Abstract: Examination of archived meteor orbits from the UKMON multi-station meteor survey in comparison to known cometary orbits via DJ criterion selection revealed meteor streaming associated with the Jupiter Family Comet 197P/LINEAR.  Extension to other multi-station meteor surveys led to a significant increase of candidate meteors helping to confirm matters.  The recent evolution of the cometary orbit suggests that this shower is not only new but may increase in activity in the years to come, with the possibility of the May iota Draconids being an early expression outlier of this stream also being discussed.

 

Methodology

Archival data from the UKMON meteor survey (e.g., Campbell-Burns and Kacerek, 2014) were obtained from the UKMON online public data archive with the orbital part of the data being analyzed utilizing the Jopek (1993) D criterion modification, henceforth referred to as DJ.  One analysis took the form of assessing the UKMON orbits against those of comets using a DJ upper threshold limit of 0.10.

After a reasonable match of ten meteor orbits were found against the Jupiter Family Comet 197P/LINEAR a wider DJ test was made using data from multi-station meteor survey publicly available data archives of SonotaCo Network (e.g., SonotaCo, 2009), CAMS (e.g., Jenniskens et al., 2018), EDMOND (e.g., Kornoš et al., 2014) and Global Meteor Network (Vida et al., 2019a; 2019b).  As various regional meteor surveys can not only provide their own dataset but contribute it to other surveys the combined datasets used in this search had the potential for some duplicates, accordingly the results were sorted on Right Ascension and any objects in the resultant output having a commonality of Right Ascension, Declination and Solar Longitude had one of the duplicates removed (this led to the removal of three orbits).  The various surveys have differing end dates for their public data releases, in the case presented here only GMN, SonotaCo and UKMON has so far provided data covering up until the end of 2021.

This resulted in a total of 161 meteor orbits meeting the DJ < 0.100 threshold for the 197P/LINEAR orbit used, of which 72 have DJ < 0.008 and 20 have DJ < 0.006.

As all the surveys have at least some regional aspects in global terms, with only some being truly global, leading to concomitant caveats with respect to nightly coverage due to local weather, as well as the dramatic increase in the number of cameras and sites used in most if not all surveys in very recent times, no year-by-year count of meteors is presented.  As survey temporal and spatial coverage increases and becomes more complete such comparisons may well be informative due to the evolution of this comet’s orbit, as outlined in the Discussion section.

 

Results

The ten UKMON discovery orbits are listed in Table 1 below.  Due to some surveys using similar software either currently and/or in the past there is a tendency for them to have similar if not identical styles for their identifiers.  Where relevant in Table 1 and also in the following Table 2 SonotaCo identifiers appear as is, the very similar EDMOND identifiers are preceded by the two-letter prefix ‘ED’ and the equally similar UKMON identifiers are preceded by the two-letter prefix ‘UK’ in order to clarify the provenance of the orbits.  At the time the data were procured GMN did not use a unique identifier and as such those orbits had a built-in running number identifier appended to them on import into a master orbits database created for analyses such as this.  This running number is in no way official.

Discussion

197P/LINEAR and its orbit

The original analysis used cometary orbits as a seed to check for potential comet–shower associations within UKMON orbit data, with 197P/LINEAR alone arising as a previously unknown candidate.  Whilst examining the data at the Minor Planet Center for this small and faint object it was noted that there were several different orbits provided since 2003 effectively representing the comet’s perihelion return nearly every five years.  Although somewhat inclined in its orbit the comet does nevertheless approach the orbit of Jupiter to within one Astronomical Unit (1 AU) at aphelion, having a Jupiter Family Comet Tisserand like value (TJ) of around 2.9.

Table 1 – The identifier, DJ criterion value relative to 197P for the UKMON orbits, radiant position as Right Ascension and declination in degrees, solar longitude λʘ in degrees, geocentric velocity vg in km/s, perihelion distance q in Astronomical Units, eccentricity e, inclination i in degrees, argument of perihelion ω in degrees and ascending node Ω in degrees are given for each associated meteor orbit followed by their mean and median value along with the standard deviation and finally the orbital details for 197P used in the test.

ID DJ R.A. Dec. λʘ vg q e i ω Ω
UK20200526_003101 0.088 235.4 53.7 64.962 16.3 0.9984 0.5873 24.15 196.1 64.97
UK20210530_235903 0.092 238.0 57.8 69.487 16.2 1.0082 0.5575 24.91 190.09 69.5
UK20200531_000246 0.054 240.0 60.2 69.741 17.8 1.0107 0.6135 27.39 187.42 69.75
UK20210531_235736 0.072 232.3 56.3 70.444 16.5 1.008 0.6376 24.13 189.97 70.46
UK20190601_235642 0.082 225.9 62.5 70.940 15.2 1.0141 0.6094 22.3 180.97 70.94
UK20210601_234528 0.077 223.1 60.5 71.394 15.4 1.0138 0.6446 22.13 182.38 71.41
UK20180604_001155 0.081 240.0 59.0 73.105 17.4 1.0108 0.6284 26.37 187.81 73.11
UK20210605_002040 0.092 240.2 59.3 74.291 17.7 1.0116 0.628 26.91 187.15 74.3
UK20210606_225702 0.098 241.6 64.6 76.150 18.3 1.0149 0.6088 28.51 180.47 76.16
Mean orbit 235.1 59.1 66.872 16.9 1.007 0.619 25.2 188.6 66.9
Median orbit 236.7 59.3 67.007 16.9 1.008 0.618 25.3 189.1 67
Stand. Dev. 6.3 4.2 5.333 1.1 0.007 0.034 2.1 5.9 5.3
197P/LINEAR 1.0599 0.6301 25.557 188.68 66.39

 

Table 2 – The identifier, DJ criterion value relative to 197P for all orbits, radiant position as Right Ascension and declination in degrees, solar longitude λʘ in degrees, geocentric velocity vg in km/s, perihelion distance q in Astronomical Units, eccentricity e, inclination i in degrees, argument of perihelion ω in degrees and ascending node Ω in degrees are given for each associated meteor orbit followed by their mean and median value along with the standard deviation, as well as the minimum and maximum value for all orbits and finally the orbital details for 197P used in the test.  The GMN running number is not official, SonotaCo orbits have no prefix, an ‘ED’ or ‘UK’ prefix denotes an EDMOND or UKMON orbit respectively.

ID DJ R.A. Dec. λʘ vg q e i ω Ω
ED20080523_224334 0.079 229.6 60.2 63.038 15.9 1.0101 0.5992 23.61 186.65 63.04
20090527_022105 0.092 234.9 52.4 65.459 15.9 0.9989 0.6431 22.38 195.43 65.46
ED20100524_220014 0.064 239.9 59.5 63.479 18.2 1.0075 0.6060 28.09 189.48 63.48
20100602_235220 0.058 234.0 62.4 71.825 16.9 1.0141 0.6482 25.16 181.14 71.83
ED060506MLA0027 0.083 241.7 65.3 75.116 16.5 1.0147 0.5848 25.39 179.77 75.12
ED20110522_222928 0.081 240.4 60.2 61.330 18.0 1.0076 0.6028 27.87 189.02 61.33
ED052425ZGR0004 0.095 243.0 60.7 63.173 19.1 1.0084 0.6021 30.00 188.58 63.17
CAMS8363 0.088 239.7 55.7 65.627 18.8 0.9996 0.6579 28.19 194.91 65.63
ED20110529_231653 0.094 228.1 55.0 68.085 16.4 1.0074 0.6998 22.93 189.94 68.09
ED20110603_003805 0.089 245.2 66.9 71.975 17.7 1.0142 0.5891 27.73 179.00 71.98
CAMS8414 0.082 224.6 59.9 72.315 15.2 1.0132 0.6008 22.22 184.40 72.32
ED20110604_015304 0.095 235.5 64.0 72.983 17.6 1.0143 0.7063 25.56 181.49 72.98
CAMS60415 0.094 231.8 52.6 58.610 16.4 0.9910 0.5817 24.07 199.26 58.61
CAMS60635 0.059 235.4 57.6 60.371 17.8 1.0014 0.6246 26.72 193.51 60.37
CAMS60798 0.051 234.4 57.4 61.539 17.2 1.0023 0.6083 25.84 193.22 61.54
CAMS60858 0.064 225.8 54.9 62.327 15.9 1.0021 0.6305 22.76 193.29 62.33
CAMS60876 0.077 239.2 55.3 62.371 17.8 0.9968 0.5957 27.10 196.63 62.37
CAMS61249 0.084 219.9 63.0 67.254 15.7 1.0132 0.6442 22.78 182.25 67.26
CAMS61346 0.077 225.8 63.2 68.165 15.5 1.0132 0.5885 23.27 182.91 68.17
ED20120529_215237 0.079 232.7 64.7 68.740 16.6 1.0137 0.5921 25.47 180.64 68.74
CAMS61674 0.058 235.6 62.2 70.119 16.8 1.0124 0.5856 25.75 185.29 70.12
CAMS62019 0.096 242.8 59.6 72.071 17.9 1.0094 0.5896 27.79 189.23 72.07
CAMS62848 0.097 230.3 64.1 78.650 16.8 1.0152 0.6267 25.28 179.59 78.65
CAMS116414 0.096 231.1 54.2 56.353 18.2 0.9916 0.6749 26.26 197.91 56.35
CAMS116669 0.092 234.3 52.2 57.486 17.4 0.9866 0.6036 25.73 200.85 57.48
CAMS116917 0.088 233.2 52.1 59.254 17.0 0.9890 0.6001 24.89 200.00 59.25
ED20130520_212457 0.082 232.1 59.7 59.826 17.1 1.0070 0.6181 25.80 189.24 59.83
20130521_205020 0.082 228.4 59.3 60.404 17.3 1.0080 0.6323 26.03 188.38 60.40
CAMS117442 0.053 230.8 57.4 63.078 16.3 1.0046 0.5995 24.26 191.85 63.07
CAMS117654 0.061 238.7 56.8 64.161 17.7 1.0016 0.6025 27.01 193.99 64.16
CAMS117745 0.064 223.2 59.5 65.970 16.2 1.0104 0.6652 23.28 186.74 65.96
CAMS117828 0.044 226.9 60.1 67.869 16.6 1.0111 0.6548 24.18 186.37 67.86
CAMS118015 0.086 227.8 54.6 69.021 15.6 1.0059 0.6166 22.43 191.54 69.02
CAMS118106 0.089 234.1 56.8 69.795 16.0 1.0070 0.5774 24.10 191.06 69.79
CAMS118212 0.085 223.9 56.4 69.947 16.1 1.0096 0.6804 22.71 188.28 69.94
20130531_214206 0.079 236.9 56.1 70.037 16.9 1.0078 0.5852 25.76 190.40 70.04
20130603_211321 0.072 231.4 57.0 72.893 16.7 1.0116 0.6386 24.76 186.84 72.89
CAMS118604 0.078 221.4 64.5 73.783 16.1 1.0145 0.6462 23.50 178.82 73.78
CAMS118684 0.098 227.4 63.2 74.670 15.3 1.0146 0.5688 23.10 181.02 74.67
CAMS187483 0.094 233.0 51.2 57.086 17.5 0.9840 0.6192 25.48 201.71 57.08
20140520_004224 0.089 237.3 57.7 58.388 16.9 1.0037 0.5901 25.51 191.85 58.39
CAMS366248 0.075 235.9 54.9 58.673 18.1 0.9940 0.6304 27.07 197.34 58.67
20140522_000305 0.066 235.8 55.1 60.286 16.7 1.0010 0.5928 24.94 193.95 60.29
CAMS188569 0.074 238.7 59.3 63.984 17.1 1.0062 0.5649 26.43 190.99 63.98
CAMS188636 0.056 230.0 60.6 64.719 16.2 1.0097 0.5972 24.26 187.56 64.72
CAMS188673 0.073 222.1 57.8 64.784 15.3 1.0088 0.6246 21.85 188.48 64.78
ED20140526_221937 0.082 225.3 62.7 65.384 15.6 1.0121 0.5963 23.24 184.21 65.38
ED20140526_231411 0.090 239.9 63.1 65.420 17.1 1.0112 0.5543 26.79 185.97 65.42
CAMS188822 0.090 227.5 55.3 65.623 15.1 1.0049 0.5782 22.03 192.14 65.62
ED20140528_003629 0.087 220.8 55.1 66.436 14.9 1.0076 0.6328 20.87 189.83 66.44
CAMS189072 0.099 235.0 55.3 66.633 16.0 1.0024 0.5602 24.11 194.09 66.63
CAMS189244 0.076 230.0 55.5 66.869 15.7 1.0048 0.5933 23.07 192.24 66.87
ED20140529_020818 0.073 243.2 59.2 67.457 18.6 1.0067 0.6115 28.79 190.80 67.46
CAMS189291 0.088 234.3 55.0 67.616 17.8 1.0021 0.6765 26.01 193.58 67.61
CAMS189423 0.054 227.0 57.1 67.820 16.0 1.0083 0.6373 23.19 189.34 67.82
CAMS189467 0.100 239.4 55.6 68.526 18.5 1.0016 0.6585 27.66 194.09 68.52
CAMS189531 0.074 224.7 61.0 68.680 15.2 1.0125 0.5921 22.49 184.72 68.68
CAMS189540 0.047 226.5 60.1 68.693 16.4 1.0115 0.6533 23.97 186.00 68.69
CAMS366360 0.079 243.1 60.5 69.302 17.9 1.0095 0.5806 28.03 188.77 69.30
ED20140531_035320 0.066 229.6 58.2 69.446 15.8 1.0097 0.5985 23.38 188.51 69.45
CAMS189805 0.089 221.5 65.8 70.432 15.7 1.0139 0.6135 23.23 178.72 70.43
CAMS190039 0.086 230.9 68.0 71.557 17.3 1.0138 0.6245 26.27 177.47 71.56
CAMS190065 0.058 230.3 60.5 71.596 17.1 1.0123 0.6621 25.20 185.54 71.60
CAMS190316 0.061 232.1 62.1 73.536 16.7 1.0137 0.6185 25.20 183.70 73.54
CAMS190680 0.097 238.8 61.1 75.484 17.7 1.0128 0.6243 27.12 185.65 75.49
CAMS190803 0.093 236.6 63.4 76.424 17.0 1.0146 0.5938 26.26 182.32 76.43
ED20140608_021817 0.100 239.5 64.8 77.045 17.6 1.0149 0.5960 27.45 181.00 77.05
CAMS190901 0.098 232.6 64.1 77.255 17.8 1.0150 0.6670 26.71 180.56 77.26
CAMS378824 0.081 234.6 56.8 57.453 18.1 0.9978 0.6377 26.99 195.18 57.45
ED20150520_204748 0.095 234.6 60.6 59.311 17.5 1.0068 0.5953 26.88 189.46 59.31
20150523_022656 0.093 235.7 60.3 61.101 15.6 1.0085 0.5883 23.20 188.23 61.10
ED20150524_220102 0.064 237.3 60.8 63.207 18.2 1.0088 0.6332 27.69 188.07 63.21
CAMS261709 0.098 222.7 57.6 74.083 15.6 1.0128 0.6613 22.16 185.33 74.08
CAMS261763 0.091 239.6 60.8 74.232 17.5 1.0122 0.6017 26.95 186.41 74.23
ED20150605_211215 0.094 241.9 61.6 74.679 17.9 1.0137 0.5923 28.03 184.06 74.68
CAMS262192 0.097 232.2 65.0 78.121 16.7 1.0151 0.5979 25.46 179.08 78.12
CAMS444956 0.100 236.5 57.5 56.541 17.5 0.9984 0.5833 26.82 195.15 56.54
20160519_002758 0.079 233.3 54.3 57.888 16.5 0.9987 0.5999 24.49 194.99 57.89
ED20160523_232311 0.060 233.7 60.0 63.013 16.7 1.0087 0.5996 25.22 188.27 63.01
ED20160524_233547 0.093 233.8 54.2 63.982 15.4 1.0009 0.5720 22.66 194.67 63.98
CAMS445444 0.081 226.5 59.3 65.312 15.2 1.0096 0.5775 22.56 187.94 65.31
CAMS445465 0.064 232.6 56.2 65.407 16.3 1.0038 0.5902 24.22 192.76 65.41
CAMS322105 0.043 235.1 59.9 65.412 18.0 1.0081 0.6540 26.97 189.12 65.41
CAMS322112 0.057 226.0 55.9 65.445 16.0 1.0057 0.6394 22.92 191.13 65.45
20160603_005430 0.072 233.2 59.1 72.307 15.5 1.0131 0.6146 22.67 184.54 72.31
CAMS322828 0.098 241.1 67.9 72.897 18.7 1.0143 0.6306 29.12 178.28 72.89
CAMS322854 0.096 228.6 62.6 72.976 15.3 1.0141 0.5618 23.16 182.45 72.98
20160604_024948 0.093 247.7 59.9 73.342 18.3 1.0110 0.6460 27.87 187.65 73.34
CAMS322981 0.073 231.8 60.3 74.029 16.7 1.0130 0.6317 24.93 185.27 74.03
ED20160606_210930 0.090 232.3 65.8 76.347 16.6 1.0143 0.5962 25.46 176.79 76.35
20170520_224425 0.096 233.1 50.3 59.494 16.5 0.9893 0.5859 24.27 200.08 59.49
20170530_013215 0.097 251.3 61.3 68.255 18.0 1.0115 0.5564 28.72 186.28 68.26
20180522_021821 0.080 233.5 59.1 60.357 16.3 1.0067 0.6387 23.68 189.51 60.36
20180527_021646 0.046 237.4 60.7 65.160 16.9 1.0102 0.6466 25.04 186.86 65.16
20180530_215143 0.089 227.6 59.9 68.821 15.3 1.0130 0.5655 23.08 183.44 68.82
20180603_032144 0.098 243.6 57.5 71.915 16.3 1.0075 0.5968 24.30 190.79 71.91
20180603_035405 0.079 249.0 66.6 71.936 17.2 1.0142 0.5810 26.72 180.57 71.94
UK20180604_001155 0.081 240.0 59.0 73.105 17.4 1.0108 0.6284 26.37 187.81 73.11
GMN4598 0.078 226.0 52.9 62.527 16.5 0.9984 0.6683 23.11 195.20 62.54
GMN4620 0.086 221.7 59.8 62.626 15.4 1.0095 0.6200 22.29 187.28 62.64
GMN4697 0.071 231.4 53.5 64.358 16.5 0.9986 0.6196 24.01 195.63 64.36
UK20190601_235642 0.082 225.9 62.5 70.940 15.2 1.0141 0.6094 22.30 180.97 70.94
GMN5079 0.100 237.3 58.5 71.206 18.6 1.0087 0.6884 27.62 189.30 71.21
GMN5215 0.082 237.9 67.1 73.274 17.8 1.0144 0.6078 27.62 178.91 73.28
GMN79106 0.090 236.4 52.3 60.136 18.1 0.9882 0.6317 26.73 200.14 60.15
GMN79107 0.097 236.9 52.7 60.136 18.7 0.9887 0.6598 27.58 199.64 60.15
GMN79373 0.094 221.2 52.3 60.981 15.6 0.9990 0.6637 21.42 194.74 60.99
GMN79472 0.068 225.8 57.1 61.169 16.7 1.0043 0.6641 23.91 191.49 61.18
GMN79497 0.069 234.7 55.7 61.240 18.3 0.9983 0.6661 26.96 195.17 61.25
GMN79505 0.075 223.8 58.0 61.252 16.3 1.0062 0.6564 23.30 190.05 61.26
GMN79507 0.090 225.3 53.4 61.253 15.2 0.9993 0.5965 21.75 195.12 61.26
GMN79675 0.081 237.7 58.5 61.945 17.0 1.0040 0.5626 26.16 192.43 61.95
GMN79677 0.088 223.9 56.4 61.958 15.0 1.0050 0.5924 21.73 191.47 61.97
GMN79689 0.080 235.2 52.8 62.071 17.6 0.9924 0.6311 25.92 198.48 62.08
GMN79764 0.068 225.5 59.7 62.391 16.4 1.0084 0.6496 23.91 188.33 62.40
GMN79902 0.082 222.3 60.8 63.219 15.9 1.0105 0.6438 23.03 186.21 63.23
GMN80106 0.076 229.3 53.5 64.300 17.0 0.9993 0.6707 24.21 194.92 64.31
UK20200526_003101 0.088 235.4 53.7 64.962 16.3 0.9984 0.5873 24.15 196.10 64.97
GMN80192 0.056 226.4 55.9 65.046 16.2 1.0052 0.6514 23.26 191.42 65.05
GMN80229 0.056 237.2 59.2 65.149 18.4 1.0065 0.6597 27.73 190.41 65.16
GMN80352 0.053 237.4 59.0 65.856 18.3 1.0066 0.6551 27.61 190.45 65.86
GMN80752 0.070 226.9 59.2 67.144 17.2 1.0099 0.6933 24.72 187.53 67.15
GMN80822 0.085 235.0 54.8 67.792 17.6 1.0015 0.6558 25.86 194.11 67.80
GMN80849 0.069 232.0 55.6 67.863 17.1 1.0044 0.6580 24.96 192.28 67.87
GMN80861 0.037 236.9 61.2 67.893 17.5 1.0105 0.6155 26.79 187.27 67.90
GMN80990 0.056 239.7 63.3 68.789 18.2 1.0123 0.6206 28.04 184.95 68.80
20200531_015313 0.074 239.6 60.3 69.455 15.7 1.0118 0.5721 23.71 186.10 69.45
UK20200531_000246 0.054 240.0 60.2 69.741 17.8 1.0107 0.6135 27.39 187.42 69.75
GMN81655 0.081 234.2 56.7 70.941 17.1 1.0071 0.6401 25.32 190.76 70.95
GMN 218148 0.079 225.0 57.2 59.711 15.9 1.0038 0.6183 22.99 191.82 59.72
GMN 218196 0.079 235.1 60.2 59.789 17.3 1.0056 0.5999 26.42 190.62 59.80
GMN 218476 0.065 235.6 54.8 61.085 17.8 0.9958 0.6306 26.53 196.69 61.09
GMN 218636 0.099 231.7 50.2 61.274 17.3 0.9870 0.6489 24.62 200.55 61.29
20210522_171348 0.081 235.6 52.8 61.539 17.7 0.9920 0.6232 26.08 198.84 61.54
GMN 218701 0.069 230.2 56.6 61.885 16.0 1.0028 0.5856 23.77 193.04 61.90
UK20210523_015210 0.075 233.9 57.0 61.885 15.9 1.0038 0.5791 23.62 192.43 61.90
GMN 218703 0.097 233.4 59.0 61.900 18.7 1.0050 0.7062 27.57 190.81 61.91
GMN 219470 0.070 231.3 64.9 66.765 17.2 1.0130 0.6319 26.03 182.41 66.77
GMN 219502 0.073 241.6 59.9 66.863 17.7 1.0079 0.5739 27.53 189.90 66.87
GMN 219858 0.082 236.9 62.7 68.462 16.5 1.0122 0.5550 25.68 185.25 68.47
GMN 220001 0.096 222.5 65.3 68.619 16.9 1.0137 0.6792 24.64 179.96 68.63
GMN 220284 0.069 234.1 58.1 69.487 16.3 1.0084 0.5885 24.66 189.73 69.50
UK20210530_235903 0.092 238.0 57.8 69.487 16.2 1.0082 0.5575 24.91 190.09 69.50
GMN 220318 0.094 216.9 60.9 69.516 14.7 1.0135 0.6172 20.96 182.47 69.53
GMN 220524 0.089 234.7 56.0 70.379 17.5 1.0057 0.6596 25.77 191.66 70.39
GMN 220543 0.077 242.4 64.7 70.400 18.2 1.0135 0.5960 28.51 182.91 70.41
GMN 220588 0.078 229.9 56.2 70.444 16.6 1.0077 0.6558 24.08 190.13 70.46
UK20210531_235736 0.072 232.3 56.3 70.444 16.5 1.0080 0.6376 24.13 189.97 70.46
GMN 220835 0.088 218.9 60.0 71.246 14.8 1.0136 0.6183 21.19 183.11 71.26
GMN 220861 0.100 239.4 68.4 71.326 18.4 1.0139 0.6261 28.62 177.79 71.33
GMN 220899 0.096 240.0 68.1 71.358 18.1 1.0140 0.6056 28.33 178.15 71.37
UK20210601_234528 0.077 223.1 60.5 71.394 15.4 1.0138 0.6446 22.13 182.38 71.41
GMN 220992 0.091 224.8 67.4 71.425 16.2 1.0137 0.6087 24.36 177.19 71.44
GMN 221122 0.084 239.0 58.8 71.627 17.2 1.0092 0.5932 26.39 189.33 71.64
GMN 221419 0.099 241.3 66.7 72.396 19.1 1.0143 0.6551 29.56 179.88 72.41
GMN 221517 0.074 239.5 62.5 73.192 18.1 1.0132 0.6292 27.81 184.66 73.20
GMN 221529 0.072 232.0 66.5 73.214 17.4 1.0144 0.6299 26.40 178.78 73.22
GMN 221564 0.090 223.9 58.1 73.261 15.2 1.0127 0.6208 21.92 185.50 73.27
UK20210605_002040 0.092 240.2 59.3 74.291 17.7 1.0116 0.6280 26.91 187.15 74.30
GMN 222340 0.096 241.0 65.3 76.150 18.3 1.0149 0.6174 28.43 180.76 76.16
UK20210606_225702 0.098 241.6 64.6 76.150 18.3 1.0149 0.6088 28.51 180.47 76.16
mean 233.1 59.1 67.112 16.9 1.007 0.619 25.2 188.5 67.1
median 233.8 59.3 67.616 16.9 1.008 0.618 25.2 188.8 67.6
stdev 6.6 4.1 5.323 1.1 0.007 0.034 2.1 5.9 5.3
min 216.9 50.2 56.353 14.7 0.984 0.554 20.9 176.8 56.3
max 251.3 68.4 78.650 19.1 1.015 0.706 30.0 201.7 78.6
197P 1.060 0.6301 25.6 188.68 66.39
MID 0.078 230.8 252.5 60.200 16.7 0.989 0.604 24.3 198.1 60.2

 

Accordingly, the orbit used in this analysis was progressed backwards to earlier epochs and also to a lesser extent to future epochs via numerical integration.  This revealed that prior to a less than 1 AU encounter with Jupiter itself in 1941 the comets perihelion distance, q, dropped below the roughly 1.2 AU previous average value and remained between roughly 1.12 and 1.17 until a nearly 0.5 AU encounter with Jupiter in 2001 which reduced q further to around 1.06 AU.  In the formal elements provided by the Minor Planet Center (see footnote 2 in the Section Methodology) so called “non-gravitational” elements are also included (although not used in the less rigorous analysis of this study), such elements being due to other effects on a comet’s motion, usually outgassing.

Thus, from just after the turn of the Millennium until now this comet, which is likely outgassing dust and ices, has had a perihelion distance getting ever close to the mean orbit of the Earth.  Indeed, this led to the recovery of the comet in 2003 where it was identified as a new asteroidal object 2003 KV2.  It was recovered during its next apparition in 2008 as 2008 E2 and soon afterwards both its association with the earlier object and its cometary nature were realized.  Following that there were returns in 2013 and 2018 with next perihelion being due in early December 2022.  Throughout these apparitions the perihelion distance remained very near to 1.06 AU, although never getting much nearer to Earth than 0.3 AU throughout.  In 2024, around the aphelion following on from the upcoming 2022 perihelion, the comet will again come within 1 AU of Jupiter after which the perihelion distance will increase to averaging around 1.1 AU and over.  This small to and from drift in q following occasional aphelion interactions with Jupiter will carry on for the rest of the Century with even a limited potential of q dipping barely just below 1 AU in the next Century, however such forward extrapolations become less secure especially given the non-gravitational effects which can be quite variable in their vector during each perihelion.

Nevertheless, it can be seen that 197P became available in recent most times in order to produce a stream.  It may have done so in the past, having danced with close approaches to Jupiter for long ages, but as it is a small and faint comet (rarely achieving much above magnitude 20 even when within 1 AU of Earth) and meteoroids from past to long past epochs may well have diffused out of the stream.  Unfortunately, its new era of closer perihelion distances coincides with the evolution and growth of multi-station video meteor surveys and accordingly it is likely impossible to disentangle the recent increase (especially in the 2020–2021 seasons) of this latest May to earliest June shower from the great increase of coverage and consequent data that have arrived in the past two or three years, even amongst the long established and previously relatively prolific monitoring groups.

However, as many of these surveys are now reaching optimal coverage to the point of near saturation such that differences due to year by year, and/or aphelion by aphelion orbit changes, along with the combination of the orbit drift and the non-gravitational forces as an indicator of material ejection, may well lead to enhanced periods of cometary activity in the last week in May and first week in June, centered around June 1st.  The various surveys, which are more effective for brighter meteors, reveal a goodly proportion of fireballs for this shower, and although some detections were as faint as magnitude 4 the mean magnitude is around 0 with the brightest meteor being magnitude –5.

 

Nomenclature of the shower

Finally, during the analysis the mean values of Table 2 for Right Ascension and Declination and Solar Longitude were compared with those of extant showers.  The shower May iota Draconids, henceforth MID (Šegon at al., 2015), was something of a distant possibility when only the UKMON data were used, its position and timing being markedly removed from said mean.  However, when the analysis was extended to include more surveys, it then became an extreme outlier to the stream identified in the current analysis, albeit the MID discovery paper not mentioning any association with the comet, despite the shower discovery date post-dating 197P’s discovery.  Indeed, another associated candidate (an asteroid) was noted in that paper, despite many of the particulars of its orbit being markedly different.

Given the evolutionary trends of the comet’s orbit there remained the possibility that the MID shower represented a stream from a discrete orbit from an earlier epoch.  Accordingly, the values given for the orbit in the MID discovery paper were tested against the orbit for 197P/LINEAR used in this analysis and gave a result for DJ of 0.078, a respectable enough value.  Therefore, given this similarity the MID shower is likely the same as the 197P shower and accordingly the former only requires its details updating following the current more complete number of orbits available, remembering that the “shower” is likely to be a collection of slightly discrete streams due to the orbital evolution of the comet with little time having passed for dynamic relaxation, and that 197P should now be noted as the parent body to the May iota Draconids.

Conclusion

Examination of UKMON meteor orbits via DJ criterion testing revealed a likely association of 10 of the orbits with the comet 197P/LINEAR.  An extended analysis using meteor orbits from other publicly available surveys extended the number of orbits by 151.  Examination of the comet revealed a succession of close approaches to Jupiter, both in the past and in the future, not only leading to the comet orbit’s perihelion distance coming within range sufficient for any meteoroids to be likely noted on Earth, but oscillating at a value for the foreseeable future likely to make this the ongoing case, with even a possibility of crossing just within Earth’s orbit in the more distant future.  However, due to the evolution of the orbit coinciding with the evolution of multi-station video meteor monitoring to ever greater spatial and temporal coverage it cannot be shown as to whether an apparent recent increase, or even discovery, of such a shower is primarily due to this increased monitoring or to the orbital evolution.  The presence of varying non-gravitational effects in the orbital particulars of the comet also suggest episodic outgassing thus complicating further any particular year’s increase and/or decrease in meteors.

Taking this drift into account and its likely effect on radiant position and Solar Longitude over time, examination of extant meteor showers revealed that the May iota Draconids, though dissimilar and already given a candidate parent body in the literature, may in fact be connected to 197P/LINEAR which would make it the true parent body.  Similarly, the larger picture provided by the increase in survey data available since the discovery of the May iota Draconids shows that the mean orbital and radiant and duration particulars need to be updated.

The periodic Jupiter Family Comet 197P/LINEAR due to aphelion interactions with Jupiter has recently evolved into an orbit with perihelion distance closer to Earth’s orbit than hitherto known.  The May iota Draconids may well be an early indication of the continued drift and evolution of the meteoroid stream.  If so, the modern radiant of the shower is now centered nearer Right Ascension 233.1 degrees, Declination +59.1 degrees and Solar Longitude 67.1 degrees, in other words a week before and a week after a date centered around June 1st.  It presents a number of slow-moving bright meteors and fireballs given its roughly
17 kms–1 geocentric velocity.  Modern surveys’ coverage availability could lead to revealing results relatable to the comet’s orbital variations whilst its parent body’s variable perihelion distance remains close enough to Earth’s orbit for at least the next Century.

 

Acknowledgment

The meteor survey groups and especially their volunteers and operatives are expressly thanked not only for their work but for making their data public and thus available for analytical examination by all instead of just wallowing in a private archive.  The individual groups are mentioned in the body text of the article and fully referenced below.  Strangely, for the case of public domain scientific data, the Global Meteor Network (GMN) and UKMON data are released under the following licence.

 

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