Meteor Activity Outlook for August 7-13, 2021

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Aaron Morris captured this fireball on the morning of August 4, 2021, at 2:51am EDT (6:51UT) from Griffin, GA, USA. ©Aaron Morris

During this period, the moon reaches its new phase on Sunday August 8th. At that time the moon lies near the sun and is invisible at night. As the week progresses the waxing crescent moon enters the evening sky but will set before the more active morning hours arrive. The estimated total hourly meteor rates for evening observers this week is near 5 as seen from mid-northern latitudes (45N) and 4 as seen from tropical southern locations (25S). For morning observers, the estimated total hourly rates should be near 30 as seen from mid-northern latitudes (45N) and 20 as seen from tropical southern locations (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. 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 7/8. 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. 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 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.

 

Radiant Positions at 22:00 LDST

Radiant Positions at 22:00 Local Daylight Saving Time

Radiant Positions at 01:00 LDST

Radiant Positions at 01:00 Local Daylight Saving Time

Radiant Positions at 04:00 LDST

Radiant Positions at 04:00 Local Daylight Saving Time

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 Net 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 14th. The radiant is currently located at 18:30 (278) +46, which places it in western Lyra, 8 degrees north of the zero magnitude star known as Vega (alpha Lyrae). This radiant is best placed near 2300 local daylight saving time (LDST), when it lies on the meridian and is located highest in the sky. With an entry velocity of 19 km/sec., the average August xi 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 Net video observations 2007–2018, Masahiro Koseki, 2021, https://www.meteornews.net/2021/02/09/february-2021-special-issue-of-emeteornews-online/ Page 147

The kappa Cygnids (KCG) are active from August 1-27, with maximum occurring on the 13th. The radiant shifts rapidly towards the northeast with each passing night. The radiant is currently located at 18:52 (283) +46, which places it in northeastern Lyra, 8 degrees northeast of Vega. This radiant is also best placed near 2300 LDST when it lies on the meridian and is located highest in the sky. With a high northern declination, these meteors are difficult to view from the southern hemisphere. Expected hourly rates this week are less than 1 no matter your location. With an entry velocity of 21 km/sec., the average meteor from this source would be of slow velocity.

The alpha Capricornids (CAP) are active from July 7 through August 15, peaking on July 31st. The radiant is currently located at 20:42 (311) -07. This position lies in northwestern Aquarius, 2 degrees northwest of the 4th magnitude star known as (3 Aquarii). Current rates are expected to be near 2 per hour no matter your location. These meteors are best seen near 01:00 LDST, when the radiant lies highest in the sky. With an entry velocity of 20 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 21:52 (328) -13. This position lies in northeastern Capricornus, 3 degrees northeast of the 3rd magnitude star known as Deneb Algedi (delta Capricornii Aa). This position is also 4 degrees northwest of the brilliant planet Jupiter. Due to the large size of this radiant, Anthelion activity may also appear from northwestern Aquarius as well as Capricornus. This radiant is best placed near 0200 LDST, 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 delta Aquariids (NDA) are a conglomeration of at least two weak radiants that peak 10 days apart. These meteors were first mentioned by Luigi G. Jacchia in his book The Moon, Meteorites and Comets. The NDA’s are active from August 2-17, with peak rates occurring on the 11th. The radiant currently is located near 22:52 (343) -00. This area of the sky is located on the Aquarius/Pisces border, 4 degrees east of the 4th magnitude star known as eta Aquarii. This radiant is best placed near 0300 LDST, when it lies on the meridian and is located highest in the sky. Hourly rates at this time should be less than 1 no matter your location. With an entry velocity of 39 km/sec., the average meteor from this source would be of medium velocity.

The Southern delta Aquariids (SDA) are active from a radiant located at 23:02 (346) -15. This area of the sky is located in southwestern Aquarius, 2 degrees northeast of the 3rd magnitude star known as Skat (delta Aquarii). This radiant is best placed near 0300 LDST, 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 the Northern Hemisphere and near 3 as seen from south of the equator, where the radiant lies higher in the sky.  With an entry velocity of 39 km/sec., the average meteor from this source would be of medium velocity.

The Piscids Austrinids (PAU) are an obscure shower, not well seen from the northern hemisphere. Recent studies by the IMO Video Network shows little activity. 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 August 1st through the 10th, with maximum activity occurring on the 7th. Using these parameters, the current position of the radiant would be 23:36 (354) -20. This area of the sky is located in southern Aquarius, near the spot occupied by the faint star known as 99 Aquarii. The radiant is best placed near 03:00 LDST, when it lies highest in the sky. Current hourly rates should be less than 1 no matter your location. With an entry velocity of 43km/sec., most activity from this radiant would be of medium velocities.

The Perseids (PER) are active from a radiant located at 02:50 (042) +57. This position lies in northwestern Perseus, near the spot occupied by the 4th magnitude star known as Miram (eta Persei A). This area of the sky is best placed for viewing during the last dark hour before dawn when it lies highest in the sky. Current hourly rates are expected to be near 10 as seen from the Northern Hemisphere and near 1 as seen from south of the equator. These rates will increase with each passing night as we approach the maximum late in the week. With an entry velocity of 59 km/sec., the average meteor from this source would be of swift velocity.

The eta Eridanids (ERI) are active from a radiant near 02:51 (043) -12. This position lies in northwestern Eridanus, 3 degrees southwest of the 4th magnitude star known as Azha (eta Eridani). This source is active until September 10th, with maximum activity occurring on August 6th. Current rates would 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 horizon in a dark sky. With an entry velocity of 64 km/sec., the average meteor from this source would be of swift speed.

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 4 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 3 per hour during the evening hours. Locations between these two extremes would see activity between the listed figures.

 

SHOWER

DATE OF MAXIMUM ACTIVITY CELESTIAL POSITION ENTRY VELOCITY CULMINATION HOURLY RATE CLASS
RA (RA in Deg.) DEC Km/Sec Local Daylight Saving Time North-South
August xi Draconids (AXD) Aug 14 18:30 (278) +46 19 23:00 <1 – <1 IV
kappa Cygnids (KCG) Aug 13 18:52 (283) +46 21 23:00 <1 – <1 II
alpha Capricornids (CAP) Jul 31 20:42 (311) -07 20 01:00 2 – 2 II
Anthelion (ANT) 21:52 (328) -13 30 02:00 2 – 3 II
Northern delta Aquariids (NDA) Aug 11 22:52 (343) -00 39 03:00 <1 – <1 IV
Southern delta Aquariids (SDA) Jul 30 23:02 (346) -15 39 03:00 2 – 3 I
Piscids Austrinids (PAU) Aug 07 23:36 (354) -20 43 03:00 <1 – <1 IV
Perseids (PER) Aug 12 02:50 (042) +57 59 07:00 10 – 1 I
eta Eridanids (ERI) Aug 06 02:51 (043) -12 64 07:00 1 – 1 IV

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3 comments

  • Paul Zeller 1 month ago

    I was observing outside on the morning of August 4 and believe that I saw at least 2 Kappa Cygnids in two hours of constant viewing. Possibly 3; but I think now that one was sporadic. Still, this seemed like a good omen that this shower might be a strong one this year, since this was 11 days prior to predicted peak?

    Reply to Paul
  • pookiebear 1 month ago

    I saw one in Brooklyn last night (august 6). Anyone else?

    Reply to pookiebear

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