(meteorobs) Meteor Activity Outlook for April 25-May 1, 2015

[Robert Lunsford]

During this period the moon reaches its first quarter phase on Saturday April 25th. At this time the moon will be located 90 degrees east of the sun and will set near 0100 local daylight saving time (LDT). As the week progresses the moon will interfere more and more with meteor observing as it waxes and sets later each morning. By the end of the week the moon will be in the sky most of the night making meteor viewing difficult as the glare from the nearly full moon obscures all but the brightest meteors. 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 9 for observers situated at mid-northern latitudes and 15 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 during this period are reduced due to 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 April 25/26. 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 Pi Puppids (PPU) are active from April 15-28 which maximum activity predicted to occur on the 24th. Some of these meteors may be seen from the southern hemisphere from a radiant located at 07:28 (112) -45. This area of the sky is located central Puppis, just southeast of the third magnitude star Sigma Puppis. This area of the sky is best seen as soon as it becomes dark during the early evening hours. No matter your location, rates are expected to be low. Observers located in the tropical northern hemisphere may also see some activity but at latitudes north of 30 degrees north, the odds are against seeing any activity at all. At 18km/sec. the Pi Puppids would produce meteors of very slow velocity.

The H Virginids (HVI) were discovered by Japanese observers using the data from SonotaCo. This short duration shower is active from April 29 through May 3 with maximum occurring on May 1st. On the first the radiant is located at 13:40 (205) -11. This position lies in southern Virgo just 3 degrees east of the 1st magnitude star known as Spica (Alpha Virginis). This area of the sky is best placed near 2300 (11pm) LDT when the radiant lies highest above the horizon. Rates at this time should be less than 1 per hour no matter your location. With an entry velocity of 17 km/sec., the these meteors would be of very slow velocity.

The center of the large Anthelion (ANT) radiant is currently located at 15:12 (228) -18. This position lies in central Libra, 5 degrees southeast of the 3rd magnitude known as Zubenelgenubi (Alpha Librae). Due to the large size of this radiant, Anthelion activity may also appear from southern Serpens Caput, western Scorpius, eastern Hydra, northern Centaurus, and eastern Virgo as well as Libra. This radiant is best placed near 0100 LDT, when it lies on the meridian and is located highest in the sky. 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.

The April Rho Cygnids (AEC) are active from April 11-May 4, with maximum activity occurring on the April 23rd. This shower was discovered by Dr. Peter Brown and associates using data from the Canadian Meteor Orbit Radar. The radiant is currently located at 21:04 (316) +45, which places it in northeastern Cygnus, 4 degrees east of the 1st magnitude star known as Deneb (Alpha Cygni). This radiant is best placed during the last dark hour before dawn when it lies highest above the horizon in a dark sky. Rates at this time should be near 1 per hour as seen from the northern hemisphere and less than 1 as seen from south of the equator. With an entry velocity of 42 km/sec., the average meteor from this source would be of medium velocity.

The Eta Aquariids (ETA) are now active and will reach maximum activity near May 7th. Rates will be low during this period and the waxing moon will not help the situation. These meteors are only visible shortly before dawn when the radiant radiant clears the horizon. The radiant is currently located near 22:08 (332) -04. This position lies in northern Aquarius, 4 degrees south of the 3rd magnitude star known as Sadalmelik (Alpha Aquarii). This radiant is best placed during the last dark hour before dawn when it lies highest above the horizon in a dark sky. Rates at this time should be near 1 per hour as seen from the northern hemisphere and 2 as seen from south of the equator. With an entry velocity of 67 km/sec., the average meteor from this source would be of swift velocity with a high percentage of persistent trains on the brighter meteors.

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 1 per hour. As seen from the tropical southern latitudes (25S), morning rates would be near 10 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. Evening rates are reduced due to interfering moonlight.

The list below offers the information from above in condensed form. Rates and 
positions are exact for Saturday night/Sunday morning except where noted in the 
shower descriptions. 
 
Pi Puppids (PPU) - 07:28 (112) -45  Velocity - 18km/sec. 
Northern Hemisphere - <1 per hr.   Southern Hemisphere - <1 per hr 
 
H Virginids (HVI) - 13:40 (205) -11  Velocity - 17km/sec. 
Northern Hemisphere - <1 per hr.   Southern Hemisphere - <1 per hr 
 
Anthelion (ANT) -   15:12 (228) -18  Velocity - 30km/sec. 
Northern Hemisphere - 2 per hr.   Southern Hemisphere - 3 per hr 
 
April Rho Cygnids (AEC) - 21:04 (316) +45  Velocity - 42km/sec. 
Northern Hemisphere - 1 per hr.   Southern Hemisphere - <1 per hr. 
 
Eta Aquariids (ETA) - 22:08 (332) -04  Velocity - 67km/sec. 
Northern Hemisphere - 1 per hr.   Southern Hemisphere - 2 per hr. 
 
Clear Skies! 
Robert Lunsford 	 
American Meteor Society