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home > observing > celestial objects > meteors

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Taking a Break

Most observers like to take a break about once an hour to get up, move around, and open the coffee thermos. Note the beginning and end times of every break. If you're writing, also record how much time you spend looking down at your clipboard if this is more than a few percent of the total. Count how many seconds the job takes per meteor; you may be surprised at how much time it adds up to.

Even if you observe without a break, separate your records with a time annotation at least once an hour. A watch that beeps on the hour will help remind you. If rates suddenly begin to rise or fall, note the time more often. Also note down the part of the sky where you spend most of the time looking.

For simple meteor counting, that's about it. If you want to do a little more, however, the IMO strongly encourages you to estimate the magnitude of each meteor you see. Large numbers of magnitudes are required for finding a shower's "population index," or r, the ratio of bright meteors to faint ones. This, in turn, is required for calculating the zenithal hourly rates for everyone who watched under a less-than-perfect dark sky. Some comparison magnitudes can be found below.

Make your magnitude estimates by imagining these stars zipping across the sky, not by trying to sum up the total light along a meteor's path. For example, when estimating magnitudes for the Leonids, a typical notation might be "L, 2.5."

It's important not to combine your counts with anyone else's! If you watch with friends, each person should conduct his or her session strictly separately and submit a separate report. In fact, you should really be positioned far enough apart so that you can't tell when someone else makes a note. The problem is not the bright meteor that draws a yell out of everybody, but the faint, questionable one that you would dismiss as an eye twitch if you didn't hear someone start muttering into a tape recorder. Including it will make your count artificially high for your limiting magnitude. It helps to watch different parts of the sky.

Nor should you confer about the sky's limiting magnitude. Your own determination needs to go with your count. If one observer finds 5.4 and another 6.0, each person is right — for the purpose of reducing his or her count.

Comparisons for Meteor Magnitudes
Mag. Object Mag. Object Mag. Object
-13 Full Moon 0.5 Procyon 2 Gamma (g) Gem
-10 Quarter Moon 1 Aldebaran 2 Gamma (g) Leo
-4.5 Venus (avg.) 1 Pollux 2.5 Delta (d) Leo
-2.5 Jupiter (avg.) 1 Spica 2.5 Gamma (g) UMa
-1.5 Sirius 1.5 Regulus 3 Gamma (g) UMi
0 Capella 2 Polaris 3 Epsilon (e) Gem
0 Arcturus 2 Beta (b) UMi 3.5 Epsilon (e) Tau
0 Vega 2 Alpha (a) UMa 3.5 Beta (b) Boo

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