During this period the moon reaches its last quarter phase on Tuesday January 13th. At this time the moon is located 90 degrees west of the sun and rises near midnight local standard time (LST). At this time evening skies are dark but the light of the half illuminated moon will interfere with observing during the morning hours. This weekend the waning gibbous moon will hamper viewing meteor activity after 2200 (10pm) LST. The estimated total hourly meteor rates for evening observers this week is near 3 as seen from the northern hemisphere (45N) and 2 as seen from southern tropical latitudes (25S). For morning observers the estimated total hourly rates should be near 10 as seen from the northern hemisphere and 8 as seen from 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. Rates during the morning hours are reduced due to interfering 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 10/11. 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 08:12 (123) +18. This position lies in western Cancer, 4 degrees west 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 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 December Leonis Minorids (DLM) are active from a radiant located at 12:04 (181) +21. This position lies in western Coma Berenices, 7 degrees northeast 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 21st so current rates would be less than 1 per hour no matter your location. At 63 km/sec. the December Leonis Minorids 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 13-18, with maximum activity occurring on the 15th. At maximum the radiant is located at 14:00 (210) +38, which places it in eastern Canes Venatici, 6 degrees west of the 3rd magnitude star Seginus (Gamma Boötis). These meteors encounter the atmosphere at 56 km/sec., which would produce mostly medium-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 X Corona Borealids (XCB) are another new shower discovered by Peter Brown and his associates at the University of Western Ontario. This shower is best seen from January 11-18, with maximum activity occurring on the 15th. At maximum the radiant is located at 16:36; (249) +30, which actually places it within the borders of Hercules, 2 degrees southwest of the 3rd magnitude star Zeta Herculis. These meteors encounter the atmosphere at 49 km/sec., which would produce meteors of average velocity. 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.
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 6 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. Rates during the morning hours are reduced due to interfering moonlight.
The list below offers the information from above in tabular form. 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)||–||08:12 (123) +18||30||00:00||2 – 1||II|
|Dec. Leonis Minorids (DLM)||Dec 21||11:14 (169) +27||64||03:00||1 – 1||II|
|Canum Venaticids (CVN)||Jan 15||14:00 (210) +38||56||06:00||<1 – <1||IV|
|X Coronae Borealids (XCB)||Jan 15||16:36 (249) +30||49||09:00||<1 – <1||IV|