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Post Info TOPIC: September 2011


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RE: September 2011
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The autumnal equinox arrives at 5:05 a.m. Sept. 23 this year. The word equinox means "equal night." There are only two days each year, the autumnal and vernal equinoxes, when everyone on Earth, except at the poles, will experience the sun rising due east and setting due west and equal days and nights. Due to our elliptical orbit around the sun, the days and nights are exactly equal a couple days after fall starts.
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Longer, clearer nights ahead for autumn stargazing

The summer constellations still dominate much of Wichita Falls evening sky with the "Summer Triangle" dazzling bright overhead as soon as evening twilight ends. Just find the three brightest stars you can see at the top of the celestial dome and that's it. It's one of the best tools for helping you navigate that part of the sky because the three stars you see, Vega, Altair and Deneb, are all the brightest stars in their respective constellations - Lyra the Harp, Aquila the Eagle and Cygnus the Swan, otherwise known as the Northern Cross. From those three constellations you can branch out with your eyes to find surrounding fainter constellations like the delightful Delphinus the Dolphin.
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Mercury: at magnitude 0.2, starts the month in the constellation of Leo.  Mercury is at its Greatest Western elongation (18 Degrees) on the 3rd September. The New Moon is close to Mercury at 7:35 UT, 27th September.
(On September 1st, RA= 9h30m15s  Dec=+14°04.0' (J2000) Distance=0.868AU  Elongation= 18°   Phase k=35%  Diameter=7.7")

Venus: is at magnitude -3.9. The planet is in constellation Leo at the start of the month. It is best seen from 6.4h - 18.7h. Venus is in conjunction in Right Ascension with Saturn at 11:06 UT, 30th September.
(On September 14th, RA=11h57m40s  Dec= +1°41.5' (J2000) Distance=1.704AU  Elongation=  8°   Phase k=99%  Diameter=9.8")

  phase.gif


Earth: Autumn Equinox at 9:04.6 UT, 23rd September   

The Moon: First Quarter Moon (declination: -22.89°) at 17:39.3 UT, 4th September. Lunar Apogee (apparent diameter: 29'54.0") at 6:12.5 UT, 15th September. Lunar Perigee (apparent diameter: 34'01.7") at 0:56.8 UT, 28th September. Last Quarter Moon (declination: 22.59°) at 13:38.6 UT, 20th September. New Moon (diameter: 33.390', declination: -6.01°) at 11:08.7 UT, 27th September. Full Moon (diameter: 29.648', declination: 0.35°) at 9:26.7 UT, 12th September.

Mars: at magnitude 1.4 starts the month in the constellation Gemini. Northern Spring on Mars begins on the 13th September.
(On September 1st,RA= 7h20m45s  Dec=+22°50.7' (J2000) Distance=1.992AU  Elongation= 50°   Phase k=93%  Diameter=4.7")

Jupiter: is in the constellation Aries. At magnitude -2.5, the planet is best seen from  22.6h - 3.7h. Jupiter is stationary: Getting Retrograde (relative to equator) at 17:39 UT, 30th August, 2011.
(On September 1st, RA= 2h32m52s  Dec=+13°33.3' (J2000) Distance=4.404AU  Elongation=118°   Diameter=44.7")

Saturn: at magnitude 0.9 sits in the constellation Virgo. The planet is best seen from 19.8h -20.0h.
(
On September 1st,RA=12h59m11s  Dec= -3°50.3' (J2000) Distance=10.452AU  Elongation= 36°   Diameter=15.8")

Uranus: is in the constellation Pisces. Uranus at magnitude 5.7, has a bluish-green hue and appears 3.7 arcseconds wide.  Uranus is at Opposition on the 25th September.
(On September 1st, RA= 0h13m35s  Dec= +0°38.0' (J2000) Distance=19.164AU  Elongation=155°   Diameter=3.7")

Neptune: is at magnitude 7.8 in the constellation Aquarius. Neptune made its closest approach to the Earth (28.995 AU) on the 22nd August, 2011.
(
On September 1st, RA=22h05m43s  Dec=-12°18.3' (J2000) Distance=29.009AU  Elongation=171°   Diameter=2.3")

Pluto: is in the constellation Sagittarius (mag 14.0). Normally, a finder chart is necessary to help in identifying the 0.1" diameter dwarf planet. The dwarf planet is best seen from 21.1h - 3.1h.  Pluto is stationary on the 16th September.
(On September 1st, RA=18h20m11s  Dec=-19°03.1' (J2000) Distance=31.622AU  Elongation=117°   Diameter=0.1")

The Sun enters the zodiac sign Libra at 9:04.6 UT, 23rd September    .



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Highlights

Autumnal Equinox
On this day, the Sun rises directly in the East, and sets directly in the West. At the South Pole, the Sun will begin to rise after six months of darkness.

Watch out for the zodiacal lights, also known as the false dawn, which maybe visible about two hours before sunrise from dark sites during the latter part of September.



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Meteor Showers

There are no major meteor showers this month...
September is a month with the best sporadic rates and a few mysterious minor showers.
The Alpha Aquarids are active from Aug. 25 to Sept. 5, normally with a ZHR of 10. this year it may be quite active
The Delta Aquarids are active September 5 thru October 10, with a ZHR of 6. It is on view until dawn. Faint, swift meteors are likely and the brighter ones may leave persistent trains.
These two form part of what is known as the Auriga-Cassiopiea-Perseus-Aries-Triangulum radiants, active from late August until mid-October.
The Piscids, active September 1 - 30, have a ZHR of 3.
The Sextanids are active September 9 through October 9. Though, this one is more of a radio/radar showerA new meteor shower,called the September Taurids, might peak this month on the evening of September 13 - 14, 2004. The exact date and time of maximum activity, however, are uncertain. The radiant, which lies between the Pleiades and Hyades star clusters, produces only 7 meteors per hour, with an average brightness of magnitude 2.7.

Shower Activity Period Maximum Radiant Velocity ZHR
  DateR.A. Dec.km/s  
Aug 25 - Sept. 5
1 September
5.5h
41°
66.0km/s
10
October Arietids
Sept-Oct
8 September
    
Piscids
Sept 1 - 30
19 September
0.7h
9.2°
30.0km/s
5
SextanidsSept-Oct25 September    
Andromedids 26 September 58.1°59.3km/s 
Gamma Piscids23 - 2828 September23.4h11.0°19.2km/s4
Pi Virginids
 
29 September
12.6h
-16.0°
8.6km/s
3


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