(meteorobs) Meteor Activity Outlook for January 24-30, 2015

[Robert Lunsford]

During this period the moon reaches its first quarter phase on Monday January 26th. At this time the moon is located 90 degrees east of the sun and will set near midnight local standard time (LST) for observers located in mid-northern latitudes. This weekend the waxing crescent moon will set prior to midnight allowing the more active morning hours to be free of interfering moonlight. As the week progresses the moon will become more of a problem as it waxes and sets later in the morning. By the end of this period there will only be a small window of dark skies available to view meteors between moon set and dawn. The estimated total hourly meteor rates for evening observers this week is near 2 for observers situated at mid-northern latitudes and 3 for observers viewing from the southern tropics (latitude 25 S.). For morning observers the estimated total hourly rates should be near 13 for observers situated at mid-northern latitudes and 12 for observers viewing from the southern tropics. Evening rates are reduced during this period 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 January 24/25. 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 09:12 (138) +15. This position lies in eastern Cancer, just a few degrees west of the brilliant planet Jupiter. Due to the large size of this radiant, Anthelion activity may also appear from western Leo, southwestern Leo Minor, eastern Gemini, Canis Minor, northwestern Hydra as well as Cancer. This radiant is best placed near 0100 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 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. At maximum the radiant is located at 12:52 (193) +15. This position lies in southern Coma Berenicids, 5 degrees northwest of the 3rd magnitude star known as Vindemiatrix (Epsilon Virginis). Hourly rates during this period would be less than 1 no matter your location. These meteors are best seen near 0400 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. The radiant is currently located at 13:00 (195) -16. This position lies in southwestern Virgo, 8 degrees southwest of the 1st magnitude star known as Spica (Alpha Virginis). 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 0400 LST, when the radiant lies highest above the horizon.

Toward the end of this period the February Epsilon Virginids (FEV) become weakly active. This shower was discovered by Dr. Peter Jenniskens and Kathryn Steakley using data from a "CAMS" network located in northern California and comet orbits from SonotaCo. This source is thought to be active from January 29 through February 9, with maximum activity occurring on February 4. On the 29th the  radiant is estimated to be 13:02 (196) +13. This area of the sky is located 2 degrees north of the 3rd magnitude star known as Vindemiatrix (Epsilon Virginis). These meteors are best seen near 0400 LST when the radiant lies highest above the horizon. Rates less than 1 are expected this week. At 64 km/sec. the February Epsilon Virginids would produce mostly swift meteors. If you look at the position for the January Comae Berenicids, this shower seems to pick up where the JCO's leave off. Therefore these two showers may be one and the same or closely related.

Toward the end of this period the Alpha Centaurids (ACE) become active. This shower is active from January 28 though February 21, with maximum activity occurring on February 8. On January 28th, the radiant is located at 13:16 (199) -56. This position lies in southern Centaurus between the bright stars Mimosa (Beta Crucis) and Epsilon Centauri. These meteors are best seen near 0400 LST when the radiant lies highest above the horizon. Current rates would be less than 1 per hour no matter your location. These meteors are not visible north of 35N latitude. They are best seen from the southern tropics where the radiant rises high into the sky and the summer nights are longer than they are at more southern locations. At 56 km/sec. the Alpha Centaurids would produce mostly swift meteors.

The Alpha Coronae Borealids (ACB) were discovered by John Greaves using data from SonotaCo Network Japan. These meteors are best seen from January 27 through February 5 with maximum activity occurring on January 28th. At maximum the radiant is located at 15:24 (231) +26. This position lies in southern Corona Borealis, close to the position occupied by the 2nd magnitude star known as Alphecca (Alpha Coronae Borealis). These meteors are best seen during the last dark hour before dawn when the radiant lies highest above the horizon in a dark sky. During this period this radiant will be the strongest in the sky, producing an average of 2 meteors per hour as seen from the northern hemisphere. Rates seen from south of the equator would be near 1 per hour. At 57 km/sec. the Alpha Coronae Borealids would produce mostly swift meteors.

As seen from the mid-northern hemisphere (45N) one would expect to see approximately 7 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 10 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. Evening rates are reduced due to 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) - 09:12 (138) +15  Velocity - 30km/sec. 
Northern Hemisphere - 2 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) - 13:00 (195) -16  Velocity - 69km/sec. 
Northern Hemisphere - <1 per hr.   Southern Hemisphere - <1 per hr 
 
February Epsilon Virginids (FEV) - 13:02 (196) +13  Velocity - 64km/sec. 
Northern Hemisphere - <1 per hr.   Southern Hemisphere - <1 per hr 
 
Alpha Centaurids (ACE) - 13:16 (199) -56  Velocity - 56km/sec. 
Northern Hemisphere - <1 per hr.   Southern Hemisphere - <1 per hr 

Alpha Coronae Borealids (ACB) - 15:24 (231) +26  Velocity - 57km/sec. 
Northern Hemisphere - 2 per hr.   Southern Hemisphere - 1 per hr 
  
Clear Skies! 
Robert Lunsford 	 
American Meteor Society