Oct 10-16 Meteors

The big story of the past week is the gradual increase in rates of the Orionids (ORI). With its peak predicted for the 21st, rates should really jump over the next night or two. Unlike most major showers which experience peak rates over the course of a night or two, the Orionids can stay near peak strength for 4-5 nights.

Below are the best video meteors of the past week.

Nice Southern Taurid (STA) shooting to the north on 2011 Oct 10 @ 10:05 UT.

Sporadic (SPO) from 2011 Oct 10 @ 10:57 UT.

Another Sporadic (SPO) from 2011 Oct 14 @ 03:41 UT.

Northern Taurid (NTA) from 2011 Oct 14 @ 05:51 UT.

Sporadic (SPO) on 2011 Oct 16 @ 07:10 UT.

Early Orionid (ORI) from 2011 Oct 16 @ 08:08 UT.

Obs  Date(UT)      Time    TOT SPO NTA STA ORI DAU GIA EPC TUM EGE
TUS  2011-10-16   09h 24m   41  17  1   8  10   -   -   -   3   2
TUS  2011-10-15   10h 57m   19  10  0   3   4   -   -   -   1   1
TUS  2011-10-14   10h 55m   24  16  3   1   4   -   -   -   0   0
TUS  2011-10-13   08h 13m   30  16  3   3   5   -   -   -   0   -
TUS  2011-10-12   10h 00m   34  25  1   5   3   -   -   0   0   -
TUS  2011-10-11   09h 58m   28  21  2   2   3   -   -   0   -   -
TUS  2011-10-10   10h 12m   31  21  2   4   1   3   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
DAU - Delta Aurigids 
GIA - Draconids 
EPC - October Eta Piscids 
TUM - Tau Ursa Majorids 
EGE - Epsilon Geminids

Oct 1 – 9 Meteors

During the night of October 8 UT the Draconids produced an outburst of activity for observers on the eastern side of the Atlantic. Based on visual reports, the IMO’s live ZHR chart showed a peak ZHR of between 300 and 400 meteor per hour. The bright Moon and preponderance of faint Draconids meant the actual observed rates were much lower.

Here in AZ the show was over by the time night fell. In fact, not a single Draconid was seen by my camera system only hours after the outburst. Except for a single meteor observed the night before the outburst, this year’s Draconids were their usual meager self for me.

With the Draconids past us, we are now looking forward to the Orionids which should peak on the 21st. Already a few Orionids have been seen each night since the 4th.

Bright (-3mag) SPO on 2011 Oct 6 @ 06:17 UT.

NTA meteor on 2011 Oct 6 @ 10:56 UT.

Obs  Date(UT)      Time    TOT SPO NTA STA ORI DAU OCA GIA EPC
TUS  2011-10-09   10h 46m   38  27  0   4   4   3   0   0   0
TUS  2011-10-08   09h 03m   28  18  3   5   1   0   0   1   0
TUS  2011-10-07   03h 01m   18  14  1   1   2   0   0   0   -
TUS  2011-10-06   06h 48m   20  14  2   0   2   1   1   -   -
TUS  2011-10-05   07h 10m   26  15  1   6   3   1   -   -   -
TUS  2011-10-04   02h 34m   8   7   0   0   1   0   -   -   -
TUS  2011-10-03   08h 18m   22  17  1   2   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)
ANT - Antihelions
NTA - Northern Taurids 
STA - Southern Taurids 
ORI - Orionids
DAU - Delta Aurigids 
OCA - October Camelopardalids 
GIA - Draconids 
EPC - October Eta Piscids

Meteor Activity Outlook for October 8-14, 2011

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 8/9. These positions do not change greatly day to day so the listed coordinates may be used during this entire period.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 full phase on Wednesday October 12th. At this time the moon will lie opposite of the sun and will be in the sky all night long. This weekend the waxing gibbous moon will set during the early morning hours and will allow a couple of hours of meteor observing in dark skies before morning twilight. The estimated total hourly rates for evening observers this week is near two as seen from the northern hemisphere and one as seen from the southern hemisphere. For morning observers the estimated total hourly rates should be near six as seen from mid-northern latitudes and four 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. Rates are reduced during this period due to the intense 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 October 8/9. These positions do not change greatly day to day so the listed coordinates may be used during this entire period.

Detailed descriptions of each shower will continue when the moonlight situation improves.The following showers are expected to be active this week. Rates and positions are exact for Saturday night/Sunday morning.

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
GIA Draconids             17h 28m  +54    20    <1    <1
STA Southern Taurids      02h 04m  +09    27     1     1
ORI Orionids              05h 44m  +16    67     1     1
OCT Oct. Camelopardalids  10h 48m  +79    45    <1    <1

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

2011 October Monthly Highlights

This feature highlights a number of meteor showers, comets and asteroids which are visible during the month of October 2011.

October 2011 Highlights
* Draconid meteor shower may produce high rates over Europe and Asia on the 8th
* Jupiter is at opposition on the 28th
* Comet C/2009 P1 (Garradd) is a nice binocular object during the evening
* Orionid meteor shower peaks on the 21st

Note: If anyone has pictures or observations of these objects/events and want to share them with my readers, send them to the Transient Sky at <transientsky1@yahoo.com>.

Planets

Evening Planets

Mercury – Mercury spends the later half of the month in a poor evening apparition. Usually such a poor apparition wouldn’t be worth observing but this month Venus can be used to find Mercury. Use the Moon to find low but brilliant (magnitude -3.9) Venus and even lower and fainter (magnitude -0.3) Mercury on the evenings of October 27 and 28.

Venus – After spending the past month or so too close to the Sun to be observed, Venus is now starting its slow crawl into the evening sky. Its elongation from the Sun grows from 13° to 20° in October. Still you will need a clear view of horizon to catch Venus low in the WSW during early twilight. Use the Moon to find low but brilliant (magnitude -3.9) Venus and even lower and  fainter (magnitude -0.3) Mercury on the evenings of October 27 and 28.

Jupiter -  The King of Planets is the King of the Night Sky this month. With the other 4 naked eye planets hugging the twilight horizon or rather faint, Jupiter is by far the brightest and best placed. Rising a little over an hour after sunset on the 1st and right at sunset on the 31st, it is at its best around midnight. Opposition occurs on October 28 when Jupiter will peak in brightness at a magnitude of -2.9. For the entire month it will be slowly retrograding in the constellation of Aries. Not that you’ll need the Moon to find Jupiter but the two will make a nice pair on the nights of the 12th and 13th.

Morning Planets

Mars - With opposition in March 2012, Mars continues to slowly brighten (magnitude +1.3 to +1.1) as it moved from Cancer into Leo this month. Mars rises after midnight and is best just before dawn. If you are out watching the Orionids, Mars will be the bright ruddy star near the Moon on the mornings of the 19th and 20th.

Saturn - Saturn passes conjunction on the far side of the Sun at mid-month (Oct 13). Those with very clear eastern horizons may be able to see Saturn an hour before sunrise by the end of the month. Saturn (magnitude +0.7) will be located ~5° to the lower right of the slightly fainter star Spica (magnitude +1.0).

Meteors

Meteor activity is still near a seasonal high in October. The year is usually split in 2 with January through June having low rates with few major showers while July through December have high rates with many major showers.

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 mornings, 10 or so Sporadic meteors can be observed per hour from a dark moonless sky. The Taurids should also contribute another 2-5 meteors per hour all night long.

Major Meteor Showers

Draconids (Giacobinids) (GIA) [Max Date = Oct 8, Max ZHR = highly uncertain between 50 and 600 per hour]

On October 8th at ~20 hours UT, the Draconid meteor shower may produce an outburst of meteors for observers in Europe and Asia. While normally a weak shower, the Draconids put on two of history’s best meteor storms in 1933 and 1946. In those years rates as high as 10,000 per hour were seen. More recently an outburst in 1998 produced a few hundred meteors per hour. This year the Earth will cross dust trails produced by Comet 21P/Giacobini-Zinner in 1900 and 1907, the same two trails that produced the 1933 and 1946 storms, as well as older trails back to 1866. Due to the older age and dispersion of these streams, a major storm is not possible this year. Still ZHRs as high as a few hundred per hour may be possible. The actual number of meteors seen by observers will be much less due to the nearly Full Moon. As a result, the shower may “only” appear as good as the Perseids or Geminids at their peak under a Moon-less sky.

If you’re like me and live in North America, well, we are probably out of luck. Chances are we will see little or no enhancement from the dust trail crossings. This will probably only be a good show for those in Europe, Asia and northern Africa. A map of visibility and much more information on this year’s shower cab be found at the International Meteor Organization’s (IMO) 2011 Draconids site.

Orionids (ORI) [Max Date = Oct 21, Max ZHR = ~35-45 per hour]

The Orionids are one of the most reliable and productive showers of the year. Another point in their favor is their high level of activity over the course of ~5 nights or so. This gives ample opportunity to catch a few Orionid meteors. This year the just past Third Quarter Moon will hamper meteor watching somewhat.

The meteors that make up the Orionid shower were originally released by the one comet everyone has heard of, Comet Halley. Computer simulations of the past movements of Halley and its dust suggest that many of this year’s Orionid meteors were released by 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).

The Orionids are usually active from Oct 3 to Nov 11 with a broad peak between Oct 18 and 24. During their peak, rates can be as high as 20-70 meteors per hour. During the last two years ZHRs reached 35-45 meteors per hour which is nearly half the rate observed in 2007 (70 per hour). This year’s activity should be similar to the last few years. With a Moon-lit sky, actual rates will be somewhat lower.

The Orionids appear to come from an area in northern Orion. This area, called the radiant, rises around 10pm local time. It is best to wait till the radiant is high in the sky before looking for meteors (say 1am). The radiant is highest around 3:30am which is the best time to look. As you can see on the sky chart, the Moon is almost on top of the radiant. Meteors can appear anywhere in the sky so you don’t have to look at the radiant.

Minor Meteor Showers

Minor showers produce so few meteors that they are hard to notice above the background of regular meteors. Info on many minor showers are provided on a weekly basis by Robert Lunsford’s Meteor Activity Outlook.

Additional information on these showers and other minor showers not included here can be found at the International Meteor Organization’s 2011 Meteor Shower Calendar.

Comets

Naked Eye Comets (V < 6.0)

None this month…

Binocular Comets (V = 6.0 – 8.0)

C/2009 P1 (Garradd)

The brightest comet of the year is long-period comet C/2009 P1 (Garradd). First seen way back on August 13, 2009 by Gordon Garradd who was observing for the Siding Spring Survey, a NASA-funded survey observing from Australia. At the time of discovery it was located at a distance 8.7 AU from the Sun, nearly the distance of Saturn. Perihelion will occur 2 days before Christmas 2011 at 1.55 AU from the Sun. Though the comet does not get very close to the Sun, it is an intrinsically bright comet and is already a borderline naked eye object for observers at very dark sites (6th magnitude).

The comet starts the month at a distance of 1.92 AU from the Sun and 1.70 AU from Earth. At mid-month it is 1.81 AU from the Sun and 1.87 AU from Earth and by month’s end it will be 1.72 and 2.01 AU from the Sun and Earth, respectively.  Visual observers are placing the comet at magnitude 6.6 to 6.8 at the end of September. It should slightly brighten this month as it slowly moves west in Hercules.

Date       RA       DEC     Delta    r    Elong   Mag
Oct 1    18h 09m  +19°23'   1.697  1.921    87    6.7
Oct 16   17h 49m  +18°51'   1.866  1.811    71    6.6
Oct 31   17h 37m  +18°44'   2.005  1.716    59    6.6

Small Telescope Comets (V = 8.0 – 10.0)

45P/Honda-Mrkos-Pajdusakova

First seen in 1948 by Japanese amateur Minora Honda, Czech astronomer Antonin Mrkos and Slovak astronomer Ludmilla Pajdusakova, this comet is on its 11th observed return since discovery (it was missed during the 1959 and 1985 returns). It is an intrinsically faint Jupiter-family comet which passes within 0.53 AU of the Sun every 5.25 years. This time perihelion passage occurred on September 28. Prior to perihelion the comet made a close approach to within 0.06 AU of Earth which was only easily visible from the Southern Hemisphere. During the next return in 2016/2017, 45P will pass within 0.08 AU of Earth on its outbound leg and will be much better placed for northern observers.

Being after perihelion, the comet will rapidly fade as it moves away from the Sun and Earth as it moves through the constellation of Leo. At the start of the month, it should still be a binocular comet at magnitude 7.6 but will be lost to binoculars within a week or so. At an elongation of 32-37° it can only be seen low on the horizon before dawn.

Date       RA       DEC     Delta    r    Elong   Mag
Oct 1    10h 26m  +08°27'   0.827  0.532    32    7.6
Oct 16   11h 17m  +05°26'   1.139  0.641    34    9.9
Oct 31   12h 03m  +01°40'   1.380  0.839    37   12.7

 

 

Meteor Activity Outlook for October 1-7, 2011

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 first quarter phase on Tuesday October 4th. At this time the half illuminated moon will lie ninety degrees east of  the sun and will set near midnight local daylight time (LDT). This weekend the waxing crescent moon will set during the early evening 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 twelve 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 October 1/2. 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:

The Draconids (GIA) (also known as the Giacobinids) reach maximum activity on October 8. This year a possible outburst is predicted to be visible from Asia, Africa, and Europe. Lesser activity may be seen on the 6th and 7th and the 9th and 10th. The nearly full moon this time of month will severely hamper observations. Detailed articles are available on the websites of the International Meteor Organization (http://www.imo.net/draconids2011) and the American Meteor Society (http://www.amsmeteors.org/2011/09/possible-draconid-outburst-in-2011/). The radiant is located at 17:28 (262) +54, which places it in southern Draco, two degrees northwest of the third magnitude star Rastaban (Beta Draconis). This star is one of the four that form the prominent head of Draco, also known as the “Lozenge”. Due to the extreme northern declination, this shower is only visible from the southern tropics northward. The radiant is best placed just as it becomes dark during the evening hours. At 20km/sec., the average Draconid is extremely slow.

The Southern Taurid (STA) radiant is now centered at 01:40 (025) +07. This area of the sky lies in southeastern Pisces, two degrees southwest of the fourth magnitude star Omicron Piscium. This radiant is best placed near 0200 local daylight time (LDT), when it lies on the meridian and is located highest in the sky. Rates at this time should be near two per hour no matter your location. With an entry velocity of 27 km/sec., the average Southern Taurid meteor would be of medium-slow speed. While looking at this area of the sky, notice how bright the variable star Mira (Omicron Ceti) is these nights. It normally is too dim to be seen with the naked eye but now stands at second magnitude, nearly the brightest star in the constellation of Cetus the whale. It lies approximately ten degrees southeast from the center of the STA radiant or just six degrees southeast of the fourth magnitude star Al Rischa (Alpha Piscium). It is probably near peak magnitude and will soon begin fading.

A new shower of bright meteors radiating from near the Draco/Camelopardalis border was discovered in 2005 and has repeated itself in most years since. The October Camelopardalids (OCT) are active on only two nights but shower members are bright and should be easy to observe. The 2011 display is predicted to occur on October 5th and 6th. The estimated position of the radiant on the 5th is 10:48 (162) +79. The nearest easy star to identify the radiant is 4th magnitude SAO1551. This area of the sky is circumpolar from nearly the entire northern hemisphere. The radiant lies highest above the horizon in a dark sky at both dusk and at dawn. Due to this unusual situation this shower would be totally invisible from the southern hemisphere. With an entry velocity of 45km/sec., most members of the October Camelopardalids would be of medium-swift velocity.

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 two 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 one 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
GIA Draconids             17h 28m  +54    20    <1    <1
STA Southern Taurids      01h 40m  +07    27     2     2
OCT Oct. Camelopardalids  10h 48m  +79    45    <1    <1

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

Oct 5/6/7 Meteors and the October Draconids and October Epsilon Piscids

From Bob’s notes from 10/6: “Cloudy skies were in the forecast for last night but the sky remained mostly clear all night with clouds ringing the horizons, well away from my camera, which is pointed high in the northern sky. We are entering a time when there are many different showers active, unfortunately most of them are weak and only produce a couple of meteors per night. The full moon does not help the situation by reducing activity 75% with its bright glare. Rates should be near a nadir tonight and I expect we will see more activity as the moon wanes and as we approach the Orionid maximum on October 22nd.”

Bob’s note does a great job of explaining the recent conditions in Tucson as well. Though we’ve had cloud trouble on both nights. The forecast is for more of the same tonight.

Monitoring has begun for 2 additional showers, the October Draconids (DRA) and the October Epsilon Piscids (EPC). The October Draconids are also referred to as the Giacobinids after their parent comet Giacobini-Zinner. Though this shower has put on some of the best meteor displays in history (10,000 per hour in 1933 and 12,000 per hour in 1946), an average year sometimes produces little to no meteor activity. With no enhanced activity predicted for this year, rates should remain very low.

The second newly active shower is the October Epsilon Piscids. This shower was only identified recently in video meteor data. We don’t know much about it other than it is a short-duration shower with a low velocity relative to Earth (~19 km/s) which suggest a Jupiter family comet as its parent. This shower will, at most, produce a meteor per hour.

Obs Date (UT)  TotTime TOT SPO NTA STA ORI OCA DRA EPC
TUS 2009-10-07 01h 00m  2   1   1   0   0   0   0   0
SDG 2009-10-07 10h 34m  10  8   -   1   1   0   0   -
TUS 2009-10-06 00h 00m  Clouds all night
SDG 2009-10-06 10h 09m  24  16  -   6   1   0   1   -

TUS – Camera in Tucson operated by Carl Hergenrother
SDG – Camera in San Diego operated by Bob Lunsford
TotTime – 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 (includes Antihelions)
STA – Southern Taurids (includes Antihelions)
ORI – Orionids
OCA – October Camelopardalids
DRA – October Draconids (Giacobinids)
EPC – September Epsilon Piscids

Meteor Activity Outlook for October 3-9, 2009

The Meteor Activity Outlook is a weekly summary of expected meteor activity written by Robert Lunsford, Operations Manager of the American Meteor Society and contributor to this blog. New Outlooks are released every Thursday (and if I had hit the “publish” button last week, you would have been reading this post last Thursday :)). The original unedited version of this week’s Meteor Activity Outlook 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 several
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 full phase on Sunday October 4th. At
this time the moon lies in the sky all night long and severely hampers
meteor observations. A small window of dark skies opens later in the week as
the waning gibbous moon rises later in the evening allowing a couple of
hours of dark sky between the end of evening twilight and moonrise. The
estimated total hourly rates for evening observers this week is near three
as seen from the northern hemisphere and two from the southern hemisphere.
For morning observers the estimated total hourly rates should be near seven
from the northern hemisphere and four as seen from the southern hemisphere.
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. All rates are severely reduced by bright
moonlight.

The radiant positions and rates listed below are exact for Saturday night/Sunday morning October 3/4. These positions do not change greatly day to day so the listed coordinates may be used during this entire period.

The full descriptions of each active meteor shower will continue next week
when the moon becomes less of a nuisance to observers.

The list below presents a condensed version of the expected activity this
week. Rates and positions are exact for Saturday night/Sunday morning or the
night of maximum activity for showers of short duration.

Shower Name               RA   DEC Vel    Rates
                                   km/s  NH   SH
GIA Draconids           17h28m +56  19   <1   <1
OPC Oct ε-Piscids       00h05m +14  19   <1   <1
STA Southern Taurids    01h46m +08  29    1    1
ORI Orionids            05h28m +16  67   <1   <1
OCT Oct Camelopardalids 11h13m +79  45   <1   <1

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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