(meteorobs) Meteor Activity Outlook for July 19-25, 2008

[Robert Lunsford]

After several months of low activity the meteor rates for both hemispheres
see a marked increase in July. In the northern hemisphere the change is not
noticeable until mid-month when several southern radiants, the Perseids, and
sporadic rates all increase in activity. Southern rates are good all month
long.

During this period the moon reaches its last quarter phase on Friday July
25. At this time the moon will rise near 0100 local daylight time (LDT) and
will be in the sky the remainder of the morning. This weekend and early next
week the intense moonlight will obscure all but the brightest meteors making
observations difficult. The estimated total hourly rates for evening
observers this week is near two for those located in the mid-northern
hemisphere (45 N) and three for those viewing from the mid-southern
hemisphere (45 S). For morning observers the estimated total hourly rates
should be near ten for those located in the mid-northern hemisphere (45 N)
and fifteen for those viewing from the mid-southern hemisphere (45 S). These
rates assume that you are watching from rural areas away from all sources of
light pollution. The actual rates will also depend on factors such as
personal light and motion perception, local weather conditions, alertness
and experience in watching meteor activity. Rates are reduced this week due
to intense moonlight.

The radiant positions and rates listed below are exact for Saturday
night/Sunday morning July 19/20. These positions do not change greatly day
to day so the listed coordinates may be used during this entire period. Most
star atlases (available at science stores and planetariums) will provide
maps with grid lines of the celestial coordinates so that you may find out
exactly where these positions are located in the sky. A planisphere or
computer planetarium program is also useful in showing the sky at any time
of night on any date of the year. Activity from each radiant is best seen
when it is positioned highest in the sky, either due north or south along
the meridian, depending on your latitude. It must be remembered that meteor
activity is rarely seen at the radiant position. Rather they shoot outwards
from the radiant so it is best to center your field of view so that the
radiant lies at the edge and not the center. Viewing there will allow you to
easily trace the path of each meteor back to the radiant (if it is a shower
member) or in another direction if it is a sporadic. Meteor activity is not
seen from radiants that are located below the horizon. The positions below
are listed in a west to east manner in order of right ascension (celestial
longitude). The positions listed first are located further west therefore
are accessible earlier in the night while those listed further down the list
rise later in the night.

The full descriptions of each active meteor shower will continue next week
when the moon becomes less of a nuisance to observers.

The table below presents a condensed version of the expected activity this
week. Rates and positions are exact for Saturday night/Sunday morning.

Alpha Capricornids (CAP)  19:56 (299) -12   Velocity - 23km/sec.
Northern Hemisphere - 1   Southern Hemisphere - 1

Antihelion (ANT) - 20:40 (310) -17   Velocity - 30km/sec.
Northern Hemisphere - 1   Southern Hemisphere - 2

Beta Aquariids (BAQ)  21:32 (323) -02   Velocity - 40km/sec.
Northern Hemisphere - <1   Southern Hemisphere - <1

Delta Aquariids (SDA)  22:12 (333) -18   Velocity - 41km/sec.
Northern Hemisphere - 1   Southern Hemisphere - 1

Piscis Austrinids (PAU)  22:16 (334) -33   Velocity - 35km/Sec.
Northern Hemisphere - <1   Southern Hemisphere - <1

Perseids (PER)  00:44 (011) +52   Velocity - 57km./sec.
Northern Hemisphere - 1   Southern Hemisphere - <1

*For a detailed explanation on the different classes of meteor showers and
other astronomical terms, please visit:
http://www.amsmeteors.org/showers.html#X2008

Clear Skies!
Robert Lunsford
American Meteor Society