(meteorobs) Meteor Activity Outlook for July 10-16, 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 new phase on Sunday July 11th. At this time the moon will be located near the sun and will 
be invisible at night. Later next week the waxing crescent moon will enter the evening sky but will set before midnight, allowing 
unhampered viewing of the morning activity. 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 twelve 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.

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 10/11. 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 20:04 (301) -19. This area of the sky lies in eastern Sagittarius. The nearest 
bright star is third magnitude Dabih (Beta Capricornii), which lies some six 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 eastern Sagittarius, Microscopium, western Capricornus, or southeastern Aquila could be a 
candidate for this shower. Rates at this time should be near two per hour as seen from the northern hemisphere and three 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 02:04 (031) +48. This area of the sky is located in northeastern Andromeda, six degrees north 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 ten 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.

Antihelion (ANT) - 20:04 (301) -19    Velocity - 30km/sec.
Northern Hemisphere - 2 per hr.   Southern Hemisphere - 3 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) - 02:04 (031) +48    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