During this period the moon reaches its last quarter phase on Saturday July 19th. At this time the half-illuminated moon will rise near midnight LDT (Local Daylight Time) as seen from mid-northern latitudes. This weekend the moon will hamper morning observations as it is above the horizon during most of the morning hours. With each passing night though, the situation becomes more favorable as the moon wanes and rises approximately 45 minutes later each night. By the end of the week the moon will not be a factor at all. The estimated total hourly meteor rates for evening observers this week is near 4 no matter your location. For morning observers the estimated total hourly rates should be near 18 as seen from the northern hemisphere and 16 as seen from southern tropical latitudes. 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. 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 brightest 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 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.
These sources of meteoric activity are expected to be active this week:
The Alpha Capricornids (CAP) are active for over a month lasting from July 6 through August 10. Unlike most showers, the Alpha Caps have a plateau-like maximum with maximum activity lasting from July 25-30. The radiant is currently located at 20:04 (301) -12. This area of the sky is located where the borders of Aquila, Sagittarius, and Capricornus meet. The 4th magnitude double star Algiedi (Alpha Capricornii) lies 3 degrees to the southeast of the center of the large radiant. The radiant is best placed near midnight LDT when it lies on the meridian and is highest in the sky. Rates this weekend would be low due to moonlight, but climbing to 2-3 per hour toward the end of the period. With an entry velocity of 22 km/sec., the average Alpha Capricornid meteor would be of slow velocity. Please note that with this radiant, along with the Anthelions and Sigma Capricornids, are all located in the same area of the sky. The only way to properly differentiate between the 3 would be to have all 3 radiants included within your field of view. Even then it could be difficult as any potential meteor could trace back to more than 1 radiant area, especially since the sizes of the CAP’s and ANT’s are larger than normal.
The center of the large Anthelion (ANT) radiant is currently located at 20:40 (310) -17. This position lies 5 degrees southeast of the 3rd magnitude known as Dabih (Beta Capricorni). These meteors may be seen all night long but the radiant is best placed near 0100 LDT when it lies on the meridian and is positioned highest in the sky. Due to the large radiant area, meteors from this source may also appear to radiant from the constellation of Microscopium, Sagittarius, southeastern Aquila, western Aquarius, and western Pisces Austrinus as well as Capricornus. Rates at this time should be near 1 per hour no matter you location. With an entry velocity of 30 km/sec., the average Anthelion meteor would be of slow velocity.
The Sigma Capricornids (SCA) were discovered by Zdenek Sekanina and are active for a month lasting from June 19 through July 24. Maximum occurred on June 27th. The radiant is located at 21:32 (323) -02. This area of the sky is located in western Aquarius, 3 degrees north of the 3rd magnitude star known as Sadalsuud (Beta Aquarii). The radiant is best placed near 0200 LDT when it lies on the meridian and is highest in the sky. Rates at this time should be less than 1 per hour no matter your location. With an entry velocity of 42 km/sec., the average Sigma Capricornid meteor would be of medium velocity.
Activity from the Delta Aquariids (SDA) will begin next week from a radiant located at 22:18 (334) -18. This position is located in southwestern Aquarius, eight degrees southwest of the third magnitude Delta Aquarii. Maximum activity is expected on July 30th. Hourly rates will depend on your latitude. Those viewing from the southern tropics will see the best rates of near 1-2 per hour. Rates seen from mid-northern latitudes will range from 0-1 per hour, depending on the haziness of your skies. The radiant rises near 2200 (10pm) LDT for observers located in the mid northern latitudes, but is best placed near 0300 LDT, when it lies highest in the sky. With an entry velocity of 42 km/sec., most activity from this radiant would be of average velocities.
The Piscids Austrinids (PAU) are a minor shower not well seen from the northern hemisphere. This radiant is active from July 15 through August 10. Maximum activity occurs on July 28 when the zenith hourly rate (ZHR) may reach five. These rates are only seen from the southern hemisphere where the radiant passes overhead. From mid-northern latitudes, rates of one per hour at maximum are usually seen. The radiant is currently located at 22:20 (335) -34. This position lies in central Piscis Austrinus, eight degrees southwest of the bright first magnitude star Fomalhaut (Alpha Piscis Austrinus). The radiant is best placed near 0300 LDT, when it lies highest in the sky. With an entry velocity of 35km/sec., most activity from this radiant would be of average velocities.
The last meteors of the July Pegasids (JPE) should be seen this week from a radiant located at 23:40 (355) +13. This area of the sky is located in southern Pegasus, 7 degrees east of the 2nd magnitude star known as Markab (Alpha Pegasi). This area of the sky is best seen during the last dark hour before dawn when the radiant lies highest in a dark sky. Maximum activity occured on July 10th so rates this week are expected to be less than 1 per hour no matter your location. With an entry velocity of 68 km/sec., the average meteor from this source would be of swift velocity.
The Perseids (PER) are active from a radiant located at 00:56 (014) +52. This position lies in southern Cassiopeia, six degrees southwest of the second magnitude star Shedar (Alpha Cassiopeiae). The radiant is best placed during the last hour before the start of morning twilight when it lies highest in a dark sky. Since the maximum is not until August 13th, current rates would be only 1-2 per hour at best, as seen from the northern hemisphere. Activity from this source is not visible south of 40 degrees south latitude. With an entry velocity of 61 km/sec., most activity from this radiant would be swift.
The last activity of the Pi Piscids (PPI) is expected this week. The radiant is currently located at 01:52 (028) +33. This area of the sky is located in western Triangulum, 4 degrees north of the 3rd magnitude star known as Ras al Muthallah (Alpha Trianguli). The radiant is best placed near 0300 LDT when it lies on the meridian and is highest in the sky. Rates at this time should be near 2 per hour as seen from the northern hemisphere and one per hour as seen from south of the equator. With an entry velocity of 69 km/sec., the average Pi Piscid meteor would be of swift velocity.
Activity from the c-Andromedids (CAN) is ending this weekend. The radiant currently lies at 02:48 (042) +50, which places it in western Perseus, 5 degrees west of the 2nd magnitude star known as Mirfak (Alpha Persei). This area of the sky is best seen during the last dark hour before dawn when the radiant lies highest in a dark sky. Observers in the northern hemisphere are better situated to view this activity as the radiant rises much higher in the sky before dawn as seen from northern latitudes. Current rates would be less than one per hour no matter your location. With an entry velocity of 60 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 8 sporadic meteors per hour during the last hour before dawn as seen from rural observing sites. Evening rates would be near 3 per hour. As seen from the tropical southern latitudes (25S), morning rates would be near 7 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. Morning rates are reduced due to lunar glare.
The table below presents a list of radiants that are expected to be active this week. Rates and positions are exact for Saturday night/Sunday morning except where noted in the shower descriptions.
|SHOWER||DATE OF MAXIMUM ACTIVITY||CELESTIAL POSITION||ENTRY VELOCITY||CULMINATION||HOURLY RATE||CLASS|
|RA (RA in Deg.) DEC||Km/Sec||Local Daylight Time||North-South|
|Alpha Capricornids (CAP)||Jul 27||20:04 (301) -12||22||00:00||1 – 1||II|
|Anthelions (ANT)||–||20:40 (310) -17||29||01:00||1 – 1||II|
|Sigma Capricornids (SCA)||Jun 27||21:32 (323) -02||42||02:00||2 – 2||IV|
|Delta Aquariids (SDA)||Jul 30||22:18 (334) -18||42||03:00||1 – 2||I|
|Piscids Austrinids (PAU)||Jul 28||22:20 (335) -34||35||03:00||<1 – <1||II|
|July Pegasids (JPE)||Jul 10||23:40 (355) +13||68||04:00||1 – 1||IV|
|Perseids (PER)||Aug 13||00:56 (014) +52||61||05:00||2 – 1||I|
|Pi Piscids (PPI)||Jul 01||01:52 (028) +33||69||06:00||2 – 1||IV|
|c-Andromedids (CAN)||Jul 10||02:48 (042) +50||60||07:00||<1 – <1||IV|