The Meteor Activity Outlook is a weekly summary of expected meteor activity written by Robert Lunsford, Operations Manager of the American Meteor Society and contributor to this blog. The original unedited version of this week’s Meteor Activity Outlook can be found at the American Meteor Society’s site.
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 wanes from a fat crescent down to a sliver that rises during the bright morning twilight. This weekend the moon will rise during the morning hours but any interference it causes can be easily avoided by keeping it out of your field of view. The lunar glare will only be a small fraction of what it is at full moon so successful meteor observing can be undertaken during this period. The estimated total hourly rates for evening observers this week is ~3 for those in the northern hemisphere and ~4 for those south of the equator. For morning observers the estimated total hourly rates should be ~6 from the northern hemisphere and ~16 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 positions and rates listed below are exact for Saturday night/Sunday morning June 5/6. These positions do not change greatly day to day so the listed coordinates may be used during this entire period.
The following showers are expected to be active this week:
The wide Antihelion (ANT) radiant is now centered at 17h:52m (268) -23. This area of the sky lies in western Sagittarius some ten degrees northwest of the second magnitude star Lambda Sagittarii. This radiant is best placed near 0200 local daylight time (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 southern Ophiuchus, southern Serpens Cauda, western Sagittarius, or Scorpius could be a candidate for this shower. Rates at this time should be near one per hour as seen from the northern hemisphere and two 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.
As seen from the mid-northern hemisphere (45N) one would expect to see approximately five sporadic meteors per hour during the last hour before dawn as seen from rural observing sites. Evening rates would be near two per hour. As seen from the mid-southern hemisphere (45S), morning rates would be near fourteen 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 slightly reduced due to moonlight.
The list below presents a condensed version of the expected activity this week. Rates and positions are exact for Saturday night/Sunday morning.
Shower Name RA DEC Vel Rates km/s NH SH ANT Antihelions 17h 52m -23 30 1 2 RA - Right Ascension DEC - Declination Vel - Velocity relative to Earth (in km per sec) Rates - Rate of visible meteors per hour from a dark site NH - Northern Hemisphere SH - Southern Hemisphere