During August observers in the northern hemisphere continue to see a rise in the meteor activity, especially near August 12, when the Perseids reach maximum strength. This peak is somewhat modified this year by the bright gibbous moon that will be present during the Perseid maximum. Observers south of the equator are seeing their rates plummet as the Perseids have little effect in producing activity from the far southern latitudes.
This week the moon will reach its first quarter phase on Thursday August 31st. This weekend the waxing crescent moon will set during the early evening hours and will not interfere with observing. The estimated total hourly rates for evening observers this week is near three for those north of the equator and two for those south of the equator. For morning observers the estimated total hourly rates should be near seventeen for those in the northern hemisphere and eight for those south of the equator. 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.
The radiant positions listed below are exact for Saturday night/Sunday morning August 26/27. 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. 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.
These showers are active this week:
The Kappa Cygnids (KCG) peaked on August 17 with an expected ZHR of 3. They are still active from a wide radiant located at 19:16 (289) +60. This position is located in southeastern Draco, six degrees north of the fourth magnitude star Kappa Cygni. Current rates would be near one shower member per hour as seen from the northern hemisphere. Due to the high northern declination (celestial latitude) this shower is poorly seen from the southern hemisphere. A large percentage of these meteors are bright, often fireball class meteors with brilliant colors. With an entry velocity of 25 km/sec. most of these meteors will appear to travel slower than average. The radiant is best placed near 2300 Local Daylight Time (11pm LDT your local time) when it lies nearly overhead for much of the northern hemisphere.
The Antihelion (ANT) radiant is now centered at 23:04 (346) -04. This area of the sky is centered in northern Aquarius, four degrees northwest of the fourth magnitude star Phi Aquarii. This radiant is best placed near 0200 local daylight time when it lies on the meridian and is highest in the sky. Rates at this time should be near two per hour regardless of your location. With an entry velocity of 30 km/sec., the average Antihelion meteor would be of medium-slow speed.
The Alpha Aurigids (AUR) peak on the morning of September 1 with an average ZHR of ten. The actual rates fluctuate greatly from one year to the next. While nothing out of the ordinary is expected from this shower in 2006, 2007 is viewed with anticipation as a possible outburst is predicted. While the moon is favorable this year, it is not in 2007 as it will be only four days past its full phase. The radiant is currently located at 05:12 (78) +42, which places it in central Auriga, four degrees south of the brilliant zero magnitude yellow star Capella (Alpha Aurigae). Rates prior to the date of maximum activity are low, rarely exceeding one shower member per hour. Due to the extreme northern declination, this shower is only visible from the southern tropics northward. The radiant is best placed just before the start of morning twilight, when it lies highest in a dark sky. The radiant actually culminates after sunrise. At 66km/sec., the average Alpha Aurigid is swift.
Sporadic rates continue to climb for observers located in the northern hemisphere. One would expect to see perhaps thirteen random meteors during the last hour before dawn from rural observing sites. During the first dark hour after the end of evening twilight, perhaps three random meteors can be seen per hour. Sporadic rates increase as the night progresses so rates seen near midnight would be near seven per hour. Sporadic rates seen from the southern hemisphere are now falling rapidly. One would see approximately six random meteors per hour during the last hour before dawn and two per hour during the first dark hour after the end of evening twilight. Rates near midnight would be near four per hour.