near optimal observation geometry to solve for the fireball trajectory.

Figure 3.16: Fireball positions measured through shadow calibrations at the Esso Station in Lashburn. The NW and SE gas pumps were calibrated independently and show excellent agreement. Arrows draw attention to the measured and actual Sun positions used to verify the calibration of the NW pump. 76

The third station used in the determination of the best fit atmospheric trajectory is

Tait’s Liquor Store in Lloydminster. The altitude and azimuth measurements obtained from this location are plotted in Figure 3.17. Similar to the Lashburn results, jumps in the data appear to correlate with significant brightening and darkening of frames, indicative of a large fragmentation event.

Figure 3.17: Fireball positions measured through shadow calibrations at Tait’s Liquor Store in Lloydminster.

Positions of four late fragmentation events and the final three fragments visible from

Biggar, Saskatchewan are plotted in Figure 3.18. The standard deviation in the mea­ surement of one large fragmentation event was σ = 0.06◦ in azimuth and σ = 0.4◦ in altitude. The uncertainty associated with the altitude is expected to be larger due to the method of measuring the fireball position. The sky was approximated as linear over small distances which can introduce more uncertainty over larger distances. There was more distance between the identified reference stars in the direction of altitude compared with azimuth leading to the larger uncertainty in the altitude measurements. 77

Figure 3.18: Positions measured from Biggar, Saskatchewan of four large fragmentation events and the three final glowing fragments before they pass behind some cloud cover.

The combined 52 shadow positions measured from the Trailside Inn, Tait’s Liquor

Store and the Lashburn Esso were input into MILIG (Boroviˇcka, 1990) to calculate an atmospheric trajectory (see Appendix D). MILIG is able to take the measurements and solve for a best fit line for all observed positions. The trajectory, summarized in Table 3.1

Table 3.1: Trajectory solution calculated by MILIG using three stations: Trailside Inn, Tait’s Liquor Store and Lashburn Esso (two cameras). N = 52 Latitude Longitude Height (km)

Beginning: 250.059 ± 0.001◦ W 53.169 ± 0.002◦ N 63.8 ± 0.7 End: 250.122 ± 0.001◦ W 52.997 ± 0.001◦ N 17.6 ± 0.2

Radiant Azimuth Zenith Sum Total Distance Residuals

RA = 300.0 ± 0.4 167.5 ± 0.4◦ 23.3 ± 0.4◦ 0.974 km DEC = 75.0 ± 0.2 and plotted on the map found in Figure 3.19, shows that the fireball was on a fairly steep path travelling downwards at an angle of 66.7◦ elevation, at a bearing of 167.5◦ azimuth. 78

It was bright enough to start casting shadows at 63.8 km height above the surface with the last measured shadow at 17.6 km above the surface. The four late fragmentations measured from Biggar were at heights 33.5 km, 31.0 km, 19.5 km and 17.7 km above the ground. The last measured shadow on the trajectory corresponds with the end of measurable positions at the Trailside Inn but shadows were still visible for an additional

five frames. These additional frames with shadows at the Trailside Inn would give a predicted altitude of 19.4◦ for the fireball. This predicted altitude was fit against the determined trajectory to indicate that the fireball cast shadows that were recorded by videos in Lloydminster until ∼12.7 km above the ground.

MILIG also calculates and outputs the residuals for every input position, measuring how much each point deviates from the calculated best fit trajectory in both the vertical and horizontal directions. The sum of the total deviations for the solution is 0.974 km, a number which may be artificially low due to the geometry of the three locations used in the solution. The results from the Trailside Inn and Tait’s Liquor Store are nearly co-planar as they both reside in Lloydminster almost along the same line of observation relative to the fireball. A minimum of two stations are needed to triangulate a solution, however, by adding more stations it allows for an evaluation of uncertainties and whether any possible systematic skewing of the solution exists. The three stations used to tri­ angulate a trajectory for Buzzard Coulee are nearly equivalent to two station geometry.

However, having all three stations offers much more confidence because the Trailside Inn and Tait’s Liquor Store were independently calibrated and gave consistent results, as is the case for the two cameras at the Lashburn Esso (which were further strengthened by the agreement in predicting the Sun’s position from its shadows).

Figure 3.20 plots the total deviations (the total displacement from the solution) for each position along the trajectory. The Trailside Inn had the largest magnitude deviation, up to 349 m total displacement from the best fit solution. This figure helps to visualize 79

Figure 3.19: Map of the atmospheric trajectory of Buzzard Coulee. The thick line beginning with the start of shadows represents the portion of the trajectory measured from the Trailside Inn, Tait’s Liquor Store and the Lashburn Esso Station. The region of the strewn field is highlighted and the impact position of the trajectory is projected to the ground. 80 which parts of the trajectory were observed by each station. The sidewalk positions mea­ sured at the Trailside Inn imaged the start of the trajectory. Tait’s Liquor Store and the

Lashburn Esso viewed positions through the middle of the trajectory, when the shadows transitioned between the sidewalk and the wall at the Trailside Inn. Measurements on the wall at the Trailside Inn overlapped with the latter positions at the Lashburn Esso

Station, but the Trailside Inn recorded positions deepest into the atmosphere. Figures

3.21 and 3.22 plot the vertical and horizontal residuals separately along the length of the trajectory. It is important that all stations show nearly equal magnitude deviations in both the positive and negative directions, otherwise one station would be systematically skewed compared with the others. All of the deviations are nearly symmetric and do not show any worrisome systematic trends. The Lashburn Esso Station shows the most deviation in the vertical sense with the largest residual being 274 m below the best fit trajectory. All of the stations have similar magnitudes of deviation in the horizontal sense with the Trailside Inn showing the greatest range of horizontal deviation.

Figure 3.20: Total distance each point is away from the best fit solution. This figure helps to visualize which portions of the trajectory are observed by each station. 81

Figure 3.21: Vertical deviations from the best fit trajectory for each of the three stations included in the solution.

Figure 3.22: Horizontal deviations from the best fit trajectory for each of the three stations included in the solution. 82

Figure 3.23: Comparison of the vertical and horizontal deviations. The line slopes are related to the geometry of observation to the fireball. The co-planar geometry of the Trailside Inn and Tait’s Liquor store is evident as positions from these locations plot along the same line.

In Figure 3.23 the vertical deviations are plotted against the horizontal deviations for each station. Residuals from each station fall onto a line related to the geometry of observation between the station and the trajectory. Equal magnitudes of positive and negative numbers help to illustrate that no major systematic trend exists in the data. However, it is not possible to determine whether the residuals are systematic from this plot alone, Figures 3.21 and 3.22 are needed to show that the residuals jump between positive and negative values along the trajectory. Figure 3.23 demonstrates the co-planar nature of the geometry between the Trailside Inn and Tait’s Liquor Store, as the two stations plot along the same line. The wide angle between the planes of observation from Lashburn and Lloydminster is seen as the lines intersect at a wide angle. Ideally obtaining three stations equally spaced around the trajectory would offer the most rigorous configuration.

Figures 3.21 through 3.23 are useful for studying possible systematic trends in the observations. Since no glaring trends in the data are apparent it can be assumed that 83 each station was well calibrated and has not skewed the trajectory solution. To assess the uncertainty in the trajectory, a Monte Carlo simulation was performed by P. Brown.

First, an average angular uncertainty for each station was determined by observing the change in altitude and azimuth if the chosen position on the calibration cloth was varied by a measurable quantity. The variation in altitude and azimuth of a position at the start and at the end of the fireball were considered in order to gain an understanding of the total possible variation over the whole trajectory. This was done because the physical distance extended by one pixel varies over an image. Pixels imaging positions nearer to the camera have better resolution than pixels imaging distant positions.3 Averages were determined for altitude and azimuth measurements from each camera site4 and taking a conservative approach, the larger value between the two was selected as the angular uncertainty for that site. These calculations resulted in the following: Trailside

Inn ±0.4◦, Tait’s Liquor Store ±0.2◦ and Lashburn Esso ±0.4◦ . A Gaussian distribution of positions with a standard deviation equal to the angular uncertainly was generated for each station. Ten thousand MILIG solutions were calculated for this distribution in the data and the variation in the trajectory solution was observed. The uncertainties of each trajectory parameter quoted in Table 3.1 indicate the results of this simulation. Of particular interest is the uncertainty in the radiant which is used to determine the error bounds in the pre-fall orbit using MORB (Ceplecha et al., 2000).

The excellent agreement between independent calibrations and the small residuals resulting from the best fit trajectory establish that the calibration and measurement of shadows is a reliable and sufficiently accurate method for determining the atmospheric trajectory of a fireball. Calibrations require considerable attention to detail so that systematic errors do not occur in the measurements. Shadows perceptible to security

3Similar in concept to the spatial resolution, ground sample distance (GSD) in remote sensing for geographic information systems (GIS). 4Uncertainties were determined and averaged for both pumps at the Lashburn Esso Station and for both the beginning and end of the wall and the sidewalk positions at the Trailside Inn. 84 cameras are only cast on the ground relatively near the geographic location below the

fireball. Although relatively large angular uncertainties are associated with the pixel resolution of the security cameras (angular pixel sizes are typically less than those of all-sky cameras), the resulting total deviations from the trajectory are relatively small

(of order hundreds of meters or smaller) because of the short camera-fireball separation distance. The shape of the fireball (i.e. after a major fragmentation event) visibly affects the projection of shadows on the ground. Shadows appear to linger in bright frames, when a large explosion alters the shape of the light in the sky, and jump forward in the next dark frame as the fireball regains its true shape, when persistent illumination of the atmosphere has ceased. The initial velocity of the fireball is difficult to constrain from shadows, although in theory if the frame rate of the camera is known an estimate could be made. Direct and precise measurements of the fireball in the sky remain the best method for establishing an initial velocity.

3.2.4 Velocity Results and Discussion

Figure 3.24 shows the positions of the start of the fireball measured from the RCMP dashboard camera in Devon, Alberta. These measurements, along with timing informa­ tion and the observations from the shadow cameras were input into MILIG. The time and distance along the trajectory of the Devon positions were used to calculate a best

fit line with the initial velocity as its slope. Figure 3.25 combines the data from both calibration images and plots a best fit line with a slope of 18.6 km/s (σ = 0.4 km/s).

The fact that the car was moving at the time of the fireball caused the best fit slope from either calibration shot to appear steepened. Combining the results from both successive calibration images helps to average out this effect but does not guarantee the result. As seen in Figure 3.25 at 0.6 s, a significant jump in the data occurs when the switch between calibration images was made. Considering first the points before 0.6 s, all of the positions 85 start below the best fit line at 0.0 s and systematically move above the line. The points after 0.6 s, which were determined using the next stellar calibration shot, appear below the line and again systematically move above it. The steepening effect occurred because of the motion of the car, as it moved futher away from the position of the calibration shot the foregound objects are larger and higher in the frame. Forcing the fit between the fireball frame and the calibration shot shifts the the fireball frame lower and hence the fireball position in the sky appears too far along its trajectory. Similarly when the change between calibration shots was made, the car had not yet reached the position of the calibration shot so the foreground objects were still too far away and too low in the frame. Fitting the video frame with the calibration image meant that the fireball was placed too high compared to the stars which made the length along the trajectory too short and created the jump observed at 0.6 s in Figure 3.25. Again as the fireball frames caught up with the position of the stellar calibration and moved past it, the fit was shifted down pulling the fireball position too far along the trajectory. This systematic effect on the velocity could be reduced by taking more frequent calibration shots in a series along the road, so that each fireball frame could be matched with a calibration shot closer to its position on the road.

An initial velocity at the top of the atmosphere prior to atmospheric deceleration was determined by P. Brown to be 18.0±0.4 km/s, using the all-sky camera record maintained by G. Sarty in Saskatoon, Saskatchewan. A plate fit with stellar residuals less than 0.1◦ in the region of the fireball was created and used to measure the fireball location in each frame. The data, together with positions measured from the Trailside Inn, Tait’s Liquor

Store and the Lashburn Esso Station, were run through MILIG to determine a solution

(see Appendix D). The results show impressively low residuals (Figure 3.26) and fit well with the solution obtained in Table 3.1. The azimuth of the trajectory adding the Sarty all-sky camera observations was the same at 167.5◦, however the altitude was outside the 86

Figure 3.24: Start of the fireball measured from Devon, Alberta. The first two stellar calibration shots in the sequence along the road were used to calibrate the first 40 frames of the RCMP dashboard camera. Using the known NTSC frame rate of the camera, these positions were used to constrain an initial velocity.

Figure 3.25: Best fit line giving an initial velocity of 18.6 km/s based on the Devon, AB measurements. The points before 0.6 s were determined using the first stellar calibration in the series along the road, and the points after 0.6 s were determined using the next stellar image. The fact that the car was moving at the time of the fireball increases the slope of the line, and thus gives an artificially fast initial velocity. 87 expected uncertainty at 23.9◦ versus the previously established 23.3 ± 0.4◦ (and for this reason the radiant position was also outside the expected uncertainty). The beginning height of 81 km plotted on the trajectory in Figure 3.19 was based on the Sarty all-sky camera. A beginning height of 85 km was obtained adding the Devon observations but the trajectory solution was altered outside the expected uncertainty (azimuth 168.0◦ , altitude 25.8◦, radiant position right ascension 295.1◦ and declination 77.2◦).

The uncertainty for the initial velocity obtained using the Devon police dashboard camera fits within the limit of uncertainty determined using the Sarty all-sky camera.

However, the effect created by the moving camera is understood to cause an artificially fast initial velocity. The surprising level of agreement between the two derived velocities, coupled with an explanation for the fast Devon result lends confidence to the initial velocity derived for Buzzard Coulee using the Sarty all-sky camera. In fact, estimating the two Devon frames with the closest fit to the two calibration shots5 results in a smaller slope of 18.1 km/s in better agreement with the result from the Sarty all-sky camera. In the future if one were to calibrate a moving camera, more calibration shots corresponding to positions for the start of the fireball are needed to obtain better fits between the calibration images and the fireball frames. An initial velocity of 18.0 ± 0.4 km/s is used with the best fit trajectory to derive a pre-fall orbit for the meteoroid.

5The two best matches are the first frame at 0.0 s with the first calibration shot and the frame at 0.867 s fit with the second calibration shot 88

Figure 3.26: Deviations of each point from the MILIG best fit solution including the Sarty all-sky video in Saskatoon, used to derive an initial velocity for Buzzard Coulee. a: The vertical deviations, b: the horizontal deviations, and c: the total deviation of each point from the best fit trajectory. 89

3.3 Pre-Fall Orbit

A heliocentric orbit can be derived if the orientation and speed of the fireball at a given time are known. Software called MORB (Ceplecha et al., 2000) takes the date, time, radiant position, initial velocity and geographic coordinates to calculate an orbit. The atmospheric trajectory and initial velocity of Buzzard Coulee were input into MORB to determine a pre-fall heliocentric orbit for the meteoroid prior to impact (the MORB input file can be found in Appendix E). The orbital parameters are summarized in

Table 3.2 and plotted in Figures 3.27 and 3.28. The uncertainties reported in Table 3.2 were determined by MORB based upon the uncertainties found with the Monte Carlo simulation of the trajectory, and the uncertainty in the initial velocity.

Table 3.2: Orbital parameters for the Buzzard Coulee meteoroid. J2000.0: a (AU) e q (AU) Q (AU)

1.25 ± 0.02 0.23 ± 0.02 0.961 ± 0.01 1.52 ± 0.06

i (◦) ω (◦) Ω (◦) ν (◦)

25.0 ± 0.8 211.3 ± 1.4 238.93739 ± 0.00008 90.2 ± 1.4

3.3.1 Discussion

Buzzard Coulee was in a modestly inclined inner Solar System orbit, as shown in Figure

3.28. Its orbital parameters satisfy the conditions for an Apollo near-Earth orbit desig­ nation with semi-major axis larger than or equal to one, and perihelion distance smaller than 1.017 AU. Buzzard Coulee was probably excavated from its asteroid parent body in a collision millions to tens of millions of years ago, based upon the cosmic ray exposure ages of H4 chondrites ranging from ∼1– 80 Ma (Graf & Marti, 1995). Its orbit was 90

Figure 3.27: Heliocentric orbit of the Buzzard Coulee meteoroid looking at the ecliptic plane. The First Point of Ares is down, and the orbits of Venus, Earth and Mars have been shown for comparison. The conditions a ≥ 1 AU and q < 1.017 AU satisfy the criteria for an Apollo orbit designation. This plot was generated by XEphem (Downey, 2006).

Figure 3.28: Heliocentric orbit of the Buzzard Coulee meteoroid looking from the First Point of Ares toward the ecliptic plane. Once again, the orbits of Venus, Earth and Mars have been included for comparison. Buzzard Coulee was in a modestly inclined orbit at 25.0◦ . This plot was created using XEphem (Downey, 2006). 91 likely dynamically altered through radiation effects until it entered one of the Asteroid

Belt’s ‘escapes’. Here its orbit would have been radically changed through gravitational interactions with a large Jovian planet (i.e. Jupiter or Saturn), over time developing its inner Solar System Apollo orbit. Its aphelion distance extends to Mars, suggesting that the object may have, at some time in the near past, had gravitational interaction with this planet as well.

Bottke et al. (2002) modeled the debiased orbital distribution of the near-Earth object population. They predicted that ∼64% of Apollo objects originate in the inner Asteroid

Belt, ∼24% from the central part of the Main Belt, ∼6% from the outer part of the Main

Belt and ∼6% from the JFC region of the Solar System. These statistics suggest that

Buzzard Coulee originated in the middle to central region of the Main Belt, but there is

∼12% probability that it came from the outer Main Belt or even further from the Sun.

Bottke et al. (2002) also predicted orbital distributions for Apollo objects, representing the true distribution untangled from observational biases (see Figure 3.29). They found that most Apollo objects have semi-major axes from 1–3 AU, a peak in eccentricity at

0.65–0.7 and a peak in inclination between 10–15◦ . Buzzard Coulee’s orbit fits into the bulk of expected semi-major axes with a = 1.25 AU. However, it shows a low value of eccentricity at 0.23, indicating a more circular orbit than the majority of other Apollo orbits. The predicted distribution of Apollo inclinations was skewed with a long tail of large values that Bottke et al. (2002) suggested could be caused by a number of inner

Solar System secular resonances. An inclination of 25.0◦ puts Buzzard Coulee to one side of the skewed distribution but this is not an unexpectedly large value. Hildebrand et al. (2006) applied the Bottke et al. (2002) model to the orbit of Tagish Lake. They observed that it had a 51% chance of being delivered from the ν6 secular resonance and a surprisingly high chance at 26% of being delivered from the outer Main Belt.6 Further

6A 26% chance of delivery from the outer Main Belt for Tagish Lake is surprising when compared 92 modeling specific to Buzzard Coulee’s orbital elements could be conducted to gain a better understanding of how this meteoroid was delivered to Earth and the probabilities associated with each possible escape route from the Asteroid Belt. Modeling could also help to understand any possible interaction between Mars and Buzzard Coulee’s orbit.

Figure 3.29: The debiased orbital distribution of Apollo objects predicted by Bottke et al. (2002). The gray shaded areas show the known Apollo objects for comparison. with the general population of near-Earth objects, which only have a ∼5% chance of coming from the outer Main Belt. 93

The uncertainties in orbital elements presented in Table 3.2 were calculated by MORB, which inputs the uncertainty in the trajectory radiant, velocity and time of fall to calcu­ late the possible variation each parameter can exhibit. The longitude of the ascending node is known with great precision because there is little uncertainty in the time of the fall (Nov. 21 2008, 00:26:43±1 s UT). The uncertainty in the radiant and initial velocity translates most directly into the uncertainties in the semi-major axis, aphelion distance and inclination. The errors in Buzzard Coulee’s orbit are greater than those for mete­ orites with orbits obtained through dedicated systems, and its orbit is most certainly not as precisely known as Almahata Sitta, which was observed by survey telescopes prior to fall (see Table 1.1). However, the level of uncertainty here is comparable with other orbits determined through serendipitous methods, such as video cameras calibrated after the fall. This result shows that the novel method of shadow calibration developed in this project can be applied to derive a sufficiently well-defined pre-fall orbit. Calibrating serendipitous camera records requires great precision and care in order to obtain credible results. Great effort was required to calibrate the shadow records of Buzzard Coulee, with numerous visits to each site to complete suitable calibrations. In this study, the difficulties associated with shadow calibration have become apparent. Of key importance is sufficient understanding of the site geometry for calibration. Detailed site surveys must be conducted, a grid pattern must be carefully deployed square to the reference system and the geometry of the object casting the shadow must be accurately known. If possi­ ble, measurement of Sun shadows at precisely known times offers a convenient, simple, yet rigorous method for checking the quality of the calibration. Also helpful and easily overlooked are taking photographs from a number of angles, showing the details of the site, which are helpful during the data reduction process. 94

Meteorites Associated with an Orbit

The orbit of Buzzard Coulee has been plotted with the 12 other meteorites with derived orbits in Figures 3.30 and 3.31. Buzzard Coulee comes from the second smallest orbit after Bunburra Rockhole which fell from an Aten orbit (a < 1 AU, Q > 0.983 AU). It also came from the second largest inclination, with only Mor´avka being more inclined at

32.2◦ (Boroviˇcka et al., 2003). pro Fit TRIAL version Villalbeto de la Pena

Peekskill Bunburra Rockhole

Buzzard Coulee

Neuschwanstein Lost City Pribram

Almahata Sitta St-Robert

Innisfree Moravka

Park Forest 0.5 AU

Tagish Lake First Point of Aries

Figure 3.30: Orbits of meteorites from Table 1.1 plotted together for comparison. Buz­ zard Coulee has the second smallest orbit after the Aten-class Bunburra Rockhole. This plot was created using XEphem (Downey, 2006). pro Fit TRIAL version

95

Moravka Pribram Buzzard Coulee Neuschwanstein

Park Forest Lost City Innisfree

Figure 3.31: Meteorite orbits from a side view of the ecliptic plane (from Table 1.1). Buz­ zard Coulee shows the second largest inclination after Mor´avka. This plot was generated by XEphem (Downey, 2006).

Figure 3.32 shows a timeline of meteorite falls with derived orbits, from Pˇr´ıbram in

1959 until the most recent, Grimsby, in 2009. The black bars represent meteorites recov­ ered by dedicated camera systems as described in Section 2.1. The striped bars represent meteorites whose orbits were derived after the fall through serendipitous instrumental recordings and the criss-crossed event belongs to Almahata Sitta, imaged through a space survey program prior to falling. The first three meteorites with a derived orbit came from camera networks, but with the proliferation of technology throughout the 1990s, momen­ tum has been building for orbits derived through serendipitous instrumental recordings.

Determining an orbit for a meteorite through haphazard recordings is time consuming, but cheaper than developing and maintaining a camera system. However, serendipitous records are restricted to brighter objects and the data must be quickly tracked down and retrospectively calibrated. Uncertainties associated with an orbit derived through haphazard records are expected to be larger than the uncertainties in an orbit obtained by camera networks. The determination of an accurate measure of the initial velocity is often of primary concern.

Five of the fourteen meteorites with a derived orbit are Canadian falls, a testament to the active research community established in Canada. This suggests an opportunity exists 96

Figure 3.32: Timeline of meteorite falls for which orbits have been derived (see Table 1.1 in Chapter 1 for details of each event) This timeline shows two additional events from Table 1.1: Buzzard Coulee in 2008 and Grimsby in 2009. Black bars denote events recovered and orbits calculated through dedicated camera networks. Striped bars indi­ cate events where seredipitous instrumental records were calibrated after meteorites were recovered and the criss-crossed bar is used for Almahata Sitta, a meteorite predicted to fall through space observations of the meteoroid. 97 with more people involved in the meteorite recovery and calibration efforts of future falls, it will be possible to have more meteorites with known orbits. Based on meteorite flux rates, it can be estimated that approximately 40 meteorites with a terminal mass larger than three kilograms, or approximately 15 meteorites with a terminal mass larger than ten kilograms, could be instrumentally recorded to fall each year onto searchable regions of the Earth (Appendix F). These numbers imply that two meteorites larger than three kilograms (one meteorite larger than ten kilograms) could be instrumentally recorded to fall onto searchable terrain in Canada every year. A lot can be learned from meteorites, especially those linked with a pre-fall orbit, about the processes acting both historically and presently within the Solar System. Spacecraft sample-return missions cost upward of hundreds of millions of dollars, but extraterrestrial material is freely delivered to Earth each year making the recovery of meteorites and the derivation of an orbit well worth the effort.

Search for Pre-Fall Images

Almahata Sitta was a particularly exciting event because the object was first discovered in space then predicted to collide with Earth. Spectra of the meteoroid were consistent with an F-class asteroid (Jenniskens et al., 2009) and the recovered meteorites were classified as an anomalous ureilite. Almahata Sitta is the first ground truth for the asteroid spectral classification system, which has so far not conclusively been matched with the meteorite collection. It also has by far the most accurate orbit of any meteorite because it was determined through space observations. With the orbit for Buzzard Coulee determined, it would be interesting if the meteoroid could be retrospectively found in space in asteroid search survey images.

The Minor Planet Center, operating out of the Smithsonian Astrophysical Observa­ tory maintains a record of astrometric observations and orbits of minor planets. As part 98

Figure 3.33: Plot of the sky coverage achieved by asteroid search telescopes for the period of January 20-27, 2010 (Minor Planet Center, 2010). 99 of the observer services offered, the Minor Planet Center can generate plots of the sky coverage by asteroid search telescopes for a given period of time. Figure 3.33 shows an example plot of the sky coverage achieved by all the search programs during the period from January 20-27, 2010. The astronomical ephemeris software XEphem Version 3.7.2

(Downey, 2006) was used to plot Buzzard Coulee’s orbit, observing its position relative to the Earth in the time leading up to the fall. XEphem shows the positions of the object in the sky before the collision. These were compared to the sky coverage plotted by the

Minor Planet Center for the relevant observation period. It turns out that LINEAR

(Lincoln Near Earth Asteroid Research at MIT) took a series of exposures in that region of the sky on the night before Buzzard Coulee’s fall. Unfortunately, Buzzard Coulee was near but outside the series of images that LINEAR took that night. It was a small but worthwhile possibility to follow up whether Buzzard Coulee had been imaged by the asteroid search telescopes but missed by their detection software. It is most unfortunate that circumstances were not such to allow for Buzzard Coulee to be found in space after its fall.

3.4 Summary and Conclusions

The large fireball on the evening of November 20, 2008 was big enough to be seen for hun­ dreds of kilometers as it explosively collided with Earth’s atmosphere. Thousands of frag­ ments survived the atmospheric transit and fell to the ground in a region of Saskatchewan known as Buzzard Coulee. The meteorites were classified as an ordinary chondrite of type

H4 based on the mineralogy and demonstrate some interesting geologic features including a number igneous textured silica polymorph inclusions of an unknown origin.

The fireball was instrumentally recorded in many locations including several proximal security cameras that imaged the shadows cast. The shadows from the fireball were 100 calibrated at three sites and used to triangulate an atmospheric trajectory. This project developed a novel approach of shadow calibration to obtain a trajectory. Accurate site surveys and unsystematic calibrations were critical in obtaining correct measurements of the fireball in the sky. Obtaining shadows cast by the Sun at known times offered a rigorous and simple verification of the quality of the calibration for one security camera record at the Lashburn Esso Station. The process of measuring shadow positions required great attention to detail, but the results had the added benefit of being close to the event so uncertainties in angular positions did not result in large deviations because of the short distance. It appears that the shape of the fireball in the sky created observable variations in the shadows cast on the ground. Large fragmentation events create an extended light source, with persistent illumination of the atmosphere behind the body, causing shadows to linger on the ground and then to jump forward when the light regains the shape of the body. A distant all-sky camera was used to determine the initial velocity of

18.0 km/s, a better estimate than the result found by calibrating a moving video, which systematically gave a faster initial velocity of 18.6 km/s. A Monte Carlo simulation was run to determine the uncertainties in the trajectory by inputting the average angular uncertainty associated with measurements from each camera station.

The orbit was computed using software called MORB (Ceplecha et al., 2000). The ini­ tial location, time and velocity were required to derive a heliocentric orbit. Uncertainties in the trajectory were given consideration by MORB to find the level of uncertainty in each orbital element. Buzzard Coulee was in a near-Earth Apollo orbit prior to collision with the Earth. It was in a moderately inclined path with an aphelion distance extend­ ing to Mars. The level of uncertainty in Buzzard Coulee’s orbit was comparable to other meteorites with orbits derived through serendipitous instrumental recordings calibrated after the fall. These results indicate that the measurement of shadows can provide a reliable method for deriving a pre-fall orbit and can be applied to other meteorite falls 101 in the future. Buzzard Coulee is the 12th fallen meteorite for which a pre-fall orbit has been derived, giving context for the geology of the recovered fragments. Bibliography

[1] M. Beech. The Buzzard Coulee Meteorite Fall. Meteorite Magazine, May 2009.

[2] J. Boroviˇcka. The comparison of two methods of determining meteor trajectories

from photographs. Bulletin of the Astronomical Institute of Czechoslovakia, 41:391–

396, 1990.

[3] J. Boroviˇcka, P. Spurn´y, P. Kalenda, and E. Tagliaferri. The Mor´avka meteorite

fall: 1. Description of the events and determination of the fireball trajectory and

orbit from video records. Meteorites & Planetary Science, 38:975–987, 2003.

[4] J. Boroviˇcka, P. Spurn´y, and J. Kecl´ıkov´a. A new positional astrometric method for

all-sky cameras. Astronomy & Astrophysics Supplement Series, 112:173–178, 1995.

[5] W. F. Bottke, A. Morbidelli, R. Jedicke, J. M. Petit, H. F. Levison, P. Michel,

and T. S. Metcalfe. Debiased Orbital and Absolute Magnitude Distribution of the

Near-Earth Objects. Icarus, 156:399–433, 2002.

[6] P. Brown, Z. Ceplecha, R. L. Hawkes, G. Wetherill, M. Beech, and K. Mossman.

The orbit and atmospheric trajectory of the Peekskill meteorite from video records.

Nature, 367:624–626, 1994.

[7] P. G. Brown, A. R. Hildebrand, D. W. E. Green, D. Pag´e, C. Jacobs, D. ReVelle,

E. Tagliaferri, J. Wacker, and B. Wetmiller. The fall of the St-Robert meteorite.

Meteorites & Planetary Science, 31:502–517, 1996.

[8] P. G. Brown, D. Pack, W. N. Edwards, D. O. ReVelle, B. B. Yoo, R. E. Spalding,

and E. Tagliaferri. The orbit, atmospheric dynamics, and initial mass of the Park

Forest meteorite. Meteorites & Planetary Science, 39:1781–1796, 2004.

102 103

[9] M. D. Campbell-Brown and A. Hildebrand. A New Analysis of Fireball Data from

the Meteorite Observation and Recovery Project (MORP). Earth, Moon and Plan­

ets, 95:489–499, 2004.

[10] Environment Canada Weather Office. http://www.weatheroffice.gc.ca/

canada_e.html, November 2008.

[11] Minor Planet Center. http://www.minorplanetcenter.org/iau/mpc.html,

March 2010.

[12] Z. Ceplecha. Spectral Data on Terminal Flare and Wake of Double-Station Meteor

No. 38421 (Ondˇrejov, April 21, 1963). Bulletin of the Astronomical Institute of

Czechoslovakia, 22:219–304, 1971.

[13] Z. Ceplecha. Fireballs Photographed in Central Europe. Bulletin of the Astronom­

ical Institute of Czechoslovakia, 28:328–340, 1977.

[14] Z. Ceplecha. Geometric, Dynamic, Orbital and Photometric Data on Meteoroids

from Photographic Fireball Networks. Bulletin of the Astronomical Institute of

Czechoslovakia, 38:222–234, 1987.

[15] Z. Ceplecha. Earth’s Influx of Different Populations of Sporadic Meteoroids

from Photographic and Television Data. Bulletin of the Astronomical Institute of

Czechoslovakia, 39:221–236, 1988.

[16] Z. Ceplecha. Meteoroid Properties from Photographic Records of Meteors and Fire­

balls. In Asteroids, Comets, Meteors 1993 (International Astronomical Union Sym­

posia), pages 343–356, 1994.

[17] Z. Ceplecha, J. Boroviˇcka, W. G. Elford, D. O. ReVelle, R. L. Hawkes, V. Porubˇcan,

and M. Simek.ˇ Meteor Phenomena and Bodies. Space Science Reviews, 84:327–471, 104

1998.

[18] Z. Ceplecha, J. Boˇcek, and M. Jeˇzkov´a. Photographic Data on the Arrach Fireball

(EN 290875, Aug. 29, 1975). Bulletin of the Astronomical Institute of Czechoslo­

vakia, 27:242–244, 1976.

[19] Z. Ceplecha, J. Boˇcek, and M. Jeˇzkov´a. Photographic Data on the BRNO Fireball

(EN 140 977, SEP 14, 1977). Bulletin of the Astronomical Institute of Czechoslo­

vakia, 30:220–225, 1979.

[20] Z. Ceplecha, J. Boˇcek, M. Jeˇzkov´a, and V. Porubˇcan. Photographic Data on the

Zvolen Fireball (EN 270 579, MAY 27, 1979) and Suspected Meteorite Fall. Bulletin

of the Astronomical Institute of Czechoslovakia, 31:176–182, 1980.

[21] Z. Ceplecha, J. Boˇcek, M. Nov´akov´a (Jeˇzkov´a), and G. Polnitzky. Photographic

Data on the Traunstein Fireball (EN 290181, Jan. 29, 1981) and Suspected Meteorite

Fall. Bulletin of the Astronomical Institute of Czechoslovakia, 34:162–167, 1983.

[22] Z. Ceplecha, J. Boˇcek, M. Nov´akov´a-Jeˇzkov´a, V. Porubˇcan, T. Kirsten, and J. Kiko.

European Network Fireballs Photographed in 1977. Bulletin of the Astronomical

Institute of Czechoslovakia, 34:195–211, 1983b.

[23] Z. Ceplecha, M. Jeˇzkov´a, J. Boˇcek, and T. Kirsten. Photographic Data on the

Leutkirch Fireball (EN 300874) (Aug. 30, 1974). Bulletin of the Astronomical Insti­

tute of Czechoslovakia, 27:18–23, 1976b.

[24] Z. Ceplecha, M. Jeˇzkov´a, J. Boˇcek, T. Kirsten, and J. Kiko. Data on Three Signifi­

cant Fireballs Photographed Within the European Network in 1971. Bulletin of the

Astronomical Institute of Czechoslovakia, 24:13–22, 1973. 105

[25] Z. Ceplecha and R. E. McCrosky. Fireball End Heights: A Diagnostic for the

Structure of Meteoric Material. Journal of Geophysical Research, 81:6257–6275,

1976.

[26] Z. Ceplecha and J. Rajchl. Programme of Fireball Photography in Czechoslovakia.

Bulletin of the Astronomical Institute of Czechoslovakia, 16:15–22, 1965.

[27] Z. Ceplecha, P. Spurn´y, and J. Boroviˇcka. MORB software to determine meteoroid

orbits. Ondˇrejov Observatory, Czech Republic, 2000.

[28] G. C. de El´ıa and A. Brunini. Collisional and dynamical evolution of the main belt

NEA population. Astronomy & Astrophysics, 466:1159–1177, 2007.

[29] E. C. Downey. XEphem Version 3.7.2. http://www.xephem.com, 2006.

[30] D. P. Galligan and W. J. Baggaley. The orbital distribution of radar-detected me­

teoroids of the Solar system dust cloud. Monthly Notices of the Royal Astronomical

Society, 353:422–446, 2004.

[31] B. J. Gladman, F. Migliorini, A. Morbidelli, V. Zappal`a, P. Michel, A. Cellino,

C. Froeschl´e, H. F. Levison, M. Bailey, and M. Duncan. Dynamical Lifetimes of

Objects Injected into Asteroid Belt Resonances. Science, 277:197–201, 1997.

[32] T. Graf and K. Marti. Collisional history of H chondrites. Journal of Geophysical

Research, 100:21247–21264, 1995.

[33] I. Halliday. Geminid Fireballs and the Peculiar Asteroid 3200 Phaethon. Icarus,

76:279–294, 1988.

[34] I. Halliday, A. T. Blackwell, and A. A. Griffin. The Innisfree Meteorite and the

Canadian Camera Network. Journal of the Royal Astronomical Society of Canada,

72:15–39, 1978. 106

[35] I. Halliday, A. T. Blackwell, and A. A. Griffin. The Frequency of Meteorite Falls on

the Earth. Science, 223:1405–1407, 1984.

[36] I. Halliday, A. T. Blackwell, and A. A. Griffin. Detailed Records of Many Unrecov­

ered Meteorites in Western Canada for Which Further Searches are Recommended.

Journal of the Royal Astronomical Society of Canada, 83:49–80, 1989.

[37] I. Halliday, A. T. Blackwell, and A. A. Griffin. The flux of meteorites on the Earth’s

surface. Meteoritics, 24:173–178, 1989b.

[38] I. Halliday, A. T. Blackwell, and A. A. Griffin. Evidence for the existence of groups

of meteorite-producing asteroidal fragments. Meteoritics, 25:93–99, 1990.

[39] I. Halliday, A. A. Griffin, and A. T. Blackwell. Detailed data for 259 fireballs

from the Canadian camera network and inferences concerning the influx of the large

meteoroids. Meteoritics & Planetary Science, 31:185–217, 1996.

[40] A. E. Hedin. MSIS-E-90 Atmosphere Model. http://omniweb.gsfc.nasa.gov/

vitmo/msis_vitmo.html, 1990.

[41] A. R. Hildebrand, P. J. A. McCausland, P. G. Brown, F. J. Longstaffe, S. D. J.

Russell, E. Tagliaferri, J. F. Wacker, and M. J. Mazur. The fall and recover of the

Tagish Lake meteorite. Meteoritics & Planetary Science, 41:407–431, 2006.

[42] A. R. Hildebrand, E. P. Milley, P. G. Brown, P. J. A. McCausland, W. Edwards,

M. Beech, A. Ling, G. Sarty, M. D. Paulson, L. A. Maillet, S. F. Jones, and M. R.

Stauffer. Characteristics of a Bright Fireball and Meteorite Fall at Buzzard Coulee,

Saskatchewan, Canada, November 20, 2008. In Lunar and Planetary Institute Sci­

ence Conference Abstracts, volume 40, 2009. 107

[43] M. L. Hutson, A. M. Ruzicka, E. P. Milley, and A. R. Hildebrand. A First Look at

the Petrography of the Buzzard Coulee (H4) Chondrite, a Recently Observed Fall

from Saskatchewan. In Lunar and Planetary Institute Science Conference Abstracts,

volume 40, 2009.

[44] Z.ˇ Ivezi´c, R. H. Lupton, M. Juri´c, S. Tabachnik, T. Quinn, J. E. Gunn, G. R. Knapp,

C. M. Rockosi, and J. Brinkmann. Color Confirmation of Asteroid Families. The

Astronomical Journal, 124:2943–2948, 2002.

[45] P. Jenniskens. The Meteoroid Stream Working List. http://www.astro.sk/~ne/ IAUMDC/STREAMLIST/, 1996.

[46] P. Jenniskens, M. H. Shaddad, D. Numan, S. Elsir, A. M. Kudoda, M. E. Zolen­

sky, L. Le, G. A. Robinson, J. M. Friedrich, D. Rumble, A. Steele, S. R. Chesley,

A. Fitzsimmons, S. Duddy, H. H. Hsieh, G. Ramsay, P. G. Brown, W. N. Edwards,

E. Tagliaferri, M. B. Boslough, R. E. Spalding, R. Dantowitz, M. Kozubal, P. Pravec,

J. Boroviˇcka, Z. Charvat, J. Vaubaillon, J. Kuiper, J. Albers, J. L. Bishop, R. L.

Mancinelli, S. A. Sanford, S. N. Milam, M. Nuevo, and S. P. Worden. The impact

and recovery of asteroid 2008 TC3. Nature, 458:485–488, 2009.

[47] A. Lee. VirtualDub. http://www.virtualdub.org/index.html, October 2009.

[48] J. S. Lewis. Physics and Chemistry of the Solar System. Academic Press, revised

edition, 1997.

[49] R. Malhotra, M. Duncan, and H. Levison. Dynamics of the Kuiper Belt. In Proto­

stars and Planets IV, pages 1231–1254. The University of Arizona Press, 2000.

[50] P. J. A. McCausland, P. G. Brown, A. R. Hildebrand, R. L. Flemming, I. Barker,

D. E. Moser, J. Renaud, and W. Edwards. Fall of the Grimsby H5 Chondrite. In

Lunar and Planetary Institute Science Conference Abstracts, volume 41, 2010. 108

[51] R. E. McCrosky and H. Boeschenstein. The Prairie Meteorite Network. SAO Special

Report, 173, 1965.

[52] R. E. McCrosky and Z. Ceplecha. Photographic Networks for Fireballs. SAO Special

Report, 288, 1968.

[53] R. E. McCrosky, A. Posen, G. Schwartz, and C. Y. Shao. Lost City Meteorite – its

Recovery and a Comparison with Other Fireballs. SAO Special Report, 336, 1971.

[54] R. E. McCrosky, C. Y. Shao, and A. Posen. Prairie Network Fireballs Data I.

Summary and Orbits. Centre for Astrophyics Preprint Series, 665:13 pages, 1976.

[55] H. Y. McSween. Meteorites and Their Parent Planets. Cambridge University Press,

second edition, 1999.

[56] A. Morbidelli, W. F. Bottke Jr., C. Froeschl´e, and P. Michel. Origin and Evolution

of Near-Earth Objects. In Asteroids III, pages 409–422. The University of Arizona

Press, 2002.

[57] S. H. Nudds. Determining the Distribution of Strength of Small Bodies of the Solar

System from Multi-Station Meteor Observations, 2007. Undergraduate Thesis, The

University of Western Ontario.

[58] J. Oberst, S. Molau, D. Heinlein, C. Gritzner, M. Schindler, P. Spurn´y, Z. Ceplecha,

J. Rendtal, and H. Betlem. The “European Fireball Network”: Current status and

future prospects. Meteoritics & Planetary Science, 33:49–56, 1998.

[59] E. J. Opik. Physics of Meteor Flight in the Atmosphere. Interscience Publishers,

Inc., 1958.

[60] W. Rasband. ImageJ - Image Processing and Analysis in Java. http://rsbweb.

nih.gov/ij/index.html, 2009. 109

[61] A. Ruzicka, G. A. Snyder, and L. A. Taylor. Mega-chondrules and large,

igneous-textured clasts in Julesberg (L3) and other ordinary chondrites: Vapor-

fractionation, shock-melting, and chondrule formation. Geochimica et Cosmochinica

Acta, 62:1419–1442, 1998.

[62] D. W. G. Sears and R. T. Dodd. Overview and classification of meteorites. In

Meteorites and the early solar system, pages 3–31. The University of Arizona Press,

1988.

[63] L. Shrben´y and P. Spurn´y. Precise data on Leonid fireballs from all-sky photographic

records. Astronomy & Astrophysics, 506:1445–1454, 2009.

[64] P. Sprun´y, P. A. Bland, J. Boroviˇcka, L. Shrben´y, T. McClafferty, A. Singleton,

A. W. R. Bevan, D. Vaughan, M. C. Towner, and G. Deacon. The Bunburra Rock-

hole Meteorite Fall in SW Australia: Determination of the Fireball Trajectory, Lu­

minosity and Impact Position from Photographic Records. In Lunar and Planetary

Institute Science Conference Abstracts, volume 40, 2009.

[65] P. Sprun´y and J. Boroviˇcka. EN310800 Vimperk Fireball: Probable Meteorite Fall

of an Aten Type Meteoroid. In Proceedings of the Meteoroids 2001 Conference,

pages 119–524, 2001.

[66] P. Sprun´y, D. Heilein, and J. Oberst. The Atmospheric Trajectory and Heliocentric

Orbit of the Neuschwanstein Meteorite Fall on April 6, 2002. In Asteroids, Comets,

and Meteors: ACM 2002, pages 137–140, 2002.

[67] P. Sprun´y and V. Porubˇcan. The EN171101 Bolide – the Deepest Ever Photographed

Fireball. In Asteroids, Comets, and Meteors: ACM 2002, pages 269–272, 2002.

[68] P. Spurn´y. Recent fireballs photographed in central Europe. Planetary Space Sci­

ence, 42:157–162, 1994. 110

[69] P. Spurn´y, J. Oberst, and D. Heinlein. Photographic observations of

Neuschwanstein, a second meteorite from the orbit of the P˘r´ıbram chondrite. Nature,

423:151–153, 2003.

[70] P. Spurn´y and L. Shrben´y. Exceptional Fireball Activity of the Orionids in 2006.

Earth, Moon and Planets, 102:141–150, 2008.

[71] J. S. Stuart and R. P. Binzel. Bias-correction population, size distribution, and

impact hazard for the near-Earth objects. Icarus, 170:295–311, 2004.

[72] J. M. Trigo-Rodr´ıguez, J. Boroviˇcka, P. Spurn´y, J. L. Ortiz, J. A. Docobo, A. J.

Castro-Tirado, and J. Llorca. The Villalbeto de la Pe˜na meteorite fall: II. De­

termination of atmospheric trajectory and orbit. Meteorites & Planetary Science,

41:505–517, 2006.

[73] M. K. Weisberg, C. Smith, G. Benedix, L. Folco, K. Righter, J. Zipfel, A. Yamaguchi,

and H. Chennaoui Aoudjehane. The Meteoritical Bulletin, No. 95. Meteorites &

Planetary Science, 44:429–462, 2009.

[74] P. R. Weissman, W. F. Bottke Jr., and H. F. Levison. Evolution of Comets into

Asteroids. In Asteroids III, pages 669–686. The University of Arizona Press, 2002.

[75] P. R. Weissman and H. F. Levison. Origin and Evolution of the Unusual Object 1996

PW: Asteroids from the Oort Cloud? The Astrophysical Journal, 488:L133–L136,

1997.

[76] R. J. Weryk, P. G. Brown, A. Domokos, W. N. Edwards, Z. Krzeminski, S. H.

Nudds, and D. L. Welch. The Southern Ontario All-sky Meteor Camera Network.

Earth, Moon and Planets, 102:241–246, 2008. 111

[77] D. K. Yeoman. Jet Propulsion Lab, NASA. http://herschel.jpl.nasa.gov/

images/, November 2003. 112

Appendix A

Fireball Networks

Table A.1: List of published works used to assemble one large data set comprised of MORP, PN and EN events. Network Reference

MORP: Halliday et al., 1989 Halliday et al., 1990 Halliday et al., 1996

PN: Ceplecha & McCrosky, 1976 McCrosky et al., 1976

EN: Ceplecha, 1971 Ceplecha et al., 1973 Ceplecha et al., 1976 Ceplecha et al., 1976b Ceplecha 1977 Ceplecha et al., 1979 Ceplecha et al., 1980 Ceplecha et al., 1983 Ceplecha et al., 1983b Spurn´y, 1994 Spurn´y et al., 2001 Spurn´y et al., 2002 Spurn´y et al., 2002b 113

Steps Required to Reduce Events Captured by the SOMN

1. Creating a plate

The plate constants (Boroviˇcka et al., 1995) of a 14th order fit are found by identify­

ing stars in a calibration shot using IDL script asrgard all sky cam cal1.pro (written

by Z. Krzeminski, Department of Physics and Astronomy, the University of West­

ern Ontario). The resulting map, or plate solution, is used as a conversion between

positions in the image to actual positions in the sky. Creating a quality plate so­

lution is arguably the most crucial step, since any systematic issues introduced at

this stage will carry through to the trajectory solution. Plate fit residuals should

be small and not show systematic trends.

2. Measurement of meteor positions and light curve

Running the IDL script asgard meteor centroid gamma auto.pro (written by Z.

Krzeminski) for each camera that captured an event, scans through each frame

and finds the meteor’s position based on the plate. As well, it creates a light curve

of the event, both with uncorrected raw values and corrected for air mass. The

light curve of the meteor is photometrically calibrated through the comparison of

instrumental magnitudes of stars with their known apparent magnitudes.

3. Obtaining a trajectory solution

First, the IDL script asgard make obs dat.pro (written by Z. Krzeminski) is run to

create an OBS.dat file containing measurements from all cameras used to determine

an atmospheric trajectory. The OBS.dat file is then read as input by MILIG

(Boroviˇcka, 1990), creating a least squares fit of the intersecting planes created

by observations from two or more locations. MILIG outputs a ZMILI.dat file

containing the residuals of all observations from the average trajectory solution, as

well as positions and heights of the start and end of the meteor event. If timing 114

information is included in the OBS.dat file then velocity information is also output.

4. Deriving an orbit

The time of the event, position and velocity of the meteor are input into MORB

(Ceplecha et al., 2000) which calculates the heliocentric orbital parameters.

Parameters Determined through Data Reduction

Table A.2: Summary of parameters required for the calculations of PE value and Tis­ serand parameter as well as the orbital elements. The ‘How obtained’ column notes how each number is determined through the data reduction process. See page ix for a list of the parameter symbol descriptions. Parameter How obtained:

ρE MILIG: HE → MSIS-E-90

m∞ Integrating photometrically calibrated light curve

v∞ MILIG

ZR MILIG

vG Equation 2.1

a MORB

e MORB

i MORB

q MORB

Q MORB

ω MORB

Ω MORB 115

Appendix B

Site Survey Schematics

Trailside Inn Site Schematics

Figure B.1: Schematic view from above the Trailside Inn showing the origin of the designated coordinate system.

Figure B.2: Schematic showing the z-axis of the Trailside Inn. 116

Figure B.3: Schematic showing the relevant geometry along the x-axis of the Trailside Inn.

Figure B.4: Left: Rotation of the coordinate system relative to North. Right: Detailed measurements of the gutter. While the fireball was high in the sky, shadows were cast onto the sidewalk by the upper lip of the gutter. Later when the fireball was lower in its trajectory, shadows were cast onto the wall by the lower edge of the gutter. 117

Lashburn Esso Station Site Schematics

Figure B.5: Schematic overhead view of the Lashburn Esso showing the ground projection of the light fixtures (L), the calibration cloth placement (C) and the origin of the chosen right-handed coordinate system designated for each pump.

Figure B.6: Schematic showing the x-axis of the Lashburn Esso. 118

Tait’s Liquor Store Site Schematics

Figure B.7: Schematic overhead view of Tait’s Liquor Store showing the cloth placement and the origin of the right-handed coordinate system.

Figure B.8: Schematic showing the x-axis of Tait’s Liquor Store. 119

Appendix C

Trailside Inn Derivation of Altitude and Azimuth

Figure C.1: Relevant parameters to define a plane in space.

A plane can be expressed as a scalar equation (Equation C.1) by taking the dot product of a normal vector (ˆn =< a, b, c >) with the positional vector Vr − rVo (where

Vr =< x, y, z > and rVo =< xo, yo, zo >).

a(x − xo) + b(y − yo) + c(z − zo) = 0 (C.1)

Two points on the roof and the corner shadow position are needed to define the planes of shadow cast by each roof. Let the corner shadow point be called C = (Cx,Cy,Cz), the two points falling along the x-roof be called X = (Xx,Xy,Xz) and χ = (χx, χy, χz), and the two points falling along the z-roof be called Z = (Zx,Zy,Zz) and ζ = (ζx, ζy, ζz). First, starting with the x-roof, two vectors can be generated lying in the plane: V V CX =< Xx − Cx,Xy − Cy,Xz − Cz > and Cχ =< χx − Cx, χy − Cy, χz − Cz >. The cross product between these two vectors gives an orthogonal vector that can be used as the shadow plane’s normal: 120

VV < x-roof⊥ > = CX × Cχ (C.2)

ˆ ˆı jˆ k

= X − C X − C X − C x x y y z z

χx − Cx χy − Cy χz − Cz

= ˆı [(Xy − Cy)(χz − Cz) − (χy − Cy)(Xz − Cz)]

−jˆ[(Xx − Cx)(χz − Cz) − (χx − Cx)(Xz − Cz)]

+ˆz [(Xx − Cx)(χy − Cy) − (χx − Cx)(Xy − Cy)]

Both points, X and χ, lie on the x-roof, therefore Xy = χy (since the roof is level) and

Xz = χz (since the roof is straight). As well, the points on the x-roof can take on any

1 real values for Xx and χx but choosing Xx = 0 and χx = 1 helps to simplify the math. The normal vector then reduces into a simplified form:

ˆ < x-roof⊥ >= ˆı (0) + jˆ (Xz − Cz) − k (Xy − Cy) (C.3)

Similarly for the z-roof, Zx = ζx, Zy = ζy and let Zz = 0, ζz = 1, the normal is found by taking the cross product of two vectors lying in the plane: V V CZ =< Zx − Cx,Zy − Cy,Zz − Cz > and Cζ =< ζx − Cx, ζy − Cy, ζz − Cz >

1 Actually, the difference between Xx and χx shows up as a multiplication factor in both the y- and z-components of the normal vector (the x-component cancels to zero), and since a “stretching” factor does not alter the direction of the normal vector it does not matter which values of Xx and χx are chosen. 121

V V < z-roof⊥ > = CZ × Cζ (C.4)

ˆ ˆı jˆ k

= Z − C Z − C Z − C x x y y z z

ζx − Cx ζy − Cy ζz − Cz

= ˆı [(Zy − Cy)(ζz − Cz) − (ζy − Cy)(Zz − Cz)]

−jˆ[(Zx − Cx)(ζz − Cz) − (ζx − Cx)(Zz − Cz)]

+ˆz [(Zx − Cx)(ζy − Cy) − (ζx − Cx)(Zy − Cy)]

Simplifying:

ˆ < z-roof⊥ > = ˆı (Zy − Cy) − jˆ(ZxCx) + k (0)

A normal vector for each plane has been defined; it is only one step further using a position vector to get the full equation for both planes, however, this step is not necessary for finding the intersecting line of the shadow planes and so it will be omitted.

In three dimensional space the equation of a line is given by a point on the line and a vector parallel to it. The vector equation of a line is given by Equation C.5, where

Vr =< x, y, z >, rVo =< xo, yo, zo >, Vv =< vx, vy, vz > (lies on the line) and t is a parameter giving the position of Vr on the line. A point in the line is already known, the shadow corner C = (Cx,Cy,Cz), now the vector parallel to the line is the critical piece of information that presents the altitude and azimuth of the fireball.

Vr = rVo + tVv (C.5)

The vector Vv, parallel to the line of intersection lies in both planes and must therefore be orthogonal to both normal vectors. Taking the cross product of the normal vectors 122

will result in vector Vv (Equation C.6). The cross product of < z-roof ⊥ > with < x­ roof ⊥ > is taken to have the correct orientation, giving a unique vector pointing toward the fireball in the sky.

Vv = < z-roof⊥ > × < x-roof⊥ > (C.6)

ˆ ˆı jˆ k

= Z − C −Z + C 0 y y x x

0 Xz − Cz −Xy + Cy

= ˆı [(Zx − Cx)(−Xy + Cy)]

−jˆ[(−Zy − Cy)(−Xy + Cy)]

+ˆz [(Zy − Cy)(Xz − Cz)]

Again, it takes only one additional step to find the equation of the line but it is not necessary and will be omitted. It is the direction of this vector that gives the bearing and elevation of the fireball. The bearing is an angle measured from the x-axis to the projection of the vector Vv onto the x- and z-planes (Equation C.7). The altitude is related to the length of the vector Vv and its projection onto the y-axis (Equation C.8).

v bearing = tan−1 z + 90◦ (C.7) vx

(Z − C )(X − C ) = tan −1 y y z z + 90◦ (−Zx + Cx)(−Xy + Cy) 123

v elevation = 90◦ − cos− 1 y (C.8) ||v||

(−Z + C )(−X + C ) = 90◦ − cos− 1 y y y y ||v|| where:

2 2 ||v|| = [(−Zx + Cx)(−Xy + Cy)] + [(−Zy + Cy)(−Xy + Cy)]

2 +[(Zy − Cy)(Xz − Cz)]

Figure B.4 shows an offset of an angle φ = 33/ 39// = 0.56083◦ in the direction of the wall from true North. A simple rotation of x and z around y must be done to obtain altitude and azimuth measurements for the fireball (Equation C.9). This transformation must be applied to both the measurements of the shadow positions and the wall geometry.

The azimuth (Equation C.10) and altitude (Equation C.11)2 of the fireball are then found by calculating the bearing and elevation in these newly transformed coordinates (Note that y = y/ since the rotation is taken about the y-axis).

⎤⎡ ⎡ ⎡⎤ ⎤ z / cos φ −sin φ z ⎢ ⎥ ⎢ ⎥ ⎢ ⎥ ⎣ ⎦ = ⎣ ⎦ ⎣ ⎦ (C.9) x/ sin φ cos φ x

z/ = South = z cos φ − x sin φ

x/ = East = z sin φ + x cos φ

2Equations C.8 and C.11 give the same result since the rotation is about the y-axis (no tilting) and the length of the vector is independent of the transformation. 124

v / azimuth = tan−1 z + 90◦ (C.10) vx/

(Z / − C / )(X / − C / ) = tan−1 y y z z + 90◦ (−Zx/ + Cx/ )(−Xy/ + Cy/ )

v / altitude = 90◦ − cos− 1 y (C.11) ||v||

(−Z / + C / )(−X / + C / ) = 90◦ − cos− 1 y y y y ||v|| where:

2 2 ||v|| = [(−Zx/ + Cx/ )(−Xy/ + Cy/ )] + [(−Zy/ + Cy/ )(−Xy/ + Cy/ )]

2 +[(Zy/ − Cy/ )(Xz/ − Cz/ )] 125

Appendix D

MILIG Files

Trajectory: MILIG Input File

The MILIG (Boroviˇcka, 1990) input file used to solve for the Buzzard Coulee atmospheric trajectory is presented in the following. Station 1 points are measured from the Trailside Inn in Lloydminster, station 2 are positions from Tait’s Liquor Store in Lloydminster and station 3 positions are measured from the Lashburn Esso Station (both gas pumps are included).

NOV202008 69.06 1.

1 -109.9984 53.2776 0.64 1.0

341.30 11.43 0 0 0.0000

342.77 13.47 0 0 0.0000

342.76 14.52 0 0 0.0000

344.15 15.45 0 0 0.0000

342.17 15.96 0 0 0.0000

343.27 16.89 0 0 0.0000

344.19 18.15 0 0 0.0000

344.49 18.46 0 0 0.0000

344.08 19.16 0 0 0.0000

344.35 20.44 0 0 0.0000

344.91 21.67 0 0 0.0000

344.19 22.38 0 0 0.0000

345.27 47.57 0 0 0.0000

344.87 49.05 0 0 0.0000

345.08 50.17 0 0 0.0000

344.89 52.24 0 0 0.0000

345.45 53.77 0 0 0.0000 126

345.35 54.70 0 0 0.0000

344.98 56.83 0 0 0.0000

345.26 58.55 0 0 0.0000

345.51 60.09 0 0 0.0000

345.71 61.38 0 0 0.0000

345.64 62.49 9 0 0.0000

2 -110.0061 53.2905 0.62 1.0

343.76 27.29 0 0 0.00

344.12 28.41 0 0 0.00

344.26 29.61 0 0 0.00

344.34 31.33 0 0 0.00

344.53 32.58 0 0 0.00

344.61 33.95 0 0 0.00

344.68 35.12 0 0 0.00

344.67 36.51 0 0 0.00

344.77 37.85 0 0 0.00

344.91 39.91 9 0 0.00

3 -109.6156 53.1239 0.62 1.0

83.76 23.87 0 0 0.0000

81.26 24.97 0 0 0.0000

75.37 28.50 0 0 0.0000

72.69 29.05 0 0 0.0000

69.27 31.58 0 0 0.0000

66.92 33.17 0 0 0.0000

64.43 35.72 0 0 0.0000

61.91 37.92 0 0 0.0000

59.38 40.59 0 0 0.0000

57.25 43.27 0 0 0.0000

55.11 46.64 0 0 0.0000

53.31 49.51 0 0 0.0000

82.54 24.89 0 0 0.0000 127

79.76 25.89 0 0 0.0000

73.38 28.36 0 0 0.0000

72.06 29.91 0 0 0.0000

68.88 31.70 0 0 0.0000

66.72 33.68 0 0 0.0000

63.60 35.91 9 0 0.0000

-1

-109.838 53.15 41.0 -109.858 53.01 13.0 8000.

RFIX 128

Trajectory: MILIG Output File

The following is the MILIG output file giving the atmospheric trajectory for the Buzzard

Coulee fireball on November 20, 2008.

INPUT DATA

FIREBALL NOV20200 TIME 8 UT THETA(GREENWICH) 69.060 DEG

STATIONS

ST SC LAMBDA FI ALTIT. WEIGHT

1 1 -109.998 53.278 .640 1.00

2 2 -110.006 53.291 .620 1.00

3 3 -109.616 53.124 .620 1.00

LINES OF SIGHT

SC NO. TIME AZIM ZEN.DIS XA YA ZA KSI ETA DZETA

1 1 .00 341.30 11.43 2887.46 -2504.58 5089.59 .5980 -.4346 .6734

1 2 .00 342.77 13.47 2887.46 -2504.58 5089.59 .6192 -.4457 .6465

1 3 .00 342.76 14.52 2887.46 -2504.58 5089.59 .6309 -.4489 .6328

1 4 .00 344.15 15.45 2887.46 -2504.58 5089.59 .6382 -.4573 .6193

1 5 .00 342.17 15.96 2887.46 -2504.58 5089.59 .6479 -.4506 .6141

1 6 .00 343.27 16.89 2887.46 -2504.58 5089.59 .6555 -.4579 .6006

1 7 .00 344.19 18.15 2887.46 -2504.58 5089.59 .6663 -.4656 .5824

1 8 .00 344.49 18.46 2887.46 -2504.58 5089.59 .6687 -.4679 .5779

1 9 .00 344.08 19.16 2887.46 -2504.58 5089.59 .6768 -.4679 .5684

1 10 .00 344.35 20.44 2887.46 -2504.58 5089.59 .6886 -.4726 .5500

1 11 .00 344.91 21.67 2887.46 -2504.58 5089.59 .6986 -.4787 .5317

1 12 .00 344.19 22.38 2887.46 -2504.58 5089.59 .7075 -.4763 .5221

1 13 .00 345.27 47.57 2887.46 -2504.58 5089.59 .8600 -.4975 .1140 129

1 14 .00 344.87 49.05 2887.46 -2504.58 5089.59 .8667 -.4908 .0894

1 15 .00 345.08 50.17 2887.46 -2504.58 5089.59 .8682 -.4913 .0697

1 16 .00 344.89 52.24 2887.46 -2504.58 5089.59 .8738 -.4851 .0345

1 17 .00 345.45 53.77 2887.46 -2504.58 5089.59 .8725 -.4886 .0069

1 18 .00 345.35 54.70 2887.46 -2504.58 5089.59 .8744 -.4852 -.0090

1 19 .00 344.98 56.83 2887.46 -2504.58 5089.59 .8788 -.4751 -.0449

1 20 .00 345.26 58.55 2887.46 -2504.58 5089.59 .8774 -.4738 -.0751

1 21 .00 345.51 60.09 2887.46 -2504.58 5089.59 .8755 -.4723 -.1021

1 22 .00 345.71 61.38 2887.46 -2504.58 5089.59 .8734 -.4708 -.1247

1 23 .00 345.64 62.49 2887.46 -2504.58 5089.59 .8730 -.4661 -.1435

2 1 .00 343.76 27.29 2886.24 -2504.21 5090.43 .7518 -.4826 .4493

2 2 .00 344.12 28.41 2886.24 -2504.21 5090.43 .7595 -.4867 .4316

2 3 .00 344.26 29.61 2886.24 -2504.21 5090.43 .7683 -.4892 .4127

2 4 .00 344.34 31.33 2886.24 -2504.21 5090.43 .7808 -.4916 .3855

2 5 .00 344.53 32.58 2886.24 -2504.21 5090.43 .7888 -.4943 .3653

2 6 .00 344.61 33.95 2886.24 -2504.21 5090.43 .7977 -.4959 .3432

2 7 .00 344.68 35.12 2886.24 -2504.21 5090.43 .8049 -.4971 .3241

2 8 .00 344.67 36.51 2886.24 -2504.21 5090.43 .8134 -.4975 .3014

2 9 .00 344.77 37.85 2886.24 -2504.21 5090.43 .8207 -.4986 .2791

2 10 .00 344.91 39.91 2886.24 -2504.21 5090.43 .8309 -.4998 .2446

3 1 .00 83.76 23.87 2914.52 -2494.13 5079.33 .1821 -.6853 .7051

3 2 .00 81.26 24.97 2914.52 -2494.13 5079.33 .1810 -.7041 .6867

3 3 .00 75.37 28.50 2914.52 -2494.13 5079.33 .1737 -.7563 .6307

3 4 .00 72.69 29.05 2914.52 -2494.13 5079.33 .1850 -.7684 .6126

3 5 .00 69.27 31.58 2914.52 -2494.13 5079.33 .1826 -.8009 .5702

3 6 .00 66.92 33.17 2914.52 -2494.13 5079.33 .1847 -.8206 .5409

3 7 .00 64.43 35.72 2914.52 -2494.13 5079.33 .1809 -.8480 .4982

3 8 .00 61.91 37.92 2914.52 -2494.13 5079.33 .1830 -.8702 .4574

3 9 .00 59.38 40.59 2914.52 -2494.13 5079.33 .1836 -.8941 .4086

3 10 .00 57.25 43.27 2914.52 -2494.13 5079.33 .1825 -.9149 .3599

3 11 .00 55.11 46.64 2914.52 -2494.13 5079.33 .1780 -.9373 .2997 130

3 12 .00 53.31 49.51 2914.52 -2494.13 5079.33 .1757 -.9530 .2467

3 13 .00 82.54 24.89 2914.52 -2494.13 5079.33 .1755 -.6994 .6928

3 14 .00 79.76 25.89 2914.52 -2494.13 5079.33 .1780 -.7178 .6731

3 15 .00 73.38 28.36 2914.52 -2494.13 5079.33 .1878 -.7598 .6224

3 16 .00 72.06 29.91 2914.52 -2494.13 5079.33 .1801 -.7785 .6012

3 17 .00 68.88 31.70 2914.52 -2494.13 5079.33 .1843 -.8029 .5670

3 18 .00 66.72 33.68 2914.52 -2494.13 5079.33 .1814 -.8257 .5341

3 19 .00 63.60 35.91 2914.52 -2494.13 5079.33 .1862 -.8508 .4914

AVERAGE TRAJECTORY SOLUTION BY THE METHOD OF LEAST SQUARES

WEIGHTS OF STATIONS:

1 2 3

1.0000 1.0000 1.0000

FIRST APPROXIMATION

BEGINNING: 2921.478 -2519.795 5113.304

END: 2917.280 -2517.951 5081.574

RADIANT: .13094 -.05752 .98972

ALF=336.283 DEL= 81.778

FOR THE END POINT: AZIMUTH= 184.937 ZNT. DISTANCE= 29.217

FOR THE FIRST APPROXIMATION:

DEVIATIONS OF LINES OF SIGHT FROM THE METEOR STRAIGHT TRAJECTORY

L VERTICAL HORIZONTAL TOTAL

SC V WEIGHT H WEIGHT D WEIGHT

1 1 -10.417 .967 .15 -7.963 1.24 8.021 1.96 131

2 1 -7.755 .996 .17 -7.706 1.35 7.770 2.04

3 1 -6.545 1.020 .19 -7.455 1.40 7.525 2.08

4 1 -5.320 1.012 .19 -7.545 1.45 7.613 2.12

5 1 -5.026 1.056 .22 -6.999 1.46 7.078 2.12

6 1 -3.879 1.053 .23 -7.046 1.51 7.124 2.16

7 1 -2.447 1.055 .24 -7.012 1.58 7.091 2.21

8 1 -2.093 1.054 .24 -7.027 1.60 7.106 2.22

9 1 -1.444 1.067 .26 -6.793 1.63 6.877 2.24

10 1 -.158 1.075 .27 -6.630 1.69 6.717 2.29

11 1 1.075 1.077 .29 -6.570 1.75 6.658 2.33

12 1 1.639 1.086 .31 -6.250 1.78 6.344 2.34

13 1 20.053 .901 .71 -3.436 2.72 3.552 2.90

14 1 20.915 .848 .75 -3.111 2.74 3.225 2.92

15 1 21.606 .845 .76 -3.092 2.76 3.205 2.93

16 1 22.819 .792 .79 -2.801 2.79 2.911 2.95

17 1 23.768 .813 .79 -2.910 2.82 3.021 2.96

18 1 24.303 .787 .80 -2.775 2.83 2.884 2.97

19 1 25.511 .710 .84 -2.397 2.84 2.500 2.98

20 1 26.529 .704 .85 -2.368 2.86 2.470 2.99

21 1 27.438 .699 .85 -2.346 2.86 2.448 2.99

22 1 28.197 .694 .86 -2.326 2.87 2.427 2.99

23 1 28.830 .664 .87 -2.189 2.86 2.288 2.99

24 2 4.245 1.153 .39 -5.708 1.92 5.823 2.39

25 2 5.232 1.151 .40 -5.655 1.97 5.771 2.42

26 2 6.234 1.146 .42 -5.525 2.02 5.642 2.45

27 2 7.616 1.136 .45 -5.306 2.09 5.426 2.49

28 2 8.609 1.130 .47 -5.202 2.15 5.324 2.52

29 2 9.658 1.120 .49 -5.049 2.20 5.171 2.56

30 2 10.534 1.110 .51 -4.923 2.24 5.047 2.58

31 2 11.545 1.096 .53 -4.742 2.29 4.867 2.61

32 2 12.512 1.084 .55 -4.616 2.34 4.742 2.64 132

33 2 13.961 1.065 .58 -4.426 2.41 4.552 2.68

34 3 8.154 .483 1.08 .629 1.41 .793 2.73

35 3 9.593 .454 1.15 .590 1.49 .745 2.82

36 3 13.347 .313 1.36 .397 1.73 .506 3.05

37 3 14.314 .536 1.39 .704 1.83 .885 3.11

38 3 16.534 .506 1.53 .662 2.00 .833 3.26

39 3 17.898 .557 1.61 .734 2.12 .922 3.35

40 3 19.734 .517 1.74 .677 2.28 .852 3.47

41 3 21.307 .581 1.84 .769 2.43 .964 3.58

42 3 23.035 .629 1.95 .838 2.59 1.047 3.70

43 3 24.623 .655 2.05 .877 2.74 1.095 3.80

44 3 26.451 .650 2.17 .868 2.90 1.085 3.91

45 3 27.944 .675 2.26 .906 3.03 1.130 3.99

46 3 9.175 .336 1.14 .428 1.46 .544 2.79

47 3 10.596 .389 1.21 .501 1.55 .634 2.87

48 3 13.742 .589 1.35 .779 1.79 .977 3.07

49 3 14.964 .447 1.44 .580 1.87 .733 3.15

50 3 16.684 .537 1.53 .706 2.02 .887 3.27

51 3 18.214 .503 1.64 .657 2.14 .828 3.37

52 3 19.986 .610 1.74 .810 2.31 1.014 3.49

SUM OF SQUARED RESIDUALS: 997.37436

ITERATIONS:

0 1.000 -.43933 7.55876 -2519.79536 5113.30364 .9973744D+03

-1.60149 .31184 -8.53708 -11.93939

1 1.000 -2.04081 7.87060 -2528.33244 5101.36425 .2577699D+03

.30089 -.35192 3.19630 -1.24455

2 1.000 -1.73992 7.51867 -2525.13614 5100.11970 .1026092D+01

.00654 -.06882 -.01623 -.14815

3 1.000 -1.73338 7.44986 -2525.15237 5099.97154 .9735135D+00 133

-.00008 .00087 -.00019 .00169

4 1.000 -1.73345 7.45072 -2525.15255 5099.97323 .9735116D+00

.00000 .00000 .00000 .00000

5 1.000 -1.73345 7.45072 -2525.15255 5099.97323 .9735116D+00

.04102 .24994 .05013 .27761

.35757D-02 .86636D-02

RESULTS

METEOR POINT: 2921.478 -2525.153 5099.973

.051 .013 .006

RADIANT: .12962 -.22469 .96577 ALF=299.980 DEL= 74.966

.587 .258

DEVIATIONS OF LINES OF SIGHT FROM THE METEOR STRAIGHT TRAJECTORY

L VERTICAL HORIZONTAL TOTAL

SC V WEIGHT H WEIGHT D WEIGHT

1 1 -34.187 -.010 .03 .251 .87 .252 1.55

2 1 -30.290 -.002 .03 .047 .97 .047 1.63

3 1 -28.445 -.004 .04 .109 1.02 .109 1.67

4 1 -26.855 .006 .03 -.219 1.06 .219 1.71

5 1 -26.065 -.015 .05 .349 1.08 .349 1.72

6 1 -24.575 -.003 .04 .085 1.13 .085 1.76

7 1 -22.660 .004 .03 -.137 1.19 .137 1.81

8 1 -22.202 .006 .03 -.218 1.20 .218 1.82

9 1 -21.207 .002 .04 -.071 1.23 .071 1.84

10 1 -19.439 .003 .04 -.117 1.30 .117 1.89

11 1 -17.813 .007 .03 -.270 1.36 .270 1.93

12 1 -16.921 .000 .04 -.010 1.39 .010 1.95

13 1 6.191 .001 .08 -.034 2.44 .034 2.59 134

14 1 7.235 -.007 .09 .184 2.48 .184 2.61

15 1 8.019 -.003 .09 .090 2.51 .090 2.63

16 1 9.438 -.008 .10 .212 2.57 .212 2.66

17 1 10.476 .002 .08 -.065 2.60 .065 2.67

18 1 11.096 .000 .08 -.003 2.62 .003 2.68

19 1 12.500 -.008 .10 .217 2.66 .217 2.70

20 1 13.625 -.003 .09 .082 2.69 .082 2.72

21 1 14.623 .001 .08 -.042 2.71 .042 2.73

22 1 15.454 .004 .08 -.143 2.72 .143 2.73

23 1 16.165 .003 .08 -.095 2.73 .095 2.74

24 2 -12.989 -.006 .06 .141 1.56 .141 2.03

25 2 -11.752 -.001 .06 .027 1.61 .027 2.07

26 2 -10.474 .000 .06 -.001 1.67 .001 2.10

27 2 -8.712 .000 .06 .003 1.74 .003 2.15

28 2 -7.477 .002 .06 -.053 1.80 .053 2.18

29 2 -6.168 .002 .06 -.062 1.85 .062 2.22

30 2 -5.081 .002 .06 -.072 1.90 .072 2.24

31 2 -3.827 .002 .07 -.044 1.96 .044 2.28

32 2 -2.650 .002 .07 -.068 2.01 .068 2.31

33 2 -.899 .003 .07 -.103 2.09 .103 2.35

34 3 -15.318 .166 .79 .134 .64 .213 1.99

35 3 -12.857 .074 .87 .059 .69 .095 2.08

36 3 -6.713 -.274 1.10 -.211 .85 .346 2.32

37 3 -5.183 .092 1.15 .074 .92 .118 2.39

38 3 -1.785 -.016 1.31 -.013 1.04 .021 2.55

39 3 .246 .037 1.42 .030 1.13 .048 2.65

40 3 2.904 -.077 1.58 -.061 1.24 .098 2.79

41 3 5.124 -.006 1.71 -.005 1.36 .008 2.91

42 3 7.496 .032 1.87 .025 1.49 .041 3.05

43 3 9.622 .039 2.03 .031 1.61 .049 3.17

44 3 12.004 -.014 2.21 -.011 1.75 .018 3.31 135

45 3 13.901 -.007 2.36 -.006 1.87 .009 3.42

46 3 -13.575 -.128 .85 -.101 .67 .163 2.05

47 3 -11.179 -.069 .93 -.055 .73 .088 2.14

48 3 -6.077 .201 1.10 .163 .89 .258 2.35

49 3 -4.178 -.079 1.20 -.062 .94 .100 2.43

50 3 -1.558 .034 1.32 .027 1.05 .043 2.56

51 3 .708 -.064 1.45 -.050 1.14 .081 2.67

52 3 3.266 .075 1.59 .060 1.27 .096 2.81

SUM OF SQUARED RESIDUALS: .97351

BEGINNING POINT:

X = 2925.909 Y = -2532.834 Z = 5132.990

.169 .045 .020

GEOGRAPHIC LAM = 250.05867 FI = 53.16929 H = 63.877 KM

.00171 .00100 .081

END POINT:

X = 2919.383 Y = -2521.521 Z = 5084.362

.105 .027 .013

GEOGRAPHIC LAM = 250.12227 FI = 52.99657 H = 17.588 KM

.00106 .00062 .050

Note: LAMBDA approximate (valid for TIME=0)

FOR THE END POINT: AZIMUTH= 167.525 ZNT. DISTANCE= 23.263

.468 .236

AVERAGE TRAJECTORY SOLUTION

Note: LAMBDA is based on the given TIME

I SC TIME LENGTH RANGE HEIGHT VELOCITY LAMBDA FI TAU

1 1 .0000 .0000 64.4997 63.8767 .0000 250.0587 53.1693 34.36 136

2 1 .0000 3.8969 61.3222 60.2921 999.0000 250.0636 53.1560 36.41

3 1 .0000 5.7417 59.8476 58.5952 999.0000 250.0659 53.1497 37.46

4 1 .0000 7.3311 58.5940 57.1333 999.0000 250.0679 53.1443 38.41

5 1 .0000 8.1212 57.9769 56.4066 999.0000 250.0689 53.1416 38.89

6 1 .0000 9.6113 56.8248 55.0362 999.0000 250.0708 53.1365 39.84

7 1 .0000 11.5269 55.3675 53.2745 999.0000 250.0732 53.1300 41.11

8 1 .0000 11.9843 55.0236 52.8538 999.0000 250.0738 53.1284 41.42

9 1 .0000 12.9794 54.2814 51.9387 999.0000 250.0750 53.1250 42.11

10 1 .0000 14.7476 52.9830 50.3127 999.0000 250.0773 53.1190 43.40

11 1 .0000 16.3740 51.8133 48.8171 999.0000 250.0793 53.1134 44.63

12 1 .0000 17.2658 51.1826 47.9971 999.0000 250.0804 53.1103 45.33

13 1 .0000 40.3771 38.6095 26.7525 999.0000 250.1096 53.0310 70.53

14 1 .0000 41.4220 38.2739 25.7924 999.0000 250.1110 53.0274 72.01

15 1 .0000 42.2055 38.0392 25.0724 999.0000 250.1120 53.0247 73.13

16 1 .0000 43.6248 37.6517 23.7682 999.0000 250.1138 53.0198 75.20

17 1 .0000 44.6622 37.4001 22.8150 999.0000 250.1151 53.0162 76.73

18 1 .0000 45.2828 37.2626 22.2448 999.0000 250.1159 53.0141 77.66

19 1 .0000 46.6868 36.9880 20.9548 999.0000 250.1176 53.0092 79.79

20 1 .0000 47.8115 36.8052 19.9214 999.0000 250.1191 53.0053 81.51

21 1 .0000 48.8098 36.6711 19.0042 999.0000 250.1203 53.0019 83.05

22 1 .0000 49.6408 36.5798 18.2408 999.0000 250.1214 52.9990 84.34

23 1 .0000 50.3511 36.5167 17.5882 999.0000 250.1223 52.9966 85.45

24 2 .0000 21.1980 49.1954 44.3816 999.0000 250.0854 53.0969 50.22

25 2 .0000 22.4342 48.4138 43.2450 999.0000 250.0870 53.0926 51.35

26 2 .0000 23.7129 47.6256 42.0694 999.0000 250.0886 53.0883 52.55

27 2 .0000 25.4744 46.5755 40.4501 999.0000 250.0908 53.0822 54.27

28 2 .0000 26.7091 45.8654 39.3150 999.0000 250.0924 53.0780 55.52

29 2 .0000 28.0188 45.1368 38.1110 999.0000 250.0940 53.0735 56.89

30 2 .0000 29.1055 44.5526 37.1122 999.0000 250.0954 53.0698 58.06

31 2 .0000 30.3599 43.9019 35.9590 999.0000 250.0970 53.0654 59.45

32 2 .0000 31.5370 43.3154 34.8771 999.0000 250.0985 53.0614 60.79 137

33 2 .0000 33.2880 42.4885 33.2677 999.0000 250.1007 53.0554 62.85

34 3 .0000 18.8683 50.2337 46.5237 999.0000 250.0825 53.1049 30.84

35 3 .0000 21.3296 48.1370 44.2606 999.0000 250.0856 53.0964 32.35

36 3 .0000 27.4738 43.0719 38.6120 999.0000 250.0933 53.0754 36.72

37 3 .0000 29.0036 41.8557 37.2058 999.0000 250.0953 53.0701 37.98

38 3 .0000 32.4019 39.2327 34.0821 999.0000 250.0996 53.0584 41.03

39 3 .0000 34.4324 37.7245 32.2159 999.0000 250.1021 53.0515 43.06

40 3 .0000 37.0910 35.8279 29.7724 999.0000 250.1055 53.0423 45.96

41 3 .0000 39.3101 34.3224 27.7331 999.0000 250.1083 53.0347 48.62

42 3 .0000 41.6829 32.8023 25.5526 999.0000 250.1113 53.0265 51.74

43 3 .0000 43.8085 31.5302 23.5994 999.0000 250.1140 53.0192 54.77

44 3 .0000 46.1902 30.2190 21.4111 999.0000 250.1170 53.0109 58.46

45 3 .0000 48.0875 29.2712 19.6679 999.0000 250.1194 53.0044 61.63

46 3 .0000 20.6113 48.7453 44.9210 999.0000 250.0847 53.0989 31.89

47 3 .0000 23.0077 46.7279 42.7178 999.0000 250.0877 53.0907 33.45

48 3 .0000 28.1097 42.5638 38.0275 999.0000 250.0941 53.0732 37.24

49 3 .0000 30.0084 41.0683 36.2821 999.0000 250.0965 53.0667 38.84

50 3 .0000 32.6282 39.0623 33.8742 999.0000 250.0998 53.0577 41.25

51 3 .0000 34.8944 37.3883 31.7913 999.0000 250.1027 53.0499 43.54

52 3 .0000 37.4528 35.5774 29.4399 999.0000 250.1059 53.0411 46.38

WARNING: NO TIME DATA - EARTH ROTATION CANNOT BE TAKEN INTO ACCOUNT! 138

Velocity: MILIG Output File

MILIG output solution used to determine an initial velocity of 18.0 km/s by Dr. Peter

Brown at the University of Western Ontario. The input includes positions measured

from the Trailside Inn, Tait’s Liquor Store, the Lashburn Esso, as well as, positions and

timing information from Gordon Sarty’s all-sky camera.

INPUT DATA

FIREBALL 20081121 TIME -002643 UT THETA(GREENWICH) 66.820 DEG

STATIONS

ST SC LAMBDA FI ALTIT. WEIGHT

1 4 -106.634 52.132 .520 81.00

2 1 -109.998 53.278 .640 1.00

3 3 -109.616 53.124 .620 1.00

4 2 -110.006 53.291 .620 1.00

LINES OF SIGHT

SC NO. TIME AZIM ZEN.DIS XA YA ZA KSI ETA DZETA

4 1 .00 120.02 73.81 3013.94 -2512.34 5012.22 -.6923 -.5054 .5150

4 2 .03 119.97 73.92 3013.95 -2512.33 5012.22 -.6934 -.5057 .5133

4 3 .07 119.92 74.02 3013.95 -2512.33 5012.22 -.6945 -.5059 .5117

4 4 .10 119.87 74.18 3013.96 -2512.32 5012.22 -.6962 -.5058 .5093

4 5 .13 119.83 74.27 3013.96 -2512.31 5012.22 -.6972 -.5059 .5079

4 6 .17 119.79 74.35 3013.97 -2512.30 5012.22 -.6980 -.5061 .5067

4 7 .20 119.77 74.45 3013.98 -2512.30 5012.22 -.6991 -.5059 .5053

4 8 .23 119.71 74.61 3013.98 -2512.29 5012.22 -.7008 -.5060 .5028

4 9 .27 119.67 74.68 3013.99 -2512.28 5012.22 -.7015 -.5062 .5017 139

4 10 .30 119.63 74.79 3013.99 -2512.27 5012.22 -.7026 -.5063 .5000

4 11 .33 119.60 74.83 3014.00 -2512.27 5012.22 -.7030 -.5066 .4992

4 12 .37 119.55 75.00 3014.01 -2512.26 5012.22 -.7048 -.5064 .4968

4 13 .40 119.51 75.07 3014.01 -2512.25 5012.22 -.7055 -.5066 .4956

4 14 .43 119.47 75.17 3014.02 -2512.25 5012.22 -.7065 -.5068 .4939

4 15 .47 119.44 75.24 3014.02 -2512.24 5012.22 -.7073 -.5068 .4929

4 16 .50 119.41 75.33 3014.03 -2512.23 5012.22 -.7082 -.5068 .4915

4 17 .53 119.34 75.49 3014.04 -2512.22 5012.22 -.7099 -.5069 .4890

4 18 .57 119.32 75.53 3014.04 -2512.22 5012.22 -.7102 -.5071 .4883

4 19 .60 119.28 75.67 3014.05 -2512.21 5012.22 -.7117 -.5070 .4862

4 20 .63 119.23 75.73 3014.06 -2512.20 5012.22 -.7122 -.5074 .4850

4 21 .67 119.18 75.81 3014.06 -2512.19 5012.22 -.7130 -.5076 .4837

1 1 .00 341.30 11.43 2787.33 -2615.50 5089.62 .5806 -.4577 .6734

1 2 .00 342.77 13.47 2787.33 -2615.50 5089.62 .6013 -.4696 .6465

1 3 .00 342.76 14.52 2787.33 -2615.50 5089.62 .6129 -.4732 .6328

1 4 .00 344.15 15.45 2787.33 -2615.50 5089.62 .6199 -.4819 .6193

1 5 .00 342.17 15.96 2787.33 -2615.50 5089.62 .6298 -.4756 .6141

1 6 .00 343.27 16.89 2787.33 -2615.50 5089.62 .6371 -.4831 .6006

1 7 .00 344.19 18.15 2787.33 -2615.50 5089.62 .6476 -.4913 .5825

1 8 .00 344.49 18.46 2787.33 -2615.50 5089.62 .6499 -.4937 .5779

1 9 .00 344.08 19.16 2787.33 -2615.50 5089.62 .6580 -.4939 .5684

1 10 .00 344.35 20.44 2787.33 -2615.50 5089.62 .6696 -.4991 .5500

1 11 .00 344.91 21.67 2787.33 -2615.50 5089.62 .6794 -.5057 .5317

1 12 .00 344.19 22.38 2787.33 -2615.50 5089.62 .6883 -.5036 .5221

1 13 .00 345.27 47.57 2787.33 -2615.50 5089.62 .8399 -.5307 .1140

1 14 .00 344.87 49.05 2787.33 -2615.50 5089.62 .8468 -.5243 .0894

1 15 .00 345.08 50.17 2787.33 -2615.50 5089.62 .8483 -.5249 .0697

1 16 .00 344.89 52.24 2787.33 -2615.50 5089.62 .8541 -.5189 .0345

1 17 .00 345.45 53.77 2787.33 -2615.50 5089.62 .8527 -.5223 .0069

1 18 .00 345.35 54.70 2787.33 -2615.50 5089.62 .8547 -.5190 -.0090

1 19 .00 344.98 56.83 2787.33 -2615.50 5089.62 .8595 -.5091 -.0449 140

1 20 .00 345.26 58.55 2787.33 -2615.50 5089.62 .8583 -.5077 -.0751

1 21 .00 345.51 60.09 2787.33 -2615.50 5089.62 .8564 -.5062 -.1021

1 22 .00 345.71 61.38 2787.33 -2615.50 5089.62 .8543 -.5045 -.1247

1 23 .00 345.64 62.49 2787.33 -2615.50 5089.62 .8541 -.4998 -.1435

3 1 .00 83.76 23.87 2814.81 -2606.14 5079.33 .1552 -.6919 .7051

3 2 .00 81.26 24.97 2814.81 -2606.14 5079.33 .1534 -.7106 .6867

3 3 .00 75.37 28.50 2814.81 -2606.14 5079.33 .1440 -.7626 .6307

3 4 .00 72.69 29.05 2814.81 -2606.14 5079.33 .1548 -.7751 .6126

3 5 .00 69.27 31.58 2814.81 -2606.14 5079.33 .1512 -.8074 .5702

3 6 .00 66.92 33.17 2814.81 -2606.14 5079.33 .1525 -.8272 .5409

3 7 .00 64.43 35.72 2814.81 -2606.14 5079.33 .1476 -.8544 .4982

3 8 .00 61.91 37.92 2814.81 -2606.14 5079.33 .1489 -.8767 .4574

3 9 .00 59.38 40.59 2814.81 -2606.14 5079.33 .1485 -.9006 .4086

3 10 .00 57.25 43.27 2814.81 -2606.14 5079.33 .1466 -.9214 .3599

3 11 .00 55.11 46.64 2814.81 -2606.14 5079.33 .1413 -.9435 .2997

3 12 .00 53.31 49.51 2814.81 -2606.14 5079.33 .1383 -.9592 .2467

3 13 .00 82.54 24.89 2814.81 -2606.14 5079.33 .1480 -.7057 .6928

3 14 .00 79.76 25.89 2814.81 -2606.14 5079.33 .1498 -.7243 .6731

3 15 .00 73.38 28.36 2814.81 -2606.14 5079.33 .1580 -.7666 .6224

3 16 .00 72.06 29.91 2814.81 -2606.14 5079.33 .1495 -.7850 .6012

3 17 .00 68.88 31.70 2814.81 -2606.14 5079.33 .1528 -.8094 .5670

3 18 .00 66.72 33.68 2814.81 -2606.14 5079.33 .1490 -.8322 .5341

3 19 .00 63.60 35.91 2814.81 -2606.14 5079.33 .1528 -.8574 .4914

2 1 .00 343.76 27.29 2786.16 -2615.10 5090.43 .7324 -.5116 .4493

2 2 .00 344.12 28.41 2786.16 -2615.10 5090.43 .7399 -.5160 .4316

2 3 .00 344.26 29.61 2786.16 -2615.10 5090.43 .7486 -.5189 .4127

2 4 .00 344.34 31.33 2786.16 -2615.10 5090.43 .7610 -.5218 .3855

2 5 .00 344.53 32.58 2786.16 -2615.10 5090.43 .7689 -.5247 .3653

2 6 .00 344.61 33.95 2786.16 -2615.10 5090.43 .7777 -.5267 .3432

2 7 .00 344.68 35.12 2786.16 -2615.10 5090.43 .7848 -.5282 .3241

2 8 .00 344.67 36.51 2786.16 -2615.10 5090.43 .7934 -.5289 .3014 141

2 9 .00 344.77 37.85 2786.16 -2615.10 5090.43 .8005 -.5303 .2791

2 10 .00 344.91 39.91 2786.16 -2615.10 5090.43 .8107 -.5319 .2446

AVERAGE TRAJECTORY SOLUTION BY THE METHOD OF LEAST SQUARES

WEIGHTS OF STATIONS:

4 1 3 2

81.0000 1.0000 1.0000 1.0000

FIRST APPROXIMATION

BEGINNING: 2824.717 -2644.972 5132.980

END: 2819.448 -2634.296 5084.220

RADIANT: .10497 -.21270 .97146

ALF=296.268 DEL= 76.279

FOR THE END POINT: AZIMUTH= 168.389 ZNT. DISTANCE= 24.589

FOR THE FIRST APPROXIMATION:

DEVIATIONS OF LINES OF SIGHT FROM THE METEOR STRAIGHT TRAJECTORY

L VERTICAL HORIZONTAL TOTAL

SC V WEIGHT H WEIGHT D WEIGHT

1 4 -19.070 .000 .27 .000 .15 .000 .37

2 4 -18.393 .031 .27 -.017 .15 .035 .37

3 4 -17.790 .041 .27 -.023 .15 .047 .37

4 4 -16.871 -.028 .27 .015 .15 .032 .37

5 4 -16.338 -.031 .28 .017 .15 .035 .37

6 4 -15.860 -.022 .28 .012 .15 .025 .37

7 4 -15.306 -.092 .28 .051 .15 .105 .37 142

8 4 -14.378 -.126 .28 .071 .16 .144 .37

9 4 -13.950 -.094 .28 .053 .16 .108 .37

10 4 -13.315 -.116 .28 .065 .16 .133 .37

11 4 -13.048 -.053 .28 .030 .16 .061 .37

12 4 -12.106 -.152 .28 .085 .16 .175 .37

13 4 -11.681 -.120 .28 .067 .16 .138 .38

14 4 -11.090 -.105 .28 .059 .16 .120 .38

15 4 -10.698 -.131 .28 .073 .16 .150 .38

16 4 -10.189 -.154 .28 .086 .16 .177 .38

17 4 -9.263 -.157 .28 .088 .16 .180 .38

18 4 -9.023 -.137 .28 .077 .16 .157 .38

19 4 -8.249 -.200 .28 .112 .16 .229 .38

20 4 -7.853 -.101 .28 .057 .16 .116 .38

21 4 -7.373 -.062 .29 .035 .16 .071 .38

22 1 .000 .000 .04 .000 .90 .000 1.55

23 1 3.780 .007 .04 -.177 1.00 .177 1.63

24 1 5.572 .004 .04 -.103 1.04 .103 1.67

25 1 7.127 .013 .03 -.422 1.09 .422 1.70

26 1 7.885 -.007 .05 .154 1.11 .154 1.72

27 1 9.346 .004 .05 -.100 1.15 .100 1.75

28 1 11.226 .011 .04 -.311 1.21 .311 1.80

29 1 11.676 .013 .04 -.389 1.23 .390 1.81

30 1 12.649 .009 .05 -.234 1.26 .234 1.83

31 1 14.387 .010 .05 -.269 1.32 .269 1.87

32 1 15.991 .013 .04 -.412 1.37 .412 1.91

33 1 16.867 .006 .05 -.144 1.41 .144 1.94

34 1 40.001 .000 .10 -.008 2.40 .008 2.53

35 1 41.061 -.011 .12 .222 2.44 .222 2.55

36 1 41.859 -.006 .11 .132 2.47 .132 2.57

37 1 43.303 -.013 .12 .267 2.52 .267 2.59

38 1 44.364 .000 .11 -.009 2.55 .009 2.61 143

39 1 44.997 -.003 .11 .058 2.56 .058 2.61

40 1 46.431 -.015 .13 .294 2.60 .294 2.63

41 1 47.584 -.008 .12 .164 2.62 .164 2.64

42 1 48.608 -.002 .12 .044 2.64 .044 2.65

43 1 49.462 .002 .11 -.054 2.65 .054 2.66

44 1 50.192 .000 .11 .000 2.65 .000 2.66

45 3 18.630 -.099 .79 -.086 .69 .131 1.98

46 3 21.025 -.215 .86 -.184 .74 .283 2.07

47 3 27.042 -.627 1.09 -.517 .90 .813 2.30

48 3 28.557 -.278 1.13 -.237 .97 .365 2.36

49 3 31.919 -.423 1.29 -.356 1.09 .553 2.51

50 3 33.937 -.391 1.39 -.330 1.17 .512 2.61

51 3 36.587 -.536 1.54 -.446 1.28 .698 2.74

52 3 38.808 -.489 1.67 -.409 1.40 .637 2.86

53 3 41.190 -.477 1.83 -.399 1.53 .621 2.99

54 3 43.332 -.493 1.97 -.412 1.65 .643 3.10

55 3 45.738 -.574 2.15 -.476 1.78 .746 3.23

56 3 47.662 -.588 2.28 -.487 1.89 .764 3.33

57 3 20.317 -.407 .85 -.343 .72 .532 2.04

58 3 22.661 -.374 .92 -.316 .78 .490 2.13

59 3 27.678 -.160 1.09 -.138 .94 .211 2.32

60 3 29.547 -.460 1.18 -.385 .99 .600 2.41

61 3 32.144 -.375 1.30 -.317 1.10 .491 2.52

62 3 34.396 -.499 1.42 -.416 1.19 .649 2.63

63 3 36.950 -.386 1.56 -.326 1.31 .506 2.76

64 2 20.824 -.002 .07 .033 1.57 .033 2.01

65 2 22.052 .003 .07 -.073 1.62 .073 2.04

66 2 23.323 .004 .07 -.093 1.67 .093 2.08

67 2 25.076 .003 .08 -.076 1.75 .076 2.12

68 2 26.308 .005 .08 -.124 1.80 .124 2.15

69 2 27.615 .005 .08 -.124 1.86 .124 2.19 144

70 2 28.702 .006 .08 -.127 1.90 .127 2.21

71 2 29.958 .004 .09 -.090 1.96 .090 2.24

72 2 31.138 .005 .09 -.106 2.01 .106 2.27

73 2 32.898 .006 .09 -.129 2.08 .129 2.31

SUM OF SQUARED RESIDUALS: 32.99227

ITERATIONS:

0 1.000 -2.02621 9.25438 -2644.97215 5132.97984 .3299227D+02

.02018 -.60788 -.88089 4.33512

1 1.000 -2.00603 8.64650 -2645.85304 5137.31496 .9149251D+01

-.00531 .05482 -.00686 -.20265

2 1.000 -2.01134 8.70131 -2645.85990 5137.11231 .5156969D+01

.00026 -.00080 .00113 -.00459

3 1.000 -2.01109 8.70051 -2645.85876 5137.10772 .5156930D+01

.00000 .00000 .00000 .00000

4 1.000 -2.01109 8.70051 -2645.85876 5137.10773 .5156930D+01

.06638 .23554 .26815 .92887

.32040D-02 .14416D-01

RESULTS

METEOR POINT: 2824.717 -2645.859 5137.108

.108 .053 .002

RADIANT: .11129 -.22381 .96826 ALF=296.439 DEL= 75.525

.754 .077

DEVIATIONS OF LINES OF SIGHT FROM THE METEOR STRAIGHT TRAJECTORY

L VERTICAL HORIZONTAL TOTAL

SC V WEIGHT H WEIGHT D WEIGHT 145

1 4 -15.114 .015 .27 -.009 .16 .017 .37

2 4 -14.437 .053 .27 -.031 .16 .062 .37

3 4 -13.833 .070 .27 -.041 .16 .081 .37

4 4 -12.912 .013 .27 -.007 .16 .015 .37

5 4 -12.379 .015 .27 -.009 .16 .018 .37

6 4 -11.900 .029 .27 -.017 .16 .034 .37

7 4 -11.344 -.033 .27 .020 .16 .038 .37

8 4 -10.414 -.056 .27 .033 .16 .066 .37

9 4 -9.986 -.020 .27 .012 .16 .023 .37

10 4 -9.350 -.035 .27 .021 .16 .041 .37

11 4 -9.084 .031 .28 -.018 .16 .036 .37

12 4 -8.138 -.057 .28 .033 .16 .066 .37

13 4 -7.713 -.020 .28 .012 .16 .023 .37

14 4 -7.122 .002 .28 -.001 .16 .002 .37

15 4 -6.729 -.019 .28 .011 .16 .022 .38

16 4 -6.219 -.037 .28 .022 .16 .043 .38

17 4 -5.292 -.029 .28 .017 .16 .034 .38

18 4 -5.052 -.006 .28 .004 .16 .007 .38

19 4 -4.276 -.060 .28 .035 .17 .069 .38

20 4 -3.880 .042 .28 -.025 .17 .049 .38

21 4 -3.401 .087 .28 -.051 .17 .101 .38

22 1 4.819 -.007 .03 .184 .90 .184 1.57

23 1 8.606 .001 .03 -.015 .99 .015 1.65

24 1 10.402 -.002 .04 .046 1.04 .046 1.69

25 1 11.952 .007 .03 -.278 1.09 .278 1.73

26 1 12.720 -.012 .05 .284 1.11 .285 1.74

27 1 14.175 -.001 .04 .024 1.15 .024 1.78

28 1 16.047 .005 .03 -.195 1.21 .195 1.82

29 1 16.494 .007 .03 -.276 1.23 .276 1.84

30 1 17.467 .004 .04 -.129 1.26 .129 1.86

31 1 19.198 .005 .04 -.175 1.32 .175 1.90 146

32 1 20.792 .008 .03 -.326 1.38 .326 1.95

33 1 21.666 .002 .04 -.067 1.42 .067 1.97

34 1 44.497 .003 .08 -.083 2.45 .083 2.59

35 1 45.537 -.005 .09 .134 2.49 .134 2.61

36 1 46.317 -.001 .09 .041 2.52 .042 2.63

37 1 47.731 -.006 .10 .164 2.57 .164 2.66

38 1 48.766 .003 .08 -.113 2.61 .113 2.67

39 1 49.385 .002 .08 -.051 2.63 .051 2.68

40 1 50.787 -.006 .10 .170 2.66 .170 2.70

41 1 51.911 -.001 .09 .036 2.69 .036 2.71

42 1 52.909 .003 .08 -.088 2.71 .088 2.72

43 1 53.740 .005 .08 -.189 2.72 .189 2.73

44 1 54.451 .004 .08 -.141 2.73 .141 2.73

45 3 23.399 .323 .80 .269 .67 .421 2.01

46 3 25.804 .218 .88 .179 .72 .282 2.10

47 3 31.822 -.164 1.11 -.130 .88 .209 2.34

48 3 33.341 .185 1.16 .151 .95 .239 2.41

49 3 36.686 .055 1.32 .045 1.07 .071 2.56

50 3 38.691 .094 1.42 .076 1.16 .121 2.66

51 3 41.315 -.037 1.58 -.029 1.27 .047 2.80

52 3 43.512 .018 1.72 .014 1.39 .023 2.92

53 3 45.864 .039 1.88 .032 1.52 .051 3.06

54 3 47.973 .031 2.03 .025 1.64 .040 3.18

55 3 50.337 -.037 2.21 -.030 1.77 .048 3.32

56 3 52.224 -.044 2.36 -.035 1.89 .056 3.42

57 3 25.089 .026 .86 .021 .69 .033 2.07

58 3 27.442 .067 .93 .054 .76 .086 2.16

59 3 32.466 .297 1.11 .246 .92 .386 2.37

60 3 34.324 .010 1.21 .008 .97 .013 2.45

61 3 36.910 .103 1.33 .084 1.08 .133 2.57

62 3 39.144 -.009 1.45 -.007 1.17 .011 2.69 147

63 3 41.676 .111 1.60 .090 1.30 .142 2.82

64 2 25.566 -.003 .06 .078 1.59 .078 2.05

65 2 26.782 .001 .06 -.034 1.64 .034 2.08

66 2 28.041 .002 .06 -.062 1.69 .062 2.11

67 2 29.775 .002 .06 -.057 1.77 .057 2.16

68 2 30.993 .004 .06 -.112 1.82 .112 2.19

69 2 32.285 .004 .06 -.121 1.88 .121 2.23

70 2 33.358 .004 .07 -.130 1.93 .131 2.26

71 2 34.597 .004 .07 -.102 1.98 .102 2.29

72 2 35.761 .004 .07 -.125 2.04 .126 2.32

73 2 37.493 .005 .07 -.159 2.11 .159 2.36

SUM OF SQUARED RESIDUALS: 5.15693

BEGINNING POINT:

X = 2826.399 Y = -2649.241 Z = 5151.742

.150 .074 .001

GEOGRAPHIC LAM = -109.96691 FI = 53.24077 H = 81.277 KM

.00171 .00086 .072

END POINT:

X = 2818.657 Y = -2633.672 Z = 5084.385

.112 .036 .010

GEOGRAPHIC LAM = -109.87683 FI = 52.99651 H = 17.622 KM

.00120 .00063 .052

Note: LAMBDA approximate (valid for TIME=0)

FOR THE END POINT: AZIMUTH= 167.527 ZNT. DISTANCE= 23.914

.409 .118

AVERAGE TRAJECTORY SOLUTION, STATION 4 148

Note: LAMBDA is based on the given TIME

I SC TIME LENGTH RANGE HEIGHT VELOCITY LAMBDA FI TAU

1 4 .0000 .0000 270.8883 81.2772 .0000-109.9669 53.2408 57.67

2 4 .0330 .6772 270.5346 80.6570 20.5215-109.9662 53.2384 57.79

3 4 .0670 1.2812 270.2212 80.1038 17.7652-109.9655 53.2363 57.90

4 4 .1000 2.2020 269.7409 79.2605 27.9022-109.9645 53.2331 58.07

5 4 .1330 2.7356 269.4669 78.7717 16.1712-109.9639 53.2313 58.17

6 4 .1670 3.2147 269.2226 78.3330 14.0896-109.9635 53.2296 58.25

7 4 .2000 3.7707 268.9384 77.8238 16.8487-109.9629 53.2277 58.35

8 4 .2340 4.7001 268.4600 76.9726 27.3364-109.9618 53.2244 58.52

9 4 .2670 5.1286 268.2445 76.5802 12.9827-109.9614 53.2229 58.60

10 4 .3000 5.7642 267.9218 75.9981 19.2616-109.9607 53.2207 58.72

11 4 .3340 6.0304 267.7918 75.7543 7.8294-109.9605 53.2198 58.77

12 4 .3670 6.9763 267.3105 74.8881 28.6637-109.9594 53.2165 58.94

13 4 .4000 7.4012 267.0995 74.4991 12.8745-109.9590 53.2150 59.02

14 4 .4340 7.9922 266.8040 73.9578 17.3831-109.9584 53.2130 59.13

15 4 .4670 8.3851 266.6105 73.5980 11.9080-109.9580 53.2116 59.21

16 4 .5000 8.8954 266.3575 73.1307 15.4627-109.9575 53.2098 59.30

17 4 .5340 9.8225 265.8936 72.2818 27.2682-109.9565 53.2066 59.47

18 4 .5670 10.0624 265.7798 72.0622 7.2678-109.9563 53.2057 59.52

19 4 .6010 10.8386 265.3951 71.3514 22.8290-109.9554 53.2030 59.66

20 4 .6340 11.2338 265.2037 70.9896 11.9764-109.9551 53.2017 59.74

21 4 .6670 11.7133 264.9703 70.5505 14.5299-109.9546 53.2000 59.83

AVERAGE VELOCITY: 17.46

AVERAGE TRAJECTORY SOLUTION, STATION 1 149

Note: LAMBDA is based on the given TIME

I SC TIME LENGTH RANGE HEIGHT VELOCITY LAMBDA FI TAU

1 1 .0000 19.9335 63.6315 63.0247 .0000-109.9412 53.1713 35.01

2 1 .0000 23.7207 60.5686 59.5580 999.0000-109.9363 53.1580 37.06

3 1 .0000 25.5162 59.1457 57.9146 999.0000-109.9340 53.1517 38.11

4 1 .0000 27.0658 57.9343 56.4963 999.0000-109.9320 53.1463 39.06

5 1 .0000 27.8346 57.3394 55.7926 999.0000-109.9310 53.1436 39.54

6 1 .0000 29.2894 56.2251 54.4612 999.0000-109.9291 53.1385 40.49

7 1 .0000 31.1612 54.8150 52.7482 999.0000-109.9267 53.1320 41.76

8 1 .0000 31.6085 54.4821 52.3388 999.0000-109.9261 53.1304 42.07

9 1 .0000 32.5814 53.7639 51.4486 999.0000-109.9248 53.1270 42.76

10 1 .0000 34.3121 52.5064 49.8648 999.0000-109.9226 53.1209 44.05

11 1 .0000 35.9060 51.3728 48.4064 999.0000-109.9205 53.1153 45.28

12 1 .0000 36.7799 50.7617 47.6067 999.0000-109.9194 53.1122 45.98

13 1 .0000 59.6111 38.5667 26.7229 999.0000-109.8898 53.0318 71.18

14 1 .0000 60.6509 38.2439 25.7721 999.0000-109.8884 53.0281 72.65

15 1 .0000 61.4312 38.0186 25.0586 999.0000-109.8874 53.0253 73.78

16 1 .0000 62.8455 37.6480 23.7654 999.0000-109.8856 53.0203 75.84

17 1 .0000 63.8803 37.4084 22.8192 999.0000-109.8842 53.0167 77.38

18 1 .0000 64.4995 37.2780 22.2532 999.0000-109.8834 53.0145 78.31

19 1 .0000 65.9011 37.0195 20.9717 999.0000-109.8816 53.0095 80.44

20 1 .0000 67.0251 36.8494 19.9441 999.0000-109.8801 53.0055 82.16

21 1 .0000 68.0233 36.7265 19.0315 999.0000-109.8788 53.0020 83.70

22 1 .0000 68.8547 36.6446 18.2714 999.0000-109.8778 52.9990 84.99

23 1 .0000 69.5657 36.5894 17.6215 999.0000-109.8768 52.9965 86.10

WARNING: NO TIME DATA - EARTH ROTATION CANNOT BE TAKEN INTO ACCOUNT! 150

Appendix E

MORB Files

MORB Input File

Input file used to determine the heliocentric orbit of the Buzzard Coulee meteoroid. The first line inputs the date and time of the event. The second line is an uncertainty in the time. The third line reads the geographic coordinates and height of an average position on the meteor trajectory. The forth line contains the radiant position (right ascension and declination coordinates), the initial velocity and an average velocity. The fifth line inputs the uncertainties of the radiant and the velocity.

2008 11 21 00. 26. 43.

20. 0. 1.

250. 7. 31. 53. 10. 9. 64.

20081121 299.98000 74.96600 18.00000 17.50000

20081121 0.36800 0.23600 0.4000 0.10000 151

MORB Output File

The computed heliocentric orbit of Buzzard Coulee in both J2000.0 and J1950.0 epochs.

MORB determines the uncertainty in each orbital element based on the uncertainties in time, radiant and velocity input.

COPYRIGHT: Z. Ceplecha, P. Spurny, J. Borovicka, Ondrejov Observatory (2000)

Orbit program version 05.08.2008 (P.Spurny)

STATION NO: 20 - RADIANTS AND ORBITAL ELEMENTS

***********************************************

NO MET YEAR MONTH DAY TIME(UT)

81121 2008 11 21 0h26m43.0s +/- 0h 0m 1.0s

APPARENT :

ALFA R DELTA R ALFA G DELTA G V EARTH Tj

299.9800 74.9660 289.9553 76.9711 30.1513 5.0428

0.3680 0.2360 0.6729 0.2890 0.0000

LAMBDA BETA L B G ELONG H ELONG

68.2420 78.0022 335.2952 24.9060 88.2297 154.5114

1.2816 0.1885 0.2101 0.7640 0.2824 0.7842

J2000.0 :

ALFA R DELTA R V INF ALFA G DELTA G VG VH 152

300.0413 74.9372 18.0000 290.0636 76.9510 14.1721 32.9173

0.3680 0.2360 0.4000 0.6692 0.2893 0.5087 0.2463

L B 1/A PI TRUE ANOM T FROM PI PERIOD

335.1770 24.9064 0.803187 90.2051 328.7346 479.95 1.38923

0.2101 0.7640 0.018280 1.4158 1.4158 18.68 0.04743

A E Q PER Q APH OMEGA ASC NODE INCL

1.24504 0.22796 0.96122 1.52886 211.26776 238.93739 25.03669

0.02834 0.01712 0.00105 0.05610 1.41587 0.00008 0.77505

B1950.0 :

ALFA R DELTA R V INF ALFA G DELTA G V G V H

300.2908 74.7973 18.0000 290.5453 76.8544 14.1721 32.9173

0.3680 0.2360 0.4000 0.6692 0.2893 0.5087 0.2463

L B 1/A PI TRUE ANOM T FROM PI PERIOD

334.4816 24.9086 0.803187 89.5082 328.7346 479.95 1.38923

0.2101 0.7640 0.018280 1.4158 1.4158 18.68 0.04743

A E Q PER Q APH OMEGA ASC NODE INCL

1.24504 0.22796 0.96122 1.52886 211.28164 238.22661 25.03956

0.02834 0.01712 0.00105 0.05610 1.41587 0.00008 0.77505 153

Appendix F

Flux of Instrumentally Recorded Meteorite Falls

Back-of-the-envelope style calculation to estimate how many instrumentally recorded meteorites could be recovered each year. The flux values determined through the MORP data by Halliday et al. (1989b) were scaled to the land area of the Earth, reduced by a rough estimate that approximately 1/2 of terrain can be searched successfully and reduced by the total possible camera recording time (clear and dark skies) estimated by

Oberst et al. (1998) for the European Network.

(3.5 meteorites/yr/106 km2) · (150×106 km2 land) · (15% observable) · (1/2) ≈ 40 > 3 kg/year

(1.3 meteorites/yr/106 km2) · (150×106 km2 land) · (15% observable) · (1/2) ≈ 15 > 10 kg/year

(Halliday et al. 89b flux) · (Total land area) · (Oberst et al. 98) · (∼ Searchable terrain)