During this period the moon reaches its full phase on Thursday September 19th. At this time the moon is located opposite the sun and will be above the horizon all night long. This weekend the waxing gibbous moon will set a few hours after midnight, allowing a few hours of dark skies before the start of dawn. The estimated total hourly meteor rates for evening observers this week is near three for observers located in the northern hemisphere and two for those viewing south of the equator. For morning observers the estimated total hourly rates should be near seventeen as seen from mid-northern latitudes and near twelve for observers viewing from tropical southern latitudes. 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 brightest 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 September 14/15. 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 sources of meteoric activity are expected to be active this week:
The Southern Taurids (STA) are currently active from a radiant located at 00:44 (011) +04. This position lies in southern Pisces, four degrees south of the fourth magnitude star Delta Piscium. These meteors may be seen all night long but the radiant is best placed near 0200 local daylight time (LDT) when it lies on the meridian and is located highest in the sky. Rates at this time should be near one per hour regardless of your location. With an entry velocity of 29 km/sec., the average Southern Taurid meteor would be of slow velocity.
The September Epsilon Perseids (SPE) produced another dramatic outburst late on September 9th, with visual rates exceeding 20 per hour and several fireballs were produced. Although Asia was favored for this display, observers in Europe and North America also were able to view enhanced rates and several fireballs. Rates have now returned to normal 2-3 meteors per hour from a radiant position located at 03:36 (054) +39. This position lies in southern Perseus, three degrees southwest of the third magnitude star Epsilon Persei. The radiant is best placed near 0500 LDT, when it lies highest above the horizon. With an entry velocity of 66 km/sec., most activity from this radiant would be swift. This activity is visible from the tropical regions of the southern hemisphere, but further south the radiant becomes too low in the sky to produce much activity.
The Orionids (ORI) are active from a radiant at 04:40 (070) +03, which places it on the Taurus/Orion border some 15 degrees south of the bright orange first magnitude star known as Aldebaran (Alpha Tauri). The faint star known as Pi 3 Orionis lies a bit closer, 3 degrees to the northeast but is more difficult to locate. This area of the sky is best placed in the sky during the last hour before dawn, when it lies highest above the horizon in a dark sky. Rates this week would be near 2 per hour no matter your location. With an entry velocity of 67 km/sec., most activity from this radiant would be of swift speed.
The Nu Eridanids (NUE) were discovered from the data obtained by SonotaCo in Japan. Information from different sources on this shower is not in agreement therefore it is difficult to offer a smooth activity period and radiant positions. The latest analysis by Sirko Molau of the IMO offers an activity period of September 18-24, with maximum activity occurring on the 18th. Pre-maximum data jumps around too much and it is difficult to associate any activity prior to September 18th with the Nu Eridanids. On the 18th, the radiant position lies at 04:56 (074) +04, which actually places it within the borders of Orion near the faint star know as Pi 5 Orionis. At maximum, rates should be near one per hour no matter your location. These meteors are best seen during the last hours before dawn when the radiant lies highest above the horizon in a dark sky. With an entry velocity of 67 km/sec., most activity from this radiant would be of swift speed. Note that this radiant is very close to the Orionids and it would be difficult to distinguish between the two unless your have both radiants near the center of your field of view and you get a very good look at each candidate.
Video studies by Molau and Rendtel has revealed a radiant active from September 7th-18th, with maximum activity occurring on the 9th. The current radiant position for the September Lyncids (SLY) is 07:48 (117) +56. This position lies in a remote area of northern Lynx. The nearest star of note is 4th magnitude Omicron Ursae Majoris, which lies 10 degrees to the northeast. This area of the sky is best placed in the sky during the last hour before dawn, when it lies highest above the horizon in a dark sky. Rates should be near 1 per hour as seen from the northern hemisphere and near zero from south of the equator. Due to the high northern declination this activity is not well seen south of the equator. With an entry velocity of 60 km/sec., most activity from this radiant would be of swift speed.
As seen from the mid-northern hemisphere (45N) one would expect to see approximately eleven sporadic meteors per hour during the last hour before dawn as seen from rural observing sites. Evening rates would be near two per hour. As seen from the tropical southern latitudes (25S), morning rates would also be near seven per hour as seen from rural observing sites and one per hour during the evening hours. Locations between these two extremes would see activity between the listed figures. Evening rates are reduced due to interfering 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.
|SHOWER||DATE OF MAXIMUM ACTIVITY||CELESTIAL POSITION||ENTRY VELOCITY||CULMINATION||HOURLY RATE||CLASS|
|RA (RA in Deg.) DEC||Km/Sec||Local Daylight Time||North-South|
|Southern Taurids (STA)||Oct 10||00:44 (011) +04||29||02:00||1 – 1||II|
|September Epsilon Perseids (SPE)||Sep 09||03:36 (054) +39||66||05:00||2 – 1||II|
|Orionids (ORI)||Oct 22||04:40 (070) +03||67||06:00||2 – 2||I|
|Nu Eridanids (NUE)||Sep 18||04:56 (074) +04||67||06:00||1 – 1||IV|
|September Lyncids (SLY)||Sep 09||07:48 (117) +56||60||09:00||<1 – <1||IV|