Meteor season finally gets going in July for the northern hemisphere. The first half of the month will be much like June. After the 15th though, both sporadic and shower rates increase significantly. For observers in the southern hemisphere, sporadic rates will be falling but the overall activity will increase with the arrival of the Delta Aquariids during the last third of the month.
During this period the moon waxes from its new phase to nearly 1/2 illuminated. This weekend the extremely thin crescent moon will set near the end of dusk and will be below the horizon the remainder of the night. The moon will set approximately 45 minutes later with each passing night but will still set early enough to allow several hours of dark viewing during the morning hours before the start of morning twilight. The estimated total hourly meteor rates for evening observers this week is near 3 for observers situated at mid-northern latitudes and 4 for observers viewing from the southern tropics (latitude 25 S.). For morning observers the estimated total hourly rates should be near 12 no matter your location. 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 June 28/29. 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 June Bootids (JBO) are usually a very weak shower that occasionally produces outbursts. Nothing out of the ordinary is expected this year but with the moon out of the way so viewing for unusual activity is warranted. These meteors are best seen from June 22nd through July 2nd with maximum activity occurring on the 27th. At maximum the radiant is located at 14:56 (224) +48. This position lies in northwestern Bootes, 15 degrees east of the second magnitude star known as Alkaid (Eta Ursae Majoris). This radiant is best placed in the evening sky just as the sky becomes dark. Observers in the northern hemisphere have a distinct advantage over those located south of the equator as the radiant lies much higher in the evening sky. No matter your location, little activity is expected from this source. With an entry velocity of 18 km/sec., the average June Bootid meteor would be of very slow velocity.
IMO shower #95 is a weak source of activity, discovered among the video data of the IMO, seen from June 27 though July 7. Maximum activity occurs on June 29 when the radiant lies at 16:50 (253) +56. This position lies in southern Draco, ten degrees northwest of the third magnitude star known as Rastaban (Beta Draconis). Activity from this source would be best seen as soon as it becomes dark. As with the June Bootids, observers in the northern hemisphere have a distinct advantage over those located south of the equator as the radiant lies much higher in the evening sky. No matter your location, little activity is expected from this source. With an entry velocity of 23 km/sec., the average meteor from this source would be of low velocity.
The center of the large Anthelion (ANT) radiant is currently located at 19:20 (290) -21. This position lies in eastern Sagittarius, 2 degrees southeast of the 3rd magnitude star known as Albaldah (Pi Sagittarii). These meteors may be seen all night long but the radiant is best placed near 0200 local daylight time (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 Serpens Cauda, Scutum, southern Aquila, and western Capricornus as well as Sagittarius. 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 Sigma Capricornids (SCA) were discovered by Zdenek Sekanina and are active for a month lasting from June 19 through July 24. Maximum occurs on June 27th when the radiant is located at 20:24 (306) -07. This area of the sky is actually located in southeastern Aquila, five degrees north of the naked eye double star Algiedi (Alpha Capricornii). 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 one 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 second half of July.
IMO shower #94 is a weak display of short duration, only active from June 29th through July 4th. Maximum activity occurs on July 3rd when the radiant lies at 23:42 (356) +29. This position lies in northeast Pegasus, five degrees west of the second magnitude star known as Alpheratz (Alpha Andromedae). This area of the sky is best placed during the last hour before dawn when the radiant lies highest above the horizon in a dark sky. Owing to the northerly declination (celestial latitude) these meteors are seen slightly better in the northern hemisphere. No matter your location, little activity is expected from this source. This radiant is close to that of the more active Pi Piscids so care must be taken to distinguish between these two sources. With an entry velocity of 69 km/sec., the average meteor from this source would be of swift velocity.
The Pi Piscids (PPI) is a new source of activity discovered by Dr. Peter Brown and his Canadian Meteor Orbit Radar (CMOR) team. Activity is found from this source throughout June and July with maximum activity occurring on July 1st. It is one of the strongest sources of meteors during late June and early July. The radiant is currently located at 00:56 (014) +24. This area of the sky is located on the Pisces/Andromeda border, where the 4th magnitude star Eta Andromeda resides. 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 two 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.
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 10. The radiant currently lies at 01:12 (018) +42, which places it in northern Andromeda, just five degrees east of the naked eye Andromeda Galaxy. 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 1-2 shower members as seen from the northern hemisphere before dawn and less than one per hour for observers situated 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 7 sporadic meteors per hour during the last hour before dawn as seen from rural observing sites. Evening rates would be near 2 per hour. As seen from the tropical southern latitudes (25S), morning rates would be near 8 per hour as seen from rural observing sites and 3 per hour during the evening hours. Locations between these two extremes would see activity between the listed figures.
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|
|June Bootids (JBO)||Jun 27||14:56 (224) +48||18||22:00||<1 – <1||III|
|IMO #95||Jun 29||16:50 (253) +56||23||00:00||<1 – <1||II|
|Anthelions (ANT)||–||19:20 (290) -21||29||02:00||1 – 2||II|
|Sigma Capricornids (SCA)||Jun 27||20:24 (306) -07||42||03:00||1 – 1||IV|
|IMO #94||Jul 03||23:42 (356) +29||69||06:00||<1 – <1||IV|
|Pi Piscids (PPS)||Jul 01||00:56 (014) +24||69||07:00||2 – 1||IV|
|c-Andromedids (CAN)||Jul 10||01:12 (018) +42||60||07:00||1 – <1||IV|