June is another slow month for meteor activity. There are no major showers
active in June and only the Anthelion source can be counted on for continuous
activity. Even the Anthelion radiant is located so far south this time of year that
rates rarely exceed two per hour as seen from the northern hemisphere. Sporadic
rates begin a slow recovery in June as seen from the mid-northern hemisphere (45 N). Sporadic rates seen from the mid-southern hemisphere (45 S) continue to be strong this month before a big falloff occurs during the second half of July.
During this period the moon wanes from nearly half illuminated to almost its new phase. This weekend the bright crescent moon will be limited to the morning hours. Unfortunately this coincides with the most active time of night for viewing meteor activity. Moonlight can be overcome keeping the moon out of your field of view. As the week progresses, the situation improves with the moon getting thinner with each passing night. The estimated total hourly meteor rates for evening observers this week is near three as seen from the northern hemisphere and four as seen from south of the equator. For morning observers the estimated total hourly rates should be near six as seen from the northern hemisphere and fifteen as seen from the southern hemisphere. 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. Morning 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 1/2. 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 center of the large Anthelion (ANT) radiant is currently located at 17:36 (264) -23. This position lies in southeastern Ophiuchus , three degrees northeast of the third magnitude star known as Theta Ophiuchi. These meteors may be seen all night long but the 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 per hour as seen from the Northern hemisphere and three per hour from south of the equator . With an entry velocity of 30 km/sec., the average Anthelion meteor would be of slow velocity.
Besides the Anthelion radiant, the only shower of note active at this time is the Daytime Arietids (ARI). At 02:10 (044) +24, this radiant is located only thirty degrees west of the sun so visual observing conditions for this display are poor at best. It is an achievement of note just to see one of these meteors just before dawn on early June mornings. Your best chance to see this activity will occur on Friday morning June 7th, when this shower reaches maximum activity. On that morning start watching one hour before the start of dawn and look toward the northeast with your center of vision positioned half-way up in the sky. Any Arietids will shoot upwards from the horizon and should last several seconds as they streak a long path through the sky. Your chances of seeing these meteors are best from the northern tropics, where the longer nights allow the radiant to rise higher into the sky. At 43km/sec. the Daytime Arietids would produce meteors of medium velocity. By the way, this is the strongest daylight shower of the year. If the circumstances were better for this shower (higher radiant in a dark sky), this display would rival the annual Perseids in intensity.
As seen from the mid-northern hemisphere (45N) one would expect to see approximately four sporadic meteors per hour during the last hour before dawn as seen from rural observing sites. Evening rates would be near two per hour. As seen from the mid-southern hemisphere (45S), morning rates would be near twelve per hour as seen from rural observing sites and three per hour during the evening hours. Locations between these two extremes would see activity between the listed figures. Morning rates are reduced due to moonlight.
The table below presents a list of radiants that are expected to be active this week. Rates and positions are exact for Saturday night/Sunday morning.
|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|
|Anthelions (ANT)||–||17:36 (264) -23||30||02:00||2 – 3||II|
|Daytime Arietids (ARI)||Jun 07||02:10 (044) +24||43||10:00||<1 – <1||IV|