Meteor Activity Outlook for June 13-19, 2009

June is another slow month for meteor activity. There are no major showers active in June and only the Antihelion source can be counted on for continuous activity. Even the Antihelion is located so far south this time of year that rates rarely exceed two per hour as seen from the northern hemisphere. Sporadic rates reach their nadir in June as seen from the mid-northern hemisphere (45 N). Sporadic rates seen from the mid-southern hemisphere (45 S) continue to rise this month toward a maximum in July.

During this period the moon reaches its last quarter phase on Monday June 15. At this time the moon lies ninety degrees west of the sun and and rises near 0100 local daylight time (LDT). The moon remains in the sky the remainder of the morning and will cause some interference for observers. This weekend will be even worse as the moon will rise earlier and will be a bit brighter. The estimated total hourly rates for evening observers this week is near two as seen from the northern hemisphere and four for those situated south of the equator. For morning observers the estimated total hourly rates should be near five for those located in the mid-northern hemisphere (45 N) and fourteen for those viewing from the mid-southern hemisphere (45 S). Locations between these two extremes would see activity between the listed figures. 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. Morning rates are reduced due to moonlight.

The radiant positions and rates listed below are exact for Saturday night/Sunday morning June 13/14. 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:

The wide Antihelion (ANT) radiant is now centered at 18:20 (275) -23. This area of the sky lies in western Sagittarius, three degrees northwest of the third magnitude star Kaus Borealis (Lambda Sagittarii). This radiant is best placed near 0200 LDT when it is located on the meridian and lies highest in the sky above the horizon. Due to the large size of this radiant, any meteor radiating from southeastern Ophiuchus, Scutum, western Sagittarius, or southern Serpens Cauda could be a candidate for this shower. Rates at this time should be near two per hour as seen from the southern hemisphere and one as seen from north of the equator. With an entry velocity of 30km/sec., the average Antihelion meteor would be of medium-slow speed.

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

The table below presents a summary of the expected activity this week. Rates and positions are exact for Saturday night/Sunday morning but may be used all week.