Meteor Activity Outlook for June 23-29, 2006

During June observers in the northern hemisphere see some of their lowest rates of the year. During this month the sporadic rates bottom out producing an average of only one meteor every ten minutes, even from dark sky sites. The active showers are also modest this month, barely adding any more activity to the nighttime scene. Observers south of the equator are enjoying some of their best rates of the year. This activity is produced from strong sporadic rates and the fact that the Antihelion radiant is positioned well south of the celestial equator this time of year. Combine this activity with long nights and the core of the Milky Way riding high in the sky, and you get an impressive scene. Unfortunately we have so few southern observers to enjoy this scenario. This is a reason that observations from south of the equator are so important.

The short nights in the northern hemisphere often make June the least active month for meteor observers. Many of the worlds most active meteor observers suffer from twilight all night long this time of year so those who live in the more temperate latitudes should make every effort to view the elusive June activity and to report their valuable data.

This week the moon will reach its new phase on Sunday June 25th. On this date the moon will rise and set with the sun and will not interfere with meteor observing, no matter the hour. As the week progresses the waxing crescent moon will enter the evening sky but will set well before the morning active morning hours arrive. The estimated total hourly rates for evening observers this week is near two for observers in the northern hemisphere and four for those south of the equator. For morning observers the estimated total hourly rates should be near ten for those in the northern hemisphere and eighteen 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 June 24/25. 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.

The June Bootids (JBO) are active this week from a radiant located at 14:52 (223) +48. This area of the sky is located in northern Bootes some fifteen degrees southeast of Alkaid (Eta Ursae Majoris), the last star in the handle of the “Big Dipper”. Due to the northern declination this shower is well seen only from the southern equatorial areas northward to the northern temperate areas. Those located north of 50 degrees north latitude will have difficulty seeing any activity due to the very short nights experienced in those latitudes this time of year. This area of the sky is best placed as soon as it gets dark during the evening hours. Peak rates are expected on June 27 but no outburst is expected this year so rates will most likely be quite low. At 18 km/sec. any June Bootids will appear to move quite slowly compared to most meteors.

The Antihelion (ANT) radiant is now centered at 19:04 (286) -22. This area of the sky is located in central Sagittarius, very close to the position occupied by the fourth magnitude star Omicron Sagittarii. 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 for those north of the equator and three per hour south of the equator. With an entry velocity of 30 km/sec., the average Antihelion meteor would be of medium-slow speed.

After six months of declining rates the Sporadic rates for the Northern Hemisphere are now finally starting to increase. One would expect to see perhaps eight random meteors during the last hour before dawn from rural observing sites. During the first dark hour after the end of evening twilight, perhaps two random meteors can be seen per hour. Sporadic rates increase as the night progresses so rates seen near midnight would be near five per hour. Sporadic rates seen from the southern hemisphere are now increasing toward a secondary maximum in July. One would see approximately sixteen random meteors per hour during the last hour before dawn and four per hour during the first dark hour after the end of evening twilight. Rates near midnight would be near ten per hour.