Japanese version Home page |
Updated on June 16, 2007 |
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.
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 Star | Name | V Mag. | B-V |
---|---|---|---|
A | HR 5685 | 2.61 | -0.11 |
B | HR 5531 | 2.75 | +0.15 |
C | HR 5487 | 3.88 | +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.
Catalog | ICQ key |
---|---|
Bright Star Catalogue 5 | YG |
Hipparcos Catalogue | HV, HK, TT |
Tycho Catalogue | TJ, TT |
Tycho-2 Catalogue | TK, TJ |
Guide Star Catalog 1.1 | HS |
USNO-A1.0 | AO |
USNO-A2.0 | UO |
TASS Mark IV Patches Catalog | TA |
* 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.