(meteorobs) Meteor Activity Outlook for October 6-12, 2012

[Robert Lunsford]

Meteor activity in general increases in October when compared to September. A major shower (the Orionids) is active all month long with many minor showers. Both branches of the Taurids become more active as the month progresses, providing slow, graceful meteors to the nighttime scene. The Orionids are the big story of the month reaching maximum activity on the 22nd. This display can be seen equally well from both hemispheres which definitely helps out observers located in the sporadic-poor southern hemisphere this time of year.

During this period the moon reaches its last quarter phase on Monday October 8th. At this time the moon is located ninety degrees west of the sun and will rise near 0100 LDT Local Daylight Time as seen from mid-northern latitudes. As the week progresses the waning crescent moon will rise later and later in the morning sky, creating more favorable viewing conditions. The estimated total hourly meteor rates for evening observers this week is near four for observers located at mid-northern latitudes and three for observers in mid-southern latitudes. For morning observers the estimated total hourly rates should be near fourteen from the mid-northern hemisphere and eight from the mid-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. Rates during the morning hours are reduced due to interfering 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 October 6/7. 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.

The following radiants are expected to be active this week:

The October Camelopardlids (OCT) are only active from September 30th through October 6th with maximum activity occurring on October 5th. The radiant position at maximum is located at 11:12 (168) +79. This position lies in a remote area of eastern Camelopardlis. The nearest bright star is Kochab (Beta Ursae Minoris), which lies a dozen degrees to the east. The radiant is somewhat unique as it is best placed during the last dark hour after dusk and before dawn. It circumpolar (never sets) for most of the northern hemisphere but is best seen from high northern latitudes. Activity is best seen only during the last two days of activity when 1-2 shower members may be seen per hour. This radiant is not well placed to be viewed from the southern hemisphere and tropical northern latitudes. With an entry velocity of 44 km/sec., most activity from this radiant would be of medium velocity.

The Draconids (GIA) (also known as the Giacobinids) reach maximum activity on October 8. The exact time of maximum activity can vary so observers are encouraged to view on the evenings of October 7-9 to try and catch any of this activity. The radiant is located at 17:28 (262) +54, which places it in southern Draco, two degrees northwest of the third magnitude star Rastaban (Beta Draconis). This star is one of the four that form the prominent head of Draco, also known as the "Lozenge". Expected rates are always a guess. The last quarter moon will not cause any interference. The best time to view this activity is as soon as it becomes dark during the early evening hours. Those located in high northern latitudes can also try viewing this shower during the morning hours, but the moon will then be above the horizon. Due to the extreme northern declination, this shower is only visible from the southern tropics northward. At 19km/sec., the average Draconid is extremely slow. An out outburst was observed over Europe last year when zenith hourly rates briefly reached 300. Although comet 21P/Giacobini-Zinner arrived at perihelion in February 2012, no exceptional activity is expected this year. Still, observers are encouraged to watch October 7-9, for any unusual activity.

The center of the large Southern Taurid (STA) radiant is currently located at 02:00 (030) +08. This position lies near the intersection of the constellations of Pisces, Cetus, and Aries. The radiant is so large that Southern Taurid activity may also appear from the aforementioned constellations plus northwestern Eridanus. This radiant is best placed near 0200 local daylight time (LDT), when it lies on the meridian and is located highest in the sky. Maximum occurs on October 9th so rates at this time are expected to be near three per hour no matter your location. With an entry velocity of 29 km/sec., the average Southern Taurid meteor would be of slow velocity.

The Orionids (ORI) are producing 2-3 shower members per hour during the last few hours before dawn, when the radiant lies highest in the sky. The radiant is currently located at 05:38 (084) +16, which is on the Orion/Taurus border, eight degrees northwest of the brilliant first magnitude orange star Betelgeuse (Alpha Orionis). Orionid meteors are equally well seen either side of the equator. With an entry velocity of 67 km/sec., most activity from this radiant would be swift. Maximum activity is predicted to occur on the 22nd when hourly rates should be near twenty.

The Epsilon Geminids (EGE) are active all month long with low hourly rates. Even at maximum activity only three shower members per hour are expected. Recent research by the IMO has indicated an earlier maximum of October 15th, rather than October 19th. The radiant position is currently located at 06:08 (092) +29. This position actually lies within the borders of Auriga, just two degrees west of the faint star Kappa Aurigae. The radiant is also best placed during the last dark hour before dawn, when it lies highest above the horizon in a dark sky. Rates would be near one per hour as seen from the northern hemisphere and less than one per hour as seen south of the equator. With an entry velocity of 70 km/sec., most activity from this radiant would be swift.

Studies of the IMO's video database by Sirko Molau and Juergen Rendtel has revealed a radiant active in Lynx this time of year. Earlier visual observations of this activity placed the radiant in eastern Auriga. Therefore the radiant is known as the Psi Aurigids (PSA). This radiant is active from October 8-18, with maximum activity occurring on the 12th. The radiant drift is not well established as positions jump around quite a bit during its ten day activity period. At maximum the radiant is located at 07:36 (114) +47. This position lies in a remote area of central Lynx. The nearest bright star is second magnitude Castor (Alpha Geminorum), which lies fifteen degrees to the south. This is a weak display and even at maximum activity rates would most likely be less than one shower member per hour, no matter you location. With an entry velocity of 68 km/sec., most activity from this radiant would be swift.

As seen from the mid-northern hemisphere (45N) one would expect to see approximately six sporadic meteors per hour during the last hour before dawn as seen from rural observing sites. Evening rates would be near three per hour. As seen from the mid-southern hemisphere (45S), morning rates would be near three per hour as seen from rural observing sites and two 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 presents a summary of the expected activity this week. Rates and
positions are exact for Saturday night/Sunday morning, but may be used all week.

October Camelopardalids (OCT) - 11:12 (168) +79   Velocity 44km/sec
Northern Hemisphere - 2 per hr   Southern Hemisphere - <1 per hour

October Draconids (GIA) - 17:28 (262) +54   Velocity 19km/sec
Northern Hemisphere - <1 per hr   Southern Hemisphere - <1 per hour

Southern Taurids (STA) - 02:00 (030) +08   Velocity 29km/sec
Northern Hemisphere - 3 per hr Southern Hemisphere - 3 per hour

Orionids (ORI) 05:38 (084) +16   Velocity 67km/sec
Northern Hemisphere - 2 per hr Southern Hemisphere - 2 per hour

Epsilon Geminids (EGE) 06:08 (092) +29   Velocity 70km/sec
Northern Hemisphere - 1 per hr Southern Hemisphere - <1 per hour

Psi Aurigids (PSA) 07:36 (114) +47   Velocity 68km/sec
Northern Hemisphere - <1 per hr Southern Hemisphere - <1 per hour

Clear Skies!
Robert Lunsford
American Meteor Society