Oct 23-30 Meteors

The last week of October witnessed a gradual decrease in meteor rates. Much of the slow-down was due to the Orionids being past their peak. Also the Taurids are past their peak as well.

Obs  Date(UT)      Time    TOT SPO NTA STA ORI EGE LMI SSA OUI ETT BCN
TUS  2011-10-30   10h 40m   30  21  2   2   4   -   -   -   -   1   0
TUS  2011-10-29   04h 38m   25  13  0   4   8   -   -   -   -   0   0
TUS  2011-10-28   09h 30m   43  17  5   3   15  -   -   -   1   1   1
TUS  2011-10-27   09h 52m   64  23  1   5   31  2   1   -   0   2   0
TUS  2011-10-26   11h 16m   52  17  1   2   25  3   1   -   0   0   3
TUS  2011-10-25   09h 52m   54  16  1   4   28  1   2   -   0   0   2
TUS  2011-10-24   10h 41m   66  19  2   3   38  2   0   1   0   1   -
TUS  2011-10-23   10h 05m   66  18  1   3   43  0   1   0   0   -   -

SAL3 - SALSA3 camera in Tucson (Carl Hergenrother)
ALLS - Near all-sky camera in Tucson (Carl Hergenrother)
VIST - Visual observations from Tucson (Carl Hergenrother)
VISH - Visual observations from Hermosillo (Salvador Aguirre)
HERM - PARENI camera in Hermosillo (Salvador Aguirre)
SDG - Camera in San Diego operated by Bob Lunsford
Time - Total amount of time each camera looked for meteors
TOT - Total number of meteors detected
SPO - Sporadics (meteors not affiliated with any particular meteor shower)
NTA - Northern Taurids 
STA - Southern Taurids 
ORI - Orionids 
EGE - Epsilon Geminids 
LMI - Leo Minorids
SSA - Sigma Arietids
OUI - October Ursa Minorids
ETT - Eta Taurids
BCN - Beta Cancrids

Oct 17-24 Meteors

The past week witnessed the annual peak of the Orionid meteor shower. The Orionids are the result of dust created by Comet Halley over 2000-3000 years ago. Visual observers recorded peak ZHRs of only 20-25 meteors per hour. This is less than the peak from the last three years with rates of 30-50 per hour and a huge step down from 2007 when rates as high as 70 per hour were seen.

Unfortunately I missed most of the shower. For three nights was observing some of the objects that create meteor showers rather than the shower itself. The plan was to leave my meteor camera in auto mode but things didn’t work out that way. As a result my system missed three nights of the Orionid peak. I’ll have to figure out how to prevent this in the future.

Obs  Date(UT)      Time    TOT SPO NTA STA ORI TUM EGE LMI
TUS  2011-10-24   10h 41m   66  21  2   3   38  -   2   0
TUS  2011-10-23   10h 05m   66  17  2   3   43  -   0   1
TUS  2011-10-22   10h 07m   76  18  4   3   48  -   1   2
TUS  2011-10-21   00h 00m   -   -   -   -   -   -   -   -
TUS  2011-10-20   00h 00m   -   -   -   -   -   -   -   -
TUS  2011-10-19   00h 00m   -   -   -   -   -   -   -   -
TUS  2011-10-18   10h 07m   48  18  2   5   20  1   2   -
TUS  2011-10-17   09h 52m   29  16  3   1   7   0   2   -

SAL3 - SALSA3 camera in Tucson (Carl Hergenrother)
ALLS - Near all-sky camera in Tucson (Carl Hergenrother)
VIST - Visual observations from Tucson (Carl Hergenrother)
VISH - Visual observations from Hermosillo (Salvador Aguirre)
HERM - PARENI camera in Hermosillo (Salvador Aguirre)
SDG - Camera in San Diego operated by Bob Lunsford
Time - Total amount of time each camera looked for meteors
TOT - Total number of meteors detected
SPO - Sporadics (meteors not affiliated with any particular meteor shower)
NTA - Northern Taurids 
STA - Southern Taurids 
ORI - Orionids 
TUM - Tau Ursa Majorids 
EGE - Epsilon Geminids
LMI - Leo Minorids

Meteor Activity Outlook for October 12-28, 2011

Sorry, I’m a few days late posting this…

The following is a slightly edited version of Bob Lunsford’s excellent weekly summary of meteor activity. The original version can be found at the American Meteor Society’s site.

Meteor activity in general increases in October when compared to September. A major shower (the Orionids) is active most of the month along with many minor showers. Both branches of the Taurids become more active as the month progresses, providing slow, graceful meteors to the nighttime scene. The Orionids are the big story of the month reaching maximum activity on the 22nd. This display can be seen equally well from both hemispheres which definitely helps out observers located in the sporadic-poor southern hemisphere this time of year.

During this period the moon reaches its new phase on Wednesday October 26th. At this time the moon will lie near the sun and will be invisible at night. This weekend the waning crescent moon will rise during the late morning hours and will not interfere with meteor observing. The estimated total hourly rates for evening observers this week is near four 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 thirty three as seen from mid-northern latitudes and twenty eight 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 October 22/23. These positions do not change greatly day to day so the listed coordinates may be used during this entire period.

The following showers are expected to be active this week:

A new radiant has been discovered by Sirko Molau and Juergen Rendtel in Draco which is active during this period. The October Ursa Minorids (OUI) are active from October 16-28, with maximum occurring on the 24th. The current radiant position lies at 18:18 (275) +75. This position lies in eastern Draco two degrees north of the faint star Chi Draconis. Older radiant positions were a bit further west in Ursa Minor.  The radiant is best placed just as soon as it becomes dark, when it lies highest in a dark sky. Meteors from the October Ursa Minorids strike the atmosphere at 28km/sec., which would produce meteors of slow velocity. Expected rates would be less than one per hour, as seen from the northern hemisphere. Activity from this shower is not visible in the southern hemisphere due to the high northerly location of the radiant.

The Northern Taurids (NTA) are now active from a large radiant centered at 02:48 (042) +20, which lies in central Aries, six degrees west of the fourth magnitude star Delta Arietis. The radiant is best placed near 0200 local daylight time (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 center of the Southern Taurid (STA) radiant now lies 02:51 (043) +11. This position lies on the Aries/Cetus border, three degrees east of the fourth magnitude star Mu Ceti. The radiant is best placed near the meridian at 0200 LDT, but activity may be seen all night long. Striking the atmosphere at 29 km/sec., the average Southern Taurid meteor travels slowly through the skies. Rates should be near two per hour no matter your location.

A new radiant has been discovered in Taurus which is active during this period. The Eta Taurids (ETT) are active from October 24 through November 3, with maximum occurring on the 24th. At maximum, the  radiant position lies at 03:42 (056) +24, which lies in western Taurus in the area of sky occupied by the famous Pleiades star cluster. The radiant is best placed near 0300 LDT, when it lies highest above the horizon. Meteors from the Eta Taurids strike the atmosphere at 47km/sec., which would produce meteors of average velocity. Expected rates would be less than one per hour, no matter your location.

The Orionids (ORI) reach maximum activity on morning of October 22nd. Rates are expected to peak between 10-20 shower members per hour on that morning. Moonlight from the waning crescent moon will reduce activity slightly. The radiant is currently located at 06:28 (97) +16. This position lies in western Gemini, close to the second magnitude star Alhena (Gamma Geminorum). The radiant is best placed near 0500 LDT, when it lies highest above the horizon. At 67km/sec., the average Orionid is swift.

The Epsilon Geminids (EGE) are active from October 16th through the 27th. Maximum activity occurred on the 19th. The radiant is currently located at 07:02 (105) +27. This position lies in central Gemini, three degrees northeast of the third magnitude star Epsilon Geminorum. This position is also close to the Orionid radiant so care must taken for correct shower association, especially since they have similar velocities. The Orionids will be more numerous. Current rates are near one per hour. The radiant is best placed near 0600 LDT, when it lies highest above the horizon. At 70km/sec., the average Epsilon Geminid is swift.

Recent studies by Sirko Molau and Juergen Rendtel have revealed a radiant in Canis Minor that is active this time of year. Old radiant positions placed it within the borders of Cancer. The Beta Cancrids (BCN) are active from October 25 through November 3, with maximum occurring on the 27th. The radiant position at maximum lies at 07:22 (111) -06, which lies in southwestern Canis Minor, three degrees west of the brilliant zero magnitude star Procyon (Alpha Canis Minoris. The radiant is best placed near 0600 LDT, when it lies highest above the horizon.Meteors from the Beta Cancrids strike the atmosphere at 65km/sec., which would produce meteors of swift velocity. Expected rates would be less than one per hour, no matter your location.

The Leonis Minorids (LMI) are active from October 16-27 with maximum activity occurring on October 23rd. ZHR’s are usually low but the radiant is far removed from the Orionids and Epsilon Geminids so that any possible shower members should be easily identified. Hourly rates should be near one this weekend. This radiant is currently located at 10:43 (161) +36, which places it in northeastern Leo Minor, two degrees east of the fourth magnitude star Beta Leonis Minoris . The radiant is best placed just before dawn when it lies highest in a dark sky. This shower is better situated for observers situated in the northern hemisphere where the radiant rises far higher into the sky before the start of morning twilight. At 60km/sec., the average Leonis Minorid is swift.

As seen from the mid-northern hemisphere (45N) one would expect to see approximately ten sporadic meteors per hour during the last hour before dawn as seen from rural observing sites. Evening rates would be near three 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.

Shower Name                 RA     DEC   Vel     Rates
                                         km/s   NH    SH
OUI Oct Ursa Minorids     18h 18m  +75    28    <1    <1
NTA Northern Taurids      02h 48m  +20    29     2     2
STA Southern Taurids      02h 51m  +11    27     2     2 
ETT Eta Taurids           03h 42m  +24    47    <1    <1 
ORI Orionids              06h 28m  +16    61    15    15
EGE Epsilon Geminids      07h 02m  +27    70     1     1
BCN Beta Cancrids         07h 22m  -06    65    <1    <1
LMI Leo Minorids          10h 43m  +36    60     2     2

RA - Right Ascension
DEC - Declination
Vel - Velocity relative to Earth (in km per sec)
Rates - Rate of visible meteors per hour from a dark site
NH - Northern Hemisphere
SH - Southern Hemisphere

In The Sky This Month – October 2008

This feature highlights a number of meteor showers, comets and asteroids which are visible during the month of October 2008.

Planets

Venus is the very bright “star” close to the southwestern horizon for an hour or so after sunset. When it is above the horizon, it is the brightest “star” in the sky.

Jupiter is located in the constellation of Sagittarius. At the beginning of the month, Jupiter starts the night almost due south in the southern part of the sky. As the night progresses, it slowly moves to the west and sets around 11 pm local time. By Halloween, Jupiter starts the night low in the southwestern sky and sets around 9 pm. Jupiter is fainter than Venus but brighter than any star.

Saturn is located low in the east just before sunrise. It is as bright as many of the brightest stars.

Mercury is too close to the Sun at the beginning of the month. By the mid-month, it will become observable as a bright “star” low in the ESE sky just before sunrise. It reaches the best time for observation on Oct 22 when it is furthest from the Sun. It will continue to be observable for the rest of the month as it slowly drops towards the horizon.

Mars is too close to the Sun to be seen.

Meteors

October sees a number of meteor showers including one of the year’s best, the Orionids.

Sporadic Meteors

Sporadic meteors are not part of any known meteor shower. They represent the background flux of meteors. Except for the few days per year when a major shower is active, most meteors that are observed are sporadics. This is especially true for meteors observed during the evening. During October, ten (10) or so Sporadic meteors can be observed per hour from a dark moonless sky.

Major Meteor Showers

Orionids (ORI)

The Orionids are the best shower during the month of October. When you see an Orionid meteor, you are seeing small pieces of Halley’s Comet which were released thousands of years ago. The Eta Aquarids of May are also from Comet 1P/Halley.

This shower is active from Oct 3 to Nov 11 with a broad peak between Oct 18 and 24. They radiate from northern Orion. During their peak, rates can be as high as 30-100 meteors per hour. Last year rates reached 70 meteors per hour and similar circumstances are predicted for this year with the best time being the morning of Oct 19 (for the US). However, a bright quarter Moon will wash out many of the fainter meteors resulting in smaller rates. Much of this year’s ORI meteors were released by Comet Halley between 1265 BC and 910 BC (for some points of reference, the Trojan War took place around 1200 BC and King David ruled around 1000 BC).

Minor Meteor Showers

Minor showers produce so few meteors that they are barely noticeable above the background of regular meteors.

Northern and Southern Taurids (NTA/STA)

The Taurids never produce more than ~5 meteors per hour. They make up for their low rates by being active for over two months and by producing many bright fireballs. Their fireballs are more apparent to the average observer because, unlike most meteor showers, the Taurids are observable all night long rather than just in the morning. They are active for the entire month of October with activity slowly building as the month progresses. Though named after the constellation of Taurus, the Taurids radiate from the constellation of Aries for most of October.

The Taurids are produced by Comet 2P/Encke. Encke is an enigmatic object with the shortest period for any known comet at 3.3 years. First observed in 1786, it has been observed over ~60 orbits and has been seen every year since 1993.

Delta Aurigids (DAU)

Until a few years ago, the September Perseids and the Delta Aurigids were considered part of the same shower. Analysis of the orbits of their meteors suggested that there are in fact two overlapping showers each originating from a different unknown long-period comet. Like the SPEs, this minor shower usually produces no more than ~3 meteors per hour at its maximum. There is some disagreement as to when this shower is active. Naked eye observations over the past few decades suggest a period of activity from Sept 18 through Oct 10 with a broad peak between Sept 23 and Oct 3. Recent video data finds a later period of activity between Oct 6 and 12 with no obvious peak. The DAUs radiate from the northern part of the constellation of Auriga just to the north of the bright star Capella.

October Camelopardalids (OCT)

This is a new shower first recognized in 2005, though sightings as early as 1902 have been recorded. A few OCAs are observable between Oct 1 and 10. The vast majority of meteors occur during a short  ~2 hour span at the time of peak activity. This year’s peak is predicted to occur within a few hours of ~14:00 UT (7:00 am PDT) on October 5. Unless the peak comes early it will occur after sunrise for observers in the western US. The peak time suggests a nice, but short, shower may be visible across the northern Pacific basin and in northeastern Asia. Since Camelopardalis is a far northern constellation, this shower is not visible from the Southern Hemisphere.

Draconids (Giacobinids) (GIA)

The Draconids have produced some of the highest rates of meteor activity in history. In both 1933 and 1946 rates were greater than 10,000 meteors per hour. Impressive rates of greater than 500 meteors per hour were also observed in 1952, 1985 and 1998. Unfortunately, this shower barely produces any meteors in non-storm years. What will this year hold in store? There are no predictions for any enhanced activity this year but we won’t know for sure unless we watch. This is another shower only observable from the Northern Hemisphere. It radiates from the constellation of Draco.

The Draconids are also known as the Giacobinids because they are produced by Comet 21P/Giacobini-Zinner. This comet was discovered by the same late 19th/early 20th century astronomer who found the recently re-discovered Comet 205P/Giacobini.

Epsilon Geminids (EGE)

This is an early morning shower which radiates from the constellation Gemini. It is visible between Oct 5 and 22 with a peak on Oct 14. At its best, only about 2 meteors per hour are visible.

Leo Minorids(LEO)

Yet another early morning shower, this time radiating from Leo Minor, a faint constellation just north of Leo. It is visible between Oct 17 and 27 with a maximum rate of only ~2 meteors per hour occurring on Oct 24.

Additional information on these showers and other minor showers not included here can be found at the following sites: Robert Lunsford’s Meteor Activity Outlook, Wayne Hally’s and Mark Davis’s NAMN Notes, and the International Meteor Organization’s 2008 Meteor Shower Calendar.

Comets

Naked Eye Comets

There are no comets bright enough to be seen without binoculars or a telescope.

Binocular Comets

Comet C/2008 A1 (McNaught)

Comet McNaught is a long-period comet that will pass closest to the Sun on Sept 29 at a distance of 1.07 AU (100 million miles or 160 million km). It was the first comet discovered in 2008 having been found by  Robert McNaught of the Siding Spring Survey back on Jan 10. It was McNaught’s 43rd comet discovery.

Since discovery this comet could only be seen from the Southern Hemisphere. This month it moves rapidly to the north and is easily visible from the Northern Hemisphere by mid-month. During October, the comet travels through the constellations of Libra and Ophiuchus. The comet is as bright as it is going to get at magnitude 6.5. A comet of this brightness can be seen in binoculars or a small telescope.

A finder chart for Comet McNaught can be found at Comet Chasing.

Small Telescope Comets

Comet 6P/d’Arrest

Comet 6P/d’Arrest was one of the first short-period comets to be observed. First seen by the Frenchman Philippe de la Hire in 1678, the comet was definitively discovered by Heinrich Louis d’Arrest of Germany on 1851 June 28.

Comet d’Arrest is in a short-period orbit with a period of 6.5 years. It passed closest to the Sun back on Aug 14 at a distance of 1.35 AU (125 million miles or 200 million km). Comet d’Arrest starts the month in the southern constellation of Grus before entering Sculptor near months end. The comet is a very difficult object for observers in the Northern Hemisphere. With a brightness of magnitude 8.5 it will require a telescope to be seen though observers at very dark sites may be able to see it in binoculars.

A finder chart for Comet d’Arrest can be found at Comet Chasing.

A nice collection of images can be found at the VdS-Fachgruppe Kometen (Comet Section of Germany) and Seiichi Yoshida’s Comet Homepage.

Asteroids

Binocular and Small Telescope Asteroids

(1) Ceres

Ceres is the biggest asteroid in the Main Belt with a diameter of 585 miles or 975 km. It is so big that it is now considered a Dwarf Planet. Classified as a carbonaceous (carbon-rich) Cg-type asteroid, there are suggestions that it may be rich in volatile material such as water. Some even propose that an ocean exists below the surface. Ceres is one of two targets for NASA’s Dawn spacecraft which is scheduled to visit it in 2015. This month Ceres is located low in the eastern sky right before sunrise in Leo at magnitude 8.7.

A finder chart (needs to be flipped upside down for Northern Hemisphere observers) can be found at the Royal Astronomical Society of New Zealand.

(2) Pallas

Pallas is also a carbonaceous asteroid though with a slightly bluish B-type spectrum. Due to its high inclination (tilt of its orbit with respect to Earth’s orbit) of 34 degrees it is a difficult target for future spacecraft missions. Pallas is large with dimensions of 350x334x301 miles or 582x556x501 km. This month it is located in the southern constellation of Lepus and brightens from magnitude 8.7 to 8.2 over the course of the month.

A finder chart (needs to be flipped upside down for Northern Hemisphere observers) can be found at the Royal Astronomical Society of New Zealand.

(4) Vesta

Though not as large as Ceres, Vesta is more reflective making it the brightest asteroid in the Main Belt. Vesta is peculiar in that it appears to have evidence of volcanism on its surface. Similar to the Moon, Vesta may be covered with large expanses of frozen lava flows. It is classified as a V-type asteroid and is the only large asteroid with this classification. Many of the smaller V-type asteroids are chips of Vesta blasted off it by past asteroid and comet impacts. Vesta is similar in size to Pallas with dimensions of 347x336x275 miles or 578×560×458 km. Vesta will also be visited by NASA’s Dawn spacecraft which will arrive in 2010. This month it is located in Cetus and brightens from magnitude 6.9 to 6.4 over the course of the month.

A finder chart (needs to be flipped upside down for Northern Hemisphere observers) can be found at the Royal Astronomical Society of New Zealand.

(9) Metis

Metis was discovered in 1848 by Andrew Graham of Ireland. It is a S-type asteroid with a composition similar to stony meteorites (ordinary chondrites). With a diameter of 140x120x85 miles or 235×195×140 km, it is much smaller than Ceres, Pallas or Vesta. In October Metis is located in Aries only a few degrees north of Vesta. It brightens from magnitude 9.4 to 8.6.

A finder chart (needs to be flipped upside down for Northern Hemisphere observers) can be found at the Royal Astronomical Society of New Zealand.

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