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芸西天文台通信<2018年12月27日号>


C/2018 Y1 (Iwamoto)の発見

 徳島県の岩本雅之さんが12月19日の5時10分頃、デジカメ(Canon EOS 6D + PENTAX 100 SDUF II(D=100mm, f=400mm))による掃索でC/2018 Y1 (Iwamoto)を発見しました。前回のC/2018 V1(Machholz-Fujikawa-Iwamoto)に続く3つ目の発見となります。
 OAA彗星課の佐藤裕久さんの計算によると近日点の通過は2019年2月6日(UT)で、2月13日に地球に0.30天文単まで接近し8等級の明るさになります。
 暫定軌道要素と位置予報は下記のとおりです。
 Orbital elements:
    C/2018 Y1 (Iwamoto)
T 2019 Feb. 6.81154 TT                                  Sato
q   1.2837540            (2000.0)            P               Q
                   Peri.  358.01023     -0.85904793     +0.47892088
                   Node   147.34145     +0.47415954     +0.61140358
e   1.0            Incl.  160.43018     +0.19289734     +0.62993687
From 99 observations 2018 Dec. 18-26, mean residual 0".52.

Ephemeris:
2018/19   R.A.(2000.0) Decl     Delta    r     m1   Mot./PA   Elong.   Moon Age
 4h JST    h  m      。 ,                   m      ,    。     。     。
Dec. 18  14 17.77  -24 46.7    1.998  1.494  13.2   2.3/355   46.0    156  0.72
Dec. 19  14 17.75  -24 44.4    1.971  1.486  13.2   2.5/349   47.0    164  0.81
Dec. 20  14 17.72  -24 41.9    1.944  1.479  13.1   2.6/343   48.0    163  0.89
Dec. 21  14 17.66  -24 39.4    1.916  1.472  13.1   2.9/338   49.0    154  0.95
Dec. 22  14 17.58  -24 36.8    1.887  1.465  13.0   3.1/333   50.1    141  0.99
Dec. 23  14 17.48  -24 34.0    1.859  1.458  13.0   3.4/329   51.1    127  1.00
Dec. 24  14 17.35  -24 31.0    1.830  1.451  12.9   3.8/326   52.1    113  0.98
Dec. 25  14 17.19  -24 27.9    1.801  1.444  12.9   4.1/323   53.1     99  0.94
Dec. 26  14 17.01  -24 24.6    1.771  1.437  12.8   4.5/320   54.2     84  0.87
Dec. 27  14 16.80  -24 21.2    1.741  1.431  12.8   4.9/317   55.2     70  0.78
Dec. 28  14 16.55  -24 17.5    1.711  1.424  12.7   5.4/315   56.3     56  0.68
Dec. 29  14 16.27  -24 13.7    1.681  1.418  12.6   5.9/314   57.4     43  0.57
Dec. 30  14 15.96  -24 09.6    1.650  1.412  12.6   6.5/312   58.5     31  0.46
Dec. 31  14 15.61  -24 05.3    1.619  1.406  12.5   7.0/311   59.6     20  0.35
Jan.  1  14 15.22  -24 00.7    1.588  1.400  12.5   7.7/309   60.7     15  0.25
Jan.  2  14 14.79  -23 55.8    1.557  1.394  12.4   8.4/308   61.8     20  0.17
Jan.  3  14 14.31  -23 50.7    1.525  1.388  12.3   9.1/307   62.9     29  0.10
Jan.  4  14 13.78  -23 45.2    1.493  1.382  12.3   9.9/306   64.0     41  0.05
Jan.  5  14 13.20  -23 39.3    1.461  1.377  12.2  10.7/306   65.2     52  0.02
Jan.  6  14 12.57  -23 33.1    1.429  1.372  12.1  11.6/305   66.4     64  0.00
Jan.  7  14 11.88  -23 26.4    1.396  1.367  12.1  12.6/304   67.6     76  0.00
Jan.  8  14 11.12  -23 19.3    1.363  1.361  12.0  13.7/304   68.8     87  0.03
Jan.  9  14 10.30  -23 11.7    1.330  1.357  11.9  14.8/303   70.0     99  0.07
Jan. 10  14 09.40  -23 03.6    1.297  1.352  11.9  16.1/303   71.2    111  0.12
Jan. 11  14 08.42  -22 54.8    1.263  1.347  11.8  17.4/303   72.5    122  0.19
Jan. 12  14 07.36  -22 45.4    1.229  1.343  11.7  18.9/302   73.8    134  0.27
Jan. 13  14 06.20  -22 35.3    1.196  1.338  11.7  20.5/302   75.1    145  0.36
Jan. 14  14 04.94  -22 24.4    1.162  1.334  11.6  22.3/302   76.4    156  0.45
Jan. 15  14 03.58  -22 12.7    1.128  1.330  11.5  24.3/302   77.8    164  0.55
Jan. 16  14 02.09  -22 00.0    1.093  1.326  11.4  26.4/301   79.2    164  0.65
Jan. 17  14 00.47  -21 46.2    1.059  1.323  11.3  28.7/301   80.6    155  0.75
Jan. 18  13 58.71  -21 31.2    1.024  1.319  11.3  31.3/301   82.1    143  0.84
Jan. 19  13 56.80  -21 14.9    0.990  1.316  11.2  34.2/301   83.6    129  0.92
Jan. 20  13 54.71  -20 57.1    0.955  1.312  11.1  37.4/301   85.2    114  0.97
Jan. 21  13 52.42  -20 37.7    0.921  1.309  11.0  41.0/301   86.8     99  1.00
Jan. 22  13 49.93  -20 16.4    0.886  1.306  10.9  45.1/301   88.5     83  0.99
Jan. 23  13 47.20  -19 52.9    0.851  1.304  10.8  49.6/301   90.2     68  0.96
Jan. 24  13 44.20  -19 27.0    0.817  1.301  10.7  54.7/301   92.0     53  0.90
Jan. 25  13 40.91  -18 58.4    0.782  1.299  10.6  60.5/302   93.9     38  0.82
Jan. 26  13 37.29  -18 26.5    0.748  1.297  10.5  67.1/302   95.9     24  0.72
Jan. 27  13 33.29  -17 51.1    0.714  1.295  10.4  74.7/302   98.0     14  0.62
Jan. 28  13 28.87  -17 11.3    0.680  1.293  10.3  83.4/302  100.3     16  0.51
Jan. 29  13 23.97  -16 26.7    0.646  1.291  10.2  93.4/302  102.7     27  0.41
Jan. 30  13 18.51  -15 36.2    0.613  1.289  10.0 105.1/303  105.2     40  0.31
Jan. 31  13 12.42  -14 39.1    0.580  1.288   9.9 118.5/303  108.0     53  0.22

Ephemeris:
2019     R.A.(2000.0) Decl     Delta    r     m1   Mot./PA   Elong.   Moon Age
 3h JST    h  m      。 ,                   m      ,    。     。     。
Jan. 31  13 12.69  -14 41.6    0.581  1.288   9.9 117.9/303  107.8     53  0.22
Feb.  1  13 05.91  -13 36.9    0.549  1.287   9.8 133.5/303  110.8     67  0.15
Feb.  2  12 58.30  -12 22.9    0.518  1.286   9.7 151.7/304  114.0     81  0.09
Feb.  3  12 49.74  -10 58.1    0.487  1.285   9.5 172.8/304  117.5     95  0.04
Feb.  4  12 40.08  -09 20.6    0.457  1.285   9.4 197.2/305  121.4    109  0.01
Feb.  5  12 29.16  -07 28.2    0.429  1.284   9.2 225.3/305  125.6    124  0.00
Feb.  6  12 16.79  -05 18.7    0.403  1.284   9.1 257.0/305  130.3    140  0.01
Feb.  7  12 02.77  -02 50.1    0.378  1.284   9.0 291.8/305  135.6    155  0.03
Feb.  8  11 46.92  +00 00.8    0.356  1.284   8.8 328.7/305  141.4    171  0.07
Feb.  9  11 29.05  +03 09.7    0.337  1.284   8.7 365.2/305  147.8    169  0.13
Feb. 10  11 09.07  +06 39.9    0.321  1.284   8.6 398.0/305  154.7    152  0.20
Feb. 11  10 46.94  +10 25.1    0.310  1.285   8.5 422.8/304  162.1    133  0.28
Feb. 12  10 22.84  +14 17.9    0.303  1.286   8.5 435.8/303  169.4    114  0.38
Feb. 13  09 57.13  +18 07.8    0.301  1.287   8.5 434.6/301  174.4     94  0.48
Feb. 14  09 30.37  +21 43.5    0.304  1.288   8.5 419.3/299  170.7     74  0.59
Feb. 15  09 03.30  +24 55.6    0.311  1.289   8.6 392.8/296  163.6     54  0.69
Feb. 16  08 36.70  +27 38.0    0.324  1.291   8.7 359.1/293  156.4     34  0.79
Feb. 17  08 11.27  +29 48.9    0.340  1.293   8.8 322.3/290  149.6     16  0.88
Feb. 18  07 47.55  +31 30.2    0.360  1.294   8.9 285.7/287  143.3     13  0.94
Feb. 19  07 25.86  +32 45.7    0.382  1.296   9.0 251.3/284  137.6     30  0.99
Feb. 20  07 06.30  +33 40.2    0.407  1.299   9.2 220.3/281  132.5     48  1.00
Feb. 21  06 48.86  +34 18.2    0.434  1.301   9.3 192.8/279  127.8     67  0.98
Feb. 22  06 33.39  +34 43.6    0.463  1.304   9.5 169.0/276  123.7     84  0.93
Feb. 23  06 19.72  +34 59.7    0.492  1.306   9.6 148.4/274  119.9    101  0.86
Feb. 24  06 07.66  +35 09.1    0.523  1.309   9.8 130.7/273  116.4    118  0.78
Feb. 25  05 57.01  +35 13.5    0.555  1.312   9.9 115.4/271  113.3    133  0.68
Feb. 26  05 47.58  +35 14.4    0.588  1.315  10.0 102.4/270  110.4    147  0.57
Feb. 27  05 39.23  +35 12.9    0.621  1.319  10.2  91.1/269  107.7    159  0.47
Feb. 28  05 31.81  +35 09.7    0.654  1.322  10.3  81.3/267  105.2    165  0.37

            m1 = 10.0 + 5 log(Delta) + 10.0 log(r)
Copyright (C) 2018 Tsutomu Seki.