During this period the moon reaches its new phase on Thursday May 25th. At that time the moon is located near the sun and is invisible at night. This weekend the waning crescent moon will rise during the early morning hours and will not interfere with meteor observing as long as one keeps the moon out of their field of view. The estimated total hourly meteor rates for evening observers this week is near 3 for those viewing from the northern hemisphere and 4 for those located south of the equator. For morning observers the estimated total hourly rates should be near 7 as seen from mid-northern latitudes (45N) and 12 as seen from tropical southern locations (25S). 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. 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 May 20/21. 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 far 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 16:52 (253) -23. This position lies in southern Ophiuchus, 7 degrees northeast of the 1st magnitude orange star known as Antares (alpha Scorpii). Due to the large size of this radiant, Anthelion activity may also appear from the nearby constellations of western Sagittarius, northern Scorpius, and southern Serpens Cauda as well as southern Ophiuchus . This radiant is best placed near 0200 local daylight saving time (LDT), when it lies on the meridian and is located highest in the sky. Hourly rates at this time should be near 2 as seen from mid-northern latitudes and 3 as seen from tropical southern latitudes. With an entry velocity of 30 km/sec., the average Anthelion meteor would be of slow velocity.
The last of the May beta Capricornids (MBC) are expected this weekend from a radiant located at 20:24 (306) -18. This area of the sky is located in western Capricornus, 3 degrees south of the 3rd magnitude star known as Dabih (beta Capricorni). This radiant is best placed during the last hour before dawn when it lies highest above the horizon in a dark sky. Current rates are expected to be less than 1 per hour no matter your location. These meteors are better suited for observing from the southern hemisphere, where the radiant lies higher in the sky during the longer autumn nights. With an entry velocity of 66 km/sec., the average meteor from this source would be of swift velocity.
The Daytime Arietids (ARI) are a strong shower but difficult to view due to the proximity of the radiant to the sun. These meteors are active from May 14 through June 24 with a peak on June 7. The radiant is currently located at 01:52 (028) +08. This area of the sky is located in southeastern Pisces, 5 degrees northwest of the position occupied by the fourth magnitude star known as Alrescha (alpha Piscium). The best time to view this activity is during the hour before the start of morning twilight, when the radiant lies highest in a dark sky. With the radiant low in the east it would be best to face halfway up in the sky in that same direction. With an entry velocity of 42 kilometers per second, these meteors will appear to move at a medium velocity.
As seen from the mid-northern hemisphere (45N) one would expect to see approximately 5 sporadic meteors per hour during the last hour before dawn as seen from rural observing sites. Evening rates would be near 2 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 3 per hour during the evening hours. Locations between these two extremes would see activity between the listed figures.
The list below offers the information from above in tabular form. 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 Saving Time||North-South|
|Anthelions (ANT)||–||16:52 (253) -23||30||02:00||2 – 3||II|
|May beta Capricornids (MBC)||May 19||20:24 (306) -18||68||05:00||<1 – <1||IV|
|Daytime Arietids (ARI)||Jun 07||01:52 (028) +08||42||11:00||<1 – <1||IV|