Meteor Activity Outlook for January 20-26, 2018

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Screenshot of a video of the AMS Event#168-2018 attached to a fireball report submitted by T. Masterson

During this period the moon will reach its first quarter phase on Wednesday January 24th. At that time the moon will lie 90 degrees east of the sun and will set near 01:00 local standard time (LST). This weekend the waxing crescent moon will lie in the western sky at dusk but will not interfere with meteor observing. The estimated total hourly meteor rates for evening observers this week is 3 as seen from mid-northern latitudes (45N) and 4 from the southern tropics (25S) . For morning observers the estimated total hourly rates should be near 11 as seen from mid-northern latitudes (45N) and 12 from the southern tropics (25S). 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 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. 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.

Radiant Positions at 7pm LST

Radiant Positions at 7:00pm
Local Standard Time

Radiant Positions at 12:00 LST

Radiant Positions at 12:00am
Local Standard Time

Radiant Positions at 5am LST

Radiant Positions at 5:00am
Local Standard Time

These sources of meteoric activity are expected to be active this week.

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The center of the large Anthelion (ANT) radiant is currently located at 08:52 (133) +17. This position lies in central Cancer, just 1 degree  southeast of the 4th magnitude star known as Asellus Australis (delta Cancri). Due to the large size of this radiant, Anthelion activity may also appear from eastern Gemini, and western Leo, as well as Cancer. This radiant is best placed near 0100 local standard time (LST), when it lies on the meridian and is located highest in the sky. Rates at this time should be near 3 per hour as seen from the northern hemisphere and 2 per hour from south of the equator. With an entry velocity of 30 km/sec., the average Anthelion meteor would be of slow velocity.

Activity from the alpha Antliids (AAN) should begin late in this period from a radiant located near 09:56 (149) -06. This position actually lies in western Sextans, 5 degrees northeast of the 2nd magnitude star known as Alphard (alpha Hydrae). I’m not certain how this stream was named as it the radiant lies a good 20 degrees north of the Antlia border. Perhaps when activity was first noticed from this source the radiant was incorrectly determined? This radiant is best placed near 0200 LST, when it lies on the meridian and is located highest in the sky. Since maximum activity is not until February 1st, current rates are expected to be less than 1 per hour no matter your location. With an entry velocity of 45 km/sec., the average meteor from this source would be of medium velocity.

The last of the January xi Ursae Majorids (XUM) are expected this weekend from a radiant is located at 11:28 (172) +32, which lies in southwestern Ursa Major, 2 degrees east of the 3rd magnitude star known as Alula Borealis (xi Ursae Majoris).  These meteors are best seen near 04:00 LST when the radiant lies highest above the horizon. Hourly rates should be less than 1 no matter your location. These meteors encounter the atmosphere at 41 km/sec., which would produce meteors of average velocity.

The eta Corvids (ECV) were recently discovered by Sirko Molau and the IMO Video Meteor Network Team. This stream is active from January 16-29, with maximum activity occurring on the 22nd. The current position of the radiant is 12:44 (191) -17, which places the radiant in northern Corvus, 3 degrees east of the 3rd magnitude star known as Algorab (delta Corvi). These meteors are best seen near 0400 LST when the radiant lies highest above the horizon. Expected hourly rates would be less than 1 per hour no matter your location. At 68 km/sec. these meteors would be fast.

The January Comae Berenicids (JCO) were first detected by Dr. Peter Jenniskens and mentioned in his book: Meteor Showers and their Parent Comets. These meteors are best seen from January 21-26 with maximum occurring on the 23rd. At maximum the radiant is located at 12:52 (193) +15. This position lies in southern Coma Berenices, 5 degrees northwest of the 3rd magnitude star known as Vindemiatrix (Epsilon Virginis). Hourly rates during this period are expected to be less than 1 no matter your location. These meteors are best seen near 0400 LST, when the radiant lies highest above the horizon. These meteors encounter the atmosphere at 64 km/sec., which would produce meteors of swift velocity.

As seen from the mid-northern hemisphere (45N) one would expect to see 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 also be near 10 per hour as seen from rural observing sites and 3 per hour during the evening hours. Locations between these two extremes would see activity between the listed figures.

 

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
Anthelion (ANT) 08:52 (133) +17 30 01:00 3 – 2 II
alpha Antliids (AAN) Feb 01 09:56 (149) -06 45 02:00 <1 – <1 IV
January xi Ursae Majorids (XUM) Jan 18 11:28 (172) +32 41 04:00 <1 – <1 IV
eta Corvids (ECV) Jan 22 12:20 (185) -14 68 05:00 <1 – <1 IV
January Comae Berenicids (JCO) Jan 23 12:52 (193) +15 64 06:00 <1 – <1 IV

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