(meteorobs) Meteor Activity Outlook for July 3-9, 2010

[Robert Lunsford]

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 noticeable 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 last quarter phase on Sunday July 4th. At this time the moon will be located ninety degrees 
west of the sun and will rise near 0100 for observers located in mid-northern latitudes. Next week the waning crescent moon will 
rise later and later, providing an expanding window of opportunity for viewing under dark skies. The estimated total hourly rates 
for evening observers this week is near three for northern observers and four 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 fifteen 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. Morning 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 July 3/4. 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 19:40 (295) -20. This area of the sky lies in eastern Sagittarius. The nearest 
bright star is third magnitude Beta Capricornii, which lies some ten degrees to the northeast. 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 Sagittarius, Scutum, western Capricornus, or southern 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 confirmed that the July Pegasids (JPE) are still an 
active shower. This shower has a much longer activity period than once thought, being active from July 7th through the 29th. Maximum 
activity occurs on July 10 when the radiant lies at 23:08 (347) +11. This area of the sky is located in southern Pegasus, just four 
degrees south of the second magnitude star (Alpha Pegasi). 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. With an entry velocity of 68 km/sec., 
the average July Pegasid meteor would be swift.

Recent studies of the IMO video database by Sirko Molau and Juergen Rendtel have revealed an active radiant in Andromeda this time 
of year. The c-Andromedids (CAN) are active from July 4th through the 16th with maximum activity occurring on the 12th. The radiant 
is currently located at 01:36 (024) +45. This area of the sky is located in northeastern Andromeda, five degrees northwest of the 
famous double star Almach (Gamma Andromedae). This radiant is best placed during the last hour before dawn when it lies highest in a 
dark sky. Hourly rates are expected to be less than one. Due to the high northern declination (celestial latitude) this shower is 
difficult to view from too far south of the equator. With an entry velocity of 59 km/sec., the average c-Andromedid meteor would be 
swift.

As seen from the mid-northern hemisphere (45N) one would expect to see approximately six 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 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 by 
moonlight.

The list 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.

Antihelion (ANT) - 19:40 (295) -20    Velocity - 30km/sec.
Northern Hemisphere - 1 per hr.   Southern Hemisphere - 2 per hr.

July Pegasids (JPE) - 23:08 (347) +11    Velocity - 68km/sec.
Northern Hemisphere - <1 per hr.   Southern Hemisphere - <1 per hr.

c-Andromedids (CAN) - 01:36 (024) +45    Velocity - 59km/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