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Meteors

March: A Month for Minor Meteors

Jane Houston Jones


March is a nothing month as major meteor showers go. March is a month of low sporadic rates and a few minor showers. Nothing major, so to speak. So, instead, I'll give a few definitions from the meteor glossary published in Guy Ottowells's Astronomical Calendar 2000. I'll also include two good websites to visit when there are no meteors to observe. Oh, and I'll mention the March meteor showers, of course. The delicate minor showers have their plusses, and many people enjoy the hunt for them. Don't forget that this month's SJAA general meeting will feature SJAA's own Mike Koop and yours truly "talking meteors" - Leonids, as in the NASA Leonid MAC Leonid Mission, that is ...

Here goes with the months pickings ...

Eta Virginids Observations of this shower indicate a duration of February 24 to March 27. Maximum is not prominent, but seems to fall on March 18 (solar longitude=358 deg), from a radiant of RA=185 deg, DEC=+3 deg. The maximum hourly rate reaches about 1 to 2. A possible southern branch of this stream seems to exist about 10 deg to the south. Virginid meteors generally emanate from a large area which slowly tracks through leo, Virgo and on towards Libra by mid-April. Virginids are normaly slow, but some can be bright, thought few leave persistent trains. Activity is generally low.

Rho Leonids Although visual observations of this shower seem virtually nonexistent, support for this stream appears in two radar studies conducted during the 1960's, as well as five photographic meteors detected over the period of 1937 to 1954. The first official detection of this stream was made by B. L. Kashcheyev and V. N. Lebedinets (Kharkov Polytechnical Institute) during a radar survey conducted in 1960. The radar was not operated continuously, but five meteors from this stream were detected during March 14-15, from an average radiant of RA=172 deg, DEC=+3 deg.

Gamma Normids The duration of this shower extends over the period of March 11 to 21. Maximum occurs on March 16 (solar longitude=356 deg), from an average radiant of RA=245 deg, DEC=-49 deg. The maximum ZHR reaches 5-9. First quarter Moon should present no problems for covering this under-observed minor southern hemisphere shower, because its radiant is well on view only after local midnight. Ok, this shower will not be visible from our latitude here in California, but your intrepid co-editors will be on their honeymoon at the South Pacific Star Party in the Blue Mountains of Australia around this time of March. We won't see it either.

Leonids - Ursids Although visual radiants of this stream are a distinct rarity, it is interesting that its strongest support for existing is based on several photographic meteors detected during the 1950's. In all, seven meteors were detected by cameras operating in the United States and Czechoslovakia, with individual details subsequently being reported in H1959, MP1961 and C1977. The indicated duration covers March 18 to April 7, while the average radiant is RA=175.7 deg, DEC=+23.0 deg.

ZHR: Zenithal Hourly Rate, the maximum number of meteors an excellent observer could see from a shower if the radiant were directly overhead and the sky perfectly clear (magnitude +6.5 stars visible). Haze, clouds and bright moonlight drastically reduce the observed number of meteors, since fainter meteors become effectively invisible. Low radiants, or times away from the shower's peak, also produce many fewer meteors.

Sporadic Meteors: Randonly distributed meteors that are visible at any time of the night throughout the year. They are normally more abundant between local midnight and dawn, and during the second half of the year for northern hemisphere observers.

Persistent Trains: Glowing ionized gas left along the paths of mainly the faster and brighter meteors. Visible only after the meteors themselves have dissappeared, they normally last only for a few seconds, at most. Much rarer examples last for minutes or longer, often twisting into an "S or Z or 2" shape before completely fading due to high-atmosphere winds.


Mail to: Jane Houston Jones
Copyright © 2000 San Jose Astronomical Association
Last updated: July 19, 2007

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