(meteorobs) Meteor Activity Outlook for January 17-23, 2015

[Robert Lunsford]

This period is dominated by numerous weak radiants best observed during the morning hours. The moon reaches its new phase on Tuesday January 20th. At this time the moon is located near the sun and cannot be seen at night. This weekend the waning crescent moon will rise shortly before dawn and will not interfere with meteor observing. Likewise, late in this period the moon will enter the evening sky but will set shortly after dusk and again will not interfere with meteor observing. The estimated total hourly meteor rates for evening observers this week is near 3 no matter your location. For morning observers the estimated total hourly rates should be near 13 no matter your location 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 January 17/18. 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 center of the large Anthelion (ANT) radiant is currently located at 08:40 (130) +16. This position lies in central Cancer, near the position of the 4th magnitude star Asellus Australis (Delta Cancri). Due to the large size of this radiant, Anthelion activity may also appear from western Leo, Gemini, Canis Minor, northwestern Hydra as well as Cancer. This radiant is best placed near midnight local standard time (LST), when it lies on the meridian and is located 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 Anthelion meteor would be of slow velocity.

The January Xi Ursae Majorids (XUM) were discovered by Japanese observers using data from SonotoCo. These meteors are active from January 16-20, with maximum activity occurring on the 18th. At maximum the radiant is located at 11:16 (169) +33. This position lies very close to the 3rd magnitude star known as Alula Borealis (Nu Ursae Majoris). These meteors would be best seen near 0200 LST when the radiant lies highest above the horizon. Hourly rates would most likely be low, less than 1 per hour no matter your location. These meteors encounter the atmosphere at 44 km/sec., which would produce meteors of average velocity.

The January Comae Berenicids (JCO) were first detected by Dr. Peter Jenniskens and mentioned in his book: Meteor Showers and their Parent Comets. These meteors are best seen from January 21-27 with maximum occurring on the 24th. When the radiant becomes active late in the period, the radiant will be located near 12:44 (191) +16. This position lies in southern Coma Berenicids, 5 degrees southwest of the 4th magnitude star known as Diadem (Alpha Comae Berenices). Hourly rates during this period would be less than 1 no matter your location. These meteors are best seen near 0300 LST, when the radiant lies highest above the horizon. These meteors encounter the atmosphere at 65 km/sec., which would produce meteors of swift velocity.

The Eta Corvids (ECV) were discovered by Sirko Molau while analyzing the data from the IMO network of video cameras. This shower is best seen from January 18-26, with maximum activity occurring on the 23rd. At maximum the radiant is located at 12:56 (194) -17. This position lies in eastern Corvus, 5 degrees east of the 3rd magnitude star known as Algorab (Delta Corvi). The IMO database has only 300 members of this shower so meteors would be fairly scarce with hourly rates less than 1, even at maximum activity. These meteors encounter the atmosphere at 69 km/sec., which would produce meteors of swift velocity. These meteors are best seen near 0300 LST, when the radiant lies highest above the horizon.

The Nu Boötids (NBO) were discovered by Yoshihiko Shigeno and Masa-yuki Yamamoto using analyses of double-station Image-Intensified video observations over Japan. These meteors are active from January 16-20 with maximum occurring on the 18th. The position of the radiant at maximum is 13:44 (206) +13. This position lies southwestern Boötes, 10 degrees southwest of the brilliant zero magnitude star known as Arcturus (Alpha Boötis). These meteors are best seen during the last few hours before dawn, when the radiant lies highest in a dark sky. Hourly rates would most likely be low, less than 1 per hour no matter your location. These meteors encounter the atmosphere at 67 km/sec., which would produce meteors of swift velocity.

The Lambda Boötids (LBO) were discovered by Peter Brown and his associates at the University of Western Ontario using the Canadian Meteor Orbit Radar. This source is only active for 2 nights with maximum occurring on January 17th.  The radiant is located at 14:48 (222) +45. This position lies in northern Boötes, 4 degrees northwest of the 3rd magnitude star known as Nakkar (Beta Boötis). These meteors are best seen during the last few hours before dawn, when the radiant lies highest in a dark sky. Hourly rates would most likely be low, less than 1 per hour no matter your location. These meteors encounter the atmosphere at 41 km/sec., which would produce meteors of average velocity.

The Gamma Ursae Minorids (GUM) were also discovered by Peter Brown and his associates at the University of Western Ontario. These meteors are active from January 18-24, with maximum occurring on the 20th. At maximum the location of the radiant is 15:12 (228) +67, which places it southern Ursa Minor, 5 degrees south of the 3rd magnitude star known as Pherkad (Gamma Ursae Minoris). These meteors are best seen during the last few hours before dawn, when the radiant lies highest in a dark sky. Like most showers active during this period the hourly rates would most likely be low, less than 1 per hour no matter your location. These meteors encounter the atmosphere at 30 km/sec., which would produce meteors of medium-slow 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 2 per hour. As seen from the tropical southern latitudes (25S), morning rates would be near 9 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.

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) - 08:40 (130) +16  Velocity - 30km/sec. 
Northern Hemisphere - 2 per hr.   Southern Hemisphere - 1 per hr. 
 
January Xi Ursae Majorids (XUM) - 11:16 (169) +33  Velocity - 44km/sec. 
Northern Hemisphere - <1 per hr.   Southern Hemisphere - <1 per hr
 
January Comae Berenicids (JCO) - 12:44 (191) +16  Velocity - 65km/sec. 
Northern Hemisphere - <1 per hr.   Southern Hemisphere - <1 per hr 
 
Eta Corvids (ECV) - 12:56 (194) -17  Velocity - 69km/sec. 
Northern Hemisphere - <1 per hr.   Southern Hemisphere - <1 per hr 

Nu Bootids (NBO) - 13:44 (206) +13  Velocity - 67km/sec. 
Northern Hemisphere - <1 per hr.   Southern Hemisphere - <1 per hr 

Lambda Bootids (LBO) - 14:48 (222) +45  Velocity - 41km/sec. 
Northern Hemisphere - <1 per hr.   Southern Hemisphere - <1 per hr 

Gamma Ursae Minorids (GUM) - 15:12 (228) +67  Velocity - 30km/sec. 
Northern Hemisphere - <1 per hr.   Southern Hemisphere - <1 per hr 
  
Clear Skies! 
Robert Lunsford 	 
American Meteor Society