Meteor Activity Outlook for August 21-27, 2010

The Meteor Activity Outlook is a weekly summary of expected meteor activity written by Robert Lunsford, Operations Manager of the American Meteor Society and contributor to this blog. The original unedited version of this week’s Meteor Activity Outlook can be found at the American Meteor Society’s site.

Meteor activity kicks into high gear in August as seen from the northern hemisphere. The main reason for this activity surge is the Perseid shower that peaks on August 13. This shower is active most of the month and remains above the level of the sporadic background for a week centered on August 13. The sporadic activity is also increasing as seen from the northern hemisphere and is now nearly double the rates from just three months ago. As seen from south of the equator, meteor rates are still decent but falling rapidly. The sporadic rates seen at the beginning of the month will be twice as high as those seen during the last days of the month. The Perseid radiant does not rise high into the sky as seen in the southern hemisphere so rates from this shower are greatly reduced when compared to the northern hemisphere.

During this period the moon reaches its full quarter phase on Tuesday August 24th. At this time the moon will be located opposite the sun and will be in the sky all night long. This weekend the waxing gibbous moon will set near the start of morning twilight, depending on your latitude. The further north one is located, the earlier the moon will set, allowing more time to observe under dark skies. The estimated total hourly rates for evening observers this week is ~2 no matter your location. For morning observers the estimated total hourly rates should be ~8 from the northern hemisphere and ~6 as seen from the southern hemisphere. 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. During this period, moonlight reduces activity seen during the morning hours.

The radiant positions and rates listed below are exact for Saturday night/Sunday morning August 21/22. These positions do not change greatly day to day so the listed coordinates may be used during this entire period.

As seen from the mid-northern hemisphere (45N) one would expect to see approximately five sporadic meteors per hour during the last hour before dawn as seen from rural observing sites. Evening rates would be near two per hour. As seen from the mid-southern hemisphere (45S), morning rates would be near fourteen per hour as seen from rural observing sites and three per hour during the evening hours. Locations between these two extremes would see activity between the listed figures. Morning rates are slightly reduced due to moonlight.

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

The detailed descriptions will be continued next week when the moonlight is not
as intense.

Shower Name                RA     DEC   Vel     Rates
                                        km/s   NH    SH
AUG August Draconids     18h 28m  +63    23    <1    <1
ANT Antihelions          22h 48m  -06    30     2     3
SDA Delta Aquariids      00h 01m  -10    42    <1    <1
PER Perseids             04h 04m  +60    61     1    <1

RA - Right Ascension
DEC - Declination
Vel - Velocity relative to Earth (in km per sec)
Rates - Rate of visible meteors per hour from a
        dark site
NH - Northern Hemisphere
SH - Southern Hemisphere