During this period the moon reaches its full phase on Thursday June 12th. At this time the moon will lie opposite the sun and will lie above the horizon most of the night as seen from mid-northern locations. This weekend the waxing gibbous moon will set a few hours before dawn, allowing a little time to view meteor activity under the dark skies between moonset and the start of dawn. The estimated total hourly meteor rates for evening observers this week is near 2 for observers situated at mid-northern latitudes and 3 for observers viewing from the southern tropics (latitude 25 S.). For morning observers the estimated total hourly rates should be near 8 for observers situated at mid-northern latitudes and 12 for observers viewing from the southern tropics. 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. Evening rates are lower this week due to the bright moonlight. 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.
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 7/8. 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.
These sources of meteoric activity are expected to be active this week:
The center of the large Anthelion (ANT) radiant is currently located at 18:00 (270) -23. This position lies in northwestern Sagittarius, 7 degrees northeast of the 3rd magnitude star known as Kaus Borealis (Lambda Sagittarii). These meteors may be seen all night long but the radiant is best placed near 0200 local daylight time (LDT) when it lies on the meridian and is positioned highest in the sky. Due to the large radiant area, meteors from this source may also appear to radiant from the constellation of Serpens Cauda, Scutum, Scorpius, and southern Ophiuchus as well as Sagittarius. Rates at this time should be near 2 per hour as seen from the northern hemisphere and 3 per hour as seen 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 45 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 this weekend when this shower will still be strong and the moon will have set. To try and see these meteors I would suggest 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 6 sporadic meteors per hour during the last hour before dawn as seen from rural observing sites. Evening rates would be near 1 per hour. As seen from the tropical southern latitudes (25S), morning rates would be near 9 per hour as seen from rural observing sites and 2 per hour during the evening hours. Locations between these two extremes would see activity between the listed figures.
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 except where noted in the shower descriptions.
|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)||–||18:00 (270) -23||29||02:00||2 – 3||II|
|Daytime Arietids (ARI)||Jun 07||02:10 (044) +24||43||10:00||<1 – <1||IV|