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(meteorobs) NAMN Call for Observations: Aquarids
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NAMN Call for Observations: The Aquarids
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The Northern Hemisphere summer nights are characterized by a number of
meteor showers being visible all at once. When combined they are able to
produce some interesting activity for visual observers. If you are like most
people though, you will tend to concentrate on the well-known Perseid meteor
shower in August. In 1998 however, the Perseids suffer from "moon-pollution"
and will be difficult to observe. But not to worry, there are other fish to
catch in the watery realm of the sky – Aquarius and Capricornus.
This time of year offers a chance to introduce some new terminology and
ideas that beginning meteor observers are liable to encounter. As you
probably already know, it is a standard practice to name a meteor shower for
the constellation its members seem to come from. In an effort to confuse us,
some showers exhibit separate "branches" which you will often hear or see
discussed. One such shower is the Taurids, with their branches being known
as the Northern and Southern Taurids. And then what seems to be an effort to
trip us up even more, there are some occasions where the shower activity is
so entangled that it is often referred to as a "complex." One such case is
the upcoming Aquarid complex.
When speaking of the Aquarid complex, we are actually talking about several
separate shower radiants. Showers included are usually the Southern and
Northern Delta Aquarids, Southern and Northern Iota Aquarids, and the
Capricornids.
The Southern Delta Aquarids (three-letter code: SDA) are visible from July
12 to August 19 and reach maximum on July 28. The typical ZHR quoted for the
SDAs is 20. The radiant is located at 22h36m (339deg), -16deg. They have a
velocity of 41 km/s. This is the strongest shower of the five we discuss as
being part of the Aquarid complex.
The Northern Delta Aquarids (three-letter code: NDA) are active from July 15
to August 25 and reach a ZHR of about 4 on August 8. The radiant is located
at 22h20m (335), –05 and they travel at 42 km/s.
The Southern Iota Aquarids (three-letter code: SIA) are active July 25 to
August 15. Their peak occurs on August 4 with a ZHR of only about 2. Shower
members appear from a radiant of 22h16m (334), –15 at 34 km/s.
The Northern Iota Aquarids (three-letter code: NIA) have a period beginning
August 11 and ending August 31. Their peak occurs on August 20 with a rate
of about 3 meteors per hour or less. The NIA radiant is located at 21h48m
(327), -06deg. These are a little slower than their southern counterparts
with a velocity of 31 km/s.
Finally, the Alpha Capricornids (three-letter code: CAP) are visible from
July 3 to August 15 and reach maximum on July 30 with a ZHR of 4. The
radiant is at 20h28m (307), –10. The Capricornids are the slowest of all
these mid-year streams with a velocity of 23 km/s.
In 1998 these showers are generally free of moonlight. With radiants that
are above the horizon most of the night, the Aquarid complex is accessible
to all observers. I encourage NAMN members to plan an extensive campaign.
For help in starting an observing program feel free to contact me.
Mark Davis
NAMN Coordinator
MeteorObs@charlestondot net