During this period the moon reaches its first quarter phase on Tuesday November 20th. At this time the moon is located ninety degrees east of the sun and will set near 2300 (1100pm) local standard time (LST). This weekend the waxing crescent moon will set during the early evening hours and will pose no problems to meteor watchers. Later in the week the gibbous moon will limit good meteor observing to the late morning morning before dawn. 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 twenty eight from the mid-northern hemisphere and twenty three 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 are reduced during the evening hours 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 17/18. 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:
Remnants from the famous Andromedid (AND) shower, noted for intense storms during the 19th century, may still be seen throughout November. The current position of this large radiant is 01:36 (024) +37. This position lies in eastern Andromeda, three degrees east of the second magnitude star Mirach (Beta Andromedae). The radiant is so diffuse that Andromedid meteors may be seen coming from Triangulum, northern Pisces, as well as Andromeda. Visual activity is expected to be low, but detectable. An inconspicuous maximum occurred on November 9, when this source was the 5th most active radiant in the sky. The Andromedid meteors are best seen near 2200 (10pm) local standard time (LST), when the radiant lies on the meridian and lies highest in the sky. At 19km/sec., the average Andromedid will appear as a very slow moving meteor.
Studies of the IMO video database by Sirko Molau and Juergen Rendtel has revealed another active radiant in Taurus this time of year. Now that the Southern Taurids are no longer detectable, the Gamma Taurids (GTA) may be distinguished within the Taurid complex. The Gamma Taurid radiant is centered at 04:04 (061) +15. This area of the sky lies in western Taurus, three degrees west of the the 4th magnitude star Hyadum I (Gamma Tauri). The radiant is best placed near 0100 LST, when it lies highest above the horizon. Maximum activity occurred on November 10th so current rates would be near one shower member per hour, no matter your location. Meteors from the Gamma Taurids strike the atmosphere at 27km/sec., which would produce meteors of slow velocity.
The Northern Taurids (NTA) are active from a radiant centered at 04:16 (064) +24. This area of the sky lies in western Taurus just three degrees west of the famous naked eye open cluster known as the Pleiades or the Seven Sisters. The radiant is best placed near 0100 LST, when it lies highest above the horizon. Maximum activity occurred on November 13th so current hourly rates would be near three from the northern hemisphere and two from south of the equator. Meteors from the Northern Taurids strike the atmosphere at 29km/sec., which would produce meteors of slow velocity.
The November Orionids (NOO) are active from a radiant located at 05:28 (082) +16. This area of the sky is located on the Orion/Taurus border, twelve degrees east of the first magnitude orange star Aldebaran (Alpha Tauri).. The peak for this radiant is not until November 30th, so rates would be less than than one shower member per hour, no matter your location. This location is close to the Taurid complex, but far enough east to be distinguishable. The faster velocity of the November should help distinguish these meteors from the slower, but more numerous Taurids. The radiant is best placed for viewing near 0200 LST when it lies on the meridian and is highest above the horizon. With an entry velocity of 44 km/sec., the November Orionids would be of medium speed.
The last few meteors from the Orionids (ORI) will be seen this week. The radiant is located at 08:00 (120) +15. This area of the sky is located on the Gemini/Cancer border, twelve degrees northeast of the zero magnitude star Procyon (Alpha Canis Minoris). The radiant is best placed for viewing near 0400 LST when it lies on the meridian and is highest above the horizon. Expected hourly rates would be less than one no matter your location With an entry velocity of 67 km/sec., most activity from this radiant would be swift.
The Leonids (LEO) are now the most active radiant in the sky, producing a dozen shower members per hour during the last couple of hours before dawn. As the weekend passes, these rates will fall to only 2-3 per hour. The radiant is currently located at 10:16 (154) +22. This position lies in northwestern Leo, within the “sickle” of Leo, two degrees northwest of the second magnitude double star Algeiba (Gamma Leonis). The Leonid radiant is best placed during the last hour before morning twilight when the radiant lies highest in a dark sky. Leonids may be seen from the southern hemisphere but the viewing conditions are not quite as favorable as those north of the equator.
Studies of the IMO video database by Sirko Molau and Juergen Rendtel has revealed an active radiant in Draco this time of year. The November Iota Draconids (NID) radiant is located at 12:36 (189) +70. This area of the sky lies in western Draco close to the position occupied by the fourth magnitude star Kappa Draconis. The radiant is best placed near 0100 LST, when it lies highest above the horizon. Maximum activity occurs on November 26th so current rates would be less than one shower member per hour, no matter your location. Due to the high northerly declination of the radiant these meteors are not visible from most of the southern hemisphere. Only southern equatorial regions would have any chance of seeing activity from this source Meteors from the November Iota Draconids strike the atmosphere at 43km/sec., which would produce meteors of medium velocity.
As seen from the mid-northern hemisphere (45N) one would expect to see approximately twelve 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 six 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. Evening rates are reduced due to moonlight.
The table below presents a condensed version of the expected activity this week. Rates and positions are exact for Saturday night/Sunday morning .
|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|
|Andromedids (AND)||Nov 09||01:36 (024) +37||19||22:00||<1 – <1||III|
|Gamma Taurids (STA)||Nov 10||04:04 (061) +15||27||01:00||1 – 1||IV|
|Northern Taurids (NTA)||Nov 13||04:16 (064) +24||29||01:00||3 – 2||II|
|November Orionids (NOO)||Nov 30||05:28 (082) +16||44||02:00||<1 – <1||II|
|Orionids (ORI)||Oct 22||08:00 (120) +15||67||04:00||<1 – <1||I|
|Leonids (LEO)||Nov 18||10:16 (154) +22||71||06:00||12 – 10||III|
|Nov. Iota Draconids (NID)||Nov 26||12:36 (189) +70||43||08:00||<1 – <1||IV|