Meteor Activity Outlook for January 1-7, 2011
January 3, 2011
The Meteor Activity Outlook is a weekly summary of expected meteor activity written by Robert Lunsford, Operations Manager of the American Meteor Society and contributor to this blog. The original unedited version of this week’s Meteor Activity Outlook can be found at the American Meteor Society’s site.
January sees a peak of sporadic activity for the southern hemisphere while rates seen north of the equator begin a steady downward turn that continues throughout the first half of the year. The sporadic activity is good for both hemispheres, but not as good as it was for northern observers in December. Once the Quadrantids have passed the shower activity for January is very quiet.
During this period the moon reaches its new phase on Tuesday January 4th. At this time the moon lies near the sun and is not visible at night. This will be the best time of the month to view meteor activity as the moon will not interfere plus the meteor rates will be at their highest. The estimated total hourly rates for evening observers this week is near eight from the northern hemisphere and two for observers south of the equator. For morning observers the estimated total hourly rates should be near forty-five from the northern hemisphere and twenty as seen from the 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.
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 1/2. These positions do not change greatly day to day so the listed coordinates may be used during this entire period.
The following showers are expected to be active this week:
The wide Antihelion (ANT) radiant is now centered at 07:36 (114) +21. This area of the sky lies in eastern Gemini, seven degrees south of the bright first magnitude star Pollux (Beta Geminorum). This radiant is best placed near 0100 local standard time (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 Gemini, Canis Minor, eastern Auriga, southern Lynx or Cancer could be a candidate for this shower. Rates at this time should be near three per hour as seen from the northern hemisphere and two per hour for observers located south of the equator. With an entry velocity of 30 km/sec., the average Antihelion meteor would be of medium-slow speed.
Alpha Hydrids (AHY)
The Alpha Hydrids (AHY) are active from December 30th through January 8th. Peak activity occurred on December 31. Rates would most likely now be less than one per hour, no matter your location. The radiant is currently located at 08:28 (127) -08. This position lies in extreme western Hydra, fifteen degrees west of the second magnitude star Alphard (Alpha Hydrae). The Alpha Hydrids are best seen near 0200 LST when the radiant lies highest above the horizon. At 45 km/sec. the Alpha Hydrids produce mostly meteors of medium velocity.
January Leonids (JLE)
Studies of the IMO’s video database by Sirko Molau and Juergen Rendtel has shown an active radiant in Leo this time of year. The January Leonids (JLE) are active from December 31st to January 5th with maximum activity occurring on January 1st. On the 1st the radiant is located at 09:46 (147) +24. This position lies in western Leo just west of the third magnitude star Algenubi (Epsilon Leonis). This is a very minor display with hourly rates of less than one expected, even at maximum activity. They are best seen near 0300 LST when the radiant lies highest above the horizon. At 54 km/sec. the January Leonids (JLE) produce mostly meteors of medium-swift velocity.
December Leonis Minorids (DLM)
The December Leonis Minorids (DLM) are active from a radiant located at 11:58 (173) +25. This position lies in a blank area of northeastern Leo, directly between the bright stars Denebola (Beta Leonis) and Nu Ursae Majoris. These meteors are best seen near 0500 LST when the radiant lies highest above the horizon. This shower peaked on December 20th so current rates would be near two per hour as seen from the northern hemisphere and one per hour as seen from south of the equator. At 64km/sec. the December Leonis Minorids produce mostly swift meteors.
The Quadrantids (QUA) or January Bootids are active from January 1st through the 10th. A sharp maximum is predicted to occur near 0100 Universal Time on the 4th. This corresponds to 20:00 (8pm) EST and 17:00 (5pm) PST on the evening of January 3. This is bad timing for viewers located in North America as the radiant will either be low or beneath the northwestern horizon. At such low radiant elevations very little Quadrantid activity can be expected to be seen. Your best bet is to wait until the morning of the 4th when the radiant was risen in the northeastern sky. From 0100 to dawn expect to see up to 25 Quadrantids per hour. Observers viewing from eastern Europe and western Asia will have the maximum occur during the morning hours when the radiant lies high in the sky. They can expect to see near 60 Quadrantids per hour, perhaps more if the shower is especially active. The radiant is located at 15:21 (230) +49. This position lies in a bare region of extreme northern Bootes, ten degrees northeast of the fourth magnitude star Beta Bootis. At 42 km/sec. the Quadrantids produce meteors of medium velocity. During exceptional activity some Quadrantid fireballs may be witnessed.
As seen from the mid-northern hemisphere (45N) one would expect to see approximately fifteen Sporadic meteors per hour during the last hour before dawn as seen from rural observing sites. Evening rates would be near three 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 list below presents a condensed version of the expected activity this week.
Rates and positions are exact for Saturday night/Sunday morning.
Shower Name RA DEC Vel Rates km/s NH SH ANT Antihelions 07h 36m +21 30 3 2 AYD Alpha Hydrids 08h 28m -08 61 <1 <1 JLE January Leonids 09h 46m +24 54 <1 <1 DLM Dec Leonis Minorids 11h 58m +25 71 2 1 QUA Quadrantids 15h 21m +49 42 5 <1 RA - Right Ascension DEC - Declination Vel - Velocity relative to Earth (in km per sec) Rates - Rate of visible meteors per hour from a dark site NH - Northern Hemisphere SH - Southern Hemisphere