
During this period, the moon reaches its last quarter phase on Monday October 13th. On that date the moon will be located 90 degrees west of the sun and will rise near 23:00 local summer time (LST). The waning moon will be a factor for morning observations early in this period, but its interference will lessen with each passing night. The estimated total hourly rates for evening observers this weekend should be near 4 as seen from mid-northern latitudes (45N) and 3 as seen from tropical southern locations (25S). For morning observers, the estimated total hourly rates should be near 7 as seen from mid-northern latitudes (45N) and 4 as seen from tropical southern locations (25S). Morning rates are reduced due to moonlight. The actual rates seen 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 brighter 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 October 11/12. These positions do not change greatly day to day so the listed positions may be used during this entire period. Most star atlases (available online and at bookstores 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. I have also included charts of the sky that display the radiant positions for evening, midnight, and morning. The center of each chart is the sky directly overhead at the appropriate hour. These charts are oriented for facing south but can be used for any direction by rotating the charts to the desired direction. 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 (culmination), either due north or south along the meridian, depending on your latitude. Radiants that rise after midnight will not reach their highest point in the sky until daylight. For these radiants, it is best to view them during the last few hours before dawn. It must be remembered that meteor activity is rarely seen at its radiant position. Rather they shoot outwards from the radiant, so it is best to center your field of view so that the radiant lies toward 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 sporadic. Meteor activity is not seen from radiants that are located far 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
The large radiant of the Southern Taurids (STA) is currently located at 02:16 (034) +10. This area of the sky is located in northeastern Cetus, 1 degree northeast of the 4th magnitude star known as Xi1 Ceti. This area of the sky is best placed for observing near 02:00 LST, when it lies highest in the southern sky. Current rates are expected to be 2 per hour, no matter your location. With an entry velocity of 27 km/sec., the average STA meteor would be of medium-slow velocity.
The Orionids (ORI) are active from October 2 through November 7, with maximum activity occurring on October 23rd. The radiant is currently located at 05:56 (089) +15, which places it in northeastern Orion, 8 degrees north of the 1st magnitude star known as Betelgeuse (alpha Orionis). This area of the sky is best placed for observing during the last dark hour prior to dawn, when it lies highest in the southern sky. Current rates are expected to be near 2 per hour, no matter your location. With an entry velocity of 66km/sec., the average ORI meteor would be of swift velocity.
The epsilon Geminids (EGE) are active from October 14th through November 7th with maximum activity occurring on October 18th. The radiant is currently located at 06:24 (096) +27. This area of the sky lies in western Gemini, 3 degrees northwest of the 3rd magnitude star known as Mebsutae (epsilon Geminorum). To best see these meteors, face toward the south during the last few dark hours prior to dawn. Rates at this time should be near 1 per hour as seen from the northern hemisphere and less than 1 as seen from south of the equator. With an entry velocity of 70 km/sec., the average EGE meteor would be of swift velocity.
Sporadic meteors are those meteors that cannot be associated with any known meteor shower. All meteor showers are evolving and disperse over time to the point where they are no longer recognizable. Away from the peaks of the major annual showers, these sporadic meteors make up the bulk of the activity seen each night. As seen from the mid-northern hemisphere (45N) one would expect to see during this period approximately 7 sporadic meteors per hour during the last hour before dawn as seen from rural observing sites. Evening rates would be near 3 per hour. As seen from the tropical southern latitudes (25S), morning rates would be near 4 per hour as seen from rural observing sites and 2 per hour during the evening hours. Locations between these two extremes would see activity between these listed figures. Morning rates are reduced due to moonlight.
The list below offers information in tabular form. Rates and positions in the table 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 Summer Time | North-South | |||
Southern Taurids (STA) | Nov 05 | 02:16 (034) +10 | 27 | 02:00 | 2 – 2 | II |
Orionids (ORI) | Oct 21 | 05:56 (089) +15 | 66 | 05:00 | 2 – 2 | I |
epsilon Geminids (EGE) | Oct 18 | 06:24 (096) +27 | 70 | 05:00 | 1 – <1 | IV |
Class Explanation: A scale to group meteor showers by their intensity:
- Class I: the strongest annual showers with Zenith Hourly Rates normally ten or better.
- Class II: reliable minor showers with ZHR’s normally two to ten.
- Class III: showers that do not provide annual activity. These showers are rarely active yet have the potential to produce a major display on occasion.
- Class IV: weak minor showers with ZHR’s rarely exceeding two. The study of these showers is best left to experienced observers who use plotting and angular velocity estimates to determine shower association. These weak showers are also good targets for video and photographic work. Observers with less experience are urged to limit their shower associations to showers with a rating of I to III.