(meteorobs) Meteor Activity Outlook for December 4-10, 2010

[lunro.imo.usa at cox.net]

No matter where you live, the first half of December provides some of the best meteor activity of the year. In the northern hemisphere the sporadic rates are still strong plus you can also count on strong activity from the Geminids, which peak on December 14. There are also several minor radiants that add a few meteors each hour. All of these centers of activity are located high in the sky during the early morning hours this time of year. Much of the activity mentioned above can also be seen from the southern hemisphere. While the sporadic rates are not as strong as those seen from the north, they are stronger than the previous months and heading for a maximum in January. The warm, but short summer nights south of the equator make for some great viewing as long as the moon does not interfere. 

During this period the moon reaches its new phase on Sunday December 5th. At this time the moon lies near the sun and cannot be seen at night. Later next week the waxing crescent moon enters the evening sky but still sets long before the busy morning hours arrive. The estimated total hourly rates for evening observers this week is near five from the northern hemisphere and three for observers south of the equator. For morning observers the estimated total hourly rates should be near fifteen from the northern hemisphere and thirteen 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 December 4/5. 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 December Phoenicids (PHO) are a periodic shower that rarely produces noticeable activity. The only impressive display produced by this shower occurred in 1956 when ZHR's were near 100. Peak activity occurs on December 6. Little activity is expected then or away from the peak night. The radiant is currently located at 01:08 (017) -53. This position lies in eastern Phoenix, five degrees northwest of the first magnitude star Archernar (Alpha Eridani). These meteors are best seen near 2000 (8pm) local standard time (LST), when the radiant lies highest above the horizon in a dark sky. Due to the southerly declination of the radiant, this shower is not visible north of the northern tropical areas. The deep southern hemisphere has the best chance of seeing any activity. At 22 km/sec. the Phoenicids produce very slow meteors. 

The center of the large Northern Taurid (NTA) radiant lies at 05:12 (078) +26. This area of the sky is located in eastern Taurus, five degrees southwest of the second magnitude star El Nath (Beta Tauri). These meteors are best seen near midnight LST, when the radiant lies highest above the horizon. This shower peaked on November 13, so rates are falling should be near three per hour. Meteors from the Northern Taurids strike the atmosphere at 29km/sec., which would produce meteors of slow velocity. This shower is also responsible for many of the fireball reports seen in November. 

The November Orionids (NOO) were recently discovered by Sirko Molau and Juergen Rendtel's studies of video radiants. For years it was lost in the maze of radiants active this time of year in this area of the sky. Due to the low activity, visual observers were unable to recognize this shower. This shower is active from November 18 through December 9. Maximum activity occurred on November 30. Once you know the radiant in advance, this shower is actually quite noticeable, producing an average of two shower members per hour near maximum. The radiant is currently located at 06:20 (095) +15. This position lies in northeastern Orion, eight degrees northeast of the orange first magnitude star Betelgeuse (Alpha Orionis). These meteors are best seen near 0100 LST when the radiant lies on the meridian and highest above the horizon. At 44 km/sec. the November Orionids produce mostly medium velocity meteors. 

The Monocerotids (MON) are active from December 7th through the 18th. Peak activity occurs on December 8th. On the night of maximum activity the radiant is located at 06:37 (099) +08. This position lies in northern Monoceros, eight degrees south of the second magnitude star Alhena (Gamma Geminorum). Rates at maximum should be near two per hour no matter your location. The Monocerotids are best seen near 0100 LST when the radiant lies highest above the horizon. At 41 km/sec. the Monocerotids produce mostly meteors of medium velocity. 

Geminid (GEM) activity begins this weekend from a radiant located at 07:16 (109) +33. This position lies in northern Gemini, four degrees west of the second star Castor (Alpha Geminorum). Expected rates this weekend would only be near one per hour as maximum is still ten days away. Although Geminid meteors can be seen all night long, they are best seen near 0200 LST when the radiant lies highest above the horizon. This shower peaks on the night of December 14, when rates can surpass 60 shower members per hour as seen from dark sites. Geminid activity can be seen from the southern hemisphere but at much reduced rate. As seen from south of the equator, Geminid activity could only be seen for a few hours before and after 0200 LST. At 35 km/sec. the Geminids produce mostly meteors of medium velocity. 

The Puppid-Velids (PUP) are a vast complex of weak radiants located in the constellations of Puppis and Vela. Visual plots and photographic studies have revealed many radiants in this area during November and December. The combined strength of these radiants can produce a ZHR of ten. Actual hourly rates will be much less unless you happen to be observing from the deep Southern Hemisphere. The center of this activity is currently located at 08:08 (122) -45. This position lies in western Vela, two degrees north of the second magnitude star Gamma Velorum. Peak rates occur near December 7. These meteors are best seen near 0300 LST when the radiant lies highest above the horizon in a dark sky. Observers located in the Southern Hemisphere have an advantage viewing this shower as the radiant will rise higher into their sky allowing more activity to be seen. At 40 km/sec. the Puppid-Velids produce meteors of average velocity. 

The Sigma Hydrids (HYD) are active from November 26 through December 20. Maximum activity occurs on December 6 from a radiant located at 08:16 (124) +03. This position lies on the Hydra/Canis Minor border, seven degrees southeast of the brilliant zero magnitude star Procyon (Alpha Canis Minoris). These meteors are best seen near 0300 LST when the radiant lies highest above the horizon. Current rates would be near two per hour no matter your location. At 61 km/sec. the Sigma Hydrids produce mostly swift meteors. 

Activity from the December Leonis Minorids (DLM) begin this weekend from a radiant located at 09:56 (149) +37. This position lies in central Leo Minor, seven degrees northeast of the fourth magnitude star Alpha Lyncis. These meteors are best seen near 0500 LST when the radiant lies highest above the horizon. This shower peaks on December 20th so current rates would be near one per hour as seen from the northern hemisphere and less than one per hour as seen from south of the equator. At 64 km/sec. the December Leonis Minorids produce mostly swift meteors. 

Another shower verified by video means are the Psi Ursa Majorids (PSU). This shower is active from November 29-December 13 with maximum activity occurring on December 5. The radiant is currently located at 11:12 (168) +43. This position lies in southern Ursa Major, one degree south of the third magnitude star Psi Ursae Majoris. This area of the sky is best placed during the last hour before dawn, when it lies highest above the horizon in a dark sky. Current rates would most likely be less than one per hour. At 61km/sec., the average Psi Ursa Majorid meteor would be swift. 

Another shower verified by video means are the December Kappa Draconids (KDR). This shower is active from November 30-December 6 with maximum activity occurring on December 3. The radiant is located at 12:30 (187) +69. This position lies in extreme western Draco, very close to the faint star Kappa Draconis. While the radiant lies above the horizon all night for most of the northern hemisphere, it is best placed during the last hour before dawn, when it lies highest above the horizon in a dark sky. Current rates would most likely be less than one per hour. At 43km/sec., the average December Kappa Draconid meteor would be of medium velocity. 

As seen from the mid-northern hemisphere (45N) one would expect to see approximately sixteen sporadic meteors per hour during the last hour before dawn as seen from rural observing sites. Evening rates would be near four per hour. As seen from the mid-southern hemisphere (45S), morning rates would be near eight 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 list below presents a condensed version of the expected activity this week. Rates and positions are exact for Saturday night/Sunday morning. 

December Phoenicids (PHO) - 01:08 (017) -53    Velocity - 18km/sec. 
Northern Hemisphere - <1 per hr. Southern Hemisphere - <1 per hr 
 
Northern Taurids (NTA) - 05:12 (078) +26    Velocity - 29km/sec. 
Northern Hemisphere - 2 per hr. Southern Hemisphere - 2 per hr. 

November Orionids (NOO) - 06:20 (095) +15   Velocity - 44km/sec. 
Northern Hemisphere - 2 per hr. Southern Hemisphere - 2 per hr 

Monocerotids (MON) - 06:37 (099) +08   Velocity - 41km/sec. 
Northern Hemisphere - 2 per hr. Southern Hemisphere - 2 per hr 

Geminids (GEM) - 07:16 (109) +33   Velocity - 35km/sec. 
Northern Hemisphere - 1 per hr. Southern Hemisphere - <1 per hr 

Puppid-Velids (PUP) - 08:08 (122) -45   Velocity - 40km/sec. 
Northern Hemisphere - <1 per hr. Southern Hemisphere - 5 per hr 
 
Sigma Hydrids (HYD) - 08:16 (124) +03   Velocity - 61km/sec. 
Northern Hemisphere - 2 per hr. Southern Hemisphere - 2 per hr 

December Leonis Minorids (DLM) - 09:56 (149) +37   Velocity - 71km/sec. 
Northern Hemisphere - >1 per hr. Southern Hemisphere - >1 per hr 

Psi Ursa Majorids (PSU) - 11:12 (168) +43   Velocity - 61km/sec. 
Northern Hemisphere - >1 per hr. Southern Hemisphere - >1 per hr 
 
December Kappa Draconids (KDR) - 12:30 (187) +69   Velocity - 43km/sec. 
Northern Hemisphere - >1 per hr. Southern Hemisphere - >1 per hr 
              
*For a detailed explanation on the different classes of meteor showers and other astronomical terms, please visit: http://www.amsmeteors.org/showers.html#X2010 

Clear Skies!
Robert Lunsford 
American Meteor Society