Meteor Activity Outlook for August 7-13, 2010

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 new phase on Tuesday August 10th. At this time the moon will be located near the sun and is not visible at night. This weekend the thin waning crescent moon will not cause any problems for morning observers. The estimated total hourly rates for evening observers this week is near four no matter your location. For morning observers the estimated total hourly rates should be near twenty-four from the northern hemisphere and twenty-one 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.

The radiant (the area of the sky where meteors appear to shoot from) positions and rates listed below are exact for Saturday night/Sunday morning August 7/8. 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 following showers are expected to be active this week:

Activity from the August Draconids (AUD) can be first detected near August 11th from a radiant located at 18:00 (270) +61. This position lies in southern Draco, close to the second magnitude star Eltanin (Gamma Draconis). Maximum activity is not predicted until August 21st so current rates would be low, less than one per night. With an entry velocity of 23 km/sec. most of these meteors will appear to move slowly. The radiant is best placed near 2200 Local Daylight Time (10pm LDT) when it lies highest in the sky. Due to its high northern declination this shower is not well seen from the southern hemisphere.

The Kappa Cygnids (KCG) are active from a wide radiant located at 18:50 (282) +47. This position is further south than previous publications. It has been updated through the use of video observations by the International Meteor Organization. The new location lies on the Lyra/Draco border, eight degrees northwest of the brilliant star Vega (Alpha Lyrae). Maximum activity is now predicted to occur on August 14th. Current rates would be one per hour from the northern hemisphere and less than one shower member per hour from south of the equator. With an entry velocity of 23 km/sec. most of these meteors will appear to travel slower than average. The radiant is best placed near 2300 LDT (11pm LDT) when it lies nearly overhead for much of the Northern Hemisphere. Due to its high northern declination this activity is not well seen from the southern hemisphere.

The Alpha Capricornids (CAP) are active from a wide radiant located at 20:45 (311) -07. This position lies in western Aquarius near the faint star 3 Aquarii. The radiant is best placed near 0100 local daylight time (LDT), when it lies on the meridian and is highest in the sky. Current rates should be near one per hour no matter your location. Don't confuse these meteors with the antihelion meteors, which have a radiant just to the east. Both radiants need to be in your field of view to properly sort these meteors. With an entry velocity of 25 km/sec., most activity from this radiant would be slow, a bit slower than the antihelions. This radiant is well seen except for far northern latitudes where it remains twilight all night long and the radiant does not rise as high into their sky.

The wide Antihelion (ANT) radiant is now centered at 21:52 (328) -11. This area of the sky lies in northeastern Capricornus, four degrees northeast of Deneb Algedi (Delta Capricornii). This radiant is best placed near 0200 LDT when it lies on the meridian and is located highest in the sky. Due to the large size of this radiant, any meteor radiating from northwestern Piscis Austrinus, Microscopium, Capricornus, Aquarius, or southeastern Aquila could be a candidate for this shower. Rates at this time should be near two per hour as seen from the northern hemisphere and three per hour as seen from south of the equator. With an entry velocity of 30 km/sec., the average Antihelion meteor would be of medium-slow speed.

The Delta Aquariids (SDA) reached maximum activity on July 30th. The shower is still active from a radiant located at 23:12 (348) -14. This position lies in central Aquarius, four degrees northeast of the third magnitude star Delta Aquarii. The radiant is best placed near 0300 LDT, when it lies highest in the sky. With an entry velocity of 42 km/sec., most activity from this radiant would be of average velocities. Expect rates of one per hour north of the equator and two per hour from the southern hemisphere.

A new shower discovered by Sirko Molau and Juergen Rendtel from the IMO's video database are the August Piscids (AUP). This shower is only active on eight nights from August 2-9 with maximum activity occurring on the 4th. The radiant is currently located at 00:44 (011) +19. This area of the sky is located in northern Pisces, ten degrees north of the fourth magnitude star Delta Piscium. This radiant is best placed during the last hour before dawn when it lies highest in a dark sky. Hourly rates are expected to be less than one. With an entry velocity of 66 km/sec., the average August Piscid meteor would be swift.

The Perseids (PER) are active from a radiant located at 02:44 (041) +56. This position lies in northwestern Perseus very close to the fourth magnitude star Eta Persei. The radiant is best placed during the last hour before the start of morning twilight when it lies highest in a dark sky. Current rates would be near five per hour but this will swell to near sixty per hour at maximum activity on the mornings of the 12th and 13th. The latest predictions have the Earth encountering a trail of debris produced by comet 109P/Swift-Tuttle in the year 441 AD. This very old trail is not expected to produce an outburst but should enhance rates by 10-15 meteors per hour near 1200 Universal Time (05:00am PDT) on the 13th. Activity from the Perseids is not visible south of 40 degrees south latitude. With an entry velocity of 61 km/sec., most activity from this radiant would be swift.

A second new shower discovered by Sirko Molau and Juergen Rendtel from the IMO's video database are the Eridanids (ERI). This shower is active from August 4th through the 18th with maximum activity occurring on the 9th. Hourly rates could reach near two per hour at maximum. The radiant is currently located at 02:50 (042) -11. This area of the sky is located in extreme eastern Cetus about a dozen degrees south of Phycochroma (Delta Ceti). This radiant could account for the activity many observers have reported (including myself) this time of year from this portion of the sky. This radiant is best placed during the last hour before dawn when it lies highest in a dark sky. Hourly rates are expected to be less than one. With an entry velocity of 64 km/sec., the average Eridanid meteor would be swift.

Still another new shower discovered by Sirko Molau and Juergen Rendtel from the IMO's video database are the Beta Perseids (BPE). This shower is active from August 4th through the 15th with maximum activity occurring on the 7th. Hourly rates are expected to remain low throughout this duration. The radiant is currently located at 03:02 (046) +40. This position lies only one degree southwest of the famous eclipsing variable star known as Algol (Beta Persei). This radiant has been suspected for many years and may have also been known as the Alpha-Beta Perseids. This radiant is best placed during the last hour before dawn when it lies highest in a dark sky. Hourly rates are expected to be less than one. With an entry velocity of 67 km/sec., the average Beta Perseid meteor would be swift.

As seen from the mid-northern hemisphere (45N) one would expect to see approximately twelve sporadic meteors per hour during the last hour before dawn as seen from rural observing sites. Evening rates would be near three per hour. As seen from the mid-southern hemisphere (45S), morning rates would be near ten 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.

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