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Accepted for publication in Monthly Notices of the Royal Astronomical Society on
16 July 2018
1
Analysis of the September ε-Perseid outburst in 2013
José M. Madiedo
1
, Jaime Zamorano
2
, Josep M. Trigo-Rodríguez
3, 4
, José L. Ortiz
5
,
José A. Docobo
6
, Jaime Izquierdo
2
, Juan Lacruz
7
, Pedro P. Campo
6
, Manuel
Andrade
8, 6
, Sensi Pastor
9
, José A. de los Reyes
9
, Francisco Ocaña
2, 10
, Alejandro
Sánchez-de Miguel
11, 2
, Pep Pujols
12
1
Facultad de Ciencias Experimentales, Universidad de Huelva. 21071 Huelva, Spain.
2
Dpto. de Física de la Tierra y Astrofísica, Facultad de Ciencias Físicas, Universidad
Complutense de Madrid, 28040 Madrid, Spain.
3
Institute of Space Sciences (CSIC), Campus UAB, Facultat de Ciències,
Torre C5-parell-2ª, 08193 Bellaterra, Barcelona, Spain.
4
Institut d’Estudis Espacials de Catalunya (IEEC), Edif.. Nexus,
c/Gran Capità, 2-4, 08034 Barcelona, Spain
5
Instituto de Astrofísica de Andalucía, CSIC, Apt. 3004, Camino Bajo de Huetor 50,
18080 Granada, Spain.
6
Observatorio Astronómico Ramón María Aller (OARMA).
Universidade de Santiago de Compostela, Avenida das Ciencias, Campus Vida.
Santiago de Compostela, Spain.
7
La Cañada Observatory (MPC J87), Ávila, Spain.
8
Departamento de Matemática Aplicada. Escola Politécnica Superior de Enxeñaría,
Universidade de Santiago de Compostela, Campus Universitario, 27002 Lugo, Spain.
9
Observatorio Astronómico de La Murta. Molina de Segura, 30500 Murcia, Spain.
10
Quasar Science Resources, S. L., Las Rozas de Madrid. 28232 Madrid, Spain.
11
Environment and Sustainability Institute, University of Exeter, Penryn, Cornwall
TR10 9FE, U.K.
12
Agrupació Astronómica d’Osona (AAO), Carrer Pare Xifré 3, 3er. 1a. 08500 Vic,
Barcelona, Spain
ABSTRACT
We analyze the outburst experienced by the September ε-Perseid meteor shower on 9
September 2013. As a result of our monitoring the atmospheric trajectory of 60 multi-
station events observed over Spain was obtained and accurate orbital data were derived
Accepted for publication in Monthly Notices of the Royal Astronomical Society on
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2
from them. On the basis of these orbits, we have tried to determine the likely parent
body of this meteoroid stream by employing orbital dissimilarity criteria. In addition,
the emission spectra produced by two events belonging to this meteor shower were also
recorded. The analysis of these spectra has provided information about the chemical
nature of their progenitor meteoroids. We also present an estimation of the tensile
strength for these particles.
KEYWORDS: meteorites, meteors, meteoroids.
1 INTRODUCTION
The September ε-Perseid (SPE) meteoroid stream gives rise to an annual display of
meteors from about September 7 to September 23, peaking around September 12
(Jenniskens 2006). This minor shower was first observed by Denning (1882), and is
currently included in the IAU list of meteor showers with code 208 SPE. No systematic
analysis of this shower was performed during the early to mid twentieth century, and the
first reliable data about this stream were analyzed in Hoffmeister (1948). The next
observations were published by Trigo-Rodríguez (1989), who clearly identified SPE
activity over the sporadic background, with often trained and bright meteors exhibiting
a peak zenithal hourly rate ZHR = 5 meteors h
-1
in 1989.
Only two outbursts of SPE meteor activity have been reported. The first of these was
unexpected and took place on 9 September 2008, with an activity consisting mostly of
bright meteors (Jenniskens et al. 2008; Rendtel and Molau 2010). This outburst was not
favourable for observers in Europe. So, despite our systems were monitoring the night
sky, we could not record this activity increase. The second SPE outburst occurred on 9
September 2013. It took place between 21h30m and 23h20m UT and was confirmed in
Jenniskens (2013). On the basis of the results obtained from the analysis of the 2008
outburst, and by assuming that SPE meteoroids were produced by a long-period comet
that ejected these particles before the year 1800 AD, Jenniskens (2013) inferred that this
dust trail should encounter Earth on 9 September 2013 at 22h15m UT. This is in good
agreement with the circumstances of the 2013 SPE outburst. However, the parent comet
of this stream has not been identified yet. Accurate orbital data obtained from the
analysis of SPE meteors could help to find the likely parent of the September ε-
Accepted for publication in Monthly Notices of the Royal Astronomical Society on
16 July 2018
3
Perseids. And meteor spectroscopy can also play an important role to derive information
about the chemical nature of these meteoroids and their progenitor body.
Optimal weather conditions over most of the Iberian Peninsula during the first half of
September 2013 allowed us to analyze the meteor activity produced by the SPE stream.
In this work we focus on the analysis of the 2013 SPE outburst. From our recordings we
have obtained orbital information about meteoroids belonging to this poorly known
stream. The tensile strength of these particles is also estimated. Besides, two emission
spectra produced by SPE meteors are also analyzed. These are, to our knowledge, the
first SPE spectra discussed in the scientific literature.
2 INSTRUMENTATION AND DATA REDUCTION TECHNIQUES
The meteor observing stations that were involved in the monitoring of the September ε-
Perseid outburst analyzed here are listed in Table 1. These employ between 3 and 12
high-sensitivity CCD video cameras (models 902H and 902H Ultimate from Watec Co.,
Japan) to monitor the night sky (Madiedo & Trigo-Rodríguez 2008; Trigo-Rodríguez et
al. 2009). Their field of view ranges from 90 x 72 degrees to 14 x 11 degrees. These
CCD devices work according to the PAL video standard and, so, they generate
interlaced video imagery at 25 fps with a resolution of 720x576 pixels. More details
about these devices and the way they are operated are given, for instance, in (Madiedo
2014). In order to obtain the atmospheric trajectory of the meteors and the heliocentric
orbit of the progenitor meteoroids we have employed the AMALTHEA software
(Madiedo et al. 2013a,b), which follows the methods described in Ceplecha (1987).
To record meteor emission we have attached holographic diffraction gratings (with 500
or 1000 lines/mm, depending on the device) to the objective lens of some of the above-
mentioned CCD video cameras. With these slitless videospectrographs we can record
the emission spectrum of meteors brighter than magnitude -3/-4 (Madiedo et al. 2013c;
Madiedo 2014). The analysis of the emission spectra obtained during the SPE observing
campaign analyzed here was performed by means of the CHIMET software (Madiedo et
al. 2013c).
3 OBSERVATIONS AND RESULTS
Accepted for publication in Monthly Notices of the Royal Astronomical Society on
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In 2013 our meteor observing stations observed activity from the September ε-Perseids
from September 1 to September 12. On 9 September 2013, at about 21h35m UT, our
CCD video devices registered a marked increase in meteor activity associated with this
stream, including some fireballs. A careful checking of these data confirmed the SPE
outburst between around 21h35m UT on September 9 and 0h 20m UT on September 10,
in good agreement with the circumstances described in Jenniskens (2013). From the
analysis of the multi-station events recorded from sites listed in Table 1 we have
obtained the atmospheric trajectory of these meteors. However, we just took into
consideration those trails for which the convergence angle was above 20 degrees. This
parameter, which is usually employed to measure the quality of the results, is the angle
between the two planes delimited by the observing sites and the meteor atmospheric
path (Ceplecha 1987). A total of 60 SPE meteors satisfied this condition. These events
are listed in Table 2, which shows the absolute peak magnitude (M), the initial
(preatmospheric) photometric mass of the progenitor meteoroid (m
p
), the initial (H
b
)
and final (H
e
) heights of the meteor, the right ascension (α
g
) and declination (δ
g
) of the
geocentric radiant (J2000.0), and the preatmospheric (V
∞
) and geocentric (V
g
)
velocities. To identify each meteor, we have employed a code with the format
DDYYEE, where DD is the day of the month (which ranges between 01 and 12 for the
meteors analyzed here), and YY corresponds to the last two digits of the recording year.
The two digits EE are employed to number meteors recorded during the same night, so
that 00 is assigned to the first meteor imaged, 01 to the second one and so on. The
averaged value for the observed initial (preatmospheric) velocity was V
∞
= 65.9 ± 0.2
km s
-1
. The photometric mass of the parent meteoroids ranged between 0.01 to 16 g
(Table 2). The orbital parameters derived for the meteoroids that gave rise to these
meteor events are listed in Table 3.
4 DISCUSSION
4.1 Parent body
The averaged orbital data calculated by taking into account a total of N = 60 SPE orbits
are shown in Table 3. This table also includes the average orbit of meteors observed
during the outburst (N=28 meteors). As can be noticed, the difference between both
averaged orbits is not significant. With these parameters we have obtained that the value
of the Tisserand parameter with respect to Jupiter yields T
J
= -0.65 ± 0.44. This agrees
Accepted for publication in Monthly Notices of the Royal Astronomical Society on
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with the assumption in Jenniskens (2013) that SPE meteoroids are produced by a long
period comet.
Besides, we have calculated the so-called K
B
parameter, which according to Ceplecha
(1988) can be employed to classify meteoroids into four different populations: A-group,
comprising particles similar to carbonaceous chondrites (7.3 ≤ K
B
< 8); B-group of
dense cometary material (7.1 ≤ K
B
< 7.3); C group of regular cometary material (6.6 ≤
K
B
< 7.1); and D-group of soft cometary material (K
B
< 6.6). This parameter is defined
by the following equation:
K
B
= log ρ
B
+ 2.5 log V
∞
− 0.5 log cos z
R
+0.15 (1)
where ρ
B
is the air density at the beginning of the luminous trajectory (in g cm
−3
), V
∞
is
the preatmospheric velocity of the meteoroid (in cm s
−1
), and z
R
is the inclination of the
atmospheric trajectory with respect to the vertical. We have obtained the air density ρ
B
by using the NRLMSISE-00 atmosphere model (Picone et al. 2002). According to our
computations, the average K
B
parameter for the SPE events in Table 2 yields K
B
= 6.9 ±
0.2. This result suggests that meteoroids in this stream belong to the group of regular
cometary materials.
We have tried to determine the likely parent comet of SPE meteoroids by means of
orbital dissimilarity criteria (Williams 2011). In this approach we have employed the
ORAS program (ORbital Association Software) to search through the Minor Planet
Center database in order to establish a potential link between the SPE stream and other
bodies in the Solar System (Madiedo et al. 2013d). This analysis has been performed by
calculating the Southworth and Hawkings D
SH
criterion (Southworth & Hawkins 1963).
However the lowest values obtained for the D
SH
function are of about 1.50, which is
well above the D
SH
<0.15 cutoff value usually adopted to validate a potential association
(Linblad 1971a,b). So we conclude that the parent comet of the SPE stream is not
catalogued.
4.2. Meteor initial and final heights
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The dependence with meteoroid mass of the beginning and final heights of meteors
analyzed in this work has been plotted in Figures 1 and 2, respectively. As can be seen
in Figure 1, the initial height H
b
increases with increasing meteoroid mass. This
behaviour has been also found for other meteor showers with a cometary origin (see,
e.g., Koten et al. 2004, Jenniskens 2004, Madiedo 2015). We have described this
behaviour by means of a linear relationship between H
b
and the logarithm of the
meteoroid photometric mass (solid line in Figure 1). The slope of this line is 2.38 ±
0.70. According to this result, the increase of the beginning height with meteoroid mass
is less important for the September ε-Perseids than for the Leonids (a = 9.9 ± 1.5), the
Perseids (a = 7.9 ± 1.3), the Taurids (a = 6.6 ± 2.2), and the Orionids (a = 5.02 ± 0.65)
(Koten et al. 2004). But more pronounced than for the ρ-Geminids (a = 1.1 ± 0.5),
which are produced by tough cometary meteoroids (Madiedo 2015), and the Geminids
(a = 0.46 ± 0.26) (Koten et al. 2004), which have an asteroidal origin (Jenniskens 2004).
Despite the preatmospheric velocity of the September ε-Perseids and the Perseids is
similar (~65 km s
-1
and ~61 km s
-1
, respectively), the beginning height exhibited by SPE
meteors is significantly lower. Thus, for instance, for SPE meteors H
b
is of below 110
km for a meteoroid mass of about 0.02 g (Figure 2), but ~120 km for Perseid members
with the same mass (Koten et al. 2004). This suggests that SPE meteoroids are tougher.
The larger is the meteoroid mass, the lower is the terminal point H
e
of the meteor
(Figure 2). The slope of the line we have employed to model this behaviour (solid line
in Figure 2) yields -2.25 ± 0.45. Since slower meteoroids tend to penetrate deeper in the
atmosphere, it is not surprising that SPE meteoroids, which exhibit an initial velocity of
~65 km s
-1
, do not penetrate as deep as the Perseids with a preatmospheric velocity of
~61 km s
-1
(Koten 2004), the Geminids with a velocity of ~36 km s
-1
(Jenniskens 2004),
or the ρ-Geminids with a velocity of about 23 km s
-1
(Madiedo 2015).
4.3 Meteoroid strength
The tensile strength of meteoroids ablating in the atmosphere can be estimated by
analyzing the flares exhibited by the corresponding meteors. According to this
approach, these flares take place as a consequence of the sudden break-up of the
meteoroid when the aerodynamic pressure overcomes the strength of the particle (Trigo-
Rodríguez & Llorca 2006). However, SPE events listed in Table 2 exhibited a quasi-
Accepted for publication in Monthly Notices of the Royal Astronomical Society on
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continuous ablation behaviour, with smooth lightcurves that revealed that no flares
occurred during their interaction with the atmosphere. So, we have employed this
technique to evaluate the maximum aerodynamic pressure suffered by SPE meteoroids,
which has provided a lower limit for their tensile strength. This aerodynamic pressure S
can be estimated by using the following relationship (Bronshten 1981)
S=ρ
atm
·v
2
(2)
where ρ
atm
and v are the atmospheric density and meteor velocity at a given height,
respectively. In this work we have calculated the air density by employing the
NRLMSISE-00 atmosphere model (Picone et al. 2002). From the analysis of the
atmospheric trajectory calculated for meteors in Table 2 we have obtained a maximum
aerodynamic pressure of (2.9 ± 0.3) ·10
5
dyn cm
-2
. This value is higher than the average
strength found for Quadrantid and Perseid meteoroids (~2·10
5
dyn cm
-2
and (1.2 ± 0.3)
·10
5
dyn cm
-2
, respectively), and below the strength of the Taurids ((3.4± 0.7)·10
5
dyn
cm
-2
) (Trigo-Rodríguez & Llorca 2006, 2007).
4.4 Emission spectra
The video spectrographs operated at stations 1 to 6 in Table 1 recorded a total of 8 SPE
emission spectra during the outburst recorded on September 9-10. Unfortunately 6 of
these were too dim to be analyzed, but the other two had enough quality to provide
information about the chemical nature of these meteoroids. These spectra were
produced by meteors labelled as SPE091327 and SPE091331 in Table 2, respectively.
They have been analyzed with the CHIMET software (Madiedo et al. 2013c), which
first deinterlaces the video files containing these signals. Then, the software performs a
dark-frame subtraction, and each video frame is flat-fielded. Next, the calibration in
wavelength is achieved by identifying emission lines typically found in meteor spectra.
Then, the intensity of the signals is corrected by taking into account the spectral
efficiency of the spectrograph. The results obtained from this procedure are shown in
Figures 3 and 4. In these plots, the most remarkable multiplets have been labelled
according to the notation given by Moore (1945). The most noticeable emissions
correspond to the atmospheric O I line at 777.4 nm, and to the K and H lines of Ca II-1
at 393.3 and 396.8 nm, respectively. These two lines produced by ionized calcium
appear blended in the spectrum. Other prominent contributions are those of Fe I-41
Accepted for publication in Monthly Notices of the Royal Astronomical Society on
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(440.4 nm), the Mg I-2 triplet (517.3 nm), and the Na I-1 doublet (588.9 nm). The
emission of atmospheric N
2
bands was also identified in the red region of the spectrum.
As in previous works (see e.g. Madiedo et al. 2014), we have investigated the chemical
nature of the progenitor meteoroids by analyzing the relative intensity of the Na I-1, Mg
I-2 and Fe I-15 multiplets in these spectra (Borovička et al. 2005). To perform this
analysis, the intensity (in arbitraty units) of the emission lines associated with these
multiplets was measured frame by frame and subsequently corrected according to the
efficiency of the spectrograph. Next the contributions in each video frame were added to
obtain the integrated intensity for each emission line along the meteor path. For the
SPE091327 spectrum the integrated intensities of the Na I-1, Mg I-2 and Fe I-15
multiplets yield 15, 23 and 7, respectively. For the SPE091331 spectrum these
intensities yield 35, 55 and 21. In this way we have obtained for the SPE091327 and
SPE091331 spectra a Na to Mg intensity ratio of 0.62 and 0.63, respectively. And the
Fe/Mg intensity ratio yields 0.29 and 0.38, respectively. The ternary diagram in Figure 5
shows the relative intensity of the emission from the Na I-1, Mg I-2 and Fe I-15
multiplets for both spectra. The solid curve in this plot corresponds to the expected
relative intensity, as a function of meteor velocity, for chondritic meteoroids (Borovička
et al. (2005)). The position on this solid line corresponding to the velocity of SPE
meteors (~65 km s
-1
) is not explicitly specified in the work published by Borovička et
al. (2005) (see Figure 6 in that work), although the authors of that paper indicate that the
points describing these high-speed meteors are located near the left edge of this curve.
By taking this into account we conclude that the points in this diagram describing both
spectra show that SPE meteoroids can be considered as normal according to the
classification given by Borovička et al. (2005). Thus, the position of these experimental
points fit fairly well the expected relative intensity for chondritic meteoroids for a
meteor velocity of ~65 km s
-1
.
5 CONCLUSIONS
We have analyzed the meteor activity associated with the September ε-Perseid
meteoroid stream in 2013. In this context we have observed the outburst experienced by
this meteor shower on September 9-10. From the analysis of our recordings we have
reached the following conclusions:
Accepted for publication in Monthly Notices of the Royal Astronomical Society on
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9
1) The dependence with meteoroid mass of the initial height observed for SPE
meteors reveals a cometary origin for this stream. The increase of the
beginning height with mass is less important for the September ε-Perseids
than for the Leonids, the Perseids, the Taurids, and the Orionids. But more
pronounced than for the ρ-Geminids and the Geminids The analysis of the
K
B
parameter suggests that SPE meteoroids consist of regular cometary
material.
2) The orbital data calculated from the analysis of our double-station meteors
support the idea that SPE meteoroids are associated with a long period
comet. However, no parent body could be identified among the objects
currently included in the Minor Planet Center database. From this we
conclude that the progenitor comet of this meteoroid stream is not yet
catalogued.
3) The tensile strength of these meteoroids has been constrained. According to
our calculations, the maximum aerodynamic pressure suffered by SPE
meteoroids is higher than the tensile strength found for Quadrantid and
Perseid meteoroids.
4) We have recorded 8 emission spectra produced by SPE meteors during the
outburst recorded on September 9-10. Two of these had enough quality to be
analyzed, and these suggest a chondritic nature for SPE meteoroids.
ACKNOWLEDGEMENTS
We acknowledge support from the Spanish Ministry of Science and Innovation (projects
AYA2015-68646-P and AYA 2015-67175-P).
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TABLES
Table 1. Geographical coordinates of the SPMN meteor observing stations that recorded
the 2013 outburst of the SPE meteor shower.
Station # Station name Longitude Latitude (N) Altitude (m)
1 Sevilla 5º 58' 50" W 37º 20' 46" 28
2 La Hita 3º 11' 00" W 39º 34' 06" 674
3 Huelva 6º 56' 11" W 37º 15' 10" 25
4 Sierra Nevada 3º 23' 05" W 37º 03' 51" 2896
5 El Arenosillo 6º 43' 58" W 37º 06' 16" 40
6 Cerro Negro 6º 19' 35" W 37º 40' 19" 470
7 Ávila 4º 29' 30" W 40º 36' 18" 1400
8 Villaverde del Ducado 2º 29' 29" W 41º 00' 04" 1100
9 Madrid-UCM 3º 43' 34" W 40º 27' 03" 640
10 La Murta 1º 12' 10" W 37º 50' 25" 400
11 Folgueroles 2º 19' 33" E 41º 56' 31" 580
12 Montseny 2º 32' 01" E 41º 43' 47" 194
13 Lugo 7º 32' 41" W 42º 59' 35" 418
14 OARMA 8º 33' 34" W 42º 52' 31" 240
Table 2. Trajectory and radiant data (J2000) for the double-station September ε-Perseid
meteors discussed in the text.
Meteor
code Date Time (UT)
±0.1s
M
±0.5
m
p
(g)
H
b
(km)
±0.5
H
e
(km)
±0.5
α
g
(º)
δ
g
(º)
V
∞
(km s
-1
)
V
g
(km s
-1
)
011301
Sep 1
4h16m25.8s
-2.0
0.17 ± 0.07
109.4
88.0
41.31±0.10
38.15±0.02
66.2±0.2
65.2±0.2
011302
Sep 1
20h50m52.3s
1.2
0.01± 0.01
109.5
100.6
42.45±0.07
37.04±0.02
66.9±0.2
65.7±0.2
011303
Sep 1
23h22m20.4s
-2.1
0.19 ± 0.08
116.6
99.5
41.88±0.08
37.45±0.02
66.6±0.2
65.4±0.2
021301
Sep 2
1h15m45.0s
-0.5
0.04± 0.01
111.2
90.5
42.03±0.10
38.14±0.04
66.5±0.2
65.3±0.2
021302
Sep 2
2h44m43.2s
-1.2
0.08 ± 0.03
112.1
95.6
42.08±0.09
37.72±0.06
66.2±0.2
65.1±0.2
031301
Sep 3
1h25m30.3s
-2.7
0.35 ± 0.14
113.3
92.0
41.58±0.12
36.55±0.10
66.3±0.2
65.1±0.2
031302
Sep 3
3h53m12.9s
-0.7
0.05 ± 0.02
109.9
91.4
42.13±0.15
37.86±0.09
66.0±0.2
65.0±0.2
041301
Sep 4
1h04m43.8s
0.5
0.01 ± 0.01
109.5
98.8
43.11±0.14
36.74±0.10
66.4±0.2
65.2±0.2
051301
Sep 5
1h17m19.2s
-2.5
0.29 ± 0.12
113.9
87.6
44.09±0.15
37.62±0.10
66.5±0.2
65.3±0.2
051302
Sep 5
21h11m18.1s
-3.6
0.86 ± 0.35
115.6
101.8
44.24±0.14
38.23±0.10
66.1±0.2
64.8±0.2
061301
Sep 6
4h59m48.6s
-3.9
1.16 ± 0.47
114.1
90.1
44.48±0.10
38.10±0.10
65.8±0.2
64.9±0.2
081301
Sep 8
2h21m15.4s
1.1
0.01 ± 0.01
107.6
96.9
45.39±0.07
38.72±0.08
65.7±0.2
64.6±0.2
081302
Sep 8
3h29m08.9s
-3.6
0.86 ± 0.35
110.4
89.8
46.47±0.12
38.40±0.09
65.9±0.2
64.9±0.2
081303
Sep 8
4h00m40.7s
-3.4
0.71 ± 0.29
115.4
84.4
45.97±0.15
38.26±0.12
65.8±0.2
64.8±0.2
091301
Sep 9
0h13m42.3s
0.8
0.01 ± 0.01
105.5
89.0
47.28±0.09
38.99±0.10
66.1±0.2
64.9±0.2
091302
Sep 9
0h52m35.4s
1.0
0.01 ± 0.01
111.0
95.4
47.16±0.09
39.01±0.08
66.0±0.2
64.8±0.2
091303
Sep 9
1h31m29.7s
-2.1
0.20 ± 0.08
113.3
97.6
47.20±0.10
38.94±0.09
66.1±0.2
65.0±0.2
091304
Sep 9
1h37m55.5s
1.5
0.01 ± 0.01
101.1
96.8
47.12±0.08
39.00±0.08
65.9±0.2
64.7±0.2
091305
Sep 9
2h34m02.9s
-0.9
0.06 ± 0.02
109.9
95.4
47.54±0.10
38.92±0.09
66.0±0.2
64.9±0.2
091306
Sep 9
21h43m34.0s
-1.2
0.08 ± 0.03
107.6
97.2
47.78±0.09
39.28±0.09
66.0±0.2
64.8±0.2
091307
Sep 9
21h53m24.2s
-5.1
3.87 ± 1.57
116.1
94.8
47.76±0.10
39.53±0.10
65.9±0.2
64.6±0.2
091308
Sep 9
21h56m32.7s
-1.9
0.16 ± 0.06
116.6
105.0
47.84±0.10
39.17±0.09
66.1±0.2
64.8±0.2
091309
Sep 9
21h56m51.3s
-3.4
0.72 ± 0.29
114.3
85.1
47.92±0.08
39.76±0.06
65.9±0.2
64.7±0.2
091310
Sep 9
21h58m13.5s
0.1
0.01 ± 0.01
101.7
97.1
47.72±0.09
39.75±0.09
65.9±0.2
64.6±0.2
091311
Sep 9
22h00m44.5s
0.3
0.02± 0.01
101.5
96.9
47.51±0.09
39.67±0.08
65.8±0.2
64.5±0.2
091312
Sep 9
22h00m56.1s
-2.8
0.39 ± 0.15
115.2
88.1
47.41±0.09
39.57±0.08
65.8±0.2
64.6±0.2
091313
Sep 9
22h01m17.6s
-5.7
7.5 ± 3.0 118.2
87.3
47.32±0.08
39.37±0.08
65.7±0.2
64.4±0.2
Accepted for publication in Monthly Notices of the Royal Astronomical Society on
16 July 2018
13
091314
Sep 9
22h02m23.9s
-0.5
0.03 ± 0.01
105.1
95.9
47.51±0.08
39.76±0.08
65.8±0.2
64.5±0.2
091315
Sep 9
22h04m01.2s
-2.2
0.20 ± 0.08
112.9
97.2
47.60±0.09
39.67±0.08
65.9±0.2
64.6±0.2
091316
Sep 9
22h04m20.3s
-5.2
4.58 ± 1.86
116.7
95.2
47.90±0.09
39.71±0.09
66.0±0.2
64.7±0.2
091317
Sep 9
22h04m46.8s
1.5
0.01 ± 0.01
100.5
96.3
47.80±0.10
39.82±0.07
65.9±0.2
64.6±0.2
091318
Sep 9
22h05m04.0s
-0.6
0.04 ± 0.02
115.6
107.1
47.81±0.09
39.47±0.08
65.9±0.2
64.6±0.2
091319
Sep 9
22h08m10.7s
-3.0
0.48 ± 0.20
111.9
95.1
47.40±0.11
39.78±0.07
65.7±0.2
64.5±0.2
091320
Sep 9
22h09m57.0s
-1.8
0.14 ± 0.05
113.0
97.0
47.88±0.10
39.48±0.08
65.9±0.2
64.6±0.2
091321
Sep 9
22h13m24.3s
-4.6
2.5 ± 1.0 115.2
86.1
47.38±0.09
39.79±0.07
65.7±0.2
64.4±0.2
091322
Sep 9
22h14m05.1s
-0.1
0.03 ± 0.01
113.2
88.4
48.00±0.09
39.49±0.09
66.0±0.2
64.7±0.2
091323
Sep 9
22h16m00.4s
0.0
0.01 ± 0.01
101.3
96.1
47.84±0.09
39.52±0.08
65.9±0.2
64.6±0.2
091324
Sep 9
22h16m48.9s
0.5
0.01 ± 0.01
101.7
97.4
47.66±0.09
39.89±0.07
65.8±0.2
64.6±0.2
091325
Sep 9
22h17m19.4s
-2.1
0.20 ± 0.08
115.1
99.1
47.86±0.10
39.41±0.09
65.9±0.2
64.6±0.2
091326
Sep 9
22h28m32.1s
-5.1
4.14 ± 1.68
120.0
95.1
47.73±0.10
39.78±0.09
65.8±0.2
64.5±0.2
091327
Sep 9
22h34m10.6s
-5.8
7.76 ± 3.14
118.6
93.4
47.95±0.10
39.65±0.09
65.8±0.2
64.6±0.2
091328
Sep 9
22h49m01.2s
-4.9
3.28 ± 1.33
114.8
92.2
47.61±0.09
39.45±0.09
65.9±0.2
64.7±0.2
091329
Sep 9
22h52m36.7s
-4.8
2.87 ± 1.16
114.9
90.4
48.05±0.07
39.34±0.07
66.0±0.2
64.8±0.2
091330
Sep 9
23h01m55.9s
1.0
0.01 ± 0.01
103.6
98.7
47.72±0.09
39.66±0.07
65.8±0.2
64.6±0.2
091331
Sep 9
23h17m15.1s
-5.3
5.23 ± 2.12
117.8
90.7
47.77±0.09
39.68±0.07
65.8±0.2
64.6±0.2
091332
Sep 9
23h23m59.8s
-4.0
1.42 ± 0.58
109.7
95.6
47.79±0.09
39.59±0.07
65.9±0.2
64.7±0.2
091333
Sep 9
23h53m01.0s
-3.3
0.64 ± 0.26
112.6
94.7
48.05±0.08
39.70±0.07
66.0±0.2
64.8±0.2
101301
Sep 10
1h46m40.3s
-4.7
2.77 ± 1.12
109.4
85.8
47.82±0.12
39.11±0.09
65.9±0.2
64.8±0.2
101302
Sep 10
2h45m22.9s
1.8
0.01 ± 0.01
105.2
97.2
47.74±0.13
39.63±0.10
65.7±0.2
64.6±0.2
101303
Sep 10
3h16m23.7s
-6.1
11.6 ± 4.7
120.7
84.4
47.98±0.15
39.58±0.12
65.8±0.2
64.8±0.2
101304
Sep 10
4h07m48.6s
-4.1
1.57 ± 0.64
113.9
92.1
48.09±0.10
39.74±0.10
65.6±0.2
64.6±0.2
101305
Sep 10
4h32m30.8s
-6.4
16.1 ± 6.5
115.9
85.6
47.54±0.10
39.67±0.10
65.5±0.2
64.6±0.2
101306
Sep 10
5h16m42.5s
-5.6
6.73 ± 2.77
113.8
89.6
47.78±0.10
39.68±0.10
65.6±0.2
64.7±0.2
111301
Sep 11
3h43m32.7s
-3.9
1.25 ± 0.50
116.2
95.6
48.12±0.11
39.75±0.09
65.4±0.2
64.4±0.2
111302
Sep 11
4h52m52.0s
-5.2
4.73 ± 1.92
115.8
90.1
49.27±0.10
39.66±0.09
65.6±0.2
64.7±0.2
111303
Sep 11
5h06m46.6s
-4.3
0.86 ± 0.75
114.5
91.7
48.44±0.12
40.13±0.10
65.3±0.2
64.4±0.2
121301
Sep 12
0h26m38.1s
-2.0
0.20 ± 0.08
108.5
97.8
49.37±0.11
40.77±0.10
65.6±0.2
64.4±0.2
121302
Sep 12
0h37m57.9s
-4.9
3.50 ± 1.42
105.7
89.3
49.15±0.10
40.10±0.12
65.7±0.2
64.5±0.2
121303
Sep 12
2h11m22.1s
-1.8
0.16 ± 0.06
105.8
90.6
49.41±0.10
40.74±0.10
65.4±0.2
64.3±0.2
121304
Sep 12
23h24m55.5s
-5.9
9.11 ± 3.69
119.5
90.7
50.00±0.08
41.10±0.09
65.4±0.2
64.2±0.2
Table 3. Orbital data (J2000) for the September ε-Perseid meteors listed in Table 2,
averaged orbit for N = 60 SPE meteors and averaged orbit for meteors recorded during
the outburst (N=28).
Meteor
code
a
(AU)
e i
(º) Ω
±10
-5
(º)
ω
(º)
q
(AU)
T
J
011301
28.4±14.5
0.972±0.014
140.29±0.11
158.71763
236.1±0.1
0.789±0.002
-0.65±0.37
011302
35.9±23.5
0.978±0.014
142.71±0.10
159.38597
237.0±0.5
0.781±0.002
-0.72±0.47
011303
29.9±16.2
0.974±0.014
141.55±0.10
159.48774
238.1±0.5
0.774±0.003
-0.67±0.39
021301
37.3±25.3
0.979±0.014
140.59±0.12
159.56395
236.6±0.5
0.784±0.002
-0.70±0.47
021302
19.2±6.6
0.959±0.013
141.13±0.14
159.62377
238.2±0.6
0.775±0.003
-0.57±0.27
031301
30.2±16.7
0.975±0.013
142.20±0.18
160.53871
243.4±0.6
0.733±0.003
-0.66±0.39
031302
26.6±13.0
0.971±0.014
140.55±0.20
160.63800
240.4±0.6
0.757±0.003
-0.63±0.35
041301
24.8±11.3
0.970±0.014
142.70±0.20
161.49337
242.7±0.6
0.739±0.003
-0.63±0.34
051301
52.7±51.4
0.985±0.013
141.75±0.20
162.47092
241.3±0.6
0.747±0.004
-0.74±0.65
051302
27.3±13.7
0.973±0.013
140.42±0.20
163.27478
242.9±0.6
0.737±0.004
-0.62±0.36
061301
29.9±16.2
0.975±0.014
140.69±0.18
163.59031
243.5±0.6
0.732±0.004
-0.64±0.38
081301
35.9±23.2
0.980±0.013
139.53±0.16
165.42414
245.6±0.6
0.714±0.003
-0.65±0.43
081302
28.2±14.5
0.974±0.013
140.89±0.18
165.46988
244.2±0.6
0.726±0.004
-0.63±0.36
081303
34.3±21.7
0.979±0.014
140.73±0.23
165.49119
245.4±0.6
0.716±0.004
-0.65±0.43
Accepted for publication in Monthly Notices of the Royal Astronomical Society on
16 July 2018
14
091301
38.3±26.7
0.981±0.013
140.24±0.16
166.30917
243.7±0.6
0.729±0.003
-0.67±0.47
091302
35.4±22.6
0.980±0.013
140.09±0.16
166.33540
244.1±0.6
0.726±0.003
-0.66±0.43
091303
56.6±58.2
0.987±0.013
140.27±0.17
166.36164
243.9±0.6
0.726±0.003
-0.72±0.66
091304
31.5±17.9
0.977±0.014
140.04±0.16
166.36597
244.4±0.6
0.724±0.003
-0.64±0.39
091305
34.6±21.7
0.978±0.013
140.49±0.17
166.40383
243.7±0.6
0.730±0.003
-0.66±0.43
091306
40.4±29.7
0.982±0.013
139.74±0.18
167.17936
244.7±0.6
0.721±0.003
-0.67±0.48
091307
34.6±21.7
0.979±0.013
139.30±0.19
167.18599
244.5±0.5
0.723±0.003
-0.64±0.43
091308
52.3±48.1
0.986±0.012
140.00±0.14
167.18811
244.6±0.5
0.721±0.003
-0.70±0.60
091309
33.8±20.7
0.978±0.013
139.06±0.14
167.18831
243.7±0.6
0.728±0.003
-0.64±0.41
091310
41.5±31.4
0.982±0.013
138.92±0.17
167.18923
244.0±0.6
0.726±0.003
-0.67±0.49
091311
34.3±21.3
0.980±0.013
139.10±0.16
167.19093
244.8±0.6
0.721±0.003
-0.64±0.41
091312
35.7±23.1
0.979±0.012
138.95±0.17
167.19106
245.1±0.6
0.718±0.003
-0.64±0.43
091313
26.7±12.8
0.973±0.013
139.13±0.14
167.19130
246.0±0.6
0.712±0.003
-0.60±0.33
091314
36.7±24.4
0.980±0.013
138.71±0.12
167.19204
244.5±0.6
0.722±0.003
-0.64±0.44
091315
44.7±36.5
0.983±0.013
139.00±0.16
167.19314
244.4±0.6
0.723±0.003
-0.67±0.52
091316
44.9±36.8
0.983±0.013
139.21±0.13
167.19336
243.6±0.6
0.729±0.003
-0.68±0.54
091317
39.9±29.0
0.981±0.013
138.88±0.14
167.19365
243.8±0.6
0.728±0.003
-0.66±0.48
091318
32.4±19.0
0.977±0.013
139.41±0.17
167.19386
244.5±0.6
0.723±0.003
-0.63±0.40
091319
30.5±16.9
0.976±0.013
138.56±0.15
167.19594
245.0±0.6
0.720±0.003
-0.61±0.37
091320
30.4±16.8
0.976±0.013
139.45±0.18
167.19716
244.4±0.6
0.724±0.004
-0.62±0.38
091321
31.1±17.5
0.977±0.013
138.53±0.17
167.19947
245.0±0.6
0.720±0.003
-0.61±0.38
091322
37.6±25.8
0.981±0.013
139.56±0.12
167.19995
244.0±0.5
0.726±0.003
-0.66±0.45
091323
32.2±18.7
0.978±0.013
139.36±0.14
167.20124
244.4±0.6
0.724±0.003
-0.63±0.39
091324
34.4±21.5
0.979±0.013
138.63±0.14
167.20177
244.1±0.6
0.726±0.003
-0.64±0.42
091325
30.0±16.3
0.976±0.013
139.54±0.16
167.20213
244.6±0.6
0.722±0.003
-0.62±0.37
091326
31.4±17.9
0.977±0.013
138.80±0.17
167.20969
244.2±0.6
0.725±0.003
-0.62±0.39
091327
24.9±11.2
0.971±0.013
139.19±0.17
167.21349
244.3±0.6
0.726±0.003
-0.58±0.32
091328
39.9±29.1
0.982±0.013
139.29±0.18
167.22352
244.9±0.6
0.719±0.003
-0.66±0.48
091329
34.1±21.0
0.979±0.013
139.81±0.12
167.22594
244.3±0.5
0.725±0.003
-0.65±0.42
091330
30.4±16.8
0.976±0.013
139.00±0.15
167.23222
244.6±0.6
0.723±0.003
-0.62±0.38
091331
30.1±16.5
0.976±0.013
139.01±0.15
167.24256
244.5±0.6
0.724±0.003
-0.62±0.37
091332
38.2±26.5
0.981±0.013
139.21±0.16
167.24711
244.4±0.6
0.723±0.003
-0.66±0.46
091333
49.8±44.9
0.985±0.013
139.24±0.14
167.26670
243.5±0.5
0.730±0.003
-0.70±0.58
101301
45.4±37.7
0.984±0.014
139.95±0.18
167.34341
245.2±0.6
0.716±0.003
-0.68±0.54
101302
40.9±30.6
0.982±0.014
139.03±0.20
167.38301
244.7±0.6
0.720±0.004
-0.66±0.49
101303
58.1±62.0
0.987±0.014
139.25±0.33
167.40395
244.2±0.6
0.724±0.004
-0.70±0.67
101304
34.7±21.8
0.979±0.013
139.10±0.19
167.43864
244.1±0.6
0.725±0.003
-0.64±0.42
101305
48.1±41.0
0.985±0.013
138.80±0.20
167.45531
245.2±0.6
0.716±0.004
-0.67±0.55
101306
54.6±54.0
0.986±0.014
139.00±0.21
167.45531
244.6±0.6
0.721±0.004
-0.70±0.62
111301
38.1±26.3
0.981±0.012
138.60±0.20
168.39366
246.7±0.6
0.704±0.004
-0.64±0.45
111302
31.3±17.7
0.977±0.013
139.65±0.19
168.44117
244.8±0.6
0.721±0.003
-0.63±0.39
111303
37.1±25.0
0.981±0.013
138.23±0.21
168.45053
245.6±0.6
0.714±0.004
-0.64±0.44
121301
48.2±42.4
0.985±0.013
137.57±0.19
169.23389
244.7±0.6
0.720±0.003
-0.66±0.54
121302
29.0±15.1
0.975±0.012
138.82±0.18
168.54458
244.8±0.6
0.721±0.003
-0.61±0.36
121303
33.5±20.3
0.978±0.013
137.56±0.19
169.30464
245.1±0.6
0.718±0.004
-0.62±0.40
121304
35.7±23.0
0.980±0.013
137.02±0.16
170.16520
245.8±0.6
0.712±0.003
-0.62±0.41
Average
(N=60)
36.2±25.1
0.978±0.013
139.60±0.16
166.10643
243.7±0.6
0.729±0.003
-0.65±0.44
Outburst
(N=28)
35.8±24.0
0.979±0.013
139.15±0.16
167.20462
244.4±0.6
0.723±0.003
-0.64±0.43
Accepted for publication in Monthly Notices of the Royal Astronomical Society on
16 July 2018
15
FIGURES
90
95
100
105
110
115
120
-3 -2,5 -2 -1,5 -1 -0,5 0 0,5 1 1,5
log (m
p
)
H
b
(km) .
Figure 1. Meteor beginning height H
b
vs. logarithm of the photometric mass m
p
of the
meteoroid. Solid line: linear fit for measured data.
70
75
80
85
90
95
100
105
110
-3 -2,5 -2 -1,5 -1 -0,5 0 0,5 1 1,5
log (m
p
)
H
e
(km) .
Figure 2. Meteor beginning height H
b
vs. logarithm of the photometric mass m
p
of the
meteoroid. Solid line: linear fit for measured data.
Accepted for publication in Monthly Notices of the Royal Astronomical Society on
16 July 2018
16
0
10
20
30
40
50
60
70
80
90
100
300 400 500 600 700 800 900
Wavelength (nm)
Relative intensity (-) .
O I
Na I-1
Mg I-2
Fe I-15
Fe I-318
N2
Ca II-1
Fe I-42
Fe I-41
Figure 3. Calibrated emission spectrum of the SPE091327 meteor.
0
20
40
60
80
100
120
140
160
180
200
300 400 500 600 700 800 900
Wavelength (nm)
Relative intensity (-) .
O I
N2
Na I-1
Mg I-2
Ca II-1
Fe I-42
Fe I-41
Fe I-318
Fe I-15
Figure 4. Calibrated emission spectrum of the SPE091331 meteor.
Accepted for publication in Monthly Notices of the Royal Astronomical Society on
16 July 2018
17
Figure 5. Expected relative intensity (solid line), as a function of meteor velocity (in km
s
-1
), of the Na I-1, Mg I-2 and Fe I-15 multiplets for chondritic meteoroids (Borovička
et al., 2005). Crosses: experimental relative intensities obtained for the SPE091327 and
SPE091331 spectra.
