Meteor Activity Outlook for June 28-July 4, 2008

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 noticable 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 new phase on Thursday July 3rd. At this time the moon will be located near the sun and will not be visible at night. This weekend the waning crescent moon will produce minor interference during the last few hours before dawn. As seen from the mid-northern hemisphere (45 N) the estimated total hourly rates during the evening observers would be near two. For morning observers the estimated total hourly rates should be near ten. For those located in the mid-southern hemisphere (45 S) morning rates would be near twenty and evening rates near four. 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 and rates listed below are exact for Saturday night/Sunday morning June 28/29. 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:

A few June Bootids (JBO) may be seen during the evening hours radiating from a position near 15:00 (225) +47. This area of the sky lies in northern Bootes, six degrees north of the fourth magnitude star Beta Bootis. This radiant is best placed as soon as it becomes dark. Rates at this time should be less than one for those located in the northern hemisphere and near zero for observers south of the equator. With an entry velocity of 18 km/sec., the average June Bootid meteor would be of very slow speed.

The large Antihelion (ANT) radiant is now centered at 19:20 (290) -21. This area of the sky lies in eastern Sagittarius, three degrees east of the third magnitude star Pi Sagittarii. Actually any meteor from western Capricornus, southern Aquila, as well as eastern Sagittarius could be a candidate for this shower. This radiant is best placed near 0200 local daylight time (LDT) when it lies on the meridian and is highest in the sky. Rates at this time should be near three for northern observers and four for observers south of the equator. With an entry velocity of 30 km/sec., the average Antihelion meteor would be of medium-slow speed.

Studies by Sirko Molau of the IMO's video data has revealed an active radiant located in southeastern Aquila. Maximum activity was reached on June 25, but activity continues through the 30th. The radiant lies at 20:16 (304) -07, which is located ten degrees southeast of the bright first magnitude star Altair (Alpha Aquilae). This radiant is best placed near 0300 LDT when it lies on the meridian and is highest in the sky. Rates are most likely less than one per hour regardless of your location. With an entry velocity of 40 km/sec., the average North June Aquilid (NZC) meteor would be of medium speed, but noticably more swift than the nearby Antihelion radiant.

As seen from the mid-northern hemisphere (45N) the Sporadic rates are finally beginning to increase. One would expect to see approximately eight random meteors during the last hour before dawn from rural observing sites and two per hour during the evening hours. As seen from the mid-southern hemisphere (45S) morning rates would be near seventeen per hour as seen from rural observing sites and four per hour during the evening hours.

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