During this period the moon reaches its last quarter phase on Thursday August 25th. At this time the moon will lie 90 degrees west of the sun and will rise near midnight local summer time (LST) for observers located at mid-northern latitudes. This weekend the waning gibbous moon will rise around 2100 LST and will remain above the horizon the remainder of the night. The bright moon will obscure many of the fainter meteors that would otherwise be seen in a darker sky. The estimated total hourly meteor rates for evening observers this week is near 3 for observers located in the northern hemisphere and 2 for observers located in tropical southern locations (25S). For morning observers the estimated total hourly rates should be near 15 for observers located in the northern hemisphere and 12 for observers located in 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 brightest meteors will be visible from such locations. Rates during this period are reduced due to interfering moonlight.
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 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 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.
Details of each source will continue next week when moonlight conditions will be more favorable.
|SHOWER||DATE OF MAXIMUM ACTIVITY||CELESTIAL POSITION||ENTRY VELOCITY||CULMINATION||HOURLY RATE||CLASS|
|RA (RA in Deg.) DEC||Km/Sec||Local Summer Time||North-South|
|kappa Cygnids (KCG)||Aug 17||18:20 (275) +55||19||23:00||1 – <1||II|
|Anthelions (ANT)||–||22:44 (341) -09||29||02:00||1 – 2||II|
|North delta Aquariids (NDA)||Aug 19||23:36 (354) +05||41||03:00||1 – 1||IV|
|August gamma Cepheids (AGC)||Aug 28||23:54 (359) +77||41||03:00||<1 – <1||IV|
|South delta Aquariids (SDA)||Jul 28||00:04 (001) -10||42||03:00||<1 – 1||I|
|Perseids (PER)||Aug 12||04:04 (061) +60||61||07:00||3 – 1||I|