Meteor shower data from video observation, Part II Meteor showers that need careful attention

Abstract: The problem with the IAU MDCSD meteor shower table is that users may assume that the meteor showers listed in the table exist exactly as they appear in the list.  0027KSE is rated as an “established shower” but KSE03, which was used as a standard in the previous paper, has been deleted.  However, 0839PSR00, located next to KSE03, is in “working status” but is active too.  The relationship between KSE and PSR will be explained in detail below.  Although there are many similar cases, we will limit the scope related to this paper and explain those in which “Part I, Research methods and summary of survey results” alone may lead to misunderstandings.  When a simple explanation is sufficient, it has been supplemented in “Part III, Radiant point distribution map and activity profile.”  The following 14 cases will be discussed in this Part II.

1. 0027KSE and 0839PSR.
2. 0040ZCY and 0348ARC.
3. 0061TAH: How to name a meteor shower related to Jupiter family comet?
4. 0372PPS and neighbor activities
5. 0165SZC and 0370MIC
6. 0012KCG and neighbor activities: 0012KCG, AXD, 0073ZDR and 0197AUD
7. 0033NIA and 0215NPI
8. The tail of Orionids
9. 0081SLY00 and 0081SLY01
10. 0480TCA and 0481OML
11. The subdivisions of 0002STA and 0017NTA
12. 0338OER and 0490DGE
13. 0340TPY00 and 0340TPY01
14. 0096NCC and 0097SCC

 

1  0027KSE and 0839PSR

The first observations of KSE were just four photographic meteors captured by Super Schmidt cameras (McCrosky and Posen, 1959).  However, no corresponding meteor shower has been found in current video observations.  The position of the PSR matches the position of the photographed meteors, but its activity period is about 10 degrees later in solar longitude.  Figure 1 shows meteor activity in the range of λ_ʘ = 10~30° centered on PSR (λ–λ_ʘ, β) = (211.69°, 34.29°).  Figure 1 (left) shows GMN observations, and Figure 1 (right) shows IAU MDCSD’s KSE with boxes (target), other meteor showers with crosses, and photographed meteors with circles (among them, those marked as KSE are circled in red).  The radiant points of IAU MDCSD that appear in Figure 1 (right) are shown in Table 1.

Although PSR seems to be able to be identified with KSE, the activity profile of PSR is narrow (see 0839PSR in Part III), and therefore the activity at the average KSE of photographic observation λ_ʘ = 14.7° is inconceivable.  IAU MDSD currently has three KSE registrations, but both KSE00 and KSE01 are based on these four photographic meteors.  KSE02 is observed by CAMS at the upper left of the 3-degree circle, and it can be assumed that this is a combination of PSR and the activity at the upper left of the 6-degree circle in Figure 1 (left).  This 6-degree circle activity corresponds to KSE03 observed by CAMS (deleted in the current IAU MDCSD).  For reference, Figure 2 shows the activity profile estimated by performing the same processing as for other meteor showers based on KSE03.  Many radiant points can be obtained in this region through both video and photographic observations (Figure 1 (right)).  What was identified as a KSE by photographic observations may be a chance association of sporadic meteors, or it may have been active half a century ago and is no longer visible.

SonotaCo Net and GMN both have PSR.  Interestingly, GMN uses KSE03, which has now been deleted from the IAU MDCSD, as the KSE entry.

Table 1 – The radiant points of IAUMDCSD and four photographic KSE meteors (circles in red in Figure 1 (right)). Code for photographic meteors, see Koseki (2009).

Code	λʘ	λ–λʘ	β	vg	Distance	Angle	x	y
0027KSE00	14.7	207.7	35.1	45	3.36	285	3.26	0.84
0517ALO00	15.5	226.9	22.1	55.7	18.06	128	-14.18	-11.19
0027KSE01	15.7	209.9	33.3	45.01	1.84	236	1.53	-1.03
0841DHE00	19.5	232.1	46.3	49.5	19.53	46	-14.07	13.54
0027KSE02	20	213.7	36.6	46.7	2.79	35	-1.6	2.29
0836ABH00	20.3	223.1	44.6	47.5	13.5	37	-8.12	10.79
0839PSR00	25.1	211.7	34.3	46.3	0	0	0	0
H1-10366	11.7	212.2	37.5	42	3.21	7	-0.41	3.18
H1-10389	12.7	212	35.6	44.4	1.29	10	-0.22	1.28
H1-10099	16.7	206.5	33.1	46.5	4.49	256	4.36	-1.1
H1-7092	17.7	201.2	31.9	46.7	9.14	258	8.93	-1.97

 

 

 

2   0040ZCY and 0348ARC

ZCY (zeta-Cygnids) was originally numbered #40 for two similar meteors out of 413 photographed meteors measured by Jacchia and Whipple in their “precision orbit” (Jacchia and Whipple, 1961).  Jenniskens combined this with radar observations of Sekanina (1976), which was more than 10 degrees away (Jenniskens, 2006).  Currently, an activity different from the photographic observation #40 is called 0040ZCY.

Figure 3 (left) shows the radiant point distribution by GMN for the period λ_ʘ = 0° to 50°, centered on (λ–λ_ʘ, β) = (307°, 59°).  0040ZCY, 0348ARC (April rho-Cygnids), and 0409NCY (nu-Cygnids) all exist in a messy radiant point distribution.  If we divide the radiant point distribution into 5-degree increments based on the solar longitude, the ARC can be relatively clearly distinguished from surrounding activities.  On the other hand, the activity of ZCY appears to be divided into two groups, one around λ_ʘ = 15° (ZCY01) and one around λ_ʘ = 30° (ZCY02), based on the activity profile.

 

For this reason, this paper divides the activities into three: ZCY01 (λ_ʘ = 5°~25°), ZCY02 (λ_ʘ = 20°~40°), and ARC00 (λ_ʘ = 30°~50°).  Figure 3 (right) represents the movement of the radiant point during each period.  ZCY01 and ARC00 are moving from right to left (west to east) on the diagram, but ZCY02 is moving strangely, almost stationary, and moving from bottom to top (slightly left to right).  However, it is ZCY02 whose activity profile shows a clear increase and decrease.

Considering the radiant shift, the activities of ARC and ZCY02 are close in the range of λ_ʘ = 30° to 35°, and the possibility that ZCY01 is connected to ARC via ZCY02 cannot be denied.  The strange movement of the radiant point of ZCY02 may be due to interference between ZCY01 and ARC.  The activity profiles of ZCY01 and ARC are influenced by the activity of ZCY02.

As seen in Figure 3 (left), the surrounding sporadic meteors are highly active, and further observations are required to draw firm conclusions.  0409NCY might be part of the sporadic meteor activity or ZCY.

Neither ZCY nor ARC appears in the J14 list of SonotaCo net.  GMN lists two, but ZCY is grouped as one.

3   0061TAH: How to name a meteor shower related to a Jupiter family comet

In 2022, meteoroid particles ejected from 73P/Schwassmann-Wachmann 3 encountered Earth, resulting in an active meteor shower (Koseki, 2022).  However, it is not appropriate to call these TAH (tau-Herculids).

One is that TAH is a meteor shower that was detected and named by Southworth and Hawkins (1963) from photographic observation using D_SH and has a very large spread of radiant points.  Figure 4 (left) shows the distribution of radiant points obtained by photographic observations with IAU MDCSD radiants during the period from λ_ʘ = 57.6° to 87.6°, centered at (λ–λ_ʘ, β) = (135.51°, 54.79°) of TAH00.  Tau Herculids was named after the two photographic meteors marked with diamonds in Figure 4 (left).  Later, Lindblad (1971) thought that the meteor shower consisting of 14 photographed meteors marked with plusses was the same, and this also came to be called tau Herculids (TAH00).  However, the meteors photographed with diamonds were observed at λ_ʘ = 89.40° and λ_ʘ = 93.80°, respectively, and appeared much later than TAH00.  This identification itself is problematic, but the photographic meteors spread over a radius of nearly 20 degrees.  Figure 4 (right) shows meteors observed by GMN during the same period, and the activity area observed in 2022 is visible in the lower right.  On the other hand, there is no noticeable concentration of video meteor radiants around TAH00.  This is a good example of how it makes a big difference whether a meteor stream is defined by orbit (D_SH, Southworth and Hawkins, 1963) or by radiant distribution and geocentric velocity.

Second, the orbits of comets and meteor showers that approach Jupiter often change greatly, and the position of the radiant point also changes significantly.  Table 2 shows the positional relationship of the radiant points with τ Herculis, which is the origin of the name, as the center.  H2-7920 and H2-12711 are the meteors that gave rise to the name tau Herculids, and TAH00 and TAH02 are meteor showers registered in the IAU MDC.  GMN is the result of observation by GMN in 2022 (Koseki, 2022), and 2022–2049 is the predicted value mentioned in Jenniskens’s book (Jenniskens, 2006).  The general principle that radiant points are named after the names of nearby stars breaks down significantly.  It is not uncommon for the radiant to move so far from its original location that it no longer lives up to its name when its orbit approaches Jupiter.  Currently, the IAU MDCSD does not use the name of the parent object, but this needs to be reconsidered.

Finally, it should be emphasized that this data is from 2022 and does not appear every year.  This means that the position of the radiant point and the activity curve will be different the next time when it appears.

Table 2 – The positional relationship of the radiant points with τ Herculis.

Source	a	d	Distance	Angle
22 tau Her	244.9	46.3
H2-7920	258.9	50.3	10.1	61.4
H2-12711	238.2	46.3	4.7	271.7
0061TAH00	228.5	39.9	13.6	247.8
0061TAH02	230.4	44.8	10.3	266.8
GMN	208.9	28	33.6	249.8
2022	210	27.4	33.3	247.7
2027	200.4	10.2	52.2	240.8
2049	200	9.3	53.2	240.5

 

4    0372PPS and neighbor activities

The radiant point distribution for the period λ_ʘ = 45° to 125° centered at (λ–λ_ʘ, β) = (282.4°, 16.4°) is shown in Figure 5 (left).  The center is PPS (phi-Piscids) and the bottom left is ETA (eta-Aquariids).  It is as if there is activity extending upward from ETA through PPS.  There is an existence called “the tail of Orionids” (Jenniskens et al., 2016a) and it can also be compared to water flowing from an aquarium to fishes (as a constellation, water flowing out of Aquarius flows into the mouth of Piscis Austrinus).  The question of how much of this flow should be considered as PPS activity is complicated, similar to the question of how to demarcate the activities within the “the tail of Orionids”.

If the radiant point at λ_ʘ = 85° is (λ–λ_ʘ, β) = (285°, 13°), find the movement of the radiant point so that the regression line converges as in the case of other meteor showers.  This operation was repeated with the next radiant point located 5 degrees before and after the solar longitude.

The results for the ecliptic latitude of the radiant point are shown in Figure 5 (right).  The activity with λ_ʘ < 85° appears to be different from the activity that precedes it.  How this activity with λ_ʘ < 85° is related to ETA remains a future issue.  Even when λ_ʘ > 85°, the movement of the radiant point (the line from λ_ʘ = 110° to 120°) calculated around λ_ʘ = 115° is heterogeneous.  If we investigate the movement of the radiant point for λ_ʘ = 115°~125° with
(λ–λ_ʘ, β) = (279.0°, 16.0°) as the center, we can find the movement indicated by plusses in the figure for λ_ʘ = 115°~125° (in the figure, this result is extrapolated 5 degrees forward and backward).  The radiant point distribution spreading from the center to the lower right in Figure 5 (left) corresponds to this movement.  In this paper, this is called PPS_1, and the period excluding this period, shown by the red curve in Figure 5 (right), is called PPS_0.

5  0165SZC and 0370MIC

In the current IAU MDCSD, what should be classified as 0370MIC (Microscopiids) is placed in 0165SZC (Southern June Aquilids).  As shown in Table 3, 0165SZC00, 01 is completely different from the reports below.  It is clear that 165SZC02 and below are the same activities as 0370MIC00.  This is thought to be because the degree of attention differs depending on whether the shower status flag (s) is 1 (established shower) or 0 (working list).  0370MIC00 was reported in 2010, and subsequent reports below 0165SZC02 should be included in 0370MIC.

 

Table 3 – Confusion between SZC and MIC in IAUMDCSD.

Code	s	α	δ	vg	λʘ	λ–λʘ	β	References
0165SZC00	1	304.8	-33.92	33.17	79.7	219.5	-13.94	1] Gartrell & Elford, 1975
0165SZC01	1	304.7	-32.8	38.6	80.5	218.89	-12.83	2] Brown et al., 2008
0165SZC02	1	319.3	-27.6	39.2	104	209.24	-11.26	3] Jenniskens et al., 2016
0165SZC04	1	320.4	-26.5	39.9	106.5	208.03	-10.51	5) Shiba, 2022
0370MIC00	0	320.3	-28.3	38	104	209.87	-12.2	1] Brown et al., 2010

 

Both 0165SZC01 and 0370MIC00 were observed by CMOR, and even now, the CMOR image clearly shows that SZC is a completely different meteor shower from MIC (Figure 6 (left)).  Note that the activity near the original SZC, λ_ʘ = 80°, was short-lived, and only a few meteors were captured by video observations.  Probably SZC has many faint meteors.  Conversely, MIC is clearly captured in video observations, but not so clearly in CMOR observations (Figure 6 (right)).

In GMN, MIC’s activities are referred to as SZC, and does neither appear in SonotaCo net’s J14 list.

6   0012KCG and neighbor activities: 0012KCG, AXD, 0073ZDR and 0197AUD

There is considerable confusion about the meteor showers in and around KCG (kappa-Cygnids).  First of all, it is important to note that KCG is active on an approximately 7-year cycle, and its activity is rarely seen in normal years.  The AXD (August xi Draconids: this is the author’s tentative name because nothing corresponding to IAU MDCSD has been observed) is located several degrees west of KCG and shows weak activity every year.  In GMN observations, there are more AXD than KCG, except in 2021, when KCG was active.  Figure 7 will be explained in detail later, but of the two radiant point groups seen in both figures, the left one is KCG and the right one is AXD.  In the current IAU MDCSD, KCG reports are inconsistent due to confusion with AXD.

The second thing that has caused confusion is that the IAU MDC has been misclassifying ZDR (zeta-Draconids) and AUD (August Draconids).  ZDR and AUD are listed as shown in Table 4 now. However, the Jenniskens meteor shower table (Jenniskens, 2006), which is the prototype of IAU MDC, covers slightly different material.  In this earliest meteor shower table, L1-167 and S3-142 in Table 5 were listed as ZDR observations, and both S3-147 and S3-149 were listed as AUD.

 

Table 4 – Meteor showers listed as ZDR or AUD in IAU MDCSD.

Code	s	α	δ	vg	λʘ	λ–λʘ	β	References
0073ZDR00	0	261.7	67.8	22.36	122	33.15	86.55	1] Molau & Rendtel, 2009
0197AUD00	1	272.45	64.91	17.3	141.9	160.51	88.06	1] Sekanina, 1976
0197AUD01	1	271.7	58.9	21.1	143	133.57	82.3	2] Jenniskens et al., 2016
0197AUD03	1			21	149			4) Shiba, 2022

Table 5 – Confusion in ZDR and AUD. For the source, see Koseki (2009).

Source	α	δ	vg	λʘ	λ–λʘ	β	Shower
L1-167	260	30	18	135	120.6	52.9	θ-Herculids
S3-142	303.2	42.7	17	139.7	184.1	60.1	Gamma-Cygnids
T1-110	270.7	54.1	21.9	148.4	123.4	77.5	ζ-Drads
L1-207	269	59	24	149.5	116.6	82.4	ζ-Draconids
S3-147	271.3	65	23.6	140.8	148.7	88.4	August Draconids
S3-149	272.4	64.9	17.3	141.2	160.6	88.1	φ-Draconids
Denning	260.5	63.3					ζ-Draconids

Table 6 – Definition of KCG and AUD by GMN.

Code	λʘmin	λʘref	λʘmax	λ–λʘ	D(λ–λʘ)	b	Db	vg	Dvg
KCG_1	93.1	113.6	125	157.943	-0.21	46.628	0.846	18.511	0.039
KCG_2	125	140.1	150	162.943	0.733	70.573	0.634	22.312	0.202
KCG_3	150	154.7	167.1	187.379	3.3	78.47	0.219	25.638	0.264
AUD_1	130.7	142.7	148	144.446	-0.468	79.238	0.881	21.114	0.184
AUD_2	148	153.5	164.9	57.173	-2.675	81.706	-0.885	21.142	-0.199

 

The scope of ZDR in the earliest table is ambiguous (L1-167 and S3-142 in Table 5), and the current IAU MDCSD ZDR is far from them.  The existence of the latter cannot be confirmed at all in past photographic observations or modern video observations.  However, there are photographic observations (T1-110 and L1-207 in Table 5) that can be identified as ζ-Draconids that appear in the classic Denning meteor shower table (Denning, 1899).  Had the IAU MDCSD adopted either of these studies, the situation would have been different.

S3-147 and S3-149 in Table 5, which are listed as AUD in the earliest tables, are both from Harvard radio observations, and the radiant points are almost the same, with only a slight difference in geocentric velocity.  It is unclear why IAU MDSD did not adopt S3-147 (August Draconids), which is the origin of the name AUD.  In addition, the radiant points of the current IAU MDC AUD00 (S3-149) and AUD01 listed above are several degrees apart, and there is also a difference in geocentric velocity, so there are some doubts about their identification.

In addition to the confusion of IAU MDC, there is also the problem of the shape of the radiant point distribution, as seen in Figure 7.  Figure 7 plots all the radiant points observed by GMN during the period λ_ʘ = 120° to 170°, centered on (λ–λ_ʘ, β) = (145°, 75°).  The two radiant point distributions are each curved.  Figure 7 (right) shows only the meteors classified to be KCG or AUD by GMN.
Table 6 quotes how GMN represents KCG and AUD, and GMN divides KCG into three parts and AUD into two parts.  λ_ʘmin and λ_ʘmax indicate the lower and upper limits of the respective periods.  λ_ʘref is the representative value for each period, and the values of λ–λ_ʘ, β, and v_g correspond to it.  Δ(λ–λ_ʘ), Δβ and Δv_g indicates the amount of change depending on the solar longitude.

 

 

As for the curve of this radiant point distribution, interestingly, a series of radiant points can be traced even before λ_ʘ = 93.1°, which GMN considers to be the start of KCG activity, as shown in Figure 8.  Figure 8 shows the radiant distribution for the period from λ_ʘ = 55° to 135°, centering on (λ–λ_ʘ, β) = (160°, 35°).  The radiant points at the top center of the figure represent the early activity of KCG.  The radiant density distribution decreases towards the center of the figure, but it appears to extend further down to the ecliptic showers (0456MPS, 0150SOP).

One idea is to set multiple definitions for a single meteor shower like GMN, but on the other hand, it is also possible to break them down into independent activities.  In this paper, we will not discuss KCG_1 and KCG_3 proposed by GMN as future issues.  In addition, AUD_1 and AUD_2 are divided into two meteor showers, AXD and ZDR, respectively.  This classification into AXD and ZDR follows the previous meteor shower table based on SonotaCo net data and the analysis using EDMOND data (Koseki, 2020).

Neither AUD nor ZDR is featured in SonotaCo net’s J14 list.  It should also be noted that the definition of KCG is different between the J5 list which was applied to the orbit catalogue until 2020 and the J14 list (KCG_ja) in the SonotaCo net shower table, as shown in Figure 9.

 

7   0033NIA and 0215NPI

NIA stands for “Northern iota-Aquariids”, while NPI stands for Northern delta-Piscids.  Although this paper assumes that NIA and NPI should be unified, the two are often separated, including in the IAU MDCSD.  It is necessary to explain the cause of this confusion.

The “Northern ι-Aquariids” came to attract attention due to research by Wright et al. (1957) using Harvard photographic observations.  They linked the detected meteor activity to the ι-Aquariids reported by McIntosh (McIntosh, 1935) in New Zealand.  It has been thought that the northern branch of the ι-Aquariids (also the southern branch) is active from late July to early August, almost the same period as the group of the δ-Aquariids.  The early radio observations by Ellyett & Roth (1955) cited by Wright et al. (1957) were also from late July to early August.  It is true that Wright et al.’s observations also include meteors in the range of λ_ʘ > 145°, but they should be distinguished from “original ι-Aquariids”.  Table 7 shows the entries reported to be part of the ““Northern ι-Aquariids” based on observations in the 20^th century, and the top three correspond to “original ι-Aquariids”.  The bottom three seem to have been named after the “original ι-Aquariids” even though NPI has been observed.

The NIA section of the IAU MDCSD contains a mixture of reports that were influenced by the “original ι-Aquariids” and reports that actually refer to NPI activities.  Table 8 shows all NIA and NPI reports listed in the IAU MDCSD.

It is thought that NIA00, 01, and 04 were attempts to observe this “original ι-Aquariids”.  The remaining NIA02, 03, 05, and 07 are reports after NPI00-02, and should be included in NPI.

Both GMN and SonotaCo Net have confusion in their treatment of NIA and NPI, and both treat them as separate groups.  However, as shown in Table 9, the estimated value from the radiant shift that combines NIA and NPI in this paper (shown as NIA + NPI) sufficiently represents the radiant points of both, and NIA and NPI should be treated as one activity.

Table 7 – Various “Northern ι-Aquariids”. For No., see Koseki (2009).

No.	α	δ	vg	λ–λʘ	β	e	q	i	ω	Ω	λʘ	Stream
LE-313	326.1	-3.4	39	208.8	9.7	0.94	0.1	28.9	328.8	118.3	118.3	Northern i-Aquariids?
K1-91	321.7	-7.8	35	200.8	6.9	0.89	0.2	12	313	120.7	120.7	N i-Aquariids
NI-61.7.11	326.9	-12.1	30	199	1.2	0.85	0.234	6.9	312.5	126	126	N.i-Aquariids?
S2-50	352.5	-0.8	28.2	200.6	2.2	0.823	0.242	3.2	313.5	152.2	152.2	Northern i-Aquariids
S3-159	350.1	0.6	26.1	198.1	4.4	0.777	0.302	5.2	307.4	153.1	153.1	Northern i-Aquariids
LI-78	354.6	1.3	31	193.5	3.3	0.83	0.326	4	299.7	162.1	162.1	Northern i Aquariids

 

Table 8 – All entries of NIA and NPI in the IAU MDCSD; “ot” means observation technique.

Code	s	a	d	vg	λʘ	λ–λʘ	b	Notes	ot	References
0033NIA00	1	327.66	-5.88	31.2	147.7	180.11	6.76	*1		1] Cook, 1973
0033NIA01	-2	328	-4.7	27.6	145.1	183.44	7.75	*1		2] DMS 2001
0033NIA02	1	356	3	28.6	159.5	198.02	4.34	*1	R	3] Brown et al., 2008
0033NIA03	1	355.4	3.4	28.7	159	198.13	4.95	*1	R	4] Brown et al., 2010
0033NIA04	1	334	-8.3	27.19	142	190.89	2.3	*1	T	5] Molau et al., 2012
0033NIA05	1	346.7	-1.2	31.3	148	199.3	4.14	*1	T	6] Jenniskens et al., 2016
0033NIA07	1	2.3	4.9	29.7	166.9	197.16	3.58		T	8) Shiba, 2022
0215NPI00	2	0.84	3.74	27.4	168.3	193.96	3.1	*2	R	1] Sekanina, 1973
0215NPI01	2	9.15	7.04	25.6	173.5	197.67	2.85	*3	R	2] Sekanina, 1976
0215NPI02	2	7.64	7.14	30.4	173.3	196.54	3.53	*4	P	3] Porubcan & Gavajdova, 1994
0215NPI03	-7	9.2	7.7	31.2	174.4	197.08	3.43	*5		4] Jenniskens, 2006
0215NPI04	2	10.2	8.6	28	176	196.75	3.87	*6	T	5] Jenniskens et al., 2010
0298IAQ00	-2							*7		1] Jenniskens, 2006

Notes:

*1: Member of 298/IAQ complex
*2; In Sekanina 1973, the shower name is Piscids (p. 257 & 260), member of 030/PSC
*3: In Sekanina 1976, the shower name is Piscids (Tab. VI, p. 285) , Member of 030/PSC
*4: In Porubcan & Gavajdova 1994, the shower name is delta-Piscids , Member of 030/PSC
*5: No original reference, member of 30/PSC
*6: ? Encke complex, member of 30/PSC
*7: Group members: 33/NUA, 3/SIA; removed, empty record; NUA is a misprint of NIA.

 

Table 9 – Comparison of SonotaCo Net’s J14 list, GMN’s list, and this article’s estimated value obtained by unifying NIA and NPI.

Code	Source	λʘ	λ–λʘ	b	a	d
NIA	GMN	162.6	197.19	3.893
	NIA+NPI	163	197.5	3.8	359	3.7
	SonotaCo	151.8634			350.535	-2.48922
	NIA+NPI	152	199.6	3.9	350.8	0.2
NPI	GMN	183.6	191.771	3.655
	SonotaCo	182.1232			12.66271	9.177
	NIA+NPI	183	193.7	3.8	14	10.1

 

8   The tail of Orionids

Figure 10 shows the radiant point distribution observed during the period from λ_ʘ = 130° to 240°, with (λ–λ_ʘ, β) = (254°, –17°) as the center and reveals unique meteor activity series: the tail of Orionids (Jenniskens et al. 2016a).  On the left is GMN’s video observation, and on the right is the distribution of meteor showers registered with the IAU MDCSD.  Table 10 gives the radiant points of the distribution map in Figure 10 (right).

The underlined showers are referred to as “The Halley Complex” in the IAU MDCSD.  Although not shown in this table, 0719LGM00 (λ_ʘ = 232°, λ–λ_ʘ = 234.06°, β = –5.01°) is also included in this group.    RER and PSO look like forked tails.

There is no general standard as to what is considered an independent activity.  In addition to ORI, this article covers ERI, PSO, and NUE, which are rated 8 or higher on a 10-point scale in our previous research (Koseki, 2023c).

A band of weak radiant points can be seen to the right of “the tail of Orionids”.  0194UCE00, 0583TTA00, and 1142SNT00 correspond to this.  Figure 11 represents the radiant point distribution and activity curve based on TTA taking the radiant shift into account.  Although the radiant distribution looks like a single meteor shower, the activity profile suggests multiple activities.  Even if this band of radiant points has some common origin, it would take some discussion to recognize it as a single meteor shower.  It is interesting that there are other bands of radiant points besides the “tail of Orionids”.  There are several other examples where “tails” or “bands” are similarly observed, so please refer to those as well, see: Section 4 “0372PPS and neighbor activities”, Section 6 “0012KCG and neighbor activities: 0012KCG, AXD, 0073ZDR and 0197AUD”, Section 12, “0338OER and 0490DGE”.

 

 

Table 10 – Radiants around the tail of Orionids in the IAU MDCSD plotted in Figure 10 (right).

Code	λʘ	x	y	Code	λʘ	x	y	Code	λʘ	x	y
0466AOC01	136.8	3.47	6.69	1087OOE00	167.3	4.69	-5.25	0718XGM00	206	3.1	6.4
0191ERI02	137	-5.59	-10.37	0337NUE00	167.9	-4.92	-3.74	1198XRO00	207.1	8.3	9.11
0535THC00	137	12.98	-1.86	0337NUE02	168.6	-4.51	-4.07	0008ORI03	207.5	6.89	9.04
0738RER00	137	-9.48	-3.36	1142SNT00	171.2	4.47	1.47	0008ORI04	207.9	6.52	9.07
0191ERI00	137.5	-5.97	-11.75	0595TTT00	175	12.5	13.33	0008ORI05	208	6.6	8.77
0191ERI01	137.6	-5.87	-10.45	0430POR00	178.4	-2.09	2.8	0008ORI01	208.6	7.33	9.45
0466AOC02	138	4.24	5.46	0896OTA00	179.3	-13.37	11.14	0008ORI00	208.7	7.41	9.43
0466AOC00	138.5	3.74	5.53	0211AOR00	182.8	-9.51	2.38	0008ORI06	209	7.24	9.27
0194UCE00	145.7	4.22	-0.17	0876ROR00	185.3	1.15	-1.87	0008ORI02	209.8	7.68	9.67
0193ZAR00	146.7	-10.39	12.73	0479SOO00	185.6	0.34	6.06	0232BCN00	214	-4.63	-10.97
0873OMI00	152.8	10.71	-4.18	0479SOO01	185.7	-0.62	4.49	0558TSM00	221	-5.7	-9.66
0552PSO01	159	-14.17	-7.94	0225SOR01	187	-6.2	-6.04	0243ZCN00	225	-0.64	10.94
0337NUE03	163	-3.16	0.72	0479SOO02	187	0.04	6.35	0558TSM01	227	-4.06	-8.46
0583TTA00	164	4.19	-0.44	0225SOR00	191.7	0.14	-9.38	0245NHD00	234.8	-5.32	-6.81
0337NUE01	165	-13.36	-5.8	0226ZTA01	196	3.79	8.28	0246AMO00	239	13.48	-3.43
0552PSO00	166.3	-13.42	-7.6	1090EOR00	196.5	12.29	-7.69	0246AMO01	239.3	13.44	-3.47
1088SEE00	166.5	13.51	-6.67	0227OMO00	206	-2.81	-7.33	1196ZCM00	239.8	13.64	-3.28

 

 

 

9  0081SLY00 and 0081SLY01

The confusion began when 0081SLY was considered a single activity by the same observer (Molau and Rendtel, 2009).  In Figure 13 (left), the upper left of the 6-degree circle is SLY00, and symmetrically, the group of spread radiants at the lower right of the circle is SLY01.  Not only are they more than 10 degrees apart in position, but there is also a 20-degree difference in solar longitude.  For this reason, SLY is on the working status, and as a result, the IAU MDCSD has given each of the two SLYs different numbers and names: 0705UYL00 = SLY00 and 0424SOL00 = SLY01.  0425PSA01 and 0613TLY00 may also be included in the SLY01 activity.

Lindblad’s “Lyncids” (Lindblad, 1971), which corresponds to SLY01, is used as 0081SLY in the Jenniskens meteor shower table (Jenniskens, 2006) , which is the prototype of IAUMDC.  Molau and Rendtel (2009). probably detected SLY01 as a counterpart to this observation and found SLY00 as another candidate.  In Figure 13 (right), triangles are meteor showers that are not listed in the IAU MDCSD, and the filled triangle are the “Lyncids”. Among the circles in the photographic observations, two meteors that Lindblad identified as belonging to the “Lyncids” are indicated by filled circles.

SonotaCo net’s J14 list takes UYL, but not SLY01.  GMN treats SLY01 as SOL.  In this paper, SLY00 will be referred to as SLY_0 and SLY01 will be referred to as SLY_1.

 

 

10   0480TCA and 0481OML

Contrary to SLY, confusion arose because the same observer (Rudawska and Jenniskens, 2014) separated 0480TCA and 0481OML into two separate activities, in this case.  Both TCA and OML are meteor showers detected by combining SonotaCo net and CAMS data.  Figure 14 shows the radiant distribution for the period λ_ʘ = 192°~232° centered on (λ–λ_ʘ, β) = (283°, 14°), and as can be seen, the two activities are continuous.  The radiant point on the lower right is due to early Leonid activity.

 

 

Both TCA and OML are on the working status in the IAU MDCSD, and a new meteor shower called 1114SGC (sigma1-Cancrids) has been added to the IAU MDCSD, which corresponds to TCA.

In GMN, the name OML is not used, and the activities at λ_ʘ = 178.5°~221.9° are referred to as TCA.  SonotaCo net’s J14 list features both TCA (λ_ʘ = 200.6°~208.1°) and OML (λ_ʘ = 216.8°~221.5°).

11   The subdivisions of 0002STA and 0017NTA

STA

IAUMDCSD annotates the following seven reports as “#2/STA component”: 0286FTA00、0625LTA00、0626LCT00、0627NPS00、0628STS00、0636MTA00、0637FTR00.  In addition to this, 0624XAR00 is also considered part of STA.  The SonotaCo net J14 list does not treat it as an independent activity and sets a long activity period of λ_ʘ = 181.57°~267.40°.  On the other hand, while GMN considers the above eight activities as activities independent of STA, it also treats STA activities during a period of λ_ʘ = 190° to 230° (see Figure 16 (left)).

As the author has argued many times, it is appropriate to think of STA in two parts (Koseki, 2012, 2020).  Just as Whipple divided the activity into October Arietids and Taurids in November (Whipple, 1940), it was also known from visual observations that the main maximum occurs in November after the less active maximum in October.  Figure 15 represents the radiant points in the range of λ–λ_ʘ = 180°~205° and β = –8~–2 during the period of λ_ʘ = 185°~245°.  As in the previous paper (Koseki, 2021), the group shown by the straight line is called STA_SE, and the group shown by the broken line is called STA_SF.  STA_SE corresponds to October Arietids, and STA_SF corresponds to Taurids in November.  STA_SF shows significant activity in the years for which David Asher noted that the Taurids activity intensifies (Asher and Clube, 1993), but STA_SE shows no change.  These two activities must be considered separately because they show clear differences in the magnitude ratio and the beginning height of the meteor path (Koseki, 2023a).

 

 

NTA

Similar to STA, there are eight reports in NTA with the annotation “#17/NTA component”: 0629ATS00, 0630TAR00, 0631DAT00, 0632NET00, 0633PTS00, 0634TAT00, 0635ATU00, 0726DEG00.  Even in this case, the SonotaCo net J14 list lumps together the activities with λ_ʘ = 199.69°~276.42°, but while GMN treats the eight activities independently, it also monitors the activities of NTA during λ_ʘ = 217°~ 241° (see Figure 16 (right)).

 

 

Table 11 – The IAU MDCSD meteor showers existing within the range of Figure 17 (left).

Code	λʘ	λ–λʘ	b	vg	Distance	Angle	x	y
0002STA05	196	195.6	-4.2	28.2	5.89	7	-0.69	5.85
0028SOA01	196	196.8	-4.2	29	6.14	18	-1.86	5.85
0002STA03	196.5	195.2	-4.3	27.92	6.07	3	-0.37	6.06
0028SOA00	198.5	195.8	-2.8	25.6	8.94	9	-1.46	8.82
0902DCT00	202.1	194.4	-13.2	32.7	0.96	79	-0.94	0.19
0002STA09	202.4	195.2	-4.6	28.6	9.1	12	-1.86	8.91
0624XAR00	205	195.1	-4.6	28.5	10.18	13	-2.32	9.92
0086OGC00	206.7	199.2	-24.5	3.3	11.5	147	-6.34	-9.6
0338OER03	230.5	184.6	-20.8	28	1.5	190	0.25	-1.48
0338OER01	232	185.7	-20	28.5	1.33	105	-1.28	-0.33
0338OER00	234.7	183.5	-21.8	26.9	1.33	175	-0.11	-1.32
1115NXE00	241.88	180.7	-24.5	26.06	1.42	183	0.08	-1.42
0490DGE00	249.3	176.1	-35.3	23.8	8.67	192	1.79	-8.48
0490DGE01	254	176.8	-29.9	24.7	0.1	178	0	-0.1
0709LCM01	273.3	175.1	-45.9	25.1	0.47	105	-0.46	-0.12
0709LCM00	286	176.4	-54.6	25.4	2.46	329	1.27	2.11
0308PIP00	290.7	198.8	-63.3	33	8.68	120	-7.51	-4.35

 

12   0338OER and 0490DGE

OER has already been set as an established shower, but OER03 has been marked with “Continue to (#490 DGE) December delta Eridanids.”  It certainly looks like that, but in fact, meteor activity that is expected to continue ahead of it has also been captured.  Figure 17 (left) shows the radiant distribution for the period from λ_ʘ = 195° to 305°, with (λ–λ_ʘ, β) = (185°, –37°) as the center.  Although it is for such a long period, the radiant points are connected in an arc shape.  The radiant cluster at the top of the figure is the STA, and the OER starts its activity hanging from here.

Figure 17 (right) shows the integrated radiant distribution if the radiants move along this arc.  Many IAU MDCSD meteor showers exist within the range of this figure, as shown in Table 11.  Among these, the codes for those within 3 degrees from the center are shown in red.  Instead of DGE00 being removed, the activity 0709LCM is included.

 

 

Furthermore, GMN describes the activities after DGE as 0308PIP, but the descriptions from 0300ZPU00 to 0318MVE00 are fragmentary visual observation reports compiled by Jenniskens from his perspective (Jenniskens, 2006).  It would be unreasonable to think of 0308PIP as an extension of all activities after DGE.

Similarly, if we count the number of meteors and draw an activity profile along the arc, we get Figure 18.  If we look at the graph of the number of meteors Nr <= 3 within 3 degrees from the center, it seems that the activity is at its maximum around λ_ʘ = 230°, but when looking at DR3_10, the maximum is around λ_ʘ = 295°.  Considering that the position of the radiant has moved considerably south and the number of meteors detected from the Northern Hemisphere will decrease, it is impossible to judge changes in activity simply by the number of meteors.  On the other hand, during the first half of these meteor shower activities, there were strong activities such as not only STA but also MON and GEM, so caution is required when considering changes in DR.  The reason that DR3_10 decreases when λ_ʘ < 220° is due to the influence of STA, and when DR3_20 is used, the influence of GEM becomes strong around λ_ʘ = 260°.  Considering these constraints, this arc-like continuous activity can be thought of as a single activity or as a combination of multiple activities.  If we calculate the changes in the orbit by linking the arc-shaped activity, it appears that the perihelion direction and semi-major axis of the orbit remain fairly constant.  Problems remain unsolved as into how many parts it will be divided, and whether it can be considered as a whole.  As mentioned above it is currently unclear what the later stage of the activity was when the radiant point moved deep to the south, so future GMN activity in the southern hemisphere is expected.

GMN treats OER and DGE as one, but the SonotaCo Net J14 list only covers OER and does not mention DGE.  GMN considers the activity to extend up to λ_ʘ = 260.5°, but around this time the radiant distribution has entered the part where it moves southward in an arc shape.

13  0340TPY00 and 0340TPY01

The IAU MDCSD has three reports for 0340TPY.  The first one is from SonotaCo net in 2009, and the latter two are both from CAMS’s first report (Jenniskens et al, 2016b).  Figure 19 shows the radiant distribution for the period from λ_ʘ = 240° to 270°, centering on (λ–λ_ʘ, β) = (260°, –35°).  Of the two TPYs, the upper one is TPY01 and 02, and the lower one is TPY00.  Although the difference in position is not so large, the confusion started because the IAU MDC accepted the CAMS report as TPY01 even though they are about 15 degrees apart in solar longitude.  Because of the difference between TPY00 and TPY01, they were set as working status each, so a duplicate report of “a new meteor shower” was registered.

In the J14 list of SonotaCo net, TPY00 is just TPY and TPY01 and 02 are DMH.  However, in GMN, TPY00 is treated as DTP, and the pair of TPY01 and 02 is treated as TPY.  Since TPY00 is reported earlier than TPY01 and 02 and before DTP, it is appropriate to use TPY00 as TPY like SonotaCo net.

In addition, in the previous paper (Koseki, 2021), these two activities were distinguished as TPY_0 and TPY_3, but since TPY03 was deleted from the IAU MDCSD, TPY_0 will remain as it is, and what used to be called TPY_3 will be referred to as TPY_1 in this paper. A new report of TPY is registered in IAUMDCSD as TPY04 that is TPY_0.

14  0096NCC and 0097SCC

Figure 20 shows the radiant point distribution for every 10 degrees in solar longitude between λ_ʘ = 235° and 315°, centering on (λ–λ_ʘ, β) = (190°, 0°).  The radiant distribution shows that while the radiant points of STA and NTA are moving to the right on the diagram, what appears to be a collection of radiant points remains near the center.  Discussion is still ongoing as to whether these activities should be collectively called NCC or SCC, divided into several parts, or whether they should be called sporadics or ANT.  It cannot be called an “established shower” like given in the IAU MDCSD.

 

Table 12 – NCC and SCC in the IAU MDCSD; “ot” means observation technique.

Code	a	d	vg	λʘ	λ–λʘ	b	Notes	ot	References
0096NCC00	130	20	25.67	297	190.17	1.57	*1	V	1] Arlt R.,1995
0096NCC01	134.19	14.2	26.7	300.2	192.38	-2.94	*2	R	2] Nilsson, 1964
0096NCC02	126.72	19.92	28	297.1	187.11	0.73	*3	P	3] Lindblad, 1971
0096NCC03	124.83	20.92	25.8	292.9	189.35	1.3	*4	R	4] Sekanina, 1973
0096NCC04	130.52	19.71	26.4	297.1	190.62	1.42	*5	R	5] Sekanina, 1976
0096NCC05	131.4	17.6	27.73	299	190.08	-0.4	*6	V	6] Molau et al., 2013
0096NCC06	127.6	21.5	27.2	296	188.63	2.47	*7	T	7] Jenniskensetal., 2016
0096NCC08	128.6	20.4	28.2	296.9	188.9	1.63		T	9) Shiba, 2022.
0097SCC00	131.68	11.91	24.36	305.7	185.15	-5.82	*8	P	1] Terentjeva, 1989
0097SCC01	118.87	7.63	24	297	182.41	-12.91	*9	R	2] Nilsson, 1964
0097SCC02	131.5	10.6	26.43	298	193.02	-7.13	*10	T	3]Molau & Rendtel, 2009
0097SCC03	125	14.4	27	296	187.9	-5.02	*11	T	4] Jenniskens et al., 2016
0097SCC05	117.5	16.1	27.9	287.1	189.34	-4.85		T	6) Shiba, 2022.

Notes:
*1: In Arlt 1995 the shower name is delta-Cancrids, member of delta-Cancsrids group (#95 in 2006 PJ)
*2: In Nilsson 1964, Tab 4 radiant 61.1.1, member of delta-Cancrids group (#95 in 2006 PJ)
*3: member of 96
*4: In Sekanina 1973, the shower name is delta-Cancrids (p. 255 & 258) member of delta-Cancrids group (#95 in PJ 2006)
*5: In Sekanina 1976, the shower name is delta-Cancrids (Tab. VI, p. 274), member of delta-Cancrids group (#95 in PJ 2006)
*6: member of 95/DCA group
*7: ecliptic antihelion source, member of delta-Cancrids group (#95 in PJ2006)
*8: In Terentjeva 1989  in Tab.1 alpha-Cnc(a), member of delta-Cancrids group (#95 in PJ2006)
*9: In Nilsson 1964, Tab 4 radiant 61.1.2,, member of delta-Cancrids group (#95 in PJ2006)
*10: ecliptic antihelion source, twin of 204/DXL, member of delta-Cancrids group (#95 in PJ2006)
*11: ecliptic antihelion source, twin of 204/DXL, member of delta-Cancrids group (#95 in PJ2006)

 

Table 12 lists what is considered NCC and SCC in the IAU MDCSD.  The notes section is lively, showing that this activity can be interpreted in any number of ways.  It can be seen that various interpretations have been made by researchers since the 1960s (Koseki, 2023b).  The fact that Terentjeva’s most important work is not cited in the IAU MDCSD is an indication of the bias of the material; Терентьева, А.К., 1966, ‘Исследование Метеоров’, No.1, 62-132.

In any case, (λ–λ_ʘ, β) = (190°, 0°) is at the center of ANT, and it is unclear what NCC or SCC refers to.  Although NCC and SCC were listed in the previous meteor shower table (Koseki, 2021), they are excluded in this article. NCC and SCC are not featured in SonotaCo net J14 list either.  On the other hand, GMN lists both.

Acknowledgment

This paper would not have been possible without the dedicated efforts of the observers, and the author would like to express his heartfelt gratitude to the members of SonotaCo net and GMN (Vida et al., 2019; 2020; 2021).

References

Asher D. J. and Clube S. V. M. (1993). “An extraterrestrial influence during the current glacial-interglacial”. Quarterly Journal of the Royal Astronomical Society., 34, 481–511. See also “Taurid swarm years”, http://www.cantab.net/users/davidasher/taurid/swarmyears.html.

Denning W.F. (1899). “General Catalogue of the Radiant Points of Meteoric Showers and of Fireballs and Shooting Stars observed at more than one station”. Memoirs of the Royal Astronomical Society, 53, 201–293.

Ellyett C. D. and Roth K. W. (1955). “The Radar Determination of Meteor Showers in the Southern Hemispheres”. Australian Journal of Physics, 8, 390–401.

Jacchia L. G., and Whipple F. L., (1961). “Precision orbits of 413 photographic meteors”. Smithsonian Contributions to Astrophysics, 4, 97–129.

Jenniskens P. (2006). Meteor Showers and their parent comets, Cambridge.

Jenniskens P., Nénon Q., Albers J., Gural P. S., Haberman B., Holman D., Morales R., Grigsby B. J., Samuels D. and Johannink C. (2016). “The established meteor showers as observed by CAMS”. Icarus, 266, 331–354.

Jenniskens P., Nénon Q., Gural P.S., Albers J., Haberman B., Johnson B., Holman D., Morales R., Grigsby B.J., Samuels D., Johannink C. (2016b). “CAMS confirmation of previously reported meteor showers”, Icarus, 266, 355–370.

Koseki M. (2009). “Meteor Shower Records: A Reference Table of Observations from Previous centuries”. WGN, the Journal of the IMO, 37, 139–160.

Koseki M. (2012). “Three components of ‘Taurids’”, WGN, the Journal of the IMO, 40, 129–138.

Koseki M. (2020). “Three components of ‘Taurids’ II”, WGN, the Journal of the IMO, 48, 36–46.

Koseki M. (2021). “The activity of meteor showers recorded by SonotaCo Net video observations 2007–2018”. eMetN, 6, 91–246.

Koseki M. (2022). “Global Meteor Network: Outburst produced by dust from 73P/Schwassmann-Wachmann3”. eMetN, 7, 369–378.

Koseki M. (2023a). “Major meteor showers based on Global Meteor Network data”. eMetN, 8, 231–245.

Koseki M. (2023b). “Remaining problems in IAUMDC Shower Database (SD)”, eMetN, 8, 288–309.

Southworth R. B. and Hawkins G. S. (1963). “Statistics of meteor streams”. Smithsonian Contributions to Astrophysics, 7, 261–285.

Vida D., Gural P., Brown P., Campbell–Brown M., Wiegert P. (2019). “Estimating trajectories of meteors: an observational Monte Carlo approach – I. Theory”. Monthly Notices of the Royal Astronomical Society, 491, 2688–2705.

Vida D., Gural P., Brown P., Campbell–Brown M., Wiegert P. (2020). “Estimating trajectories of meteors: an observational Monte Carlo approach – II. Results”. Monthly Notices of the Royal Astronomical Society, 491, 3996–4011.

Vida D., Šegon D., Gural P. S., Brown P. G., McIntyre M. J. M., Dijkema T. J., Pavletić L., Kukić P., Mazur M. J., Eschman P., Roggemans P., Merlak A., Zubrović D. (2021). “The Global Meteor Network – Methodology and first results”. Monthly Notices of the Royal Astronomical Society, 506, 5046–5074.

Whipple F.L. (1940). “Photographic Meteor Studies. III. The Taurid Shower”. Proceeding of the American Philosophical Society, 83, No.5, 711–745.

Wright F. W., Jacchia L. G., & Whipple F. L. (1957). “Photographic ι-Aquariid meteors and evidence for the northern ι Aquariids”. Astronomical Journal, 62, 225–233.