During this period, the moon reaches its new phase on Friday July 9th. At that time the moon is located near the sun and is invisible at night. This weekend a bright crescent moon will illuminate the morning sky. Successful meteor watches can still be held at this time as long as you keep the moon well out of your field of view. As the week progresses the moon becomes thinner and less of a problem until it disappears entirely into the morning twilight late in the period. The estimated total hourly meteor rates for evening observers this week is near 2 as seen from mid-northern latitudes (45N) and 3 as seen from tropical southern locations (25S). For morning observers, the estimated total hourly rates should be near 7 as seen from mid-northern latitudes (45N) and 10 as seen from tropical southern locations (25S). 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. Rates are reduced by moonlight during this period. Note that the hourly rates listed below are estimates as viewed from dark sky sites away from urban light sources. Observers viewing from urban areas will see less activity as only the brighter meteors will be visible from such locations.
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 sporadic. Meteor activity is not seen from radiants that are located far 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.
These sources of meteoric activity are expected to be active this week.
The alpha Capricornids (CAP) are active from July 3 through August 15 with maximum activity occurring on July 30th. The radiant is currently located at 18:56 (284) -16, which places it on the Sagittarius/Scutum border, 5 degrees north of the 4th magnitude star known as xi1 Sagittarii. This radiant is best placed near 0100 local summer time (LST) when it lies on the meridian and is located highest in the sky. Hourly rates at this time should be less than 1 no matter your location. With an entry velocity of 23 km/sec., the average alpha Capricornid meteor would be of slow velocity.
The center of the large Anthelion (ANT) radiant is currently located at 19:40 (295) -21. This position lies in eastern Sagittarius, 5 degrees east of the 3rd magnitude star known as Albaldah (pi Sagittarii A). Due to the large size of this radiant, Anthelion activity may also appear from western Capricornus as well as Sagittarius. This radiant is best placed near 0200 LST, when it lies on the meridian and is located highest in the sky. Rates at this time should be near 1 per hour as seen from the Northern Hemisphere and 2 per hour as seen from south of the equator. With an entry velocity of 30 km/sec., the average Anthelion meteor would be of slow velocity.
The July Pegasids (JPE) are active from July 4-17 with maximum activity occurring on July 10th. The radiant is currently located at 22:50 (342) +09. This area of the sky is located in southern Pegasus, 3 degrees southeast of the 3rd magnitude star known as Homam (zeta Pegasi). This radiant is best placed near 0500 LST, when it lies on the meridian and is located highest in the sky. Rates are expected to be less than 1 per hour this week no matter your location. With an entry velocity of 64 km/sec., the average meteor from this source would be of swift velocity.
As seen from the mid-northern hemisphere (45N) one would expect to see approximately 7 sporadic meteors per hour during the last hour before dawn as seen from rural observing sites. Evening rates would be near 1 per hour. As seen from the tropical southern latitudes (25S), morning rates would be near 9 per hour as seen from rural observing sites and 2 per hour during the evening hours. Locations between these two extremes would see activity between the listed figures. Evening rates are reduced by moonlight during this period.
|SHOWER||DATE OF MAXIMUM ACTIVITY||CELESTIAL POSITION||ENTRY VELOCITY||CULMINATION||HOURLY RATE||CLASS|
|RA (RA in Deg.) DEC||Km/Sec||Local Summer Time||North-South|
|alpha Capricornids (CAP)||Jul 30||18:56 (284) -16||23||01:00||<1 – <1||II|
|Anthelion (ANT)||–||19:40 (295) -21||30||02:00||1 – 2||II|
|July Pegasids (JPE)||Jul 10||22:50 (342) +09||64||05:00||<1 – <1||II|