During this period the moon reaches its new phase on Monday January 23rd. At this time the moon will be located near the sun and will not be visible at night. This will be the best time of the month to try and view meteor activity as the moon will not interfere with observations, no matter the time of night. As the week progresses the waxing crescent moon will enter the evening sky but will set long before the active morning hours arrive. The estimated total hourly rates for evening observers this week is near three no matter your location. For morning observers the estimated total hourly rates should be near ten as seen from mid-northern latitudes and twelve from mid-southern latitudes. 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 (the area of the sky where meteors appear to shoot from) positions and rates listed below are exact for Saturday night/Sunday morning January 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 large Antihelion (ANT) radiant is currently located at 08:56 (134) +16. This position lies in central Cancer, four degrees north of the fourth magnitude star Acubens (Alpha Cancri). Due to the large size of this radiant, Antihelion activity may also appear from western Leo and northwestern Hydra. This radiant is best placed near 0100 LST, when it lies on the meridian and is located highest in the sky. 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 slow velocity.
The December Leonis Minorids (DLM) are active from a radiant located at 12:36 (189) +16. This position lies in a blank area of southern Coma Berenices. The nearest bright star is second magnitude Denebola (Beta Leonis), which lies ten degrees to the west. These meteors are best seen near 0500 local standard time (LST) when the radiant lies highest above the horizon. This shower peaked on December 20th so current rates would be less than one per hour no matter your location. At 64 km/sec. the December Leonis Minorids produce mostly swift meteors.
As seen from the mid-northern hemisphere (45N) one would expect to see approximately eight 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 ten 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.
The table below presents a condensed version of the expected activity this week. Rates and positions are exact for Saturday night/Sunday morning.
|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|
|Antihelions (ANT)||–||08:56 (134) +16||30||01:00||2 – 2||II|
|December Leonis Minorids (DLM)||Dec 20||12:36 (189) +25||64||05:00||<1 – <1||II|