International Meteor Organization-News- WGN Vol. 42, No. 5
WGN - Journal of the International Meteor Organization
Volume 42, Number 5, October 2014, pages 155-204
The new issue of this Journal is now in print. It will be posted
shortly; subscribers should receive it soon. Subscribers can also access
the Journal in PDF format immediately through the IMO's web site
<http://www.imo.net/imo/wgn>.
All WGN subscribers will receive this. Those who are also IMO Members
will receive the new Administrative Booklet as well.
The Journal contents are below.
Letter - Meteoroid streams, meteor showers
Juergen Rendtel ................................................ 155
From the Treasurer - IMO Membership/WGN Subscription Renewal
for 2015
Marc Gyssens ................................................... 157
Letter - The CMN catalogue of orbits for 2012
Croatian Meteor Network ........................................ 157
International Meteor Conference 2014 report
Auriane Egal ................................................... 158
First announcement of the International Meteor Conference 2015
Thomas Weiland ................................................. 160
Details of the Proceedings of the International Meteor Conference,
Poznan, Poland, 22-25 August 2013
Marc Gyssens, Paul Roggemans, and PrzemyslZoladek, editors ..... 160
Various meteor scenes I: the perception and the conception of
a 'meteor shower'
Masahiro Koseki ............................................... 170
Various meteor scenes II: Cygnid-Draconid Complex (kappa-Cygnids)
Masahiro Koseki ............................................... 181
Meteorite producing fragment on the Apophis' orbit
Alexandra Terentjeva, Elena Bakanas ............................ 198
Results of the IMO Video Meteor Network - June 2014
Sirko Molau, Javor Kac, Stefano Crivello, Enrico Stomeo, Geert
Barentsen, Rui Goncalves, and Antal Igaz ......................... 201
Those who do not subscribe to this Journal, but wish to, should see the
IMO's web site
http://www.imo.net
and follow the link to WGN. As well as subscribing to WGN, you can
apply to join IMO at the same time. We encourage you to do this.
Writing for WGN
---------------
This Journal welcomes papers submitted for publication. Papers could
include (but are not limited to) theoretical articles, shower analyses,
observing reports, and other meteor related articles.
All papers are reviewed for scientific content, and edited for English
and style. Instructions for authors can be found in WGN 31:4, 124-128,
and at <http://www.imo.net/docs/writingforwgn.pdf>.
--
Javor Kac
Editor-in-Chief
WGN, Journal of the International Meteor Organization
http://www.imo.net/imo/wgn
2014 The Year of "CERTAIN Uncertainty" ™; Meteors, Asteroids, Comets, and MORE!!
Showing posts with label International Meteor Organization. Show all posts
Showing posts with label International Meteor Organization. Show all posts
14 November 2014
30 August 2011
Meteor/Meteorite News 30AUG2011
| Fireball UFO seen in Auckland Open Minds UFO News An unusual light was seen in the sky above Auckland, New Zealand on Saturday evening. Auckland Now describes, “The descending point of light, which revealed a U-shaped nimbus when zoomed in on, was filmed in the sky west of Auckland about 6pm on ... (appears to be a high altitude aircraft contrail recorded near sunset...NOT a meteor or UFO!) |
| Earth-bound asteroids come from stony asteroids Space Daily Analysis of these dust particles, detailed in a special issue of the journal Science this week, confirms a long-standing suspicion: that the most common meteorites found here on Earth, known as ordinary chondrites, are born from these stony, or S-type, ... |
http://twitter.com/#!/mzmznet تابعني على تويتر مرور نيزك ناري وملتهب فوق مدينة كوسكو في البيرو ولم يستطع العلماء تحديد فيما اذا كان هبط على سطح الأرض ام لا ...
www.youtube.com/watch?v=WKvnWOJNFNI (Peru Aircraft Contrail- NOT meteor; report in Arabic)
NASA meteor expert will address annual meeting at Pisgah Astronomical Research ...
Mountain Xpress (blog)
Dr. William J. Cooke, Lead Scientist in charge of the NASA Meteoroid Environments Office at the Marshall Space Flight Center, will be the keynote speaker at the Friends of PARI Annual Meeting and Symposium Friday, September 9. ...
New Mineral Discovered in Meteorite NWA 1934: Brearleyite
" Researchers at Caltech and several author institutions have named a newly discovered mineral in a meteorite, “brearleyite,” in recognition of University of New Mexico Professor and Chair of Earth and Planetary Sciences Adrian Brearley for his contributions to meteorite mineralogy.
“I’m deeply honored and humbled to say the least,” said Brearley. “It doesn’t happen to too many people.”
Brearleyite is an extremely rare, fine-grained mineral that is a new meteoritic Ca-Al (calcium-aluminum) and Cl-rich phase. The sample was discovered in a carbonaceous chondrite meteorite found in Northwest Africa in 2003. It likely formed from a reaction of krotite with hot Cl-bearing gases or fluids on a small asteroid, 4.56 billion years ago. Krotite is another recently discovered mineral that is named after Dr. Alexandre Krot, a colleague and collaborator of Brearley’s at the University of Hawai’i, Manoa.
The mineral and its name, “brearleyite,” have been approved by the Commission on New Minerals, Nomenclature and Classification (CNMNC) of the International Mineralogical Association. Three round, thin sections of one inch diameter contain the material. "
source:
http://news.unm.edu/2011/08/newly-discovered-mineral-in-meteorite-named-after-unm-professor/ (29th August 2011)
paper: http://www.minsocam.org/msa/ammin/toc/Abstracts/2011_Abstracts/AS11_Abstracts/Ma_p1199_11.pdf
“I’m deeply honored and humbled to say the least,” said Brearley. “It doesn’t happen to too many people.”
Brearleyite is an extremely rare, fine-grained mineral that is a new meteoritic Ca-Al (calcium-aluminum) and Cl-rich phase. The sample was discovered in a carbonaceous chondrite meteorite found in Northwest Africa in 2003. It likely formed from a reaction of krotite with hot Cl-bearing gases or fluids on a small asteroid, 4.56 billion years ago. Krotite is another recently discovered mineral that is named after Dr. Alexandre Krot, a colleague and collaborator of Brearley’s at the University of Hawai’i, Manoa.
The mineral and its name, “brearleyite,” have been approved by the Commission on New Minerals, Nomenclature and Classification (CNMNC) of the International Mineralogical Association. Three round, thin sections of one inch diameter contain the material. "
source:
http://news.unm.edu/2011/08/newly-discovered-mineral-in-meteorite-named-after-unm-professor/ (29th August 2011)
paper: http://www.minsocam.org/msa/ammin/toc/Abstracts/2011_Abstracts/AS11_Abstracts/Ma_p1199_11.pdf
California's second witnessed meteorite fall, Red Canyon Lake now official!
In 2007 Robert Ward spent two weeks triangulating a large fireball captured by the Yuba City Sentinal camera, and witnessed by thousands in California. Ward organized a sizable search exploiting several avenues of rather unusual nature as the region was remote, being some twenty miles from the nearest road. A single stone of 18.4 grams was recovered, an H5 chondrite. Here is the link to the Meteoritical Bulletin regarding this fall. http://www.lpi.usra.edu/meteor/metbull.php?code=53502
Daylight Fireball August 27, 2011
The American Meteor Society has received several reports of a rare daylight fireball over the state of Minnesota, plus southern Manitoba, and western Ontario. This event occurred near 5:15pm CDT Saturday afternoon August 27th. Of the half dozen reports received so far, white is the most mentioned color. The average brightness reported by witnesses was between the light produced by a full moon and that of the sun.In the AMS fireball table, located at:
http://www.amsmeteors.org/fireball2/public.php?start_date=2011-01-01&end_date=2011-12-31
Refer to event #920 for 2011. This reference number is subject to a slight change.
Clear Skies!
Robert Lunsford
American Meteor Society
Washington-Oregon Fireball August 26, 2011
The American Meteor Society has received numerous reports of a very bright fireball over the states of Washington and Oregon, occurring near 11:10pm PDT Friday evening August 26th. Of the two dozen reports received so far, yellow was the most mentioned color. The average brightness reported by witnesses was near the light produce by a half moon.In the AMS fireball table, located at:
http://www.amsmeteors.org/fireball2/public.php?start_date=2011-01-01&end_date=2011-12-31
refer to event #917 for 2011. This reference number is subject to a slight change.
Clear Skies!
Robert Lunsford
American Meteor Society
Meteor Measured From Space Station: How Big Was That Perseid ...
NASA scientists have analyzed the photograph taken by Ron Garan aboard the ...
www.space.com/12699-meteor-measured-space-station-big-pe...
NASA scientists have analyzed the photograph taken by Ron Garan aboard the ...
www.space.com/12699-meteor-measured-space-station-big-pe...
Corsica, South Dakota, US: Meteor flashes across area skies ...
A Mitchell police dispatch log that described a "strange sighting near Corsica" shortly before 10 p.m. Tuesday was one of many such meteor sightings, said Mike ...
www.sott.net/.../234119-Corsica-South-Dakota-US-Meteor-fla...
A Mitchell police dispatch log that described a "strange sighting near Corsica" shortly before 10 p.m. Tuesday was one of many such meteor sightings, said Mike ...
www.sott.net/.../234119-Corsica-South-Dakota-US-Meteor-fla...
Read 'Space Radar Captures Echoes of Meteor Shower' on Yahoo! News. A space radar picked up the sounds of a meteor shower as it delighted skywatchers ...
news.yahoo.com/space-radar-captures-echoes-meteor-shower-...
news.yahoo.com/space-radar-captures-echoes-meteor-shower-...
IMCA EoM : Meteor-Center collection
http://www.meteor-center.com. Expand/Collapse About Me About Me. French meteorite collector and meteorite hunter. Member of IMCA, architect of the first ...
www.encyclopedia-of-meteorites.com/collection.aspx?id=2947
http://www.meteor-center.com. Expand/Collapse About Me About Me. French meteorite collector and meteorite hunter. Member of IMCA, architect of the first ...
www.encyclopedia-of-meteorites.com/collection.aspx?id=2947
NASA Tracks Aug. 8 Meteor to Valley, Looking for Fragments ...
The meteor entered the atmosphere about 54 miles above Lake Erie and traveled south at more than 50000 miles an hour before breaking up over Northeast ...
www.wkbn.com/...8.../MG6tmeEnTUqhe2e_cEiaog.cspx
The meteor entered the atmosphere about 54 miles above Lake Erie and traveled south at more than 50000 miles an hour before breaking up over Northeast ...
www.wkbn.com/...8.../MG6tmeEnTUqhe2e_cEiaog.cspx
Did meteor land here? » Local News » The Herald, Sharon, Pa.
SHENANGO VALLEY — A meteor captured by NASA cameras Aug. ... Pieces of the meteor, or meteorites, were seen “raining down” on Doppler radar out of ...
sharonherald.com/local/x2080078750/Did-meteor-land-here
SHENANGO VALLEY — A meteor captured by NASA cameras Aug. ... Pieces of the meteor, or meteorites, were seen “raining down” on Doppler radar out of ...
sharonherald.com/local/x2080078750/Did-meteor-land-here
Asteroid Sample Nails Meteorite Source (Hayabusa/Itokawa)
Asteroid sample nails meteorite sourceDust shows where most space rocks come from
By Nadia Drake
Science News
August 25, 2011
Scientists have scraped the heavens and seen the solar system in a speck
of dust.
Well, more than 1,500 specks, most less than 50 millionths of a meter in
diameter. Plucked from the surface of the asteroid Itokawa by Japan's
Hayabusa spacecraft, the tiny grains carry a record of the solar
systemâ' early days. Now, scientists have decoded the particles and read
in them a tale of the asteroid's history, a story that spans billions of
years, from the asteroid's birth to its future demise....
Technology Review (MIT)
August 22, 2011
Life-carrying rocks ejected from Earth by asteroid impacts could have
made their way to Jupiter and beyond, say astronomers
Astronomers have long studied meteorites that have clearly come from the
Moon and Mars. These are the result of massive asteroid impacts which
eject material with such force that it ends up in interplanetary space,
eventually being washed up here....
August 22, 2011
Life-carrying rocks ejected from Earth by asteroid impacts could have
made their way to Jupiter and beyond, say astronomers
Astronomers have long studied meteorites that have clearly come from the
Moon and Mars. These are the result of massive asteroid impacts which
eject material with such force that it ends up in interplanetary space,
eventually being washed up here....
[IMO-News] Meteor Activity Outlook for August 27- September 2, 2011
During this period the moon reaches its new phase on Monday August 29th. At this time the moon will lie near the sun and will not be visible at night. Next week the waxing crescent moon will enter the evening skies but will set soon after dusk, allowing meteor observers to view under dark conditions during the late night and early morning hours. The estimated total hourly rates for evening observers this week is near six as seen from the northern hemisphere and three as seen from the southern hemisphere. For morning observers the estimated total hourly rates should be near fifteen as seen from mid-northern latitudes and seven from mid-southern latitudes. 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.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 August 27/28. 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 showers are expected to be active this week:
The last of the August Draconids (AUD) will occur this weekend from a radiant located at 18:39 (280) +63. This position lies in southeastern Draco, five degrees southwest of the fourth magnitude star Delta Draconis. Maximum activity occurred on August 21st so rates would be low, less than one per hour at best. With an entry velocity of 23 km/sec. most of these meteors will appear to move slowly. The radiant is best placed near 2200 Local Daylight Time (10pm LDT) when it lies highest in the sky. Due to its high northern declination this shower is not well seen from the southern hemisphere.
The wide Antihelion (ANT) radiant is now centered at 23:08 (347) -04. This area of the sky lies on the Pisces/Aquarius border, twenty degrees south of the second magnitude star Markab (Alpha Pegasi). This radiant is best placed near 0200 LDT, when it lies on the meridian and is located highest in the sky. Due to the large size of this radiant, any meteor radiating from Aquarius, western Pisces, western Cetus, or southern Pegasus could be a candidate for this shower. Rates at this time should be near one per hour as seen from the northern hemisphere and two per hour as seen from south of the equator. With an entry velocity of 30 km/sec., the average Antihelion meteor would be of medium-slow speed.
The Aurigids (AUR) are first seen on August 28 and peak on Thursday morning September 1st. On that morning of maximum activity, the radiant will be located at 06:02 (091) +39. This position lies in central Auriga, two degrees north of the third magnitude Theta Aurigae. The radiant is best placed during the last hour before the start of morning twilight when it lies highest in a dark sky. Hourly rates this weekend will be very low, less than one per hour no matter your location. At maximum, hourly rates during the last hour before dawn will range from 2-5 as seen from the northern hemisphere. South of the equator, this shower is not well seen as it lies low in the northern sky during the morning hours. With an entry velocity of 67 km/sec., most activity from this radiant would be swift.
As seen from the mid-northern hemisphere (45N) one would expect to see approximately fourteen sporadic meteors per hour during the last hour before dawn as seen from rural observing sites. Evening rates would be near five per hour. As seen from the mid-southern hemisphere (45S), morning rates would be near five 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.
The list below presents a condensed version of the expected activity this week.
Rates and positions are exact for Saturday night/Sunday morning.
August Draconids (AUD) 18:39 (280) +63 Velocity - 23km/sec
Northern Hemisphere - <1 per hour Southern Hemisphere - <1 per hour
Antihelion (ANT) 23:08 (347) -04 Velocity - 30km/sec
Northern Hemisphere - 1 per hour Southern Hemisphere - 2 per hour
Aurigids (AUR) 06:02 (091) +39 Velocity - 67km/sec
Northern Hemisphere - <1 per hour Southern Hemisphere - <1 per hour
Clear Skies!
Robert Lunsford
International Meteor Organization
China: "Super UFO" (Or Possible Fireball?) Spotted in Both Beijing ...
On the night of August 20th, numerous people and pilots in both Beijing and Shanghai reported seeing a strange ball of light that grew bigger and bigger over ...
www.sott.net/.../234138-China-Super-UFO-Or-Possible-Fireba...
| 'Too Bright' Meteor Streaks Over Atlanta Skies (NASA VIDEO and PHOTOS) International Business Times By IBTimes Staff Reporter | August 30, 2011 12:06 AM EDT A very bright meteorshowed up over the skies of Atlanta, Georgia, on the night of Aug. 28, 2011, NASA scientists revealed on Monday. NASA said that the meteor was “too bright for the all sky ... |
Belfast arrived from google.co.uk on "Latest Worldwide Meteor/Meteorite News" by searching for did anyone see a flash over northern ireland on the 23rd august ...
lunarmeteoritehunters.blogspot.com/.../mbiq-indicates-meteor-...
|
 | Bright Meteor Lights Up Atlanta Skies3 sec This video shows a very bright meteor that streaked over the skies of Atlanta, Ga., on the night of Aug. 28, 2011. The view is from ...youtube.com |
23 April 2011
Meteor Activity Outlook for April 23-29, 2011
Meteor Activity Outlook for April 23-29, 2011
by Robert Lunsford
During this period the moon reaches its last quarter phase on Monday April 25.
At this time the moon will lie ninety degrees east of the sun and will rise near
0100 LDT (Local Daylight Time) for those situated in the mid-northern latitudes.
While the moonlight will cause interference for meteor observing, the effects
will be much less than when the moon is near its full phase. The estimated total
hourly rates for evening observers this week is near two as seen from the
northern hemisphere and three as seen from the southern hemisphere. For morning
observers the estimated total hourly rates should be near nine from the northern
hemisphere and twelve as seen from south of the equator. 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.
Morning rates are reduced 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 April 23/24.
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 showers are expected to be active this week:
The elusive Pi Puppids (PPU) are now active from a radiant located at 07:20
(110) -45. This area of the sky lies in south-central Puppis near the third
magnitude star Sigma Puppis. This radiant is best placed as soon as it becomes
dark as it culminates during the afternoon hours when the sun is still above the
horizon. These meteors are nearly non-existent away from the night of April
24th. Even on that night it would be lucky to spot just one, especially from the
northern hemisphere, where the radiant lies low in the southwest at dusk. This
shower has produced outbursts in the past so it should be monitored whenever
possible, especially from the southern hemisphere. With an entry velocity of
only 18 km/sec., the average Pi Puppid meteor would crawl through the sky at a
snails pace.
Studies of the IMO video database by Sirko Molau and Juergen Rendtel has
revealed a weak radiant active at this time in the constellation of Virgo. Video
data shows that the Sigma Leonids (SLE) are active from April 18th through the
25th with maximum activity falling on the 21st. The radiant is currently located
at 13:46 (207) +04. This position lies in eastern Virgo, five degrees northwest
of the fourth magnitude star Tau Virginis. The radiant is best placed near
midnight LDT, when it lies highest above the horizon. At 20km/sec. the Sigma
Leonids would produce obvious, slow meteors. Expected rates are less than one
per hour no matter your location.
There is also a second new radiant active in Virgo this time of year. Video data
shows that the h Virginids (HVR) are active from April 22-25 with maximum
activity occurring on the 22nd. On the evening of the 21st (22nd UT), the
radiant is located at 14:16 (214) -11. This position lies on the Virgo/Libra
border, two degrees southeast of the fourth magnitude star Kappa Virginis. The
radiant is best placed near 0200 LDT, when it lies on the meridian and is
highest above the horizon. At 24km/sec. the h Virginids would produce more slow
meteors. Expected rates would also be less than one per hour no matter your
location.
The wide Antihelion (ANT) radiant is now centered at 15:04 (226) -18. This area
of the sky lies in central Libra, four degrees southeast of the third magnitude
star Zubenelgenubi (Alpha Librae). This radiant is best placed near 0200 LDT
when it lies on the meridian and is located highest in the sky. Due to the large
size of this radiant, any meteor radiating from Libra, extreme eastern Hydra,
northern Lupus, or western Scorpius could be a candidate for this shower. Rates
at this time should be near one per hour as seen from the northern hemisphere
and two per hour as seen from south of the equator. With an entry velocity of 30
km/sec., the average Antihelion meteor would be of medium-slow speed.
The major shower known as the Lyrids (LYR) are active from April 16th through
the 25th. Maximum activity occurs on the 23rd. The radiant is currently located
at 18:13 (273) +32. This position lies on Hercules/Lyra border, nine degrees
southwest of the brilliant blue-white zero magnitude magnitude star known as
Vega (Alpha Lyrae). The radiant is best placed during the last dark hour before
dawn, when it lies highest above the horizon. At 48km/sec. the Lyrids would
produce meteors of medium velocity. Expected rates this weekend are near two per
hour during the last dark hour before dawn. Due to the northerly declination of
the radiant, these meteors are not well seen from high southern latitudes.
The team of Sirko Molau and Juergen Rendtel have a third weak radiant active at
this time in the constellation of Cygnus. Video data shows that the Nu Cygnids
(NCY) are active from April 18th through May 7th. Maximum activity occurred on
the morning of April 20th. The radiant is currently located at 20:50 (312) +42.
This position lies in central Cygnus, three degrees south of the first magnitude
star Deneb (Alpha Cygni). The radiant is best placed during the last dark hour
before dawn, when it lies highest above the horizon in a dark sky. At 42km/sec.
the Nu Cygnids would produce meteors of medium velocity. Expected rates are near
one per hour during the last dark hour before dawn. Due to the northerly
declination of the radiant, these meteors are not well seen from south of the
equator.
Activity from the Eta Aquariids (ETA) may be seen late next week. This major
shower is active from April 28 through May 21. This shower is caused by
particles from Halley's Comet, produced in Earth-crossing orbits many centuries
ago. We pass closest to these orbits from May 5 through the 9th. During this
period the Eta Aquariids are at their best, capable of producing ZHR's of
seventy. The actual visible rates are most often less than half this figure due
to the low altitude of the radiant at dawn. Observed hourly rates at maximum
normally vary from zero at 60 degrees north latitude to 25 near the equator and
back down to near zero again in Antarctica, where the radiant elevation is very
low. Hourly rates this week are anywhere from zero to two per hour depending on
your latitude and observing conditions. Rates will increase significantly as we
approach the May 7 maximum. On April 28, the radiant will be located at 22:12
(333) -04. This area of the sky is located in northern Aquarius, three degrees
southwest of the fourth magnitude star Gamma Aquarii. The best time to view this
activity is just before the start of morning twilight, when the radiant lies
highest in a dark sky. No matter your location these meteors will appear from
the eastern sky and shoot in all
directions. If the radiant has sufficient altitude Eta Aquariid meteors can also
be seen shooting down toward the eastern horizon. With an entry velocity of 67
kilometers per second, a majority of these meteors will appear to move swiftly
with a high percentage of the bright meteors leaving persistent trains.
Surprisingly, this shower produces very few fireballs.
As seen from the mid-northern hemisphere (45N) one would expect to see
approximately six sporadic meteors per hour during the last hour before dawn as
seen from rural observing sites. Evening rates would be near one per hour. As
seen from the mid-southern hemisphere (45S), morning rates would be near nine
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. Morning 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.
Pi Puppids (PPU) 07:20 (110) -45 Velocity - 18km/sec
Northern Hemisphere - <1 per hour Southern Hemisphere - <1 per hour
Sigma Leonids (SLE) 13:46 (207) +04 Velocity - 20km/sec
Northern Hemisphere - <1 per hour Southern Hemisphere - <1 per hour
h Virginids (HVR) 14:16 (214) -11 Velocity - 24km/sec
Northern Hemisphere - <1 per hour Southern Hemisphere - <1 per hour
Antihelion (ANT) 15:04 (226) -18 Velocity - 30km/sec
Northern Hemisphere - 1 per hour Southern Hemisphere - 2 per hour
Lyrids (LYR) 18:13 (273) +32 Velocity - 48km/sec
Northern Hemisphere - 2 per hour Southern Hemisphere - <1 per hour
Nu Cygnids (NCY) 20:50 (312) +42 Velocity - 42km/sec
Northern Hemisphere - <1 per hour Southern Hemisphere - <1 per hour
Eta Aquariids (ETA) 22:12 (333) -04 Velocity - 67km/sec
Northern Hemisphere - <1 per hour Southern Hemisphere - 1 per hour
Clear Skies!
Robert Lunsford
International Meteor Organization
At this time the moon will lie ninety degrees east of the sun and will rise near
0100 LDT (Local Daylight Time) for those situated in the mid-northern latitudes.
While the moonlight will cause interference for meteor observing, the effects
will be much less than when the moon is near its full phase. The estimated total
hourly rates for evening observers this week is near two as seen from the
northern hemisphere and three as seen from the southern hemisphere. For morning
observers the estimated total hourly rates should be near nine from the northern
hemisphere and twelve as seen from south of the equator. 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.
Morning rates are reduced 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 April 23/24.
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 showers are expected to be active this week:
The elusive Pi Puppids (PPU) are now active from a radiant located at 07:20
(110) -45. This area of the sky lies in south-central Puppis near the third
magnitude star Sigma Puppis. This radiant is best placed as soon as it becomes
dark as it culminates during the afternoon hours when the sun is still above the
horizon. These meteors are nearly non-existent away from the night of April
24th. Even on that night it would be lucky to spot just one, especially from the
northern hemisphere, where the radiant lies low in the southwest at dusk. This
shower has produced outbursts in the past so it should be monitored whenever
possible, especially from the southern hemisphere. With an entry velocity of
only 18 km/sec., the average Pi Puppid meteor would crawl through the sky at a
snails pace.
Studies of the IMO video database by Sirko Molau and Juergen Rendtel has
revealed a weak radiant active at this time in the constellation of Virgo. Video
data shows that the Sigma Leonids (SLE) are active from April 18th through the
25th with maximum activity falling on the 21st. The radiant is currently located
at 13:46 (207) +04. This position lies in eastern Virgo, five degrees northwest
of the fourth magnitude star Tau Virginis. The radiant is best placed near
midnight LDT, when it lies highest above the horizon. At 20km/sec. the Sigma
Leonids would produce obvious, slow meteors. Expected rates are less than one
per hour no matter your location.
There is also a second new radiant active in Virgo this time of year. Video data
shows that the h Virginids (HVR) are active from April 22-25 with maximum
activity occurring on the 22nd. On the evening of the 21st (22nd UT), the
radiant is located at 14:16 (214) -11. This position lies on the Virgo/Libra
border, two degrees southeast of the fourth magnitude star Kappa Virginis. The
radiant is best placed near 0200 LDT, when it lies on the meridian and is
highest above the horizon. At 24km/sec. the h Virginids would produce more slow
meteors. Expected rates would also be less than one per hour no matter your
location.
The wide Antihelion (ANT) radiant is now centered at 15:04 (226) -18. This area
of the sky lies in central Libra, four degrees southeast of the third magnitude
star Zubenelgenubi (Alpha Librae). This radiant is best placed near 0200 LDT
when it lies on the meridian and is located highest in the sky. Due to the large
size of this radiant, any meteor radiating from Libra, extreme eastern Hydra,
northern Lupus, or western Scorpius could be a candidate for this shower. Rates
at this time should be near one per hour as seen from the northern hemisphere
and two per hour as seen from south of the equator. With an entry velocity of 30
km/sec., the average Antihelion meteor would be of medium-slow speed.
The major shower known as the Lyrids (LYR) are active from April 16th through
the 25th. Maximum activity occurs on the 23rd. The radiant is currently located
at 18:13 (273) +32. This position lies on Hercules/Lyra border, nine degrees
southwest of the brilliant blue-white zero magnitude magnitude star known as
Vega (Alpha Lyrae). The radiant is best placed during the last dark hour before
dawn, when it lies highest above the horizon. At 48km/sec. the Lyrids would
produce meteors of medium velocity. Expected rates this weekend are near two per
hour during the last dark hour before dawn. Due to the northerly declination of
the radiant, these meteors are not well seen from high southern latitudes.
The team of Sirko Molau and Juergen Rendtel have a third weak radiant active at
this time in the constellation of Cygnus. Video data shows that the Nu Cygnids
(NCY) are active from April 18th through May 7th. Maximum activity occurred on
the morning of April 20th. The radiant is currently located at 20:50 (312) +42.
This position lies in central Cygnus, three degrees south of the first magnitude
star Deneb (Alpha Cygni). The radiant is best placed during the last dark hour
before dawn, when it lies highest above the horizon in a dark sky. At 42km/sec.
the Nu Cygnids would produce meteors of medium velocity. Expected rates are near
one per hour during the last dark hour before dawn. Due to the northerly
declination of the radiant, these meteors are not well seen from south of the
equator.
Activity from the Eta Aquariids (ETA) may be seen late next week. This major
shower is active from April 28 through May 21. This shower is caused by
particles from Halley's Comet, produced in Earth-crossing orbits many centuries
ago. We pass closest to these orbits from May 5 through the 9th. During this
period the Eta Aquariids are at their best, capable of producing ZHR's of
seventy. The actual visible rates are most often less than half this figure due
to the low altitude of the radiant at dawn. Observed hourly rates at maximum
normally vary from zero at 60 degrees north latitude to 25 near the equator and
back down to near zero again in Antarctica, where the radiant elevation is very
low. Hourly rates this week are anywhere from zero to two per hour depending on
your latitude and observing conditions. Rates will increase significantly as we
approach the May 7 maximum. On April 28, the radiant will be located at 22:12
(333) -04. This area of the sky is located in northern Aquarius, three degrees
southwest of the fourth magnitude star Gamma Aquarii. The best time to view this
activity is just before the start of morning twilight, when the radiant lies
highest in a dark sky. No matter your location these meteors will appear from
the eastern sky and shoot in all
directions. If the radiant has sufficient altitude Eta Aquariid meteors can also
be seen shooting down toward the eastern horizon. With an entry velocity of 67
kilometers per second, a majority of these meteors will appear to move swiftly
with a high percentage of the bright meteors leaving persistent trains.
Surprisingly, this shower produces very few fireballs.
As seen from the mid-northern hemisphere (45N) one would expect to see
approximately six sporadic meteors per hour during the last hour before dawn as
seen from rural observing sites. Evening rates would be near one per hour. As
seen from the mid-southern hemisphere (45S), morning rates would be near nine
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. Morning 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.
Pi Puppids (PPU) 07:20 (110) -45 Velocity - 18km/sec
Northern Hemisphere - <1 per hour Southern Hemisphere - <1 per hour
Sigma Leonids (SLE) 13:46 (207) +04 Velocity - 20km/sec
Northern Hemisphere - <1 per hour Southern Hemisphere - <1 per hour
h Virginids (HVR) 14:16 (214) -11 Velocity - 24km/sec
Northern Hemisphere - <1 per hour Southern Hemisphere - <1 per hour
Antihelion (ANT) 15:04 (226) -18 Velocity - 30km/sec
Northern Hemisphere - 1 per hour Southern Hemisphere - 2 per hour
Lyrids (LYR) 18:13 (273) +32 Velocity - 48km/sec
Northern Hemisphere - 2 per hour Southern Hemisphere - <1 per hour
Nu Cygnids (NCY) 20:50 (312) +42 Velocity - 42km/sec
Northern Hemisphere - <1 per hour Southern Hemisphere - <1 per hour
Eta Aquariids (ETA) 22:12 (333) -04 Velocity - 67km/sec
Northern Hemisphere - <1 per hour Southern Hemisphere - 1 per hour
Clear Skies!
Robert Lunsford
International Meteor Organization
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