During this period the moon reaches its last quarter phase on Tuesday April 22nd. At this time the moon will lie 90 degrees west of the sun and will rise near 0200 local daylight time (LDT) as seen from mid-northern latitudes. This weekend the waning gibbous moon will lie above the horizon during the more active morning hours preventing good views of the meteor activity. 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 9 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. Morning rates are reduced during this period due to interfering 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 19/20. 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 sources of meteoric activity are expected to be active this week:
Activity from the Pi Puppids (PPU) may be seen from the southern hemisphere from a radiant located at 07:16 (109) -45. This area of the sky is located central Puppis, just southwest 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 center of the large Anthelion (ANT) radiant is currently located at 14:48 (222) -16. This position lies on the Virgo/Libra border, 7 degrees northwest of the 3rd magnitude star known as Zubeneschemali (Beta Librae). 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 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 Caput, Libra, eastern Hydra, and eastern Virgo, Rates at this time should be near 1 per hour no matter your location. With an entry velocity of 30 km/sec., the average Anthelion meteor would be of slow velocity.
Activity from the Lyrid (LYR) shower reaches maximum activity on the morning of April 22th with the radiant located at 18:08 (272) +33. This area of the sky is actually located in eastern Hercules, two degrees southwest of the faint star known as Kappa Lyrae. This position also lies six degrees southwest of the brilliant zero magnitude star Vega (Alpha Lyrae). The radiant is best placed just before the break of dawn when the radiant lies highest in the sky. While Lyrid meteors can be seen in both hemispheres, the north is favored as the radiant lies much higher in the sky. Hourly rates at maximum are expected to be near 10 shower members during the last couple of hours before dawn. South of the equator rates would most likely be near 5 Lyrids per hour. At 48km/sec. the Lyrids would produce meteors of medium-swift velocity.
The Nu Cygnids (NCY) are active from April 2nd through May 4th with maximum activity occurring on April 18th. The radiant is currently located near the position of 20:52 (313) +41. This position lies in central Cygnus, 5 degrees south of the 1st magnitude star known as Deneb (Alpha Cygni). This position is best suited for viewing from the northern hemisphere where the radiant lies high in the northeastern sky during the last couple of hours before dawn. During the same time of night, as seen from the southern tropics, the radiant lies low in the northeast therefore diminished activity will be seen from the southern hemisphere. At 44 km/sec. these meteors would have a medium-swift velocity.
As seen from the mid-northern hemisphere (45N) one would expect to see approximately 3 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 7 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|
|Pi Puppids (PUP)||Apr 23||07:16 (109) -45||18||18:00||<1 – <1||III|
|Anthelions (ANT)||-||14:48 (222) -16||29||02:00||1 – 1||II|
|Lyrids (LYR)||Apr 22||18:08 (272) +33||48||05:00||3 – 1||IV|
|Nu Cygnids (NCY)||Apr 18||20:52 (313) +41||44||08:00||1 – <1||IV|