January is best known for the Quadrantids, which have the potential of being the best shower of the year. Unfortunately this shower is short lived and occurs during some of the worst weather in the northern hemisphere. Due to the high northern declination (celestial latitude) and short summer nights, little of this activity can be seen south of the equator. There are many very minor showers active throughout the month. Unfortunately most of these produce less than 1 shower member per hour and do not add much to the overall activity total. Activity gets interesting as seen from the southern hemisphere as ill-defined radiants in Vela, Carina, and Crux become active this month. This activity occurs during the entire first quarter of the year and moves eastward into Centaurus in February and ends in March with activity in Norma and Lupus. Sporadic rates are generally similar in both hemispheres this month. Sporadic rates are falling though for observers in the northern hemisphere and rising as seen from the southern hemisphere.
During this period the moon reaches its first quarter phase on Tuesday January 7th. At this time the moon will lie 90 degrees east of the sun and will set near midnight local standard time (LST) . This weekend the waxing crescent moon will set during the late evening hours and will not interfere with meteor observing during the more active morning hours. The estimated total hourly meteor rates for evening observers this week is near 3 for observers located in the northern hemisphere and 2 for those viewing south of the equator. For morning observers the estimated total hourly rates should be near 18 for observers in the northern hemisphere and 10 for observers situated south of the equator. 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. Evening rates are reduced due to moonlight. 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 4/5. 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 sources of meteoric activity are expected to be active this week:
The large Antihelion (ANT) radiant is currently located at 07:48 (117) +20. This position lies in eastern Gemini, 8 degrees south of the first magnitude star Pollux (Beta Geminorum). Due to the large size of this radiant, Antihelion activity may also appear from Cancer, northwestern Monoceros, Canis Minor, as well as Gemini. 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 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 Alpha Hydrids (AHY) are active from December 27th through January 8th. Peak activity occurred on December 31st. Rates now would most likely be less than 1 per hour, no matter your location. The radiant is currently located at 08:20 (125) -07. This position lies in extreme western Hydra, fifteen degrees west of the second magnitude star Alphard (Alpha Hydrae). The Alpha Hydrids are best seen near 0200 LST when the radiant lies highest above the horizon. At 45 km/sec. the Alpha Hydrids produce mostly meteors of medium velocity.
The January Leonids (JLE) were discovered by Dr. Peter Brown using a meteoroid stream survey based upon the Canadian Meteor Orbit Radar data. This weak shower is active from January 1st to 5th with maximum activity occurring on January 1st. The radiant is located at 09:53 (148) +24. This position lies in western Leo just east of the third magnitude star Algenubi (Epsilon Leonis). This is a very minor display with hourly rates of less than one expected, even at maximum activity. They are best seen near 0300 LST when the radiant lies highest above the horizon. At 54 km/sec. the January Leonids (JLE) produce mostly meteors of medium-swift velocity.
The December Leonis Minorids (DLM) are active from a radiant located at 11:44 (176) +24. This position lies in northeastern Leo, 9 degrees north of the 2nd 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 1 per hour as seen from the northern hemisphere and less than 1 per hour as seen from south of the equator. At 64 km/sec. the December Leonis Minorids produce mostly swift meteors.
The Quadrantids (QUA) or January Bootids are active from January 1st through the 10th. A sharp maximum is predicted to occur near 2000 Universal Time on the 3rd. Unfortunately this corresponds to the afternoon hours across North America and early evening hours in Europe. This timing is most favorable for eastern Asia where the radiant will lie high in a dark sky at the time of predicted maximum. Observers in Europe may be able to see 30-40 Quadrantids per hour on the morning of the 4th, depending on their latitude. For North America, rates would only be 20-30 per hour on the mornings of the 3rd and the 4th, again depending on your latitude. At maximum the radiant is located at 15:21 (230) +49. This position lies in a barren region of extreme northern Bootes, ten degrees northeast of the fourth magnitude star Beta Bootis. As seen from the northern hemisphere, this area of the sky lies close to the northern horizon during the evening hours. Only after midnight does the radiant rise high into the northeastern sky. As seen from the southern hemisphere, this radiant is poorly placed as it only clears the northeastern horizon just before the start of morning twilight. Observers near the equator are a bit better off as the radiant rises at least 1 hour before the start of morning twilight. At 42 km/sec. the Quadrantids produce meteors of medium velocity. During exceptional activity some Quadrantid fireballs may be witnessed. Rates away from the night of maximum are poor, especially near the extremes of the activity period
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 be near 8 per hour as seen from rural observing sites and 1 per hour during the evening hours. Locations between these two extremes would see activity between the listed figures. Evening rates are lower during this period due to moonlight.
The table below presents a list of radiants that are expected to be active this week. Rates and positions are exact for Saturday night/Sunday morning except where noted in the shower descriptions.
|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)||–||07:48 (117) +20||29||00:00||2 – 1||II|
|Alpha Hydrids (AHY)||Dec 31||08:20 (125) -07||45||01:00||<1 – <1||IV|
|January Leonids (JLE)||Jan 01||09:53 (148) +24||54||02:00||<1 – <1||IV|
|Dec. Leonis Minorids (DLM)||Dec 17||11:44 (176) +24||64||04:00||1 – <1||II|
|Quadrantids (QUA)||Jan 03||15:21 (230) +49||42||08:00||5 – <1||I|