Meteor Activity Outlook for 23-29 December 2017

During this period the moon will reach its first quarter phase on Tuesday December 26th. At that time the half-illuminated moon will lie 90 degrees east of the sun and will set near midnight local standard time (LST) as seen from mid-northern latitudes. As the week progresses the waxing gibbous moon will set later in the morning as the window of opportunity to view under dark conditions diminishes. The estimated total hourly meteor rates for evening observers this week is 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 19 as seen from mid-northern latitudes and 15 from the southern tropics. The evening rates during this period are reduced due to 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 December 23/24. 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 near 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 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.

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Now that the activity from particles produced by comet 2P/Encke have ceased encountering the Earth, the Taurid showers for 2017 are over and we resume reporting activity from the Anthelion (ANT) radiant. This is not a true radiant but rather activity caused by the Earth’s motion through space. As the Earth revolves around the sun it encounters particles orbiting in a pro-grade motion that are approaching their perihelion point. They all appear to be radiating from an area near the opposition point of the sun, hence the name Anthelion. These were once recorded as separate showers throughout the year but it is now suggested to bin them into their category separate from true showers and sporadics. There are several lists that have the Chi Orionids currently active, but we include them with the Anthelions as the celestial positions overlap. This radiant is a very large oval some thirty degrees wide by fifteen degrees high. Activity from this radiant can appear from more than one constellation. The position listed here is for the center of the radiant which is currently located at 06:56 (104) +23. This position lies in western Gemini, 4 degrees southeast of the 3rd magnitude star known as Mebsuta (epsilon Geminorum). Since the radiant is so large, Anthelion activity may also appear from eastern Taurus, northeastern Orion, southern Auriga, northern Monoceros, and northern Canis Minor as well as western Gemini. This radiant is best placed near midnight 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 Monocerotids (MON) are active from November 27th through December 27th with the peak activity occurring on December 13th. The radiant is currently located at 07:36 (114) +07. This position lies in central Canis Minor, just northwest of the brilliant zero magnitude star known as Procyon (alpha Canis Minoris). Current rates should be less than 1 per hour no matter your location. The Monocerotids are best seen near 0100 LST when the radiant lies highest above the horizon. At 41 km/sec. the Monocerotids produce mostly meteors of medium velocity.

The alpha Hydrids (AHY) were discovered by Dr. Peter Brown and associates using the meteoroid stream survey provided by the Canadian Meteor Orbit Radar. This long duration stream is active for a month with maximum activity occurring on January 3rd. The current position lies at 07:48 (117) -06, which places the radiant in eastern Monoceros, 10 degrees south of the brilliant zero magnitude star known as Procyon (alpha Canis Minoris). Current rates should be less than 1 per hour no matter your location. The alpha Hydrids are best seen near 0100 LST when the radiant lies highest above the horizon. At 43 km/sec. the alpha Hydrids produce mostly meteors of medium velocity.

Studies by the IMO’s Sirko Molau of video data obtained from Australian cameras has confirmed part of the Puppid-Velid complex that is active from December 26-31. The c Velids (CVE) peak on December 29th from a radiant located at 09:20 (140) -54. This position lies in southern Vela, just north of the position occupied by the 2nd magnitude star known as Markeb (Kappa Velorum). Due to the far southern declination (celestial latitude) these meteors are only visible from the northern tropics southward. They are best seen near 0300 LST when the radiant lies highest above the horizon. Hourly rates at maximum would likely be less than 1 as seen from the northern hemisphere and 1 as seen south of the equator. At 39 km/sec. the c Velids would produce mostly meteors of medium velocity.

The December Leonis Minorids (DLM) are a shower of long duration active from December 6th through January 18th. Maximum occurs near December 21st when rates may reach 3 an hour. The radiant is currently located at 10:52 (163) +29, which lies in southeast Leo Minor, 4 degrees northwest of the faint star known as 54 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.

The Coma Berenicids (COM) are active this week from a radiant located at 12:12 (183) +16. This area of the sky lies in southwestern Coma Berenices, 5 degrees northeast of the 2nd magnitude star known as Denebola (beta Leonis). These meteors are best seen near 0500 LST when the radiant lies highest above the horizon. Maximum activity is not expected until the 31st so current rates would be less than 1 per hour no matter your loication. At 70 km/sec. the Coma Berenicids produce mostly swift meteors.

The December chi Virginids (XVI) were discovered by Japanese observers using the data of SonotaCo. This source is active from December 16-24 with maximum activity occurring on the 19th. The current radiant location is at 13:12 (198) -14, which places it in southern Virgo, 4 degrees southwest of the bright star known as Spica (alpha Virginis). Current rates would most likely be less than 1 per hour no matter you 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 69 km/sec. the December Chi Virginids would produce mostly swift meteors.

The December Sigma Virginids (DSV) was discovered by John Greaves using the data of SonotaCo. IMO video cameras confirmed that this source is active during most of December. Visual observers have their best chance at catching these meteors from December 17-31. Peak rates occur near December 24th. The current radiant location is at 14:04 (211) +02 which place it in northern Virgo, very close to the 4th magnitude star known as tau Virginis. Current hourly rates should be near 2 shower members no matter you 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.

The last of the Ursids (URS) should be seen this weekend from a radiant is located at 14:36 (219) +75, which places it in western Ursa Minor, just northwest of the 2nd magnitude star known as Kochab (beta Ursae Minoris). This area of the sky is circumpolar for most of the northern hemisphere and lies highest above the horizon in a dark sky just before dawn. Expected rates should be less than 1 per hour no matter your location. At 33 km/sec. the Ursids would produce mostly medium speed meteors.

The Quadrantids (QUA) or January Bootids are active from December 22 through January 17th. A sharp maximum is predicted to occur near 2000 Universal Time on January 3rd. Rates are very low away from the night of maximum activity. The radiant is currently located at 14:56 (224) +52. This position lies in northern Bootes, 5 degrees east of the 4th magnitude star known as Asellus Primus (theta Bootis). This part of the sky is best placed for viewing during the last hour before dawn when the radiant lies highest above the horizon in a dark sky. At 41 km/sec. the Quadrantids would produce mostly meteors of medium velocity .

As seen from the mid-northern hemisphere (45N) one would expect to see approximately 11 sporadic meteors per hour during the last hour before dawn as seen from rural observing sites. Evening rates would be near 3 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 the listed figures. Evening rates are reduced 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.