Sunday March 16, 2014 - March Meteors Observed in 2007

  After plotting the meteor seen after midnight today, I realized that I'd made an entry in the past about meteors that seemed to radiate from this area of the sky in early March. This morning I started going through old logs and found the record . The observations had been on two consecutive nights; the mornings of March 11 and March 12, 2007. I'd seen a total of three meteors, and when I plotted them on a chart printed off the Heavens-Above website, then extended their paths in the sky backward, all three meteors seemed to converge at a point close to the bright star Arcturus in Bootes. I thought that maybe I was seeing a Minor Meteor Shower at the time. Here's the plot that I made seven years ago ... though after studying materials about visual meteor observing, I realize now that this plot has some issues! I'll describe these also.

  Meteor #1 was seen at 1:35 AM (6:35 UT) on Sunday, March 11, 2007. It was about 1.0 magnitude and fast with no train, and seemed to cross right through Bootes.
  Meteor #2 was seen just one minute after the first one, at 1:36 AM (6:36 UT) Sunday, March 11, 2007. This one was fainter at 3.0 magnitude, fast, and also had no train. It zipped from near the star Arcturus to south of Corona Borealis.
  Meteor #3 was seen the following night at 1:15 AM (5:15 UT) on Monday, March 12, 2007. (Daylight Saving Time had occurred after the first two meteors were observed, hence the difference in UT conversion from one night to the next!) This was a bright meteor of about 1.0 magnitude that was fast with no train, and it zipped from the southern part of Ursa Major all the way to the constellation Gemini.

  Here are the problems with this plot that I made back then. First of all, I realize now that to be really accurate, one has to plot meteor paths on a chart that uses gnomonic projection, like the BRNO Atlas that I've downloaded from the IMO website this year. Secondly, I didn't realize until reading through IMO materials that there's a relationship between the apparent meteor path length and the radiant. From what I understand now, at least for meteors higher than 30 degrees, the distance between the radiant and the start point of a plotted meteor has to be at least twice as long as the meteor path itself. Using this general rule, the first meteor I saw probably originated from a radiant between and south of Virgo and Libra, while the second one probably had a radiant southwest of the brighter stars of Virgo. The third one may have had a radiant as far away as Serpens. Of course I'm still making these estimates using the wrong kind of chart and I'm also assuming that the path lengths of the three that I drew seven years ago are accurate.

  I think now that the first two meteors could have been from the almost-year-long Anthelion source, like last night's meteor may have been. The only problem with this is that I described the speed of all three meteors then as "fast" and Anthelion Meteors are lower in velocity than most other types. It's possible that all three of them were just random Sporadics also.

  If nothing else, going back to this entry from 2007 shows me that my own observing methods for meteors are evolving over time! As the year goes on I hope to get out to do more plotting and counting during the major and minor showers so I can contribute some good data to the IMO. There's still a lot about meteor showers that remains to be discovered. It's a wide-open area of amateur astronomy!