Comet for Windows Tutorial

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Updated on June 16, 2007

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    Observation of Comet Hyakutake    

o Make a plan of observation.

Comet for Windows can calculate various information useful for making a plan of observation. Here let's make a plan to observe Comet Hyakutake when it passed close by the earth.

Comet Hyakutake passed close by the earth in late March, 1996. The motion of the comet was very fast at that time, and the condition of observation had been changing day by day. So it was necessary to make a detailed plan.

Please launch Comet for Windows, and select "Menu" - "Ephemeris" menu.

First of all, please select "Setting" - "Location" menu and input the longitude and latitude, etc., at your location.

Please select "Setting" - "Select Comets" menu, and select "C/1996 B2 (Hyakutake)". Then today's position of Comet Hyakutake is displayed.

Next, please select "Setting" - "Date" menu and set the date and time to calculate the ephemeris. Here, let's calculate daily positions at 00:00:00 from 1996 March 1 to April 30. After pushing "OK" button, daily positions at 0 o'clock (UT) of this period are displayed.

To make a plan of observation, important part of configuration starts here.

Please select "View" - "Setting" menu and open "View Setting" dialog. Various options in this dialog help to calculate various information useful to make a plan of observation.

Function to calculate the best time is useful to make a plan. So here check "Best Time (Local)" check box to use that function. Because the motion of Comet Hyakutake is very fast, please check "Calculate Position at Best Time" check box, too.

In addition, please check "Change of Altitude" to glance over the hourly change of altitude per night. And check "Rise/Set Time (Local)" and "Output Azimuth/Altitude/Elongation/Illuminating Ratio of Moon" check boxes, too.

And change the style of date as "Hour/Minute" and "Local Time".

After pushing "OK" button, the following data are displayed.


C/1996 B2 (Hyakutake)
    Date    Time     R.A.      Decl.     r       d     Elong   m1    Mot.(') p.a.   Rise(A)     Set(A)      0  1  2  3  4  5  6 ... 18 19 20 21 22 23 24  Best Time(A, h)  Moon(A, h) elg k    
1996- 3- 1   4:15  14 51.58  -22 47.0   1.519   0.825   113    6.4     16.0  24.4  23:20(297)  9:06( 61)    6 15 23 29 32 31 27 ...                    6   4:15 (  0, 32)  (117, -7) 117 0.81  
1996- 3- 2   4:11  14 52.04  -22 31.7   1.501   0.792   114    6.2     17.3  21.5  23:16(297)  9:04( 62)    6 16 24 29 32 31 27 ...                    7   4:12 (  0, 32)  (108,  0) 105 0.88  
1996- 3- 3   4:07  14 52.49  -22 14.7   1.483   0.759   115    6.1     18.9  18.8  23:11(297)  9:01( 62)    7 17 25 30 32 31 26 ...                    8   4:08 (  0, 33)  ( 99,  8)  93 0.93  
1996- 3- 4   4:05  14 52.91  -21 55.9   1.464   0.725   116    5.9     20.7  16.2  23:07(296)  8:59( 62)    8 17 25 30 33 31 26 ...                    9   4:05 (  0, 33)  ( 90, 15)  81 0.97  
1996- 3- 5   4:00  14 53.32  -21 35.0   1.446   0.692   117    5.8     22.8  13.8  23:02(296)  8:57( 63)    9 18 26 31 33 31 26 ...                 0 10   4:01 (  0, 33)  ( 80, 23)  69 1.00  
1996- 3- 6   3:57  14 53.69  -21 11.6   1.427   0.659   118    5.6     25.3  11.7  22:57(295)  8:54( 63)   10 19 27 32 33 31 26 ... ..              0 11   3:58 (  0, 34)  ( 68, 30)  57 1.00  
1996- 3- 7   3:54  14 54.05  -20 45.5   1.409   0.626   119    5.5     28.2   9.7  22:52(295)  8:52( 64)   11 20 27 32 34 32 26 ... ..              1 12   3:54 (  0, 34)  ( 54, 36)  44 0.98  
1996- 3- 8   3:51  14 54.37  -20 16.1   1.390   0.593   120    5.3     31.6   7.9  22:46(294)  8:50( 65)   12 21 28 33 34 32 26 ... ..              2 13   3:51 (  0, 35)  ( 39, 40)  31 0.94  
1996- 3- 9   3:46  14 54.66  -19 42.9   1.371   0.560   121    5.1     35.6   6.3  22:41(293)  8:49( 65)   13 22 29 34 35 32 26 ... ..              3 14   3:47 (  0, 35)  ( 22, 42)  18 0.88  
1996- 3-10   3:43  14 54.91  -19  5.2   1.352   0.527   122    4.9     40.5   4.8  22:35(292)  8:47( 66)   14 23 30 34 35 32 27 ... ..              4 15   3:43 (  0, 36)  (  4, 41)   6 0.80  
1996- 3-11   3:40  14 55.13  -18 22.2   1.333   0.494   123    4.8     46.3   3.5  22:28(291)  8:46( 67)   15 24 31 35 36 33 27 ... ..              5 16   3:40 (  0, 37)  (347, 38)   9 0.71  
1996- 3-12   3:35  14 55.30  -17 32.8   1.314   0.461   124    4.6     53.3   2.3  22:22(290)  8:44( 68)   16 25 32 36 37 33 27 ... ..              7 17   3:36 (  0, 37)  (332, 32)  23 0.61  
1996- 3-13   3:32  14 55.43  -16 35.5   1.294   0.429   126    4.3     62.0   1.3  22:14(289)  8:44( 69)   17 26 33 37 38 34 27 ... ..              8 19   3:32 (  0, 38)  (318, 24)  37 0.49  
1996- 3-14   3:27  14 55.49  -15 28.6   1.275   0.396   127    4.1     72.9   0.4  22:07(287)  8:43( 71)   19 28 35 39 39 35 28 ... ..             10 20   3:28 (  0, 40)  (306, 16)  51 0.38  
1996- 3-15   3:23  14 55.49  -14  9.4   1.256   0.364   128    3.9     86.7 359.6  21:58(285)  8:44( 73)   20 29 36 40 40 35 28 ... ..           0 11 22   3:24 (  0, 41)  (295,  7)  65 0.27  
1996- 3-16   3:20  14 55.41  -12 34.7   1.236   0.332   130    3.6    104.4 359.0  21:49(283)  8:45( 75)   22 31 38 42 41 37 29 ... ..           2 13 24   3:20 (  0, 42)  (285, -2)  80 0.18  
1996- 3-17   3:15  14 55.23  -10 39.8   1.216   0.301   131    3.3    127.5 358.4  21:38(280)  8:46( 77)   24 33 40 44 43 38 30 ... ..           4 16 26   3:16 (  0, 44)  (274,-12)  95 0.10  
1996- 3-18   3:11  14 54.92   -8 18.0   1.196   0.270   133    3.0    158.9 358.0  21:26(277)  8:49( 80)   26 36 43 46 45 39 31 ... ..           6 18 29   3:12 (  0, 47)  (262,-21) 110 0.04  
1996- 3-19   3:07  14 54.45   -5 19.7   1.176   0.240   134    2.7    202.0 357.6  21:11(273)  8:54( 84)   29 39 46 49 47 42 33 ... ..           9 21 33   3:07 (  0, 50)  (249,-29) 125 0.01  
1996- 3-20   3:02  14 53.76   -1 30.0   1.156   0.210   136    2.4    262.9 357.3  20:53(267)  9:01( 89)   33 43 50 53 51 44 35 ... ..        1 13 25 37   3:03 (  0, 54)  (234,-36) 139 0.00  
1996- 3-21   2:58  14 52.76    3 32.8   1.136   0.182   137    2.0    351.2 357.1  20:30(259)  9:11( 96)   37 47 55 58 55 48 37 ... ..        6 18 30 42   2:58 (  0, 59)  (217,-40) 150 0.02  
1996- 3-22   2:52  14 51.29   10 21.8   1.116   0.155   137    1.6    479.9 356.8  19:59(249)  9:27(105)   42 53 62 65 61 52 41 ... ..     0 12 24 37 49   2:53 (  0, 65)  (198,-42) 154 0.06  
1996- 3-23   2:46  14 49.04   19 44.8   1.095   0.132   135    1.1    662.5 356.6  19:13(234)  9:54(118)   49 61 71 74 68 57 .. ... ..     8 19 31 43 56   2:46 (  0, 75)  (180,-41) 146 0.12  
1996- 3-24   2:38  14 45.35   32 32.8   1.075   0.114   130    0.8    890.4 356.1  17:51(214) 10:47(138)   56 68 81 85 73 60 .. ... ..  9 18 28 38 49 59   2:39 (  0, 88)  (163,-37) 129 0.20  
1996- 3-25   2:27  14 38.47   48 58.4   1.054   0.103   120    0.5   1081.8 354.9    -          -          59 69 75 74 67 58 .. ... .. 22 28 35 42 48 53   2:28 (180, 76)  (148,-31) 108 0.28  
1996- 3-26   2:07  14 21.90   67  3.7   1.033   0.103   107    0.4   1097.3 351.5    -          -          53 57 57 56 52 48 .. ... .. 33 36 38 40 42 42   2:08 (180, 58)  (134,-21)  88 0.37  
1996- 3-27  19:41   5 22.23   84 21.2   0.996   0.124    85    0.7    750.7 222.5    -          -          42 42 41 39 37 35 .. ... .. 39 38 37 35 33 31  19:42 (175, 39)  ( 49, 65)  66 0.54  
1996- 3-28  19:42   3 43.41   74 23.2   0.975   0.145    76    0.9    546.1 193.2    -          -          31 29 27 26 25 25 .. ... .. 42 38 34 30 26 22  19:43 (161, 40)  ( 22, 70)  66 0.63  
1996- 3-29  19:43   3 26.00   66 43.5   0.953   0.171    69    1.2    397.6 189.0    -          -          22 19 17 16 16 17 .. ... .. 43 37 31 25 20 16  19:44 (151, 39)  (351, 68)  70 0.72  
1996- 3-30  19:44   3 18.81   61  3.2   0.931   0.198    64    1.4    295.8 187.3    -          -          16 12 10  9 10 12 .. ... .. 42 35 28 21 15 11  19:45 (144, 37)  (328, 63)  79 0.80  
1996- 3-31  19:45   3 14.83   56 46.2   0.910   0.227    60    1.6    226.2 186.7    -          -          11  7  5  4  5  8 .. ... .. 41 33 25 18 12  7  19:46 (139, 36)  (314, 55)  89 0.87  
1996- 4- 1  19:45   3 12.25   53 27.0   0.887   0.257    57    1.8    177.7 186.3    -          -           7  3  1  0  2  5 .. ... .. 40 31 23 15  9  3  19:46 (135, 34)  (305, 45) 100 0.93  
1996- 4- 2  19:47   3 10.38   50 48.6   0.865   0.287    54    1.9    143.0 186.3   4:07(194)  0:59(166)    3  0        0  3 .. ... .. 39 30 21 13  6  1  19:47 (133, 32)  (298, 35) 111 0.97  
1996- 4- 3  19:48   3  8.91   48 39.7   0.843   0.318    52    2.1    117.9 186.5   4:38(200)  0:15(160)    1              1 .. ... .. 38 28 19 11  4     19:48 (131, 30)  (293, 24) 123 1.00  
1996- 4- 4  19:49   3  7.69   46 52.6   0.820   0.349    49    2.2     98.9 186.9   4:54(205) 23:25(152)                   0 .. ... .. 36 27 17  9  2     19:49 (129, 29)  (289, 12) 134 1.00  
1996- 4- 5  19:50   3  6.62   45 21.9   0.797   0.381    47    2.2     84.6 187.4   5:05(208) 23:08(149)                   0 .. ... .. 35 25 16  8  0     19:50 (128, 27)  (284,  1) 143 0.98  
1996- 4- 6  19:51   3  5.64   44  3.9   0.774   0.413    46    2.3     73.5 188.1   5:11(210) 22:54(147)                     .. ... .. 34 24 14  6  0     19:51 (127, 26)  (280,-10) 150 0.93  
1996- 4- 7  19:52   3  4.71   42 55.6   0.751   0.444    44    2.4     64.9 189.0   5:16(212) 22:41(146)                     .. ... .. 33 23 13  5        19:52 (127, 24)  (275,-22) 151 0.86  
1996- 4- 8  19:52   3  3.80   41 55.0   0.727   0.476    42    2.4     58.2 190.0   5:18(214) 22:30(144)                     .. ... .. 32 21 12  3        19:53 (126, 23)  (269,-34) 145 0.77  
1996- 4- 9  19:53   3  2.90   41  0.5   0.703   0.509    41    2.4     53.0 191.2   5:20(215) 22:19(143)                     .. ... .. 30 20 11  2        19:54 (126, 21)  (260,-45) 136 0.67  
1996- 4-10  19:54   3  1.99   40 10.7   0.680   0.541    39    2.4     48.9 192.6   5:21(217) 22:09(141)                     .. ... .. 29 19  9  1        19:55 (126, 20)  (248,-55) 124 0.56  
1996- 4-11  19:55   3  1.05   39 24.7   0.655   0.573    38    2.5     45.7 194.1   5:20(218) 22:00(140)                     .. ... .. 28 18  8  0        19:56 (126, 19)  (227,-63) 112 0.45  
1996- 4-12  19:57   3  0.07   38 41.7   0.631   0.606    36    2.5     43.4 195.6   5:20(219) 21:51(139)                     .. ... .. 27 16  7           19:58 (126, 17)  (197,-66)  99 0.33  
1996- 4-13  19:59   2 59.06   38  0.8   0.607   0.638    35    2.5     41.8 197.3   5:19(220) 21:43(138)                     .. ... .. 26 15  6           19:59 (126, 16)  (167,-63)  85 0.23  
1996- 4-14  20:00   2 57.98   37 21.6   0.582   0.671    33    2.6     40.7 198.8   5:17(221) 21:34(137)                     .. ... .. 25 14  5           20:00 (126, 15)  (147,-55)  72 0.14  
1996- 4-15  20:01   2 56.85   36 43.6   0.557   0.704    32    2.6     40.3 200.5   5:16(222) 21:26(136)                     .. ... .. 23 13  3           20:01 (126, 13)  (134,-45)  59 0.07  
1996- 4-16  20:02   2 55.65   36  6.1   0.532   0.737    31    2.6     40.3 202.0   5:14(223) 21:18(135)                     .. ... .. 22 12  2           20:02 (126, 12)  (126,-34)  46 0.03  
1996- 4-17  20:03   2 54.37   35 28.7   0.507   0.770    29    2.6     40.8 203.4   5:12(224) 21:10(135)                     .. ... .. 21 10  1           20:03 (126, 10)  (119,-23)  34 0.00  
1996- 4-18  20:03   2 53.00   34 51.0   0.481   0.803    28    2.5     41.8 204.6   5:10(225) 21:01(134)                     .. ... .. 20  9  0           20:04 (127,  9)  (114,-12)  24 0.00  
1996- 4-19  20:04   2 51.54   34 12.5   0.456   0.836    26    2.5     43.3 205.7   5:07(226) 20:53(133)                     .. ... .. 18  8  0           20:05 (127,  8)  (109, -1)  19 0.03  
1996- 4-20  20:05   2 49.99   33 32.7   0.431   0.869    25    2.5     45.3 206.5   5:05(227) 20:44(132)                   0 .. ... .. 17  7              20:06 (127,  6)  (104,  8)  22 0.07  
1996- 4-21  20:06   2 48.32   32 51.1   0.406   0.902    23    2.4     47.9 207.0   5:03(227) 20:36(131)                   0 .. ... .. 16  5              20:07 (127,  5)  ( 99, 18)  30 0.13  
1996- 4-22  20:07   2 46.54   32  7.1   0.381   0.935    22    2.4     51.0 207.3   5:00(228) 20:27(130)                   0 .. ... .. 14  4              20:08 (128,  3)  ( 93, 28)  41 0.20  
1996- 4-23  20:08   2 44.65   31 20.1   0.356   0.968    20    2.3     54.9 207.4   4:58(229) 20:18(129)                   0 .. ... .. 13  2              20:09 (128,  1)  ( 86, 37)  52 0.28  
1996- 4-24  20:11   2 42.62   30 29.2   0.332   1.001    19    2.2     59.4 207.1   4:55(231) 20:08(128)                   0 .. ... .. 11  1              20:11 (129,  0)  ( 77, 45)  64 0.37  
1996- 4-25  20:12   2 40.48   29 33.8   0.309   1.034    17    2.1     64.7 206.4   4:53(232) 19:58(127)                   0 .. ... .. 10  0              20:12 (129, -2)  ( 65, 53)  76 0.46  
1996- 4-26  20:13   2 38.23   28 32.9   0.288   1.065    15    2.0     70.7 205.5   4:50(233) 19:48(125)                   1 .. ... ..  8                 20:13 (129, -4)  ( 49, 58)  88 0.56  
1996- 4-27  20:14   2 35.89   27 25.7   0.269   1.096    13    1.9     77.3 204.1   4:48(234) 19:38(124)                   1 .. ... ..  6                 20:14 (130, -6)  ( 28, 61) 100 0.65  
1996- 4-28  20:15   2 33.51   26 11.3   0.253   1.125    12    1.9     84.5 202.5   4:47(236) 19:27(122)                   2 .. ... ..  4                 20:15 (130, -8)  (  5, 60) 113 0.74  
1996- 4-29  20:15   2 31.15   24 49.4   0.240   1.152    10    1.8     91.3 200.4   4:45(238) 19:16(120)                   2 .. ... ..  2                 20:16 (130,-10)  (345, 56) 126 0.82  
1996- 4-30   3:36   2 30.44   24 22.8   0.237   1.160     9    1.8     93.3 199.7   4:44(239) 19:04(118)                   2 .. ... ..  1                  3:37 (229,-11)  ( 95, -6) 130 0.85  

This ephemeris implies many information.

First, we can see that Comet Hyakutake transits meridian in the morning and locates around the same altitude until mid March. The condition is bad around March 10 because full moon locates near by the comet.

After mid March, the earlier meridian transit time becomes, the higher the altitude at meridian transit becomes while moving towards north rapidly. Around March 25 when the comet passes near by the earth, the comet locates almost at zenith just after midnight. After that, the comet becomes visible all through the night. In addition, the condition is very good from mid March to the date of approach to the earth, without moon light.

After passing by Polaris on March 27, the comet becomes visible in the evening on the other hand. It keeps visible all through the night until end of March, however, we can see the altitude at the best time is getting lower rapidly. In addition, the condition becomes worse too, with the influence of moon light.

In April, there is no influence of moon light. However, the comet becomes only visible in the evening low sky for a short time. After April 24, the comet becomes invisible at night, so the data is displayed in weak green color on the display.

The hourly change of altitude per night clearly shows that we can observe the comet for a long time in March, however, for a very short time in April.

o Determine magnitude from observation.

The magnitude of a comet is determined by comparing the brightness with those of stars around the comet in observation. Comet for Windows is helpful to look up the magnitude of comparison stars. It is also helpful to estimate the diameter and tail length.

For example, let's see you observed Comet Hyakutake on March 15, 1996.

Here is the result of your observation. It had a tail towards Spica.

In order to determine the magnitude of the comet, we have to look up the magnitude of these three stars, which you compared the brightness with, from a star catalog. Here let's use the Bright Star Catalogue 5.

First of all, please download the following file of the Bright Star Catalogue 5 provided by the NASA Astronomical Data Center.

ftp://dbc.nao.ac.jp/DBC/NASAADC/catalogs/5/5050/catalog.dat.gz

Please launch Comet for Windows and select "Menu" - "Chart" menu. And select "View" - "Catalog" - "Bright Star Catalogue 5" menu, and select the file "catalog.dat.gz" you downloaded. Then Pleiades is displayed.

Next, please select "Setting" - "Select Comets" menu, and select "C/1996 B2 (Hyakutake)".

Pease select "Setting" - "Date" menu, and set the date as March 15, 1996.

Please select "View" - "Setting" menu, and select the position of Comet Hyakutake on March 15, 1996. Here set the field of view as 50 degree, and the limiting magnitude as 7 mag.

Then the chart around Comet Hyakutake is displayed.

A bright star at right side is Spica. A bright star near by the left bottom corner is Antares.

When you click a star on the chart, the star name and magnitude are displayed.

The data of the three stars, which you compared the brightness with, are as follows.

Comparison StarNameV Mag.B-V
AHR 56852.61-0.11
BHR 55312.75+0.15
CHR 54873.88+0.38

Based on this result, your magnitude estimation of Comet Hyakutake becomes 3.0 mag.

When you click a star on the chart, the magnitude reference key is also displayed to be used in the report to ICQ. In this case, you should report your observation to ICQ with "YG" key.

Comet for Windows can read the following catalogs and draw chart.

CatalogICQ key
Bright Star Catalogue 5YG
Hipparcos CatalogueHV, HK, TT
Tycho CatalogueTJ, TT
Tycho-2 CatalogueTK, TJ
Guide Star Catalog 1.1HS
USNO-A1.0AO
USNO-A2.0UO
TASS Mark IV Patches CatalogTA

* Please see the FAQ "Where to download catalog files to draw star chart?" to obtain these catalogs.

Then, let's estimate the length and position angle of the tail. The comet had a tail towards Spica. The length of the tail was about one eighth of the distance between the head of the comet and Spica.

First, click the mark of Comet Hyakutake on the char, and the information of the comet is displayed.

Next, click Spica at right side on the chart. Then the distance and position angle from the last click point, that is the head of Comet Hyakutake, are displayed in addition to the information of Spica.

The comet had a tail towards Spica, so the position angle of the tail becomes 275 degree. The length of the tail was one eighth of the distance between the head of the comet and Spica, so it becomes 2.8 degree, 22.3 degree divided by 8.

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Copyright(C) Seiichi Yoshida (comet@aerith.net). All rights reserved.