During this period, the moon reaches its first quarter phase on Sunday January 9th. At that time the moon lies 90 degrees east of the sun and sets between 23:00 and midnight. As the week progresses the waxing gibbous moon will encroach upon the morning sky, limiting the window of opportunity of viewing under moonless conditions with each passing night. The estimated total hourly meteor rates for evening observers this week is near 2 as seen from mid-northern latitudes (45N) and 2 as seen from tropical southern locations (25S). For morning observers, the estimated total hourly rates should be near 15 as seen from mid-northern latitudes (45N) and 13 as seen from tropical southern locations (25S). Evening rates are reduced by 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 brighter 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 8/9. 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. I have also included charts of the sky that display the radiant positions for evening, midnight, and morning. The center of each chart is the sky directly overhead at the appropriate hour. These charts are oriented for facing south but can be used for any direction by rotating the charts to the desired direction. 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 sporadic. Meteor activity is not seen from radiants that are located far 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 large Anthelion (ANT) is currently centered at 08:04 (121) +19. This position lies in western Cancer, 3 degrees south of the faint star known as Mu2 Cancri. Due to the large size of this radiant, these meteors may also be seen from eastern Gemini as well as Cancer. This radiant is best placed near 01:00 local standard time (LST) when it lies on the meridian and is highest in the sky. Rates at this time should be near 3 per hour as seen from the northern hemisphere and 2 per hour as seen from south of the equator. With an entry velocity of 30 km/sec., the average Anthelion meteor would be of slow velocity.
The December Leonis Minorids (DLM) is a shower of long duration active from December 1st all the way through February 10th. Maximum occurred near December 19th when rates may have reached 3 an hour. During this period, I would expect hourly rates of 2 from a radiant located at 12:00 (180) +21. This position lies on the border of Leo and Coma Berenices, 7 degrees northeast of the 2nd magnitude star known as Denebola (beta Leonis). These meteors are best seen near 0400 LST when the radiant lies highest above the horizon. At 63 km/sec. the December Leonis Minorids produce mostly swift meteors. These meteors are most commonly known as the Comae Berenicids.
The gamma Ursae Minorids (GUM) are another source discovered by Dr. Peter Brown and associates. These meteors are active from January 9-20, with maximum activity occurring near January 18. The radiant is currently located at 14:36 (219) +71, which places it southern Ursa Minor only 3 degrees west 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. Current rates are 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.
The Quadrantids (QUA) are active from December 26th through January 16th. Maximum occurred on January 3rd. The radiant is currently located at 15:36 (234) +48. This position lies in northern Bootes. The nearest star of note is 3rd magnitude Edasich (iota Draconis), which lies 9 degrees to the northwest. These meteors are best seen during the last hour before dawn when the radiant lies highest above the horizon in a dark sky. Current rates are expected to be less than one per hour no matter your location. At 40 km/sec. the Quadrantids produce meteors of moderate velocity. These meteors are visible from the southern tropics but not seen from the deep southern hemisphere.
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 also 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 by moonlight during this period.
|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|
|Anthelions (ANT)||—||08:04 (121) +19||30||01:00||3 – 2||II|
|December Leonis Minorids (DLM)||Dec 19||12:00 (180) +21||64||05:00||2 – 1||II|
|gamma Ursae Minorids (GUM)||Jan 18||14:36 (219) +71||31||07:00||<1 – <1||IV|
|Quadrantids (QUA)||Jan 03||15:36 (234) +48||40||08:00||<1 – <1||I|