(meteorobs) Meteor Activity Outlook for February 2-8, 2013

[Robert Lunsford]

February offers the meteor observer in the northern hemisphere a couple of weak showers plus falling sporadic rates. This may not seem too exiting but you never know when surprises are in store. An errant earth-grazer from the Centaurid complex may shoot northward. Better yet, a bright fireball may light up the sky. February is the start of the fireball season, when an abundance of fireballs seem to occur. This lasts well into April and seems to occur mostly during the early evening hours.

Observers in the southern hemisphere are treated to the Alpha Centaurid peak on the 8th plus the entire Centaurid complex of radiants is active all month long. Sporadic rates also peak this month south of the equator this month adding to the celestial show.

During this period the moon reaches its last quarter phase on Sunday February 3rd. At this time the moon is located ninety degrees west of the sun. The half illuminated moon will rise near midnight local standard time and will remain in the sky the remainder of the night. While producing much less light than a full moon, the last quarter moon will still hamper meteor observations during the morning hours. If your skies are transparent meteor observers can simply face the opposite direction of the moon and still carry on successful observations. As the week progresses the moon will less of a problem as the phase wanes and it rises later in the morning with each passing night. The estimated total hourly meteor rates for evening observers this week is near three no matter your location. For morning observers the estimated total hourly rates should be near seven from the mid-northern hemisphere and ten from the mid-southern hemisphere. 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 due to moonlight.

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 2/3. 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 large Anthelion (ANT) radiant is currently centered at 09:48 (147) +11. This position lies in western Leo, four degrees west of the first magnitude star Regulus (Alpha Leonis). These meteors may be seen all night long but the radiant is best placed near 0100 LST when it lies on the meridian and is highest in the sky. Rates at this time should be near two per hour as seen from the northern hemisphere and one per hour from south of the equator. With an entry velocity of 30 km/sec., the average Antihelion meteor would be of slow velocity.

The Alpha Centaurids (ACE) are now active from a radiant located at 13:36 (204) -58. This position lies in southeastern Centaurus, five degrees northwest of the first magnitude star Hadar (Beta Centauri). These meteors cannot be seen north of the northern tropical regions. They are best seen from mid-southern latitudes where the radiant lies high in the sky near 0500 local summer time. As seen from the southern hemisphere rates will be rising this week and will peak on February 8th, when they should be near five per hour during the morning hours. At 56km/sec. the Alpha Centaurids would produce mostly swift meteors.

IMO Shower #22 is a weak unnamed shower active from January 29 through February 9. Peak activity occurs on February 8th from a radiant located at 13:42 (206) +09. This position is located in extreme southwestern Bootes, ten degrees southwest of the zero magnitude star Arcturus (Alpha Bootis). These meteors are best seen near 0400 LST, 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 65 km/sec. IMO Shower #22 would produce mostly swift meteors. It is possible that these meteors are a continuation of the Coma Berenicids which were active In December and January.

As seen from the mid-northern hemisphere (45N) one would expect to see approximately five 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 seven per hour as seen from rural observing sites and two per hour during the evening hours. Locations between these two extremes would see activity between the listed figures. Morning rates are reduced this week due to moonlight.

The list below presents a condensed version of the expected activity this week. Rates and positions are exact for Saturday night/Sunday morning .

Anthelions (ANT) - 09:48 (147) +11   Velocity - 30km/sec.
Northern Hemisphere - 2 per hr.   Southern Hemisphere - 1 per hr

Alpha Centaurids (ACE) - 13:36 (204) -58   Velocity - 56km/sec.
Northern Hemisphere - <1 per hr. Southern Hemisphere - 2 per hr

IMO #22- 13:42 (206) +09   Velocity - 65km/sec.
Northern Hemisphere - <1 per hr. Southern Hemisphere - <1 per hr

Clear Skies!
Robert Lunsford
American Meteor Society