Meteor season finally gets going in July for the northern hemisphere. The first half of the month will be much like June. After the 15th though, both sporadic and shower rates increase significantly. For observers in the southern hemisphere, sporadic rates will be falling but the overall activity will increase with the arrival of the Delta Aquariids.
During this period the moon reaches its full phase on Tuesday July 3rd. At this time the moon will be located opposite of the sun and will rise as the sun sets and will set as the sun rises. This weekend the waxing gibbous moon will set near the start of morning twilight. One may get in an hour of decent viewing just before dawn but this disappears on Monday as the moon will remain above the horizon the entire night. The estimated total hourly meteor rates for evening observers this week is near two for observers in the northern hemisphere and three for those south of the equator. For morning observers the estimated total hourly rates should be near four as seen from mid-northern latitudes and eight from mid-southern latitudes. 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 during this period 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 June 30/July 1. 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 table below presents a condensed version of the expected activity this week. Details of each radiant will be posted again next week when moonlight is not as bad.
|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|
|June Bootids (JBO)||June 27||15:02 (226) +47||18||22:00||<1 – <1||III|
|f-Ophiuchids (FOP)||June 29||18:16 (274) +07||21||01:00||<1 – <1||IV|
|Antihelions (ANT)||–||19:28 (292) -21||30||02:00||1 – 2||II|
|c-Andromedids (CAN)||July 12||01:36 (024) +45||59||09:00||<1 – <1||IV|