During this period the moon wanes from a full phase down to nearly half illuminated. This weekend the nearly full moon will be in the sky all night long. This is the worst time of the month to try and view meteor activity. As the week progresses, the moon will rise later in the evening but will still interfere with observing during the prime morning hours. The estimated total hourly rates for evening observers this week is near one no matter your location. For morning observers the estimated total hourly rates should be near five from the northern hemisphere and six as seen from south of the equator. 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. Rates are reduced this week due to 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 July 16/17. 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 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.
The following showers are expected to be active this week. Details concerning each shower will continue next week when the moon will not be so troublesome.
|SHOWER||DATE OF MAXIMUM ACTIVITY||CELESTIAL POSITION||ENTRY VELOCITY||CULMINATION||HOURLY RATE||CLASS|
|RA (RA in Deg.) DEC||Km/Sec||Local Daylight Time||North-South|
|Mu Lyrids (MUL)||July 18||18:04 (271) +40||23||00:00||<1 – <1||IV|
|Alpha Capricornids (CAP)||July 30||19:52 (298) -14||25||01:00||<1 – 1||II|
|Antihelion (ANT)||–||20:28 (307) -18||30||02:00||<1 – 1||II|
|July Pegasids (JPE)||July 11||23:32 (353) +13||71||05:00||<1 – <1||IV|
|Perseids (PER)||Aug 13||00:36 (009) +51||61||06:00||1 – <1||I|