M
MeteorWayne
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<ol style="margin-top:0in"><li class="MsoNormal" style="margin-top:0in;margin-left:0in;margin-right:0in;tab-stops:list.5in"><font face="Times New Roman" size="3">ORI-Halley’s Comet Dust Returns Again…</font></li></ol><font face="Times New Roman" size="3"> </font> <p style="margin-top:0in;margin-left:0in;margin-right:0in" class="MsoNormal"><font face="Times New Roman" size="3">The major Orionid meteor shower will be a challenge in 2008 considering the position and timing of the first quarter moon. However, during the last two years activity has been 2 to 3 times normal and modeling has indicated such enhanced rates may continue for another few years. So despite the moon, we should make an effort to monitor it.</font></p><font face="Times New Roman" size="3"> </font> <p style="margin-top:0in;margin-left:0in;margin-right:0in" class="MsoNormal"><font face="Times New Roman" size="3">The Orionids are one of two annual showers created by Halley’s comet. The eta- Aquarids in May occur when the Earth impacts outbound particles, while the Orionids sample the incoming particles of the same stream. The Orionids approach the solar system from below and are visible after about 10 PM. However, a useful radiant elevation for scientific data does not occur until after midnight. Unfortunately, this year the 65% illuminated moon rises only about an hour later than the radiant on the peak morning of the 21<sup>st</sup>, and is only 15 degrees away. As I said, it’s a challenge. The best advice I can give is to try and keep the moon behind a building or umbrella, and place your field of view to the west in southwestern Taurus, or even Cetus. The radiant is about halfway between Betelgeuse and the feet of Gemini, well above the main rectangle of Orion’s 4 corner stars. The moon will rise a little later the next morning (Oct 22), so there will be a bit more dark sky time, and more distance between Luna and the radiant. That also means that the nights before the peak will be even worse. On the morning of the 20<sup>th</sup> (night of the 19<sup>th</sup>) the 75% full moon will rise before the radiant. If I may say so, yuck!! However the Orionid above normal rates have lasted nearly 5 days in the last two years, and each night the moon rises later, so during the morning hours by midweek, quite a few could be seen.</font></p><font face="Times New Roman" size="3"> </font> <p style="margin-top:0in;margin-left:0in;margin-right:0in" class="MsoNormal"><font face="Times New Roman" size="3">Fortunately, the Orionids are bright, so you can attempt some data collection even on the moonlit nights; however with such a bright moon in the sky, the limiting magnitude polygons that the IMO and NAMN use will not help define the brightness of the sky with much precision. Make an extra effort to count the areas you use near your field of view with as much detail as you can. </font></p><font face="Times New Roman" size="3"> </font> <p style="margin-top:0in;margin-left:0in;margin-right:0in" class="MsoNormal"><font face="Times New Roman" size="3">Recent IMO video data has shown low but steady activity from the Orionids as early as the beginning of September lasting until late November! In future years this will need to be taken into account. Outside of the IMO visual radiant period listed below I have shown the video indicated positions. To add to the fun, a second nearby radiant has show up that parallels the ORIs. I have listed them as XGE in the position charts below. This extends only from the 16<sup>th</sup> (in the Full Moon whiteout) to the 25<sup>th</sup>. While it will be difficult, there’s still plenty to be gained by making and reporting careful observations this year.</font></p><font face="Times New Roman" size="3"> </font> <p style="margin-top:0in;margin-left:0in;margin-right:0in" class="MsoNormal"><font face="Times New Roman" size="3">ORI- Orionids velocity 66 km/sec (very fast) </font></p> <div class="Discussion_UserSignature"> <p><font color="#000080"><em><font color="#000000">But the Krell forgot one thing John. Monsters. Monsters from the Id.</font></em> </font></p><p><font color="#000080">I really, really, really, really miss the "first unread post" function</font><font color="#000080"> </font></p> </div>