(meteorobs) Meteor Activity Outlook for November 15-21, 2014

[Robert Lunsford]

During this period the moon wanes from half illuminated to nearly its new phase. During this entire period the moon is only visible during the morning hours, allowing dark skies prior to midnight. This weekend the waning crescent moon will rise during the early morning hours. Since it will be less than half illuminated it will not compromise meteor watching unless you view directly toward the moon. As the week progresses viewing conditions improve as the lunar phase thins plus the moon rises later each night.  The estimated total hourly meteor rates for evening observers this week is near 4 as seen from the northern hemisphere and 3 as seen from southern tropical latitudes. For morning observers the estimated total hourly rates should be near 17 for observers located in mid-northern latitudes and 12 for south tropical observers. Rates are slightly reduced during the morning hours due to moonlight. 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. 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 November 15/16. 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:

The Andromedids (AND) are still active from a radiant located at 01:40 (025) +34, which lies in western Triangulum, 6 degrees west of the 2nd magnitude star Mirach (Beta Andromede). This is a famous shower that produced some brilliant displays during the 19th century. Since then the main orbit of the particles from comet 3D/Biela have moved away from the Earth. Still, remnants may be seen from October 26 through November 20 with maximum activity occurring on November 8.  These meteors are best seen near 2300 (10pm) local standard time (LST) when the radiant lies highest above the horizon. Rates would most likely be less than 1 per hour no matter your location. With an entry velocity of 16 km/sec., the average Andromedid meteor would be of slow velocity.

The Southern Taurids (STA) are still active from a large radiant centered at 04:04 (061) +16. This position lies in western Taurus, 8 degrees west of the 1st magnitude orange star known as Aldebaran (Alpha Tauri). These meteors may be seen all night long but the radiant is best placed near midnight LST when it lies on the meridian and is located highest in the sky. Rates at this time should be near 1 per hour regardless of your location. With an entry velocity of 29 km/sec., the average Southern Taurid meteor would be of slow velocity.

The Northern Taurids (NTA) are active from a large radiant centered at 04:08 (062) +23. This position lies in western Taurus, 4 degrees southeast from the famous naked eye open cluster known and the Pleiades or Seven Sisters. The radiant is best placed near midnight LST, when it lies highest above the horizon. Meteors from the Northern Taurids strike the atmosphere at 27km/sec., which would produce meteors of slow velocity. Expected rates would be near 3 per hour as seen from the northern hemisphere and 2 per hour as seen from south of the equator.

The November Orionids (NOO) are now active from a radiant located at 05:28 (082) +16. This area of the sky is located on the Orion/Taurus border, twelve degrees east of the first magnitude orange star Aldebaran (Alpha Tauri).. The peak for this radiant is not until November 28th, so current rates would be less than than one shower member per hour, no matter your location. This location is close to the Taurid complex, but far enough east to be distinguishable. The faster velocity of the November Orionids should help distinguish these meteors from the slower, but more numerous Taurids. The radiant is best placed for viewing near 0200 LST when it lies on the meridian and is highest above the horizon. With an entry velocity of 44 km/sec., the November Orionids would be of medium speed.

The Alpha Monocerotids (AMO) are a variable shower known for strong but short outbursts in 1985 and 1995. In most years just a few of meteors from this source are seen near November 22nd. Activity is limited to November 21-23 with a radiant located at 07:52 (118) +01. The area of the sky is located in southeastern Canis Minor just 5 degrees southeast of the brilliant 0 magnitude star known Procyon (Alpha Canis Minoris). The radiant was thought to originate in nearby Monoceros but recent refinements have placed it within Canis Minor. These meteors are best seen near 0400 LST, when the radiant lies highest above the horizon. With an entry velocity of 68 km/sec., most activity from this radiant would be of swift speed.

The last of the Orionids (ORI) will be seen this week from a radiant located at 07:56 (119) +15, which places it on the Gemini/ Cancer border, 12 degrees east of the 4th magnitude star known as Lambda Geminorum. This area of the sky is best placed in the sky near 0400 LST, when it lies highest above the horizon. Rates this week should be less than 1 per hour no matter your location. With an entry velocity of 67 km/sec., most activity from this radiant would be of swift speed.

The Leonids (LEO) are now the most active radiant in the sky, producing a half dozen shower members per hour during the last couple of hours before dawn. Maximum is predicted for Monday morning the 17th, when hourly rates may reach 10 per hour.  The Earth also encounters the trail produced in 1567 near 09:17 Universal Time on November 21st. Rates for this secondary encounter are expected to be low with no noticeable increase in activity. It does bear watching though as lunar conditions are excellent. The radiant is currently located at 10:16 (154) +22. This position lies in northwestern Leo, within the "sickle" of Leo, two degrees northwest of the second magnitude double star Algeiba (Gamma Leonis). The Leonid radiant is best placed during the last hour before morning twilight when the radiant lies highest in a dark sky. Leonids may be seen from the southern hemisphere but the viewing conditions are not quite as favorable as those north of the equator. With an entry velocity of 70 km/sec., most activity from this radiant would be of swift speed with numerous persistent trains on the brighter meteors.

The November Iota Draconids (NID) were discovered by Dr. Peter Brown during his 7 year meteoroid stream survey using the Canadian Meteor Orbit Radar. This source is active from November 11 through the 1st of December with maximum activity occurring on November 26th. The radiant is currently located at 12:08 (182) +74. This area of the sky lies in western Draco, 5 degrees northwest of the fourth magnitude star Kappa Draconis. The radiant is best placed during the last hour before morning twilight when the radiant lies highest in a dark sky. Since maximum activity is still more than a week away current rates would be less than one shower member per hour, no matter your location.  Due to the high northerly declination of the radiant these meteors are not visible from most of the southern hemisphere. Only southern equatorial regions would have any chance of seeing activity from this source. Meteors from the November Iota Draconids strike the atmosphere at 41km/sec., which would produce meteors of medium velocity.

As seen from the mid-northern hemisphere (45N) one would expect to see approximately 8 sporadic meteors per hour during the last hour before dawn as seen from rural observing sites. Evening rates would be near 3 per hour. As seen from the tropical southern latitudes (25S), morning rates would be near 5 per hour as seen from rural observing sites and 2 per hour during the evening hours. Locations between these two extremes would see activity between the listed figures. Moonlight reduces the number of meteors seen during the morning hours during this period.

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.

Andromedids (AND) -  01:40 (025) +34  Velocity - 16km/sec. 
Northern Hemisphere - <1 per hr.   Southern Hemisphere - <1 per hr. 

Southern Taurids (STA) - 04:04 (061) +16  Velocity - 29km/sec. 
Northern Hemisphere - 1 per hr.   Southern Hemisphere - 1 per hr. 
 
Northern Taurids (NTA) - 04:08 (062) +23  Velocity - 27km/sec. 
Northern Hemisphere - 3 per hr.   Southern Hemisphere - 2 per hr. 
 
November Orionids (NOO) - 05:28 (082) +16  Velocity - 44km/sec. 
Northern Hemisphere - <1 per hr.   Southern Hemisphere - <1 per hr.

Alpha Monocerotids (AMO) - 07:52 (118) +01  Velocity - 68km/sec. 
Northern Hemisphere - <1 per hr.   Southern Hemisphere - <1 per hr.
 
Orionids (ORI) - 07:56 (119) +15  Velocity - 67km/sec. 
Northern Hemisphere - <1 per hr.   Southern Hemisphere - <1 per hr.
 
Leonids (LEO) - 10:16 (154) +22  Velocity - 70km/sec. 
Northern Hemisphere - 5 per hr.   Southern Hemisphere - 4 per hr 
 
Nov. Iota Draconids (NID) - 12:08 (182) +74  Velocity - 41km/sec. 
Northern Hemisphere - <1 per hr.   Southern Hemisphere - <1 per hr 
  
Clear Skies! 
Robert Lunsford 	 
American Meteor Society