Meteor Activity Outlook for July 29 – August 4, 2017

Meteor activity kicks into high gear in August as seen from the northern hemisphere. The main reason for all this activity is the Perseid shower that peaks on August 12th. This shower is active most of the month and remains above the level of the sporadic background for a week centered on August 12th. The sporadic activity is also near maximum as seen from the northern hemisphere and is now more than double the rates from just three months ago. As seen from southern hemisphere, meteor rates are still decent but falling rapidly. The sporadic rates continue their downward slide and the Perseid radiant does not rise high into the sky as seen in the southern hemisphere. So rates for the Perseids are greatly reduced when compared to those seen from the northern hemisphere.

During this period the moon will reach its first quarter phase on Sunday July 30. At this time the moon will be located 90 degrees east of the sun and will set near midnight local summer time (LST). As the week progresses the waxing gibbous moon will impede upon the morning sky shrinking the window of opportunity to view under dark skies. The estimated total hourly meteor rates for evening observers this week is near 4 for those viewing from the northern hemisphere and 3 for those located south of the equator. For morning observers the estimated total hourly rates should be near 32 as seen from mid-northern latitudes and 35 from the southern tropics. 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. Evening rates are reduced during this period due to interfering 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 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 29/30. 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 gamma Draconids (GDR) were first noticed by Japanese observers using SonotoCo and the IMO’s network team of Sirko Molau and Juergen Rendtel in 2009. This stream is active from July 22-30 with maximum activity occurring on July 28. The radiant is currently located at 18:44 (281) +50, which places it in southeastern Draco, 10 degrees southeast of the 2nd magnitude star known as Eltanin (gamma Draconis). The radiant also lies 12 degrees due north of the brilliant zero magnitude star Vega (alpha Lyrae). This radiant is best placed near midnight (LST), when it lies on the meridian and is located highest in the sky. With an entry velocity of 28 km/sec., the average gamma Draconid meteor would be of slow velocity. Rates this weekend are expected to less than 1 per hour, no matter your location

The alpha Capricornids (CAP) are active from July 3 through August 11 with maximum activity occurring during the last week of July. The broad maximum occurs anywhere from July 25 to the 30th with visual rates usually around 3 per hour. The radiant is currently located at 20:24 (306) -09, which places it in northwestern Capricornus, 5 degrees northeast of the naked eye double star known as Algedi (alpha 2 Capricorni). This radiant is best placed near 0100 LST, when it lies on the meridian and is located highest in the sky. With an entry velocity of 22 km/sec., the average alpha Cap meteor would be of slow velocity.

The center of the large Anthelion (ANT) radiant is currently located at 21:16 (319) -16. This position lies in northern Capricornus, 2 degrees northwest of the 4th magnitude star known as iota Capricorni. Due to the large size of this radiant, Anthelion activity may also appear from western Aquarius as well as Capricornus. This radiant is best placed near 0200 LST, when it lies on the meridian and is located highest in the sky. Hourly rates at this time should be near 2 as seen from mid-northern latitudes and 3 as seen from tropical southern latitudes. With an entry velocity of 30 km/sec., the average Anthelion meteor would be of medium-slow velocity.

The Northern delta Aquariids (NDA) are active from July 23 through August 27. The radiant is currently located at 22:15 (334) -04. This position is located in northern Aquarius, 3 degrees southeast of the 3rd magnitude star known as Sadalmelik (alpha Aquarii). Maximum activity is not expected until August 14, so hourly rates will low at this time. The radiant is best placed near 0300 LST, when it lies highest in the sky. With an entry velocity of 38 km/sec., these meteors would be of medium velocities. This shower seems to be a continuation of the Northern June Aquilids, which had been active since early June.

The Southern Delta Aquariids (SDA) reach maximum activity on July 30 from a radiant located at 22:42 (340) -16. This position is located in southwestern Aquarius, 3 degrees west of the 3rd magnitude star known as Skat (delta Aquarii). Hourly rates will depend on your latitude. Those viewing from the southern tropics will see the best rates of near 20-25 per hour. Rates seen from mid-northern latitudes will range from 5-15 per hour, depending on the haziness of your skies. The radiant rises near 2200 (10pm) LST 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 41 km/sec., most activity from this radiant would be of average velocities.

The Piscids Austrinids (PAU) are an obscure shower, not well seen from the northern hemisphere. Recent studies by the IMO Video Network shows no activity at all. Other studies have indicated that this shower is active later than previously thought. We will go along with that idea until more information is available. It is now thought that this radiant is active from July 30 through August 18, with maximum activity occurring on the 8th. Using these parameters, the current position of the radiant would be 22:56 (344) -24. This area of the sky is located in northeastern Piscis Austrinus, 4 degrees north of the bright 1st magnitude star known as Fomalhaut (alpha Piscis Austrini). The radiant is best placed near 0300 LST, when it lies highest in the sky. Current rates would most likely be less than 1 per hour, no matter your location. With an entry velocity of 44km/sec., most activity from this radiant would be of average velocities.

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 occurred on July 10th. The radiant is currently located at 00:16 (004) +16. This area of the sky is located in southeastern Pegasus, close to the spot occupied by the 3rd magnitude star known as Algenib (gamma 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. Rates are expected to be less than 1 per hour this week 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 01:52 (028) +54. This position lies in northwestern Perseus, 7 degrees southeast of the 3rd magnitude star known as Ruchbah (delta Cassiopeiae). This area of the sky is best placed for viewing during the last dark hour before dawn when it lies highest in the sky. Maximum is not until August 12 so current rates are expected to be near 5 per hour as seen from the northern hemisphere and 2 as seen from south of the equator. Unfortunately these meteors are not well seen from the southern hemisphere. With an entry velocity of 59 km/sec., the average meteor from this source would be of swift velocity.

The eta Eridanids (ERI) were discovered by Japanese observers back in 2001. Activity from this stream is seen from July 23 though September 17 with maximum activity occurring on August 11. The radiant currently lies at 02:16 (034) -16, which places it in eastern Cetus, 4 degrees east of the 4th magnitude star known as tau Ceti. This area of the sky is best seen during the last dark hour before dawn when the radiant lies highest in a dark sky. Current rates are expected to be less than 1 per hour during this period no matter your location. With an entry velocity of 65 km/sec., the average meteor from this source would be of swift velocity.

The 49 Andromedids (FAN) were discovered by Željko Andreić et al of the Croatian Meteor Network, using databases from SonotaCo, 2013 and CMN, 2013). These meteors are active from July 6 through August 14 with maximum activity occurring on July 21. The current position of the radiant is 02:20 (035) +52. This position lies in extreme northwestern Perseus, 5 degrees west of the 4th magnitude star known as tau Persei. This location is very close to the Perseid radiant and care must be taken to distinguish between these two sources. This area of the sky is best placed for viewing during the last dark hour before dawn when it lies highest in the sky. Rates are currently expected to be less than 1 per hour no matter your location. With an entry velocity of 60 km/sec., the average 49 Andromedid meteor would be of swift velocity.

The phi Piscids (PPS) were also discovered by Dr. Peter Brown and associates. 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 8 through August 2 with maximum activity occurring on July 5. The current position of the radiant is 02:44 (041) +35. This position lies in southwestern Perseus, 3 degrees southwest of the faint star known as 16 Persei. This area of the sky is best placed for viewing during the last dark hour before dawn when it lies highest in the sky. Rates are currently expected to be less than 1 no matter your location. With an entry velocity of 66 km/sec., the average phi Piscid meteor would be of swift velocity.

The psi Cassiopeiids (PCA) were discovered by Zdenek Sekanina in his study of radio streams. These meteors are active from July 5 through August 7 with maximum activity occurring on July 22. The current position of the radiant is 03:12 (048) +76. This position lies in northeastern Cassiopeia, 8 degrees northeast of the faint star known as 50 Cassiopeiae. This area of the sky is best placed for viewing during the last dark hour before dawn when it lies highest in the sky. Rates are currently expected to be less than 1 per hour no matter your location. With an entry velocity of 42 km/sec., the average psi Cassiopeiid meteor would be of medium speed. Note that current radar activity charts provided by Dr. Peter Brown show a very large, strong radiant for this shower located closer to 00:50 (013) +64, just north of 2nd magnitude gamma Cassiopeiae. Unfortunately radar is most sensitive to meteors that are too faint to be seen with the naked eye. Therefore any of this activity from either radiant is most likely to be faint.

The July chi Arietids (JXA) were discovered by two investigating teams in Europe using video data from European video Meteor Network Database (EDMOND), SonotaCo, 2013; and CMN, 2013. Activity from this stream is seen from July 2 though August 1 with maximum activity occurring on July 13. The radiant currently lies at 03:28 (052) +14, which places it in western Taurus, 2 degrees north of the faint star known as 5 Tauri. This area of the sky is best seen during the last dark hour before dawn when the radiant lies highest in a dark sky. Current rates are expected to be less than 1 per hour during this period. With an entry velocity of 69 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 12 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 9 per hour as seen from rural observing sites and 1 per hour during the evening hours. Evening rates are reduced during this period due to moonlight. Locations between these two extremes would see activity between the listed figures.

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.