During this period the moon reaches its last quarter phase on Saturday February 22nd. At this time the moon will lie 90 degrees west of the sun and will rise near midnight LST (Local Standard Time) as seen from mid-northern latitudes. The one-half illuminated moon will interfere with meteor observing, but not as badly as with a full moon in the sky. The glare of the moon can be avoided if your view in a portion of the sky away from the moon. The moon will continue to wane this week and will rise approximately 45 minutes later with each passing night. Therefore observing conditions towards the end of this period will be more favorable than those this weekend. The estimated total hourly meteor rates for evening observers this week is near 3 for observers situated at mid-northern latitudes and 4 for observers viewing from the southern tropics (latitude 25 S.). For morning observers the estimated total hourly rates should be near 5 for observers situated at mid-northern latitudes and 11 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 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 February 22/23. 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:
The center of the large Anthelion (ANT) radiant is currently located at 11:08 (167) +04. This position lies in southeastern Leo, 3 degrees southwest of the faint star known as Sigma Leonis. Due to the large size of this radiant, Anthelion activity may also appear from Sextans, Crater, western Virgo as well as Leo. This radiant is best placed near 0100 local standard time (LST), when it lies on the meridian and is located highest in the sky. Rates at this time should be near 1 no matter your location. With an entry velocity of 30 km/sec., the average Anthelion meteor would be of slow velocity.
Activity from the Gamma Normids (GNO) begins on Tuesday morning February 25th. Maximum activity does not occur until March 14 so current rates would be very low. In fact this shower has been on the bubble for removal from active lists as there has been little activity recorded from this source in recent years. Even the current radiant position is suspect due to lack of data. The suspected radiant is thought to be located near 15:32 (233) -52. This position is located on the Lupus/Norma border, 3 degrees east of the third magnitude star known as Zeta Lupi. These meteors are best seen near during the last dark hour before dawn when the radiant lies highest above the horizon in a dark sky. Rates would mostly likely be less than one shower member per hour, no matter your location. At 56 km/sec. the Gamma Normids would produce mostly swift meteors. Due to the far southern declination (celestial latitude) these meteors are best seen from the southern hemisphere. Observers in the northern tropics may see a few of these meteors shooting upward from the southeastern horizon during the last couple of hours before dawn. This is possibly one of the last active branches of the southern summer complex, which begins in Carina in January and works its way eastward through Vela and Centaurus in February. This is similar to the northern summer complex, active in Cassiopeia, Perseus, and Auriga from July through September.
As seen from the mid-northern hemisphere (45N) one would expect to see approximately 4 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 10 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. Morning rates are reduced due to interfering 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 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 Standard Time||North-South|
|Anthelions (ANT)||–||11:08 (167) +04||29||01:00||1 – 1||II|
|Gamma Normids (GNO)||Mar 14||15:32 (233) -52||56||05:00||<1 – <1||II|