During this period, the moon reaches its full phase on Thursday January 25th. At that time the moon will lie opposite the sun and will lie above the horizon all night long. This weekend the waxing gibbous moon will set during the early morning hours, allowing meteor observers an opportunity to view under dark sky conditions between moon set and dawn. This window of opportunity shrinks with each passing night until the moon will lie above the horizon all night long by mid-week. The estimated total hourly rates for evening observers this weekend should be near 4 as seen from mid-northern latitudes (45N) and 3 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 11 as seen from tropical southern locations (25S). The actual rates seen 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 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 20/21. 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. Radiants that rise after midnight will not reach their highest point in the sky until daylight. For these radiants, it is best to view them during the last few hours before dawn. It must be remembered that meteor activity is rarely seen at its radiant position. Rather they shoot outwards from the radiant, so it is best to center your field of view so that the radiant lies toward 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.
Radiant Positions at 19:00 Local Standard Time
Radiant Positions at Midnight Local Standard Time
Radiant Positions at 05:00 Local Standard Time
These sources of meteoric activity are expected to be active this week
The large Anthelion (ANT) is currently centered at 08:52 (133) +17. This position lies in central Cancer, 2 degrees southeast of the 4th magnitude star known as Asellus Australis (delta Cancri). Due to the large size of this radiant, these meteors may also be seen from western Leo 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 2 per hour as seen from the northern hemisphere and 1 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 alpha Hydrids (AHY) were discovered by Dr. Peter Brown and are mentioned in his article “A meteoroid stream survey using the Canadian Meteor Orbit Radar”. This shower is active from December 15 through January 22 with maximum activity occurring on January 6th. The radiant is currently located at 09:13 (138) -12. This position lies in western Hydra, 3 degrees southwest of the 2nd magnitude star known as Alphard (alpha Hydrae). These meteors are best seen near 0200 LST when the radiant lies highest above the horizon. At 41 km/sec. the alpha Hydrids produce meteors of medium velocity. The expected rates this week are less than 1 per hour no matter your location.
The alpha Antliids (AAN) were discovered by D. P. Galligan and W. J. Baggaley by using the Advanced Meteor Orbit Radar in New Zealand*. This very weak display is active from January 20 through February 10. There are two weak maximums occurring near January 27 and February 2. On January 27, the radiant lies at 09:56 (149) -05. This position lies in western Sextans, 6 degrees northeast of the 2nd magnitude star known as Alphard (alpha Hydrae). I’m not certain why these meteors were called alpha Antliids as this position lies 20 degrees north of the constellation of Antlia. These meteors are best seen near 0200 LST when the radiant lies highest above the southern horizon. At 44 km/sec. the alpha Antliids produce meteors of medium velocity. Expected rates this week are less than 1 per hour no matter your location.
*Gary Kronk, Meteor Showers-An Annotated Catalog, 2nd Edition Page 45
The omicron Leonids (OLE) were also discovered by Damir Šegon and the Croatian Meteor Network team based on studying SonotaCo and CMN observations (SonotaCo 2007-2011, CMN 2007-2010). These meteors are active from December 20 through January 22. Maximum activity occurs on January 9th. The radiant is currently located at 09:56 (149) +08. This position lies in southwestern Leo, 3 degrees southeast of the 4th magnitude star known as omicron Leonis. These meteors are best seen near 0200 LST when the radiant lies highest above the horizon. At 44 km/sec. the omicron Leonids produce meteors of medium velocity. Expected rates this week are less than 1 per hour no matter your location.
The January xi Ursae Majorids (XUM) were discovered by Japanese observers of SonotoCo based on video observations in 2007-2008. This shower is active from January 10-25, with maximum activity occurring on the 19th. The radiant is currently located at 11:23 (171) +32, which lies in southern Ursa Major, near the spot occupied by the 4th magnitude star known as Alula Australis (xi Ursae Majoris). These meteors are best seen near 03:00 LST when the radiant lies nearly overhead. Hourly rates are expected to be less than one per hour no matter your location. These meteors encounter the atmosphere at 40 km/sec., which would produce meteors of medium velocity.
The Comae Berenicids (COM) is a shower of long duration active from December 5th all the way through February 4th. Maximum occurred near December 15th when rates may have reached 3 an hour. During this period, I would expect hourly rates of 1 from a radiant located at 12:38 (190) +16. This position lies in southern Coma Berenices, 6 degrees northwest of the 3rd magnitude star known as Vindemiatrix (epsilon Virginis). These meteors are best seen near 0500 LST when the radiant lies highest above the horizon. At 63 km/sec. the Comae Berenicids produce mostly swift meteors.
The eta Corvids (ECV) were recently discovered by Sirko Molau and the IMO Video Meteor Network Team. This stream is active from January 7-February 5, with maximum activity occurring on January 21st. The current position of the radiant is 12:43 (191) -18, which places the radiant in central Corvus, 3 degrees southeast of the 3rd magnitude star known as Gienah (gamma Corvi A). These meteors are best seen near 0500 LST when the radiant lies highest above the horizon. Current hourly rates would be less than 1 per hour no matter your location. At 68 km/sec. these meteors would be fast.
The December sigma Virginids (DSV) was discovered by John Greaves using the data of SonotaCo. This source is active from November 28 through January 24 with peak rates occurring 0near December 21st. The current radiant location is at 15:31 (233) -00, which places it in western Serpens Caput, 4 degrees northwest of the 4th magnitude star known as mu Serpentis. Current hourly rates would be less than 1 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 66 km/sec. the December Sigma Virginids would produce mostly swift meteors.
Sporadic meteors are those meteors that cannot be associated with any known meteor shower. All meteor showers are evolving and disperse over time to the point where they are no longer recognizable. Away from the peaks of the major annual showers, these sporadic meteors make up the bulk of the activity seen each night. As seen from the mid-Northern Hemisphere (45N) one would expect to see during this period approximately 8 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 9 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 these listed figures.
Those interested in detecting meteor via radio waves may start noticing activity from the Capricornid/Sagittarids (DCS). These meteors can be detected from January 13 through February 4, with maximum activity occurring near February 1st. These meteors would be best detected during the morning hours of 8-10am, when the radiant lies approximately half-way up in the sky. It should be noted that meteors do not emit radio waves, but they act as mirrors and reflect radio waves from distant transmitters which aren’t heard otherwise. This is called forward scatter, opposed to backscatter where the transmitter and receiver are at the same place (radar). For practical reasons the frequency range 50 – 150 MHz (wavelength 6 m – 2 m) is used. This includes amongst others the FM band and TV transmitters which haven’t switched yet to digital. Most reflections are short (less than a second), but brighter meteors can cause reflections lasting minutes. The shortest radio reflections are caused by faint meteors, fainter than visual ones. Radio reflections can be observed regardless of daylight or clouds, allowing more complete views of streams. For those interested in meteor observing via radio waves we invite you to visit RMOB.
You can keep track of the activity of these meteor showers as well as those beyond the limits of visual observing by visiting the NASA Meteor Shower Portal. You can move the sky globe to see different areas of the sky. Colored dots indicate shower meteors while white dots indicate sporadic (random) activity. The large orange disk indicates the position of the sun so little activity will be seen in that area of the sky.
The list below offers the information in tabular form of the showers that I feel are within reach of the visual observer to discern. Hourly rates are often less than 1 but noting parameters such as the duration, radiant distance and the elevation of each meteor, one can compute the probability of shower association. Most showers discovered by video means have rates less than 1 meteor per night away from maximum, so the showers listed in these articles are not as weak as they seem. Rates and positions are exact for Saturday night/Sunday morning.
|DATE OF MAXIMUM ACTIVITY
|RA (RA in Deg.) DEC
|Local Standard Time
|08:52 (133) +17
|alpha Hydrids (AHY)
|09:13 (138) -12
|<1 – <1
|alpha Antliids (AAN)
|09:56 (149) -05
|<1 – <1
|omicron Leonids (OLE)
|09:56 (149) +08
|<1 – <1
|January xi Ursae Majorids (XUM)
|11:23 (171) +32
|<1 – <1
|Comae Berenicids (COM)
|12:38 (190) +16
|eta Corvids (ECV)
|12:43 (191) -18
|December sigma Virginids (DSV)
|15:31 (233) -00
|<1 – <1
Class Explanation: A scale to group meteor showers by their intensity:
- Class I: the strongest annual showers with Zenith Hourly Rates normally ten or better.
- Class II: reliable minor showers with ZHR’s normally two to ten.
- Class III: showers that do not provide annual activity. These showers are rarely active yet have the potential to produce a major display on occasion.
- Class IV: weak minor showers with ZHR’s rarely exceeding two. The study of these showers is best left to experienced observers who use plotting and angular velocity estimates to determine shower association. These weak showers are also good targets for video and photographic work. Observers with less experience are urged to limit their shower associations to showers with a rating of I to III.