(meteorobs) Meteor Activity Outlook for June 19-25, 2010

[Robert Lunsford]

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 first quarter phase on Saturday June 19th. At this time the moon will be located ninety 
degrees east of the sun and will set near 0100 for observers located in mid-northern latitudes. Next week the waxing gibbous moon 
will set later and later, shrinking the window of opportunity to view in optimum, dark conditions. The estimated total hourly rates 
for evening observers this week is near two for northern observers and three for those viewing from south of the equator. For 
morning observers the estimated total hourly rates should be near eight from the northern hemisphere and eighteen 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. Evening rates are reduced during this period due to moonlight.

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 June 19/20. 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:

Perhaps a few June Bootids (JBO) may be seen this week during the evening hours, radiating from a position near 14:44 (221) +49. 
This area of the sky lies in northern Bootes, ten degrees northwest 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. Maximum activity is expected on June 27th. With an entry velocity of 18 km/sec., the 
average June Bootid meteor would be of very slow speed.

The wide Antihelion (ANT) radiant is now centered at 18:44 (281) -23. This area of the sky lies in western Sagittarius some four 
degrees northeast of the third magnitude star Kaus Borealis (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, Sagittarius, Scutum, or southwestern Aquila 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.

Recent studies of the IMO video database by Sirko Molau and Juergen Rendtel have revealed an active radiant in Pisces this time of 
year. The Delta Piscids (DPI) are only active for five nights (June 20-24) with maximum activity occurring on June 23rd. On that 
morning the radiant is located at 00:44 (011) +06. This area of the sky is located in central Pisces near 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. Even at maximum 
activity hourly rates are expected to be less than one. This shower would be better seen from locations south of the equator where 
the nights are longer and the radiant would located higher in the eastern sky at the start of morning twilight. With an entry 
velocity of 71 km/sec., the average Delta Piscid meteor would be swift.

As seen from the mid-northern hemisphere (45N) one would expect to see approximately seven 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 sixteen 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 list below presents a condensed version of the expected activity this week. Rates and positions are exact for Saturday 
night/Sunday morning.

June Bootids (JBO) - 14:44 (221) +49    Velocity - 18km/sec.
Northern Hemisphere - <1 per hr.   Southern Hemisphere - 0 per hr.

Antihelion (ANT) - 18:44 (281) -23   Velocity - 30km/sec.
Northern Hemisphere - 1 per hr.   Southern Hemisphere - 2 per hr.

Delta Piscids (DPI) - 00:44 (011) +06   Velocity - 71km/sec.
Northern Hemisphere - <1 per hr.   Southern Hemisphere - <1 per hr.

*For a detailed explanation on the different classes of meteor showers and other astronomical terms, please visit: 
http://www.amsmeteors.org/showers.html#X2010

Clear Skies!
Robert Lunsford
American Meteor Society