(meteorobs) Meteor Shower Activity for December 27, 2014-January 2, 2015

[Robert Lunsford]

During this period the moon reaches its first quarter phase on Sunday December 28th. At this time the moon is located 90 degrees east of the sun and sets near midnight local standard time (LST). The dark observing window between moon set and dawn shrinks with each passing night, being only an hour long at the end of this period. The estimated total hourly meteor rates for evening observers this week is near 3 as seen from the northern hemisphere (45N) and 2 as seen from southern tropical latitudes (25S). For morning observers the estimated total hourly rates should be near 18 as seen from the northern hemisphere and 15 as seen from south of the equator. 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. Rates during the evening hours are reduced due to interfering moonlight. Note that the hourly rates listed below are estimates as viewed from dark sky sites away from urban light sources. Observers viewing from urban areas will see less activity as only the brightest meteors will be visible from such locations.

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 27/28. 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.

These sources of meteoric activity are expected to be active this week.

Now that the activity from particles produced by comet 2P/Encke has ceased encountering the Earth, the Taurid showers for 2014 are over and we resume reporting activity from the Anthelion (ANT) radiant. This is not a true radiant but rather activity caused by the Earth's motion through space. As the Earth revolves around the sun it encounters particles orbiting in a pro-grade motion that are approaching their perihelion point. They all appear to be radiating from an area near the opposition point of the sun, hence the name (Anti)helion. These were once recorded as separate showers throughout the year but it is now suggested to bin them into their category separate from true showers and sporadics. This radiant is a very large oval some thirty degrees wide by fifteen degrees high. Activity from this radiant can appear from more than one constellation. The position listed here is for the center of the radiant which is currently located at 07:16 (109) +21. This position lies in central Gemini, just west of the position occupied by the 4th magnitude star Wasat (Delta Geminorum). Anthelion activity may also appear from eastern Taurus, northeastern Orion, Cancer, Canis Minor, Monoceros, southern Lynx, or southern Auriga. This radiant is best placed near midnight local standard time (LST) when it lies on the meridian and is highest in the sky. Rates at this time should be near 2 per hour as seen from the northern hemisphere and 1 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 Hydrids (AHY) were discovered by Dr. Peter Brown and other members of the Department of Physics and Astronomy, University of Western Ontario, London, Ontario Canada. They were using a meteoroid stream survey from the Canadian Meteor Orbit Radar to isolate radiants.  This shower is active from December 22nd through January 7th. Peak activity occurs on December 31st from a radiant located at 08:20 (125) -07. This position lies in extreme western Hydra, fifteen degrees west of the second magnitude star Alphard (Alpha Hydrae). Rates would most likely be near one per hour, no matter your location. The Alpha Hydrids are best seen near 0100 LST when the radiant lies highest above the horizon. At 43 km/sec. the Alpha Hydrids produce mostly meteors of medium velocity.

Studies by the IMO's Sirko Molau of video data obtained from Australian cameras has confirmed part of the Puppid-Velid complex that is active from December 27-30. The c Velids (CVE) peak on December 29th from a radiant located at 09:20 (140) -54. This position lies in southern Vela, just north of the position occupied by the 2nd magnitude star known as Markeb (Kappa Velorum). Due to the far southern declination (celestial latitude) these meteors are only visible from the northern tropics southward. They are best seen near 0200 LST when the radiant lies highest above the horizon. Hourly rates at maximum would likely be less than 1 as seen from the northern hemisphere and 1 as seen south of the equator. At 39 km/sec. the c Velids would produce mostly meteors of medium velocity.

The January Leonids (JLE) were also discovered by Dr. Peter Brown. This weak shower is active from December 31st to 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 59 km/sec. the January Leonids produce mostly meteors of medium-swift velocity.

The December Leonis Minorids (DLM) are active from December 6th through January 18th. The radiant is currently located at 11:14 (169) +27. This position lies in northern Leo, 6 degrees north of the third magnitude star Zosma (Delta Leonis). These meteors are best seen near 0400 LST when the radiant lies highest above the horizon. This shower peaked on December 21st so rates would be near 2 per hour as seen from the northern hemisphere and 1 per hour as seen from south of the equator. At 63 km/sec. the December Leonis Minorids produce mostly swift meteors.

The Coma Berenicids (COM) are best seen from December 24 through January 3. Maximum activity occurs on December 31st when this shower is the fourth strongest in the sky. The current radiant position lies at 12:07 (182) +14. This position lies southwestern Coma Berenices, 5 degrees east of the 2nd magnitude star known as Denebola (Beta Leonis). Current hourly rates should be near 2 shower member per hour no matter your location. These meteors are best seen near 0500 LST when the radiant lies highest above the horizon. At 69 km/sec. The Coma Berenicids would produce mostly swift meteors.

The December Sigma Virginids (DSV) were discovered by John Greaves using data from SonotoCo. This radiant is active from December 6-31 with maximum occurring on the 24th. The current radiant location is 13:49 (207) +03, which places it in central Virgo, 5 degrees northeast of the third magnitude star Heze (Zeta Virginis). These meteors are best seen during the last dark hour before dawn, when the radiant lies highest above the horizon in a dark sky. Current hourly rates would most likely be less than 1 no matter your location. At 68 km/sec. the December Sigma Virginids would produce mostly swift meteors.

The Alpha Draconids (DAD) are strange in that they have two activity periods. One is December 5-18 and the other is December 26-January 1. The maximum of the 2nd period occurs on December 30th when the radiant lies at 14:51 (223) +54. This position actually lies in extreme northern Bootes, 4 degrees northeast of the 4th magnitude star known as Asellus Primus (Theta Bootis). These meteors are best seen during the last dark hour before dawn, when the radiant lies highest above the horizon in a dark sky. Hourly rates, no matter your location,  would most likely be less than 1, even at maximum activity. At 42 km/sec. the Alpha Draconids would produce mostly medium velocity meteors. It should be noted that this position is close to that of early Quadrantids and care should be taken to separate these two sources.

The Quadrantids (QUA) or January Bootids are active from December 30 through January 12th. A sharp maximum is predicted to occur near 0200 Universal Time on the 4th. This corresponds to the early evening hours of January 3 across North America and early morning hours in Europe and Africa. This timing is most favorable for Europe and western Asia where the radiant will lie high in a dark sky at the time of predicted maximum. Maximum rates are unpredictable for this shower. The full moon will certainly reduce activity so the best rates will be no more than 50 per hour no matter where you are located.  At maximum the radiant is located at 15:24 (231) +49. This position lies in a barren region of extreme northern Bootes, ten degrees northeast of the fourth magnitude star Beta Bootis. As seen from the northern hemisphere, this area of the sky lies close to the northern horizon during the evening hours. Only after midnight does the radiant rise high into the northeastern sky. As seen from the southern hemisphere, this radiant is poorly placed as it only clears the northeastern horizon just before the start of morning twilight. Observers near the equator are a bit better off as the radiant rises at least 1 hour before the start of morning twilight. At 41 km/sec. the Quadrantids produce meteors of medium velocity. During exceptional activity some Quadrantid fireballs may be witnessed. Rates away from the night of maximum are poor, especially near the extremes of the activity period.

As seen from the mid-northern hemisphere (45N) one would expect to see approximately 10 sporadic meteors per hour during the last hour before dawn as seen from rural observing sites. Evening rates would be near 2 per hour. As seen from the tropical southern latitudes (25S), morning rates would be near 8 per hour as seen from rural observing sites and 1 per hour during the evening hours. Locations between these two extremes would see activity between the listed figures. Rates during the evening hours are reduced due to interfering moonlight.

The list below offers the information from above in a condensed form. Rates and 
positions are exact for Saturday night/Sunday morning except where noted in the 
shower descriptions. 
 
Anthelion (ANT) - 07:16 (109) +21  Velocity - 30km/sec. 
Northern Hemisphere - 2 per hr.   Southern Hemisphere - 1 per hr. 
 
Alpha Hydrids (AHY) - 08:20 (125) -07  Velocity - 43km/sec. 
Northern Hemisphere - 1 per hr.   Southern Hemisphere - 1 per hr. 

c Velids (CVE) - 09:20 (140) -54  Velocity - 39km/sec. 
Northern Hemisphere - <1 per hr.   Southern Hemisphere - 1 per hr.

January Leonids (JLE) - 09:46 (147) +24  Velocity - 59km/sec. 
Northern Hemisphere - <1 per hr.   Southern Hemisphere - <1 per hr. 
 
Dec. Leonis Minorids (DLM) - 11:14 (169) +27  Velocity - 63km/sec. 
Northern Hemisphere - 2 per hr.   Southern Hemisphere - 1 per hr. 
 
Coma Berenicids (COM) - 12:07 (182) +14  Velocity - 69km/sec. 
Northern Hemisphere - 2 per hr.   Southern Hemisphere - 2 per hr. 

Dec. Sigma Virginids (DSV) - 13:49 (207) +03  Velocity - 68km/sec. 
Northern Hemisphere - <1 per hr.   Southern Hemisphere - <1 per hr. 

Alpha Draconids B (DAD) - 14:51 (223) +54  Velocity - 42km/sec. 
Northern Hemisphere - <1 per hr.   Southern Hemisphere - <1 per hr. 
 
Quadrantids (QUA) - 15:24 (231) +49  Velocity - 41km/sec. 
Northern Hemisphere - <1 per hr.   Southern Hemisphere - <1 per hr 
  
Clear Skies! 
Robert Lunsford 	 
American Meteor Society