Meteor Activity Outlook for 18-24 August 2018

During this period the moon will reach its first quarter phase on Saturday August 18th. At that time the moon will lie 90 degrees east of the sun in the sky and will set near midnight local summer time (LST) as seen from mid-northern latitudes. As the week progresses the waxing gibbous moon will encroach upon the morning hours, limiting the time observers have to view under moonless conditions. The estimated total hourly meteor rates for evening observers this week is near 4 as seen from mid-northern latitudes and also 3 for those viewing from subtropical southern latitudes (25S). For morning observers the estimated total hourly rates should be near 23 for those viewing from mid-northern latitudes and also 15 for those viewing from subtropical southern latitudes (25S). 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 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 August 18/19. 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 near 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 August Draconids (AUD) were discovered by Zdenek Sekanina in his study of meteor streams using radio methods. This stream is active from August 13-19 with maximum activity occurring on the 16th. The radiant is currently located at 18:12 (273) +59, which places it in southern Draco, 8 degrees northeast of the 2nd magnitude star known as Eltanin (gamma Draconis). This radiant is best placed near 2200 local summer time (LST), when it lies on the meridian and is located highest in the sky. With an entry velocity of 21 km/sec., the average August Draconid meteor would be of slow velocity. Rates this week are expected to be less than 1 per hour no matter your location

The last of the kappa Cygnids (KCG) are expected this weekend from a radiant located near 19:16 (289) +55. This area of the sky lies in northwestern Cygnus, 1 degree north of the 4th magnitude star known as kappa Cygni. This radiant is best placed near 2300 LST, when it lies on the meridian and is located highest in the sky. Rates should be less than 1 per hour no matter your location. Unfortunately these meteors are not well seen from the southern hemisphere due to their low radiant altitude. With an entry velocity of 21 km/sec., the average meteor from this source would be of slow velocity.

The center of the large Anthelion (ANT) radiant is currently located at 22:36 (339) -09. This position lies in central Aquarius, 4 degrees southeast of the 4th magnitude star known as Ancha (theta Aquarii). Due to the large size of this radiant, Anthelion activity may also appear from eastern Capricornus and western Pisces, as well as Aquarius. 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 no matter your location. 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 23:28 (352) +04. This position is located in western Pisces, 3 degrees south of the 4th magnitude star known as theta Piscium. Maximum activity was expected on August 14, so hourly rates should be near 1 per hour no matter your location. 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 last of the Southern delta Aquariids (SDA) are expected this week from a radiant located at 23:58 (359) -09. This position is located in western Cetus, 3 degrees west of the 4th magnitude star known as Deneb Kaitos Shemali (iota Ceti). Hourly rates are now less than 1 per hour no matter your location. The radiant is best placed near 0400 LST, 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 last of the beta Hydrusids (HDY) is expected this weekend. Activity from this stream is seen from August 15-19 with maximum activity occurring on the 17th. At maximum the radiant lies at 02:25 (036) -75, which places it in southern Hydrus between the bright stars known as beta and gamma Hydri. Due to the far southern location, these meteors are not visible from the northern hemisphere. For southern observers, 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 23 km/sec., the average meteor from this source would be of slow 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 03:24 (051) -10, which places it in western Eridanus, 2 degrees west of the 4th magnitude star known as Ran (epsilon Eridani). 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 near 1 per hour as seen from the northern hemisphere and near 2 per hour as seen from south of the equator. With an entry velocity of 65 km/sec., the average meteor from this source would be of swift velocity. These meteors were noticeable during the recent Perseid maximum.

The Perseids (PER) are still active from a radiant located at 03:46 (057) +59. This position lies in southern Camelopardalis, 7 degrees northeast of the 3rd magnitude star known as gamma 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 from dark sky sites 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 as the numbers decrease to zero from mid-southern latitudes (S45). With an entry velocity of 59 km/sec., the average meteor from this source would be of swift velocity.

New evidence from video cameras suggest that the Aurigids (AUR) are active as early as August 18. If so, the radiant would be currently located at 04:54 (074) +39. This area of the sky is located on the Perseus/Auriga border, 3 degrees southwest of the 3rd magnitude star known as Haedus (eta Auriga). 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 expected to be less than 1 no matter your location. With an entry velocity of 66 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 14 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 8 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. Rates are reduced during the evening hours 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.