During this period the moon reaches its first quarter phase on Monday July 11th. At this time the moon will lie 90 degrees east of the sun and will set near midnight local summer time (LST) as seen from mid-northern latitudes. Toward the end of the period the waxing gibbous moon will be present in the sky most of the night, making meteor observing difficult as the lunar glare will obscure all but the brightest meteors. The estimated total hourly meteor rates for evening observers this week is near 2 for observers located in the northern hemisphere and 3 for observers located in tropical southern locations (25S). For morning observers the estimated total hourly rates should be near 16 no matter your location. Evening rates are reduced this week due to moonlight. 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. 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 9/10. 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 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 for over a month lasting from July 5 through August 9. Unlike most showers, the Alpha Caps have a plateau-like maximum with maximum activity lasting from July 25-30. Since maximum activity is still 2 weeks away, hourly rates will be less than 1 no matter your location. The radiant is currently located at 19:44 (296) -14. This area of the sky is located in northeastern Sagittarius, 8 degrees west of the 3rd magnitude star known as Dabih (beta Capricornii). This radiant area lies within the area that also produces meteors from the Anthelion source. Care must be taken to try and differentiate between these two sources. The average Alpha Cap meteor would be slightly slower than an Anthelion meteor. The radiant is best placed near 0100 (LST) when it lies on the meridian and is highest in the sky. With an entry velocity of 22 km/sec., the average Alpha Capricornid meteor would be of slow velocity.
The center of the large Anthelion (ANT) radiant is currently located at 20:00 (300) -21. This position lies in eastern Sagittarius, 7 degrees southwest of the the 3rd magnitude star known as Dabih (beta Capricornii). Due to the large size of this radiant, Anthelion activity may also appear from the nearby constellations of Aquarius, southern Aquila, and western Capricornus as well as Sagittarius. This radiant is best placed near 0100 LST, when it lies on the meridian and is located highest in the sky. Hourly rates at this time should be near 1 as seen from mid-northern latitudes and 2 as seen from tropical southern latitudes. 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 currently located at 21:08 (317) -04. This area of the sky is actually located in northwestern Aquarius, 4 degrees northeast of the 3rd magnitude star known as Sadalsuud (beta Aquarii). The radiant is best placed near 0300 LST 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. This velocity is significantly faster than the stronger Alpha Capricornids, which appear from the same general area of the sky during the remainder of July.
The July Pegasids (JPE) have been noticed for some time now but have had a checkered history. It has been added, dropped, and then re-added to several radiant lists. Video studies within the past 10 years has positively identified this source as an active radiant during the entire month of July. Maximum activity occurs on July 10th when the radiant is located at 23:12 (348) +11. This area of the sky is located in southern Pegasus, 4 degrees southeast 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. Rates at maximum should be near 2 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 first members of the famous Perseid (PER) meteor shower should begin to appear this week. Don’t expect these early Perseids to appear from Perseus as the actual radiant lies much further west at 00:06 (001) +49. This area of the sky lies in southern Cassiopeia, 10 degrees due south of the 2nd magnitude star known as Caph (beta Cassiopeiae). This position is 45 degrees west of the position of the Perseid radiant on the night of maximum activity (August 12th). Since the maximum is still a month away, rates are expected to be low, probably around 1 per hour during the late morning hours. Observers south of the equator will have difficulty seeing any activity at all as the radiant lies low in the north during the last hours before dawn. With an entry velocity of 61 km/sec., the average Peresid meteor would be of swift speed.
The Psi Cassiopeiids (PSA) were discovered by Zdenek Sekanina and are active from July 12-18, with maximum activity occurring on the 16th. The radiant is currently located at 01:21 (020) +69. This position lies in north-central Cassiopeia, 9 degrees north of the 3rd magnitude star known as Ksora (Delta Cassiopeiae) . Rates at maximum are expected to be near 1 per hour as seen from the northern hemisphere. These meteors are not well seen from south for the equator. With an entry velocity of 46 km/sec., the average Psi Cassiopeiid meteor would be of medium speed.
The Pi Piscids (PPS) were discovered by Dr. Peter Brown in his meteoroid stream survey using the Canadian Meteor Orbit Radar. This shower was later verified by Dr. Peter Jenniskens and David Holman using data from the CAMS network in northern California. These meteors are active from June 11 through July 25 with maximum activity occurring on July 1st. The current position of the radiant is 01:29 (022) +30. This position lies in extreme northern Pisces, 6 degrees west of the 3th magnitude star known as Ras al Muthallah (alpha Trianguli). Rates are currently expected to be near 1 per hour as seen from the northern hemisphere and less than 1 per hour as seen from south of the equator. With an entry velocity of 68 km/sec., the average Pi Piscid meteor would be of swift speed.
The c-Andromedids (CAN) was discovered by Sirko Molau and Juergen Rendtel using video data from the IMO network. Activity from this source is seen from June 26 though July 20 with maximum activity occurring on July 12. The radiant currently lies at 02:01 (030) +47, which places it in northern Andromeda, 5 degrees north of the famous double star known as Almach (gamma Andromedae). 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 should be near 2 per hour as seen from the northern hemisphere and 1 as seen from south of the equator. 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 1 per hour. As seen from the tropical southern latitudes (25S), morning rates would be near 10 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 during this period due to moonlight.
The list below offers the information from above in tabular form. 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 Summer Time||North-South|
|alpha Capricornids (CAP)||Jul 26||19:44 (296) -14||22||01:00||<1 – <1||II|
|Anthelions (ANT)||–||20:00 (300) -21||30||01:00||1 – 2||II|
|sigma Capricornids (SCA)||Jun 27||21:08 (317) -04||42||03:00||1 – 1||IV|
|July Pegasids (JPE)||Jul 10||23:12 (348) +11||68||05:00||2 – 2||IV|
|Perseids (PER)||Aug 13||00:06 (001) +49||61||06:00||1 – <1||I|
|psi Cassiopeiids (PSA)||Jul 16||01:21 (020) +69||46||07:00||1 – <1||IV|
|phi Piscids (PPS)||Jul 02||01:29 (022) +30||68||07:00||1 – <1||IV|
|c-Andromedids (CAN)||Jul 12||02:01 (030) +47||60||08:00||2 – 1||IV|