October 25-31, 2014 - Meteor Activity Outlook
During this period the moon reaches its first quarter phase on Thursday October 30th. At this time the moon is located 90 degrees east of the sun and sets near 2300 local daylight time as seen from mid-northern latitudes. The estimated total hourly meteor rates for evening observers this week is near 3 as seen from the northern hemisphere and 2 as seen from southern tropical latitudes. For morning observers the estimated total hourly rates should be near 22 for observers located in mid-northern latitudes and 17 for south tropical observers. Rates are reduced for the evening hours during this period 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 October 25/26. 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:
The first activity from the Andromedids (AND) will be seen this week. This is a famous shower that produced some brilliant displays during the 19th century. Since then the main orbit of the particles from comet 3D/Biela have moved away from the Earth. Still, remnants may be seen from October 26 through November 20 with maximum activity occurring on November 8. The radiant is currently located at 01:20 (020) +22, which lies in eastern Pisces, 10 degrees west of the 2nd magnitude star Hamal (Alpha Arietis). Rates would most likely be less than 1 per hour no matter your location. With an entry velocity of 19 km/sec., the average Andromedid meteor would be of slow velocity.
The Southern Taurids (STA) are currently active from a radiant located at 03:04 (046) +12. This position lies in southeastern Aries, 8 degrees north of the 3rd magnitude star known Menkar (Alpha Ceti). These meteors may be seen all night long but the radiant is best placed near 0100 LDT when it lies on the meridian and is located highest in the sky. Rates at this time should be near 3 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 Northern Taurids (NTA) are now active from a large radiant centered at 03:08 (047) +20, which lies in eastern Aries, close to the position occupied by the fourth magnitude star known as Delta Arietis. The radiant is best placed near 0200 LDT, when it lies highest above the horizon. Meteors from the Northern Taurids strike the atmosphere at 29km/sec., which would produce meteors of slow velocity. Expected rates would be near two per hour, no matter your location.
The Orionids (ORI) are active from a radiant at 06:36 (099) +16, which places it in southwestern Gemini, close to the spot occupied by the 2nd magnitude star known as Alhena (Gamma Geminorum). This area of the sky is best placed in the sky near 0500 LDT, when it lies highest above the horizon. The maximum for the Orionids was weak so rates this week should only be near 3 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 Epsilon Geminids (EGE) are still active from a radiant is located at 07:08 (107) +27. This area of the sky lies in central Gemini, directly between the 1st magnitude star Pollux (Beta Geminorum) and 3rd magnitude Mebsuta (Epsilon Geminorum). The radiant is best placed in the sky during the last hour before dawn, when it lies highest above the horizon in a dark sky. Current rates should be near 2 per hour as seen from the northern hemisphere and near 1 when view south of the equator. With an entry velocity of 70 km/sec., most activity from this radiant would be of swift speed.
The last of the Leonis Minorids (LMI) will be seen this week. The radiant is currently located at 10:56 (164) +36. This position lies in northeastern Leo Minor near the faint star known as 46 Leonis Minoris. This position is also close to the mid-way point between the brighter stars Nu and Upsilon Ursae Majoris. 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. Current rates 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 68 km/sec., most activity from this radiant would be of swift speed.
The Lambda Ursae Majorids (LUM) are a recent discovery by Zeljko Andreic. This weak shower is active from October 24 through November 1st with maximum activity occurring on the 27th. The radiant currently located at 10:20 (155) +50. This position lies in a sparse area of central Ursa Major, between the 2nd magnitude star Merak (Beta Ursae Majoris) and 3rd magnitude Tania Borealis (Lambda Ursa Majoris). 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. Current rates 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 62 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 7 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. Moonlight reduces the number of meteors seen during the evening hours during this period.
Shower ........... Date of Max. activity Celestial position - Culmination - hr rate Class
Andromedids (AND) Nov 08 01:20 (020) +22 19 ................ 23:00 ..........<1 – <1 III
Southern Taurids (STA) Oct 10 03:04 (046) +12 29 ............01:00 ...........3 – 3 ..II
Northern Taurids (NTA) Oct 22 03:08 (047) +20 29 ............01:00 ...........2 – 2 ..II
Orionids (ORI) Oct 22 06:36 (099) +16 67 ....................05:00 ...........3 – 3 ...I
Epsilon Geminids (EGE) Oct 22 07:08 (107) +27 70 ............06:00 ...........2 – 1 ..II
Lambda Ursa Majorids (LUM) Oct 27 10:20 (155) +50 62 ........09:00 ...........1 – <1 .IV
Leonis Minorids (LMI) Oct 22 10:56 (164) +36 60 .............10:00 ...........1 – <1 .II
Orionids Active from October 4th to November 14th 2014 - Peak night Oct 21-22
The Orionids are a medium strength shower that sometimes reaches high strength activity. In a normal year the Orionids produce 20-25 shower members at maximum. In exceptional years, such as 2006-2009, the peak rates were on par with the Perseids (50-75 per hour). At this time we are unable to predict exactly when the Orionids will be exception
Radiant: 06:20 +15.5° - ZHR: 25 - Velocity: 41 miles/sec (swift - 67km/sec) - Parent Object: 1P/Halley
Southern Taurids Active from September 7th to November 19th 2014 - Peak night Oct 8-9
The Southern Taurids are a long-lasting shower that reaches a barely noticeable maximum on October 9 or 10. The shower is active for more than two months but rarely produces more than five shower members per hour, even at maximum activity. The Taurids (both branches) are rich in fireballs and are often responsible for increased number of fireball reports from September through November.
Radiant: 02:08 +8.7° - ZHR: 5 - Velocity: 17 miles/sec (slow - 28km/sec) - Parent Object: 2P/Encke
Quadrantids Active from January 1st to 10th 2014 - Peak night Jan 2-3
Lyrids Active from April 16th to 25th 2014 Peak night - Apr 21-22
Eta Aquariids Active from April 19th to May 26th 2014 - Peak night May 5-6
Delta Aquariids Active from July 21st to August 23rd 2014 - Peak night Jul 27-28
Alpha Capricornids Active from July 11th to August 10th 2014 - Peak night Jul 28-29
Perseids Active from July 13th to August 26th 2014 - Peak night Aug 11-12
Northern Taurids Active from October 19th to December 10th 2014 - Peak night Nov 12-13
Leonids Active from November 5th to 30th 2014 - Peak night Nov 17-18
Geminids Active from December 4th to 16th 2014 - Peak night Dec 13-14
Ursids Active from December 17th to 23rd 2014 - Peak night Dec 21-22
No comments:
Post a Comment