The Meteor Activity Outlook is a weekly summary of expected meteor activity written by Robert Lunsford, Operations Manager of the American Meteor Society and contributor to this blog. The original unedited version of this week’s Meteor Activity Outlook can be found at the American Meteor Society’s site.
No matter where you live, the first half of December provides some of the best meteor activity of the year. In the northern hemisphere the sporadic rates are still strong plus you can also count on strong activity from the Geminids, which peak on December 14. There are also several minor radiants that add a few meteors each hour. All of these centers of activity are located high in the sky during the early morning hours this time of year. Much of the activity mentioned above can also be seen from the southern hemisphere. While the sporadic rates are not as strong as those seen from the north, they are stronger than the previous months and heading for a maximum in January. The warm, but short summer nights south of the equator make for some great viewing as long as the moon does not interfere.
During this period the moon reaches its last quarter phase on Saturday November 27th. At this time the moon lies ninety degrees west of the sun and rises near midnight LST (Local Standard Time). Thus morning observers will have moonlight to contend with this weekend. Successful observations can still be undertaken as long as the moon is kept out of your field of view. The light of the last quarter moon is much less intense than that of a full moon and many meteors can still be seen, especially under transparent skies. As the week progresses the waning crescent moon becomes less of a problem as it grows dimmer and rises later and later during the early morning hours. The estimated total hourly rates for evening observers this week is ~5 from the northern hemisphere and ~3 for observers south of the equator. For morning observers the estimated total hourly rates should be ~15 from the northern hemisphere and ~13 as seen from the southern hemisphere. 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. Morning rates are reduced due to moonlight.
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 November 27/28. These positions do not change greatly day to day so the listed coordinates may be used during this entire period.
The following showers are expected to be active this week:
December Phoenicids (PHO)
The December Phoenicids (PHO) are a periodic shower that rarely produces noticeable activity. The only impressive display produced by this shower occurred in 1956 when ZHR’s were near 100. Peak activity occurs on December 6. Little activity is expected away from the peak night. The radiant is currently located at 00:50 (012) -52. This position lies in central Phoenix some ten degrees southeast of the second magnitude star Ankaa (Alpha Phoenicis). These meteors are best seen near 2100 (9pm) LST, when the radiant lies highest above the horizon in a dark sky. Due to the southerly declination of the radiant, this shower is not visible north of the northern tropical areas. The deep southern hemisphere has the best chance of seeing any activity. At 22 km/sec. the Phoenicids produce very slow meteors.
Sirko Molau and Juergen Rendtel’s studies of video radiants has revealed that activity from the famous Andromedid shower, noted for intense storms during the 19th century, may still be seen throughout November. The current
position of the large radiant is 01:44 (026) +45. This position lies in eastern Andromeda, three degrees south of the fourth magnitude star 51 Andromedae. Visual activity is expected to be low, but detectable. An inconspicuous maximum occurs on November 12. The Andromedid meteors are best seen near 2200 (10pm) LST (Local Standard Time) when the radiant lies on the meridian. At 19km/sec., the average Andromedid will appear as a very slow moving meteor. Sirko mentions that these meteors are “conspicuously slow and of almost constant activity” during this period.
Northern Taurids (NTA)
The center of the large Northern Taurid (NTA) radiant lies at 04:49 (072) +25. This area of the sky is located in central Taurus, eight degrees north of the orange first magnitude star Aldebaran (Alpha Tauri). These meteors are best seen near 0100 LST, when the radiant lies highest above the horizon. This shower peaked on November 13, so rates are falling should be ~2 per hour. Meteors from the Northern Taurids strike the atmosphere at 29km/sec., which would produce meteors of slow velocity. This shower is also responsible for many of the fireball reports seen in November.
November Orionids (NOO)
The November Orionids (NOO) were recently discovered by analyzing video data. For years it was lost in the maze of radiants active this time of year. Due to the low activity, visual observers were unable to detect this shower. This shower is active from November 18 through December 9. Maximum activity occurs on November 30. Once you know the radiant in advance, this shower is actually quite noticeable, producing an average of 2 shower members per hour near maximum. The radiant is currently located at 05:58 (090) +15. This position lies in northeastern Orion, seven degrees north of the orange first magnitude star Betelgeuse (Alpha Orionis). These meteors are best seen near 0200 LST when the radiant lies on the meridian and highest above the horizon. At 44 km/sec. the November Orionids produce mostly medium velocity meteors.
The Puppid-Velids (PUP) are a vast complex of weak radiants located in the constellations of Puppis and Vela. Visual plots and photographic studies have revealed many radiants in this area during November and December. The combined strength of these radiants can produce a ZHR of 10. Actual hourly rates will be much less unless you happen to be observing from the deep Southern Hemisphere. The center of this activity is currently located at 07:52 (118) -45. This position lies in eastern Puppis, four degrees northwest of the second magnitude star Gamma Velorum. Peak rates occur near December 7. These meteors are best seen near 0300 LST when the radiant lies highest above the horizon in a dark sky. Observers located in the Southern Hemisphere have an advantage viewing this shower as the radiant will rise higher into their sky allowing more activity to be seen. At 40 km/sec. the Puppid-Velids produce meteors of average velocity.
Psi Ursa Majorids (PSU)
Another shower verified by video means are the Psi Ursa Majorids (PSU). This shower is active from November 29-December 13 with maximum activity occurring on December 5. The radiant is currently located at 10:38 (159) +45. This position lies in southwestern Ursa Major, five degrees west of the third magnitude star Kappa Ursae Majoris. This area of the sky is best placed during the last hour before dawn, when it lies highest above the horizon in a dark sky. Current rates would most likely be less than one per hour. At 61km/sec., the average Psi Ursa Majorid meteor would be swift.
This week is your last chance to see the Leonids (LEO) for 2010. This shower peaked on the Thursday morning November 18 and current rates are well below 1 per hour no matter your location. The radiant is located at 10:41 (160) +19. This position lies in central Leo, four degrees east of the second magnitude star Algeiba (Gamma Leonis). The area of the sky does not clear the eastern horizon until the late evening hours so no Leonid activity can be seen during the early evening hours. These meteors are best seen during the last hour before the onset of morning twilight, when the radiant lies highest above the horizon in a dark sky. At 71km/sec., the average Leonid is swift with a high percentage of trains.
December Kappa Draconids (KDR)
Another shower verified by video means are the December Kappa Draconids (KDR). This shower is active from November 30-December 6 with maximum activity occurring on December 3. Activity from this source is not expected this weekend. On the night of maximum the radiant will be located at 12:22 (185) +72. This position lies in extreme western Draco, two degrees northwest of the faint star Kappa Draconis. While the radiant lies above the horizon all night for most of the northern hemisphere, it is best placed during the last hour before dawn, when it lies highest above the horizon in a dark sky. Current rates would most likely be less than one per hour. At 43km/sec., the average December Kappa Draconid meteor would be of medium velocity.
Shower Name RA DEC Vel Rates km/s NH SH PHO December Phoencids 00h 50m -52 18 <1 <1 AND Andromedids 01h 44m +45 19 <1 <1 NTA Northern Taurids 04h 49m +25 29 2 2 NOO November Orionids 05h 58m +15 44 2 2 PUP Puppid-Velids 07h 52m -45 40 <1 2 PSU Psi Ursa Majorids 19h 38m +45 61 <1 <1 LEO Leonids 10h 41m +19 71 <1 <1 KDR Dec Kappa Draconids 12h 22m +72 43 <1 <1 RA - Right Ascension DEC - Declination Vel - Velocity relative to Earth (in km per sec) Rates - Rate of visible meteors per hour from a dark site NH - Northern Hemisphere SH - Southern Hemisphere