Meteor Activity Outlook for September 19-25, 2015

During this period the moon reaches its first quarter phase on Sunday September 20th. On that date the moon will be located 90 degrees east of the sun and will set near midnight local daylight saving time as seen from mid-northern latitudes. As the week progresses the moon will start to interfere with viewing in the morning sky as it sets later each morning. The estimated total hourly meteor rates for evening observers this week is near 3 as seen from mid-northern latitudes (45N) and 2 as seen from tropical southern locations (25S). For morning observers the estimated total hourly rates should be near 16 as seen from mid-northern latitudes (45N) and 10 as seen from tropical southern locations (25S). Evening rates are reduced during this period due to interfering 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 19/20. 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.

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

We are now encountering debris from comet 2P/Encke, which has a radiant superimposed upon the anthelion radiant. Since it has been shown that meteors from 2P/Encke are more numerous we shall recognize this activity as the Southern Taurids (STA) until December 5th, when the Earth no longer encounters these particles. The maximum was once thought to occur in early November when the radiant was located in Taurus. Video studies have shown that the peak usually occurs near October 10th but that there is also a period of enhancement during the last week of October and the first week of November, when the Northern Taurids are also active. The center of the large radiant is currently located at 01:12 (018) +05. This position lies in southeastern Pisces, just south of the faint star Zeta 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 2 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) are past their peak but still should be producing activity from a radiant located at 03:58 (060) +41. This position lies in central Perseus, just south of the 3rd magnitude star known as Epsilon Persei. The radiant is best placed near 0500 LDT, when it lies highest above the horizon. Hourly rates are expected to be near 1 per hour as seen from the northern hemisphere and less than 1 as seen south of the equator. With an entry velocity of 66 km/sec., most activity from this radiant would be swift.

The September Pi Orionids (POR) are a short duration shower discovered by John Greaves during his studies of video data from the SonotaCo Network in Japan. This shower is only active from September 16-20 with no discernible maximum. The average position of the radiant is 04:08 (062) +06 which places the radiant in southern Taurus between the 4th magnitude stars Nu and Upsilon Tauri. This position is also close to that of the Orionid radiant so care must be taken to differentiate between the two sources. Activity is expected to be low, with rates most likely less than 1 per hour. 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. These meteor may be seen equally well from both hemispheres. With an entry velocity of 66 km/sec., most activity from this radiant would be swift.

You may be surprised to see the Orionids (ORI) as an active radiant this time of year, but there is clear evidence from the IMO database that this shower is active long before its October 22nd maximum. In fact it is in the top four most active radiants throughout September. Expected rates this week are near 2 per hour no matter your location. This radiant is currently located at 05:04 (076) +05, which places it in the western Orion, 5 degrees southwest of the 2nd magnitude star known as Bellatrix (Gamma Orionis. 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. With an entry velocity of 67 km/sec., most activity from this radiant would be of swift speed.

The Delta Aurigids (DAU) are active from September 23-29, with a peak on the 27th. On the night of maximum activity the radiant is located at 05:08 (077) +57. This area of the sky lies in southern Camelopardalis, 10 degrees north of the zero magnitude star known as Capella (Alpha Aurigae). 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. Rates this week would be less than 1 per hour no matter your location. With an entry velocity of 61 km/sec., most activity from this radiant would be of swift speed.

The Beta Aurigids (BAU) are active on only 5 nights centered on September 23rd. On the night of maximum activity the radiant lies at 05:52 (088) +48, which lies in northern Auriga, 3 degrees northwest of the 2nd magnitude star known as Menkalinan (Beta Aurigae). 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. Hourly rates would be near 1 as seen from the northern hemisphere. Due to the low elevation as seen from the southern hemisphere, hourly rates would be less than 1 as seen from south of the equator. With an entry velocity of 69 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 10 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 be near 6 per hour as seen from rural observing sites and 1 per hour during the evening hours. Locations between these two extremes would see activity between the listed figures.

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.