Meteor Activity Outlook for February 21-27, 2009

February is the only month of the year that sees a fall in rates in both hemispheres. As seen from the northern hemisphere, sporadic rates continue the fall that began in January. This will continue until June when rates reach their nadir. After a brief peak of activity in January, sporadic rates in the southern hemisphere also slide downward until March. Shower activity is low this month but decidedly more interesting in the southern hemisphere. During February there are several sources of activity in the southern morning sky. Most notable is the Alpha Centaurids, which are active during the entire month of February. Other sources are scattered from Carina through Puppis, Vela, and on into Centaurus and Lupus. None of these even rate as a minor shower but together, along with the Alpha Centaurids, create some interesting viewing during the summer nights south of the equator. Only a trace of this activity can be seen from the northern tropics. The Antihelion radiant remains north of the celestial equator and produces a modest 1-2 meteors per hour from Leo. The weak Delta Leonids become active at mid-month but are few and far between, even at maximum activity.

During this period the moon reaches it new phase on Wednesday February 25th. At this time the moon lies near the sun in the sky and is not visible at night. This weekend the waning crescent moon will cause no interference for the meteor observer. The estimated total hourly rates for evening observers this week is near three as seen from the northern hemisphere and four for those situated south of the equator. For morning observers the estimated total hourly rates should be near thirteen for those located in the mid-northern hemisphere (45 N) and sixteen for those viewing from the mid-southern hemisphere (45 S). Locations between these two extremes would see activity between the listed figures. These rates assume that you are watching from rural areas away from all sources of light pollution. 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.

The radiant positions and rates listed below are exact for Saturday night/Sunday morning February 21/22. 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 showers are expected to be active this week:

The weak Delta Leonids (DLE) reach maximum on Wednesday February 25th. Visual rates will only be near one per hour at this time, no matter your location. The radiant is now located at 11:00 (165) +18. This area of the sky lies in central Leo, four degrees northwest of the third magnitude star Theta Leonis. This radiant is best placed near 0100 local standard time when it lies on the meridian and is highest in the sky. With an entry velocity of 23 km/sec., the average Delta Leonid meteor would be of slow speed. Do not confuse these meteors with the overlapping Antihelion radiant, whose center lies thirteen degrees to the south. To separate these meteors, the observer must be facing in a direction that allows both radiants to be included within your field of view.

The wide Antihelion (ANT) radiant is now centered at 11:04 (166) +05. This area of the sky lies in a remote area of southeastern Leo. The nearest easily seen star is fourth magnitude Sigma Leonis, located three degrees northeast of the center of the radiant. This radiant is best placed near 0100 LST, when it lies on the meridian and is located highest in the sky. Due to the large size of this radiant, any meteor radiating from southern Leo, western Virgo, or Sextans could be a candidate for this shower. Rates at this time should be near two per hour no matter your location. With an entry velocity of 30 km/sec., the average Antihelion meteor would be of medium-slow speed.

The Gamma Normids (GNO) reach an ZHR of one on Wednesday February 25th. At that time the radiant is located at 14:48 (222) -52. This area of the sky is located in southern Lupus, four degrees southeast of the second magnitude star Alpha Lupi. Current visual rates would be less than one shower member per hour, no matter your location. These meteors are best seen between 0400 and 0500 local standard time, when the radiant lies highest above the horizon. This shower is best seen from the southern hemisphere, where the radiant lies high in the sky at dawn. Meteors from this shower are not visible north of 40 degrees north latitude and also poorly seen throughout most of the northern hemisphere. An occasional shower member may be seen from the northern tropics, shooting upwards from the southern horizon. At 56 km/sec. the Gamma Normids will usually produce meteors of swift velocity.

As seen from the mid-northern hemisphere (45N) one would expect to see approximately ten Sporadic meteors per hour during the last hour before dawn as seen from rural observing sites. Evening rates would be near two per hour. As seen from the mid-southern hemisphere (45S), morning rates would be near thirteen per hour as seen from rural observing sites and three per hour during the evening hours. Locations between these two extremes would see activity between the listed figures.

The table below presents a summary of the expected activity this week. Rates and positions are exact for Saturday night/Sunday morning but may be used all week.