(meteorobs) Meteor Activity Outlook for May 31-June 6, 2008

lunro.imo.usa at cox.net lunro.imo.usa at cox.net
Fri May 30 06:36:29 EDT 2008


June is another slow month for meteor activity. There are no major showers active in June and only the Antihelion can be counted on for continuous activity. Even the Antihelion is located so far south this time of year that rates rarely exceed two per hour as seen from the northern hemisphere. Sporadic rates reach their nadir in June as seen from the mid-northern hemisphere (45 N). Sporadic rates seen from the mid-southern hemisphere (45 S) continue to rise this month toward a maximum in July. 

During this period the moon reaches its new phase on Tuesday June 3rd. At this time the moon will be located near the sun and will be invisible at night. As seen from the mid-northern hemisphere (45 N) the estimated total hourly rates during the evening observers would be only one. For morning observers the estimated total hourly rates should be near six. For those located in the mid-southern hemisphere (45 S) morning rates would be near fourteen and evening rates near three. These rates assume that you are watching from rural areas away from all sources of light pollution. 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. 

The radiant positions and rates listed below are exact for Saturday night/Sunday morning May 31/June 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 following showers are expected to be active this week: 

The large Antihelion (ANT) radiant is now centered at 17:36 (264) -23. This area of the sky lies in southern Ophiuchus, three degrees northeast of the third magnitude star Theta Ophiuchi. Actually any meteor from northern Scorpius, western Sagittarius, as well as southern Serpens Cauda could be a candidate for this shower. This radiant is best placed near 0200 LDT when it lies on the meridian and is highest in the sky. Rates at this time should be near two for northern observers and three for observers south of the equator. With an entry velocity of 30 km/sec., the average Antihelion meteor would be of medium-slow speed. 

During late May and early June, an occasional long meteor may shoot upwards from the northeastern horizon just before dawn. Most likely these are members of the Daytime Arietid (DAR) meteor shower. The radiant lies approximately thirty degrees west of the sun therefore only a trace of this shower can ever be seen by the visual observer. Dawn becomes too bright before the radiant can achieve sufficient altitude to provide a good display. 

If this shower were visible in a dark sky it would be among the strongest displays of the year. This shower is the strongest daylight/radio shower of the year. The current position of the radiant is 02:40 (040) +20. This position lies in central Aries, eight degrees southeast of the second magnitude star Hamal (Alpha Arietis). Shower members would be visible only during the last hour before dawn with rates at or less than one per hour. With an entry velocity of 37 km/sec., the average Daytime Arietid meteor would be of medium speed. 

As seen from the mid-northern hemisphere (45N) the Sporadic rates are near their lowest rates of the year. One would expect to see approximately six random meteors during the last hour before dawn from rural observing sites and only one per hour during the evening hours. As seen from the mid-southern hemisphere (45S) morning rates would be near fifteen per hour as seen from rural observing sites and three per hour during the evening hours. 

The table below presents a condensed version of the expected activity this week. Rates and positions are exact for Saturday night/Sunday morning. 

Antihelion (ANT) - 17:36 (264) -23  Velocity - 30km/sec.
Northern Hemisphere - 2   Southern Hemisphere - 3  

Daytime Arietid (DAR)  07 02:40 (040) +20 Velocity - 37km/sec.
Northern Hemisphere - 1   Southern Hemisphere - <1

*For a detailed explanation on the different classes of meteor showers and other astronomical terms, please visit: http://www.amsmeteors.org/showers.html#X2008 

Clear Skies!
Robert Lunsford 
American Meteor Society



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