(meteorobs) Meteor Activity Outlook for June 20-26, 2015

[Robert Lunsford]

During this period the moon reaches its first quarter phase on Tuesday June 23rd. At this time the moon will be located 90 degrees east of the sun and will set near midnight local daylight time (LDT) for observers located in mid-northern latitudes. This upcoming weekend the waxing crescent moon will set during the late evening hours and will not interfere with meteor observing during the more active morning hours. The estimated total hourly meteor rates for evening observers this week is near 2 for observers situated at mid-northern latitudes and 3 for observers viewing from the southern tropics (latitude 25 S.). For morning observers the estimated total hourly rates should be near 10 for observers situated at mid-northern latitudes and 15 for observers viewing from the southern tropics. 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 June 20/21 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. These meteors are best seen from June 22nd through July 2nd with maximum activity occurring on the 24th. At maximum the radiant is located at 14:58 (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.

The center of the large Anthelion (ANT) radiant is currently located at 18:48 (282) -23. This position lies in central Sagittarius, 4 degrees northwest of the 2nd magnitude star known as Nunki (Sigma Sagittarii). Due to the large size of this radiant, Anthelion activity may also appear from eastern Scorpius, southern Serpens Cauda, southeastern Ophiuchus and Scutum as well as Sagittarius. This radiant is best placed near 0100 Local Daylight Time (LDT), when it lies on the meridian and is located highest in the sky. Rates at this time should be near 2 per hour as seen from the northern hemisphere and 3 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 Northern June Aquilids (NCZ) were discovered by Zdenek Sekanina through his Radio Meteor Project at Havana, Illinois. These meteors are active from June 10-26, which maximum activity occurring on the 17th. The current position of the radiant is 20:08 (302) -09. This position lies in a remote area of southern Aquila near the Capricornus border. The nearest notable star is 3rd magnitude Algiedi (Alpha Capricorni), which lies 4 degrees to the southeast. Rates are expected to be less than 1 per hour, no matter your location. With an entry velocity of 41 km/sec., the average Northern June Aquilid meteor would be of medium speed.

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.

The June Iota Pegasids (JIP) were discovered by John Greaves using data from SonotaCo. These meteors are active for only 3 nights centered on June 25th. On that date the radiant lies at 22:06 (332) +29. This position lies in northwestern Pegasus, 4 degrees north of the 4th magnitude star known as Iota Pegasi. Rates are expected to be near 1 per hour as seen from the northern hemisphere and less than 1 as seen from south of the equator. With an entry velocity of 59 km/sec., the average June Iota Pegasid meteor would be of swift 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 2nd. The current position of the radiant is 00:24 (006) +20. This position lies in north-central Pisces, between the faint stars known as 52 Piscium and Chi Pegasi. Rates are currently expected to be less than 1 per hour no matter your location. With an entry velocity of 68 km/sec., the average Pi Piscid meteor would be of swift speed.

The Delta Piscids (DPI) were discovered by Sirko Molau and Juergen Rendtel using data provided by the IMO video network. These meteors are active from June 20-26 with maximum activity occurring on the 24th. The current position of the radiant is 00:40 (010) +04. This position lies in southern Pisces, 4 degrees southwest of the 4th magnitude star known as Delta Piscium. Rates are expected to be less than 1 per hour, even at maximum, no matter your location. With an entry velocity of 69 km/sec., the average Pi Piscid meteor would be of swift speed.

The last of the Daytime Arietids (ARI) will be seen this week from a position located at radiant is 03:52 (058) +25. This position lies in western Taurus, just east of the naked eye open cluster known as the Pleiades or M45. Despite being a strong source of meteors, visual members of this shower are rare due to the low altitude of the radiant. If this radiant was better placed in the sky it would rival the better known Perseids of August. These meteors are the strongest source of radio meteors for the entire year. With an entry velocity of 42 km/sec., the average Daytime Arietid meteor would be of medium speed.

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 11 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 list below offers the information from above in a condensed form. Rates and positions are exact for Saturday night/Sunday morning unless specified.

June Bootids (JBO) -   14:58 (224) +48  Velocity - 18km/sec. 
Northern Hemisphere - <1 per hr.   Southern Hemisphere - <1 per hr 

Anthelion (ANT) -   18:48 (282) -23  Velocity - 30km/sec. 
Northern Hemisphere - 2 per hr.   Southern Hemisphere - 3 per hr 

Northern June Aquilids (NCZ) -   20:08 (302) -09  Velocity - 41km/sec. 
Northern Hemisphere - <1 per hr.   Southern Hemisphere - <1 per hr 
 
Sigma Capricornids (SCA) -   20:24 (306) -07  Velocity - 42km/sec. 
Northern Hemisphere - <1 per hr.   Southern Hemisphere - <1 per hr 
 
June Iota Pegasids (JIP) -   22:06 (332) +29  Velocity - 59km/sec. 
Northern Hemisphere - 1 per hr.   Southern Hemisphere - <1 per hr 

Pi Piscids (PPS) -   00:24 (006) +20  Velocity - 68km/sec. 
Northern Hemisphere - <1 per hr.   Southern Hemisphere - <1 per hr 
 
Delta Piscids (DPI) -   00:40 (010) +04  Velocity - 69km/sec. 
Northern Hemisphere - <1 per hr.   Southern Hemisphere - <1 per hr 
 
Daytime Arietids (ARI) -   03:52 (058) +25  Velocity - 42km/sec. 
Northern Hemisphere - <1 per hr.   Southern Hemisphere - <1 per hr 
 
Clear Skies! 
Robert Lunsford 	 
American Meteor Society