Oct 20/21 Meteors and the Peak of the Orionids?

Based on visual reports submitted to the International Meteor Organization, the Orionids may have reached their peak intensity. The Zenithal Hourly Rate (ZHR) has been around ~35 for the past 2 nights. The ZHR is the number of meteors that would be seen per hour IF, and these are important IFs; 1) your sky is dark enough to see stars down to magnitude 6.5, 2) the radiant of the shower was directly overhead and 3) there are no obstructions in your field of view. Last year, the Orionids reached a ZHR of ~70. The Orionids only have another night or two to reach last year’s level. The Orionids normally reach a ZHR of ~20-30 so this year’s activity is still better than usual. The hope was that last year’s enhanced activity would occur again.

Both my video and naked eye observations are consistent with rates being nearly the same over the past 2 nights. Video detections were about the same, 54 last night versus 52 the night before. I spent an hour watching from my backyard. Under magnitude 4.7 skies, I counted 18 meteors in that hour with the following breakdown (18 TOT, 3 SPO, 3 NTA/STA, 11 ORI, 1 LMI). There was on big difference between this morning’s meteors and the previous morning. The Orionids were on average much brighter this morning. Of the 11, 5 were 0th magnitude or brighter (brighter than all but a very few of the brightest stars).

Bob says “Fog threatened observing from home, along the coast, so I drove 35 miles inland where the sky was beautifully clear both nights. I believe the excessive Epsilon Geminid rates are not real, but that the meteor recognition program has difficulty separating them from the Orionids.”

Bob’s camera in San Diego always sees more meteors than my Tucson camera because it is much more sensitive. This means it can see fainter meteors. His numbers from last night are amazing. If you compare them to his numbers from previous nights you can see just how many more meteors can be observed from a dark site.

The Orionids should produce the same level of activity, and maybe even more, tonight. The Moon is slowly becoming less of a problem as its phase decreases and it moves further from the Orionid radiant.

Obs  Date (UT)   TotTime TOT SPO NTA STA ORI EGE LMI
Carl 2008-10-21  10h 11m  74  13  2   2   54  2   1
Bob  2008-10-21   4h 05m 225  36  6   3  153 18   9

TotTime – Total amount of time each camera looked for meteors
TOT – total number of meteors detected
SPO – Sporadics (meteors not affiliated with any particular meteor shower)
NTA – Northern Taurids
STA – Southern Taurids
ORI – Orionids
EGE – Epsilon Gemininds
LMI – Leo Minorids

About Carl Hergenrother
I am a professional astronomer specializing in the study of comets, asteroids and meteors. This blog will focus on my professional and amateur work in this field

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