During this period the moon reaches its new phase on Friday January 11th. At this time the moon is located near the sun and will remain invisible at night. Next week the waxing crescent moon will enter the evening sky but will set long before the more active morning hours arrive. The estimated total hourly meteor rates for evening observers this week is near three no matter your location. For morning observers the estimated total hourly rates should be near fifteen from the mid-northern hemisphere and eleven from the mid-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 January 12/13. 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 large Antihelion (ANT) radiant is currently centered at 08:20 (125) +18. This position lies in central Cancer, four degrees west of the fourth magnitude star Asellus Australis (Delta Cancri). These meteors may be seen all night long but the radiant is best placed near 0100 local standard time (LST) when it lies on the meridian and is highest in the sky. Rates at this time should be near two per hour as seen from the northern hemisphere and one 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 December Leonis Minorids (DLM) are currently the most active shower in the sky. The radiant is located at 12:16 (184) +19. This position lies in southwestern Coma Berenices, seven degrees northeast of the second magnitude star Denebola (Beta Leonis). These meteors are best seen near 0400 LST when the radiant lies highest above the horizon. This shower peaked on December 17th so current rates would be near two per hour as seen from the northern hemisphere and one per hour as seen from south of the equator. At 64 km/sec. the December Leonis Minorids produce mostly swift meteors.
IMO Shower #14 is an unnamed shower active in mid-January. Peak activity occurs on January 18th from a radiant located at 13:16 (199) -20. This position is located in southwestern Virgo, nine degrees south of the first magnitude star Spica (Alpha Virginis). This radiant does not rise until after midnight so activity is strictly limited to the morning hours. Rates would mostly likely be less than one shower member per hour, no matter your location. These meteors are best seen during the last dark hour before dawn, when the radiant lies highest above the horizon in a dark sky. At 70 km/sec. IMO Shower #14 would produce mostly swift meteors.
The Canum Venaticids (CVN) are a new shower discovered by Peter Brown and his associates at the University of Western Ontario, using meteor orbits obtained by radar. This activity was verified by the IMO video network which has 271 possible candidates in its database. This shower is best seen from January 11-17, with maximum activity occurring on the 11th. Rates never exceed one shower member per hour yet it is the 3rd strongest radiant in the sky on the mornings of January 13 and 14. The radiant is located near 14:08 (212) +36, which places it in southeastern Canes Venatici. This position also lies 5 degrees southwest of the famous third magnitude double star known as Cor Caroli (Alpha Canum Venaticorum). Do not be too strict with this position as the radiant is not well defined at this point. Any meteors from this area this time of year should be suspected as possible Canum Venaticids. I would suggest using radiant distance and velocity to further determine possible shower association. These meteors encounter the atmosphere at 59 km/sec., which would produce mostly swift meteors. These meteors are best seen during the last few hours before dawn, when the radiant lies highest in a dark sky. This activity would be difficult to view from the southern hemisphere as the radiant lies low in the north at dawn.
The Theta Coronae Borealids (TCB) are another new shower discovered by Peter Brown and his associates at the University of Western Ontario, using meteor orbits obtained by radar. This activity was also verified by the IMO video network which has 189 possible candidates in its database. This shower is only active on six nights centered on January 16th. Rates again never exceed one shower member per hour yet it is the 3rd strongest radiant in the sky on January 16th. On that morning the radiant is located at 15:40 (235) +51, which places it twenty degrees north of Theta Coronae Borealis. Earlier visual observations must have placed the radiant much too far south. Either that or this shower is completely different from the early TCB radiant. The closest bright star to the radiant is third magnitude Edasich (Iota Draconis), which lies eight degrees to the north. These meteors are best seen during the last dark hour before dawn, when the radiant lies highest above the horizon in a dark sky. At 39 km/sec. the Theta Coronae Borealids would produce meteors of medium velocity.
As seen from the mid-northern hemisphere (45N) one would expect to see approximately ten sporadic meteors per hour during the last hour before dawn as seen from rural observing sites. Evening rates would be near two 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 table below presents a condensed version of the expected activity this week. Rates and positions are exact for Saturday night/Sunday morning .
|SHOWER||DATE OF MAXIMUM ACTIVITY||CELESTIAL POSITION||ENTRY VELOCITY||CULMINATION||HOURLY RATE||CLASS|
|RA (RA in Deg.) DEC||Km/Sec||Local Standard Time||North-South|
|Antihelions (ANT)||-||08:20 (125) +18||30||01:00||2 – 1||II|
|Dec. Leonis Minorids (DLM)||Dec 17||12:16 (184) +19||64||05:00||2 – 1||II|
|IMO #14||Jan 18||13:16 (199) -20||70||06:00||<1 – <1||IV|
|Caneum Venaticids(CVN)||Jan 11||14:08 (212) +36||59||07:00||<1 – <1||IV|
|Theta Coronae Borealids (TCB)||Jan 16||15:40 (235) +51||39||08:00||<1 – <1||IV|