Meteor Activity Outlook for 19-25 August 2023

During this period, the moon reaches its first quarter phase on Thursday August 24th. At that time the half-illuminated moon will be located 90 degrees east of the sun and will set near 22:00 local summer time (LST). This weekend the waxing crescent moon will set during the late evening hours and will not hinder meteor observing during the active morning hours. The estimated total hourly rates for evening observers this week should be near 4 as seen from mid-northern latitudes (45N) and 3 as seen from tropical southern locations (25S) For morning observers, the estimated total hourly rates should be near 23 as seen from mid-northern latitudes (45N) and 12 as seen from tropical southern locations (25S). Evening rates are slightly reduced due to moonlight. The actual rates seen 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 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 19/20. 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. I have also included charts of the sky that display the radiant positions for evening, midnight, and morning. The center of each chart is the sky directly overhead at the appropriate hour. These charts are oriented for facing south but can be used for any direction by rotating the charts to the desired direction. 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. Radiants that rise after midnight will not reach their highest point in the sky until daylight. For these radiants, it is best to view them during the last few hours before dawn. It must be remembered that meteor activity is rarely seen at its radiant position. Rather they shoot outwards from the radiant, so it is best to center your field of view so that the radiant lies toward 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 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.

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The August xi Draconids (AXD) was discovered by Masahiro Koseki in his study of SonotaCo video observations 2007–2018. These meteors were long considered part of the kappa Cygnids but Koseki states that they are clearly distinct*. This stream is active from August 4-28 with maximum activity occurring on the 15th. The radiant is currently located at 18:12 (273) +59, which places it in southeastern Draco, 4 degrees northeast of the 4th magnitude star known as Grumium (xi Draconis A). To best see these meteors, face low toward the north near 2200 LST, when it lies on the meridian and is located highest in the northern 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 no matter your location. Due to the high northern declination these meteors are difficult to observe from the southern hemisphere.

*The activity of meteor showers recorded by SonotaCo video observations 2007–2018, Masahiro Koseki, 2021, https://www.emeteornews.net/2021/02/09/february-2021-special-issue-of-emeteornews-online/ Page 147

The zeta Draconids (AUD) were discovered by Zdenek Sekanina in his study of meteor streams using radio methods. This stream is active from August 12-September 5 with maximum activity occurring on August 26. The radiant is currently located at 18:28 (277) +62, which places it in southeastern Draco, 5 degrees northeast of the 4th magnitude star known as Grumium (xi Draconis A). This radiant is best placed near 2200 LST, when it lies on the meridian and is located highest in the northern sky. With an entry velocity of 22 km/sec., the average zeta Draconid meteor would be of slow velocity. Rates this week are expected to be less than 1 no matter your location. Due to the high northern declination these meteors are difficult to observe from the southern hemisphere. This position is close to that of the August xi Draconids radiant so care should be taken to differentiate between these meteors. These meteors are synonymous with the August Draconids (AUD).

The kappa Cygnids (KCG) are active from August 1-27, with maximum occurring on the 14^th. The radiant is currently located at 19:17 (289) +55. This area of the sky is located in northwestern Cygnus, 1 degree north of the 4th magnitude star known as kappa Cygni. This position is close to the radiant of the August xi Draconids so care must be taken to separate these two showers. To best see these meteors, face low toward the north near 2200 LST when it lies on the meridian and is located highest in the northern sky. With a high northern declination, these meteors are difficult to view from the southern hemisphere. Expected hourly rates this week are near 1 as seen from the northern hemisphere and less than 1 as seen from south of the equator. With an entry velocity of 23 km/sec., the average meteor from this source would possess a slow velocity.

The large Anthelion (ANT) radiant is currently centered at 22:40 (340) -11. This position lies in central Aquarius, 4 degrees east of the 4th magnitude star known as Ancha (theta Aquarii). This position is also 3 degrees east of the bright (zero magnitude) planet Saturn. This radiant is best placed near 01:00 LST when it lies on the meridian and is highest in the northern sky. Rates at this time should be near 2 per hour no matter your location. With an entry velocity of 30 km/sec., the average Anthelion meteor would be of medium-slow velocity.

The August beta Piscids (NDA) are part of the Northern delta Aquariid complex, active from August 18-September 8. This second peak of the NDA’s occurs on August 21^st, when the radiant lies well within the boundaries of the constellation of Pisces. The radiant currently is located near 23:27 (352) +04. This area of the sky is located in western Pisces, 3 degrees south of the 4th magnitude star known as theta Piscium. To best see these meteors, look high in the northern sky near 0200 LST, when it lies on the meridian and is located highest in the sky. Hourly rates at this time should be near 1 no matter your location. With an entry velocity of 38 km/sec., the average meteor from this source would be of medium velocity.

The last of the Southern delta Aquariids (SDA) are expected this weekend from a radiant located at 23:36 (354) -13. This area of the sky is located in eastern Aquarius, 3 degrees southeast of the 4th magnitude star known as Omega² Aquarii. This radiant is best placed near 0300 LST, when it lies on the meridian and is located highest in the northern sky. Hourly rates at this time should be less than 1 no matter your location.  With an entry velocity of 38 km/sec., the average meteor from this source would be of medium velocity.

The August gamma Cepheids (AGC) are a recent discovery by Damir Šegon and the Croatian Meteor Network team based on studying SonotaCo and CMN observations (SonotaCo 2007-2011, CMN 2007-2010). Meteors from this source are expected from August 17 through September 6, with maximum activity occurring on August 29. The current position lies at 23:48 (357) +74, which lies in northern Cepheus, 4 degrees south of the 3rd magnitude star known as Errai (gamma Cephei A). To best see these meteors, face half-way up toward the north near 0200 LST, when it lies on the meridian and is located highest in the northern sky. Rates at this time should be less than 1 per hour as no matter your location. With an entry velocity of 43 km/sec., the average meteor would be of medium velocity. These meteors are not visible south of latitude 20 South.

The eta Eridanids (ERI) are active from a radiant near 03:29 (052) -09. This position lies in northwestern Eridanus, 1 degree northwest of the 4th magnitude star known as Ran (epsilon Eridani). This source is active until September 10^th, with maximum activity occurring on August 7^th. Current rates are expected to be near 1 per hour no matter your location. These meteors are best seen during the last dark hour prior to dawn when the radiant lies highest above the southeastern horizon in a dark sky. With an entry velocity of 64 km/sec., the average meteor from this source would be of swift speed.

The Perseids (PER) are still active from a radiant located at 03:54 (059) +59. This position lies in southern Camelopardalis, 10 degrees northeast of the 2nd magnitude star known as Mirfak (alpha Persei). This area of the sky is best placed for viewing during the last dark hour before dawn when it lies highest in the northern sky. Rates this weekend are expected to be near 5 as seen from the northern hemisphere and 1 as seen from south of the equator. With an entry velocity of 59 km/sec., the average meteor from this source would be of swift velocity. Viewers in the southern hemisphere have a limited view of this shower as the radiant only rises just before dawn and is located low in their northern sky.

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.

You can keep track of the activity of these meteor showers as well as those beyond the limits of visual observing by visiting the NASA Meteor Shower Portal. You can move the sky globe to see different areas of the sky. Colored dots indicate shower meteors while white dots indicate sporadic (random) activity. The large orange disk indicates the position of the sun so little activity will be seen in that area of the sky.

The list below offers the information in tabular form of the showers that I feel are within reach of the visual observer to discern. Hourly rates are often less than 1 but noting parameters such as the radiant distance and the elevation of each meteor, one can compute the probability of shower association. Most showers discovered by video means have rates less than 1 meteor per night away from maximum, so the showers listed in these articles are not as weak as they seem. Rates and positions are exact for Saturday night/Sunday morning except where noted in the shower descriptions.

Class Explanation: A scale to group meteor showers by their intensity:

• Class I: the strongest annual showers with Zenith Hourly Rates normally ten or better.
• Class II: reliable minor showers with ZHR’s normally two to ten.
• Class III: showers that do not provide annual activity. These showers are rarely active yet have the potential to produce a major display on occasion.
• Class IV: weak minor showers with ZHR’s rarely exceeding two. The study of these showers is best left to experienced observers who use plotting and angular velocity estimates to determine shower association. These weak showers are also good targets for video and photographic work. Observers with less experience are urged to limit their shower associations to showers with a rating of I to III.