In the Sky This Month – January 2010

This feature highlights a number of meteor showers, comets and asteroids which are visible during the month of January 2010. Mars is at its closest and brightest towards the end of the month. Bright red Mars anchors the eastern sky in the early evening while even brighter yellow Jupiter rules the western sky. The month’s single major meteor shower, the Quadrantids, will be washed out by bright moonlight (they will have already passed by the time you read this due to this entry’s late posting).

Note: If anyone has pictures or observations of these objects/events and want to share them, send me a comment and I’ll post them on the blog.

Planets

Mercury and Venus - Both planets start the month to close to the Sun for observation. Venus slowly moves into the evening sky after ~9 months in the morning sky. By month’s end it will still be a very difficult object to observe. Only those with a clear sky and no obstructions on their WSW horizon have a chance of catching Venus a few minutes after sunset. This coming evening apparition will allow for easy Venus viewing from March through September. For observers in the Southern Hemisphere this will be a great apparition, especially from July to October.

Mercury is traveling the other way and will pop out in the morning sky by mid-month. It will be located in the SE sky an hour or less before sunrise. This apparition is also better for southern observers.

Jan 4 - Mercury at Inferior conjunction
Jan 11 - Venus at Superior conjunction
Jan 27 - Mercury at Greatest elongation (West/Morning)

Jupiter - Jupiter is slowly sinking in the SW sky during the early evening hours. At magnitude -2.1, Jupiter is still many times brighter than the brightest stars. This is the last month to easily see the king of the planets.

  Jan 18 - Moon passes 4° from Jupiter

Neptune – Jupiter is rapidly pulling away from Neptune after the third of their 3 conjunctions last year. As a result, it is getting harder to use Jupiter as a guide to locate Neptune. A detailed PDF star chart for finding Neptune can be downloaded at the end of this Sky & Telescope article.

Uranus – Uranus is located in western Pisces and is bright enough to be seen in small binoculars at magnitude +5.9 but will still require a telescope in order to see it as anything other than a star (it’s disk is only 3.5″ across). A detailed PDF star chart for finding Uranus can be downloaded at the end of this Sky & Telescope article.

Mars – This month Mars is at opposition (the point opposite the Sun in the sky) on January 29. Opposition means Mars is closest to Earth and at its brightest. It also means it is visible nearly all night long, rising in east in the early evening, at its highest around midnight, and setting in the west around dawn.

Mars spends the whole month retrograding (moving from east to west) in the constellation of Cancer. Already a bright magnitude -0.7 at the start of the month, Mars will peak at magnitude -1.3 on opposition before slightly fading to -1.2 by month’s end. It’s opposition brightness almost matches that of Sirius, the brightest star. Note that unlike the stars which twinkle, Mars shines with an unwavering red glow.

Jan 3 - Moon passes close (6°) to Mars
Jan 27 - Closest to Earth (0.664 AU)
Jan 29 - Opposition
Jan 30 - Moon passes close (6°) to Mars

Saturn – Saturn is easy to observe during the morning hours and is sufficiently high enough to be observed in the eastern sky by midnight. Located in Virgo, the planets will appear as bright as a magnitude +0.8 star. Telescope users should note that Saturn’s rings are still close to edge-on.

Jan 6 - Moon and Saturn within 7° of each other

Meteors

January hosts one of the better annual showers of the year in the Quadrantids. Unfortunately this year’s display will be wrecked by bright moonlight. The background rate of meteors crashes in January.  The year is usually split in 2 with January through June having low rates with few major showers while July through December (really through the 1st week of January) 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 January, 8-10 or so Sporadic meteors can be observed per hour from a dark moonless sky.

Major Meteor Showers

Quadrantids (QUA)

The Quadrantids are the best shower that you’ve probably never heard of. It’s bad enough that this shower peaks in the middle of winter in the northern hemisphere, but it is also named after a long defunct constellation. When first identified in the early 1800s, the meteors were observed to radiate from the small faint constellation of Quadrans Muralis (the Mural Quadrant). Unfortunately, the constellation didn’t make the cut when the official list of 80 constellations was set in 1930. Today, Quadrans Muralis and the radiant of the Quadrantids can be found north of the constellation of Bootes.

Another strike against observing the Quadrantids is their short duration. Showers, like the Perseids and Orionids, produce high rates of meteors for a few days near their maximum. The Quadrantids are only highly active for 12-24 hours. As a result, the shower can be missed if the peak does not coincide with your early morning observing.

This years display was predicted to peak on the night of Jan 2/3. A very bright nearly full Moon will keep rates very low.

Minor Meteor Showers

Minor showers produce so few meteors that they are hard to notice above the background of regular meteors. Starting this month, info on most of the minor showers will be 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 following sites: Wayne Hally’s and Mark Davis’s NAMN Notes, and the International Meteor Organization’s 2008 Meteor Shower Calendar.

Comets

Naked Eye Comets (V < 6.0)

None

Binocular Comets (V = 6.0 – 8.0)

None

Small Telescope Comets (V = 8.0 – 10.0)

Comet 81P/Wild 2

Comet Wild 2 is a short-period Jupiter-family comet on a 6.4 year orbit. In 1974 a close approach to Jupiter placed the comet on its current orbit which allows (relatively) close approaches to the Sun and Earth. Swiss professional astronomer Paul Wild found the comet photographically on its first close perihelion in 1978. During its last perihelion passage it was the target of the NASA Stardust spacecraft which flew through its coma, collected cometary dust, and returned the dust to Earth. Though Wild 2 has become bright enough to be seen in small backyard telescopes before, this year’s apparition will be its best since discovery. Not till 2042 will it come closer, and even then only marginally so.

This year Wild 2 will reach perihelion on February 22 at 1.60 AU and closest approach to Earth will occur on April 5 at 0.67 AU. Though the comet will only reach a brightness of magnitude ~9.2 to 9.5 in March, it will remain brighter than magnitude 10.0 from January through May.

Currently the comet is around magnitude 10.0 to 10.5 and should be around magnitude 10.0 or even brighter by the end of the month. Currently the comet is located in Virgo (not far from Saturn) at a distance of 1.64 AU from the Sun and 1.10 AU from Earth.

A finder chart for Comet Siding Spring can be found at Comet Chasing and Aktuelle Kometen (in German).

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

Comet C/2007 Q3 (Siding Spring)

This long-period comet was first seen on 2007 August 25 by Donna Barton of the Siding Spring Survey in Australia. This past Oct. 7th the comet reached a rather distant perihelion at 2.25 AU from the Sun. Unfortunately, the comet and Earth are located on opposite sides of the Sun so the comet is rather far from Earth. Still the comet is observable in the early morning hours as a slowly fading ~9.5 to 10.5 magnitude comet in Bootes. At mid-month the comet is 2.52 AU from the Sun and 2.23 AU from Earth.

A finder chart for Comet Siding Spring can be found at Comet Chasing and Aktuelle Kometen (in German).

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 (V < 9.0)

(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 347×336x275 miles or 578×560×458 km. Vesta will also be visited by NASA’s Dawn spacecraft which will arrive in 2010.

Vesta is once again observable in the morning sky before the start of dawn. It is brightening from magnitude 7.1 to 6.5 as it travels to the northeast of Regulus in Leo.

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

Jan 3/4 Meteors

A night after their peak the number of Quadrantids are down sharply. Amazingly the total number of meteors was up from a night ago as the number of Sporadics made up for the lack of Quadrantids.

Bob’s notes from the night of Jan 3/4 : “Thick high clouds delayed the start of recording tonight. It was mostly clear between 3 and 11 UT (7pm to 3am PST). After 11 UT, thick high clouds obscured the sky effectively ending observations for the night.”

Obs  Date(UT)      Time    TOT SPO ANT DLM AHY JLE QUA
TUS  2010-01-04   11h 28m   32  19  2   5   1   0   5
SDG  2010-01-04   07h 36m   35  24  6   2   2   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)
ANT - Antihelions
DLM - December Leonis Minorids
AHY - Alpha Hydrids
JLE - January Leonids
QUA - Quadrantids

Jan 2/3 Meteors

The peak of the Quadrantids was predicted to happen a few hours after sunrise this morning (Tucson time, MST). Activity was elevated and 13 Quadrantids from 2 Tucson cameras and 20 from a sole San Diego camera is a dramatic increase compared to only 1 total (TUS and SDG) from the previous night. Still it was a poor showing compared to last year when a single Tucson camera picked up 73 Quadrantids.

There have been few reports of Quadrantid activity from last night. Most likely many observers took a pass on watching the shower due to the bright moonlight.

Bob’s notes from the night of Jan 2/3 : “Despite the bright moon, it was a good night for meteor activity. It was totally clear all night long except for a few patches of thin cirrus that occasionally drifted by. In addition to the Quadrantids, the sporadic count was abnormally high. My first thought was that perhaps some Quadrantids were misidentified as sporadics. After a close inspection of the plots it was determined that this was not the case.”

Obs  Date(UT)      Time    TOT SPO ANT DLM AHY JLE QUA
TUS  2010-01-03   10h 01m   30  12  2   3   0   0   13
SDG  2010-01-03   11h 59m   75  43  6   3   2   1   20

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)
ANT - Antihelions
DLM - December Leonis Minorids
AHY - Alpha Hydrids
JLE - January Leonids
QUA - Quadrantids

Dec 23/24 to Jan 1/2 Meteors

Hope everyone had a fun and safe holiday season.

The past week has seen rather low meteor activity with the bright Moon has helped to keep meteor counts low. Also there weren’t too many active showers with only the December Leonis Minorids producing consistent, if low, activity.

This should all change tonight when the Quadrantid meteor shower peaks. This is actually one of the better showers yet it is notoriously difficult to observe. For starters, it is located at a high northern declination which makes it impossible to see from most of the Southern Hemisphere. Even for northern observers, the time of peak intensity is vitally important. Unlike the Geminids, Orionids and Perseids which have broad peaks and produce high meteor numbers for a few days, the Quadrantids have a very sharp peak. So unless you are observing within hours of its peak, meteor numbers may be much lower than expected.

Last year the peak was perfectly timed for observers in North America and ZHR rates as high as 160 per hour were reported. From my moderately light polluted skies, I observed ~60 per hour. This year the peak is predicted for Jan 3 at ~19 hours UT. That’s 6+ hours after sunrise from North America. Based on last year’s activity profile the ZHR rate will be in the 40-80 per hour range. Unfortunately the bright Moon is poorly placed for meteor watching this time and the actual rates will be much lower. Add the fact that most observers are located under skies with some amount of light pollution and actual observable rates may only be in the 5-15 per hour range.

Bob’s notes from the night of Jan 1/2 : “After a cloudy day the clouds began thinning during the evening hours. I was able to start the camera shortly after 2300 PST. Skies remained clear the remainder of the night. Morning meteor activity was significantly weaker than what was observed on the previous night. Despite being only one day before maximum, the Quadrantids are barely showing any signs of life.”

… for the night of Dec 31/ Jan 1 : “The sky was clear most of the night except for a few wisps of high clouds that drifted by during the late morning hours. Despite the light from the full moon, meteor rates were decent throughout the night.”

… for the night of Dec 30/31 : “I woke to clear skies after a cloudy and wet evening. I figured that a small sample of the night’s activity was better than nothing!”

… for the night of Dec 29/30 : “After a couple of days of clouds the skies cleared tonight. The timing was perfect as more clouds arrived at dawn and did not affect observations. Rates were reduced due to the bright moon but the transparent skies still made observations worthwhile.”

… for the night of Dec 26/27 : “Clouds prevented observations during the early evening hours. I noticed the sky had cleared at 23:00 PST so I started the camera shortly thereafter. The sky remained clear until near 4:00am PST (12UT) when a thick layer of cirrus moved in from the west. This greatly reduced the observed activity during the final 1.83 hours of observations.”

… for the night of Dec 25/26 : “Meteor activity was a bit more uniform tonight. Totals were nearly identical to the previous two nights. It was mostly clear except for some cirrus and cumulus clouds toward the end of the session.”

… for the night of Dec 24/25 : “It was another strange night for meteor activity. There was some cirrus present as dusk but they were thin and soon dissipated. Despite the clear skies evening rates were very low, beyond the effect of the first quarter moon. Once again the morning hours saw variable rates under clear skies. A full third of the entire night’s activity occurred between 11-12 UT (3-4am PST).”

… for the night of Dec 23/24 : “It was clear until 1100 UT (3:00 AM PST) when cirrus clouds began to drift over. Rates were compromised the remainder of the session.”

Obs  Date(UT)      Time    TOT SPO ANT DLM AHY JLE QUA
TUS  2010-01-02   12h 08m   6   5   0   0   1   0   0
SDG  2010-01-02   06h 32m   20  16  0   3   0   0   1
TUS  2010-01-01   11h 31m   8   7   0   0   0   0   1
SDG  2010-01-01   11h 49m   39  33  2   0   3   0   1
TUS  2009-12-31   01h 51m   4   3   0   1   0   0   -
SDG  2009-12-31   01h 45m   6   6   0   0   0   0   -
TUS  2009-12-30   05h 30m   2   2   0   0   -   -   -
SDG  2009-12-30   11h 36m   33  28  4   1   0   -   -
TUS  2009-12-29   00h 10m   1   1   0   0   -   -   -
SDG  2009-12-29   00h 00m   Clouds all night
TUS  2009-12-28   11h 30m   1   1   0   0   -   -   -
SDG  2009-12-28   00h 00m   Clouds all night
TUS  2009-12-27   11h 29m   15  9   2   4   -   -   -
SDG  2009-12-27   06h 45m   25  19  4   2   -   -   -
TUS  2009-12-26   11h 28m   15  11  0   4   -   -   -
SDG  2009-12-26   11h 44m   43  39  3   1   -   -   -
TUS  2009-12-25   11h 29m   11  8   0   3   -   -   -
SDG  2009-12-25   12h 05m   42  36  1   5   -   -   -
TUS  2009-12-24   08h 09m   11  3   4   4   -   -   -
SDG  2009-12-24   12h 05m   42  32  6   4   -   -   -

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)
ANT - Antihelions
DLM - December Leonis Minorids
AHY - Alpha Hydrids
JLE - January Leonids
QUA - Quadrantids

Meteor Activity Outlook for January 2-8, 2010

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. The original unedited version of this week’s Meteor Activity Outlook can be found at the American Meteor Society’s site.

January sees a peak of sporadic activity for the southern hemisphere while rates seen north of the equator begin a steady downward turn that continues throughout the first half of the year. The sporadic activity is good for both hemispheres, but not as good as it was for northern observers in December. Once the Quadrantids have passed the shower activity for January is very quiet.

During this period the moon reaches its last quarter phase on Thursday January 7th. On that date the moon lies ninety degrees west of the sun and rises near midnight local standard time (LST). This weekend the waning gibbous moon is in the sky most of the night making meteor observations difficult at best. The estimated total hourly rates for evening observers this week is ~2 no matter your location. For morning observers the estimated total hourly rates should be ~10 from the northern hemisphere and ~8 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. Rates are reduced this week due to moonlight.

The radiant positions and rates listed below are exact for Saturday night/Sunday morning January 2/3. 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 full descriptions of each active meteor shower will continue next week when the moon becomes less of a nuisance to observers.

The table below presents a condensed version of the expected activity this week. Rates and positions are exact for Saturday night/Sunday morning but may be used all week long.

Shower Name                RA     DEC   Vel     Rates
                                        km/s   NH    SH
ANT Antihelions          07h 40m  +20    30     2     1
AHY Alpha Hydrids        08h 31m  -08    45    <1    <1
JLE January Leonids      09h 50m  +24    54    <1    <1
DLE Dec Leonis Minorids  11h 34m  +24    64     1    <1
QUA Quadrantids          15h 18m  +50    42    10     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

Meteor Activity Outlook for December 19-25, 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. The original unedited version of this week’s Meteor Activity Outlook can be found at the American Meteor Society’s site.

No matter where you live, the first half of December provides some of the best meteor activity of the year. In the northern hemisphere the sporadic rates are still strong plus you can also count on strong activity from the Geminids, which peak on December 13. There are also several minor radiants that add a few meteors each hour. All of these centers of activity are located high in the sky during the early morning hours this time of year. Unfortunately this year the bright moon spoils the show during the first week of the month. During the second week of December the moon will pass its last quarter phase and will not be such a nuisance .

As seen from the southern hemisphere the sporadic rates are increasing toward a January maximum. Shower rates are also good but the Geminids suffer a bit from the lower elevation seen from southern locations. Still with the warmer weather now occurring south of the equator, December is a great time to view celestial fireworks.

During this period the moon reaches its full phase on Thursday December 31st. On that date the moon lies opposite the sun and is in the sky the entire night. This weekend the waxing gibbous moon sets during the early morning hours allowing a couple of hours of viewing in dark conditions before the onset of morning twilight. The estimated total hourly rates for evening observers this week is ~3 no matter your location. For morning observers the estimated total hourly rates should be ~20 from the northern hemisphere and ~15 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. Rates are reduced this week due to moonlight.

The radiant positions and rates listed below are exact for Saturday night/Sunday morning December 26/27. 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.

Antihelions (ANT)

Now that the activity from particles produced by comet 2P/Encke has ceased encountering the Earth, the Taurid showers for 2009 are over and we resume reporting activity from the Antihelion radiant. This is not a true radiant but rather activity caused by the Earth’s motion through space. As the Earth revolves around the sun it encounters particles orbiting in a pro-grade motion that are approaching their perihelion point. They all appear to be radiating from an area near the opposition point of the sun, hence the name Antihelion. These were once recorded as separate showers throughout the year but it is now suggested to bin them into their category separate from true showers and sporadics. This radiant is a very large oval some thirty degrees wide by fifteen degrees high. Activity from this radiant can appear from more than one constellation. The position listed here is for the center of the radiant which is currently located at 07:12 (108) +22. This position lies in central Gemini, 2 degrees west of the fourth magnitude star Delta Geminorum. Since the radiant is so large, Antihelion activity may also appear from eastern Taurus, northeastern Orion, western Cancer, or southern Auriga. This radiant is best placed near 0100 local standard time (LST) when it lies on the meridian and is highest in the sky. Rates at this time should be ~3 per hour as seen from the northern hemisphere and ~2 per hour from south of the equator. With an entry velocity of 30 km/sec., the average Antihelion meteor would be of slow speed.

Alpha Hydrids (AHY)

Activity from the Alpha Hydrids (AHY) begin to appear on the morning of December 30th. This shower reaches maximum activity on the 31st from a radiant located at 08:24 (126) -08. This position lies in extreme western Hydra, 15 degrees west of the second magnitude star Alphard (Alpha Hydrae). These meteors are best seen near 0200 LST when the radiant lies highest above the horizon. Due to the intense moonlight present at maximum, hourly rates from this shower will be < 1 per hour no matter your location. At 45 km/sec. the Alpha Hydrids produce meteors of medium velocity.

December Leonis Minorids (DLM)

The December Leonis Minorids (DLM) are active from a radiant located at 11:10 (168) +27. This position lies in a blank area of the sky where the borders of Leo Minor, Leo, and Ursa Major meet. The nearest bright stars are Nu and Xi Ursae Majoris which lie 5 degrees to the northeast. These meteors are best seen near 0500 LST when the radiant lies highest above the horizon. This shower peaked on December 20th so current rates would be ~2 per hour as seen from the northern hemisphere and < 1 per hour as seen from south of the equator. At 64 km/sec. the December Leonis Minorids produce mostly swift meteors.

As seen from the mid-northern hemisphere (45N) one would expect to see ~15 Sporadic meteors per hour during the last hour before dawn as seen from rural observing sites. Evening rates would be ~2 per hour. As seen from the mid-southern hemisphere (45S), morning rates would be ~12 per hour as seen from rural observing sites and ~2 per hour during the evening hours. Locations between these two extremes would see activity between the listed figures. Evening rates are reduced this week 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 but may be used all week long.

Shower Name                RA     DEC   Vel     Rates
                                        km/s   NH    SH
ANT Antihelions          07h 12m  +22    30     3     2
AHY Alpha Hydrids        08h 24m  -08    45    <1    <1
DLE Dec Leonis Minorids  11h 10m  +27    64     2    <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

Dec 22/23 Meteors

A relatively strong (at least for AZ) storm moved through the region over the past few nights. Similar to the storm from a few weeks back, one of my cameras again suffered from condensation in its lens. The problem is not the lenses but my all-weather enclosure which is no longer “all-weather”. For the time being, I’ll be down to a single camera again until after the holidays when I’ll have time to fix the faulty enclosure.

The aforementioned storm shut me out for a 2nd straight night. Luckily the storm had moved far enough to the east to allow Bob to get some good data.

Bob’s notes from the night of Dec 22/23 : “Clouds and rain prevented any useful video observations on the 22nd, which was bad timing as this was the maximum night for the Ursid meteor shower. The skies cleared near midnight last night and remained clear the remainder of the morning. Meteor rates varied significantly without any rhyme or reason. No Ursids remained from the maximum that occurred the previous morning.”

Due to the holidays, postings will be sparse. If anything exciting happens I’ll put something out. Until then, Merry Christmas and Happy New Year!

Obs  Date(UT)      Time    TOT SPO ANT DLM URS
TUS  2009-12-23   00h 00m  No meteors - Clouds/Rain
SDG  2009-12-23   05h 42m   43  36  4   3   0 

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)
ANT - Antihelions
DLM - December Leonis Minorids
URS - Ursids

Dec 18/19/20/21/22 Meteors

The “big” meteor story for this week is the peak of the Ursids. Scheduled for last night the Ursids are not considered a major shower but can often produce rates as high as 10-15 per hour. On occasion they can do much better. Unfortunately Arizona was socked in last night and my systems didn’t detect a single meteor.

Salvador Aguirre was able to observe a few Ursids visually 2 nights before the predicted peak (Dec 19/20). From Hermosillo, Salvador was able to detect 34 meteors in ~2 hours of observing under a sky with a limiting magnitude of +6.40. Of those 34 meteors, 10 were Ursids, 10 were Coma Berenicids, 6 were December Leonis Minorids, 2 were Antihelions, and 6 were Sporadics.

Bob’s notes from the night of Dec 18/19 : “The cloud cover was not as bad as the previous night but still reduced rates by roughly half. The Coma Berenicids finally came to life last night producing 5 shower members.”

… and for the night of Dec 19/20/21 : “High clouds severely compromised observing sessions the past two nights. It does not appear the weather will improve before the Ursid maximum on December 22.”

Obs  Date(UT)      Time    TOT SPO ANT HYD MON DLM COM URS
TUS  2009-12-19   12h 12m   36  18  4   5   2   4   0   3
SDG  2009-12-19   12h 04m   39  25  5   2   0   2   5   0
TUS  2009-12-20   12h 11m   33  16  2   3   2   7   3   0
SDG  2009-12-20   12h 03m   19  13  3   1   -   2   0   0
TUS  2009-12-21   02h 57m   9   7   1   0   -   1   0   0
SDG  2009-12-21   11h 11m   9   7   0   -   -   2   0   0
TUS  2009-12-22   00h 00m   No Meteors - Clouds all night
SDG  2009-12-22   00h 00m   No Meteors - Clouds all night

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)
ANT - Antihelions
HYD - Sigma Hydrids
MON - Monocerotids
DLM - December Leonis Minorids
COM - Coma Berenicids
URS - Ursids

Meteor Activity Outlook for December 19-25, 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. The original unedited version of this week’s Meteor Activity Outlook can be found at the American Meteor Society’s site.

No matter where you live, the first half of December provides some of the best meteor activity of the year. In the northern hemisphere the sporadic rates are still strong plus you can also count on strong activity from the Geminids, which peak on December 13. There are also several minor radiants that add a few meteors each hour. All of these centers of activity are located high in the sky during the early morning hours this time of year. Unfortunately this year the bright moon spoils the show during the first week of the month. During the second week of December the moon will pass its last quarter phase and will not be such a nuisance .

As seen from the southern hemisphere the sporadic rates are increasing toward a January maximum. Shower rates are also good but the Geminids suffer a bit from the lower elevation seen from southern locations. Still with the warmer weather now occurring south of the equator, December is a great time to view celestial fireworks.

During this period the moon reaches its first quarter phase on Thursday December 24th. On that date the moon lies ninety degrees east of the sun and sets near midnight local standard time (LST). This weekend the waxing crescent moon will set during the evening hours and will not cause any interference during the more active morning hours. The estimated total hourly rates for evening observers this week is ~3 no matter your location. For morning observers the estimated total hourly rates should be ~20 from the northern hemisphere and ~15 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. Rates are reduced during the evening hours this week due to moonlight.

The radiant positions and rates listed below are exact for Saturday night/Sunday morning December 19/20. 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.

Antihelions (ANT)

Now that the activity from particles produced by comet 2P/Encke has ceased encountering the Earth, the Taurid showers for 2009 are over and we resume reporting activity from the Antihelion radiant. This is not a true radiant but rather activity caused by the Earth’s motion through space. As the Earth revolves around the sun it encounters particles orbiting in a pro-grade motion that are approaching their perihelion point. They all appear to be radiating from an area near the opposition point of the sun, hence the name Antihelion. These were once recorded as separate showers throughout the year but it is now suggested to bin them into their category separate from true showers and sporadics. This radiant is a very large oval some thirty degrees wide by fifteen degrees high. Activity from this radiant can appear from more than one constellation. The position listed here is for the center of the radiant which is currently located at 06:44 (101) +23. This position lies in
central Gemini, two degrees south of the third magnitude star Epsilon Geminorum. Since the radiant is so large, Antihelion activity may also appear from eastern Taurus, northeastern Orion, or southern Auriga. This radiant is best placed near 0100 local standard time (LST) when it lies on the meridian and is highest in the sky. Rates at this time should be ~3 per hour as seen from the northern hemisphere and ~2 per hour from south of the equator. With an entry velocity of 30 km/sec., the average Antihelion meteor would be of slow speed.

December Leonis Minorids (DLM)

The December Leonis Minorids (DLM) are active from a radiant located at 10:46 (162) +31. This position lies in eastern Leo Minor, approximately 8 degrees northeast of the third magnitude star Zeta Leonis. These meteors are best seen near 0500 LST when the radiant lies highest above the horizon. This shower peaks on December 20th so current rates would be ~2 per hour as seen from the northern hemisphere and < 1 per hour as seen from south of the equator. At 64 km/sec. the December Leonis Minorids produce mostly swift meteors.

Coma Berenicids (COM)

The Coma Berenicids (COM) are active from a radiant located at 11:48 (177) +18. This position actually lies in eastern Leo, 3 degrees north of the second magnitude star Denebola (Beta Leonis). These meteors are best seen near 0600 LST when the radiant lies highest above the horizon. This shower peaked on December 16th so current rates would be ~1 per hour no matter your location. At 65 km/sec. the Coma Berenicids produce mostly swift meteors.

Ursids (URS)

The Ursids (URS) peak on December 22 with an average ZHR of 10. The location of this radiant on that morning is 14:32 (218) +75. This area of the sky is located in southern Ursa Minor, close to the orange second magnitude star Kochab (Beta Ursae Minoris). This area of the sky is circumpolar (never sets) for most of the northern hemisphere. While activity may be seen during the entire night, these meteors are best seen during the last dark hour before dawn when the radiant lies highest above the horizon. Due to the high northern declination (celestial latitude), this shower is not visible to observers located south of the equator. At 33 km/sec. the Ursids will usually produce meteors of medium to slow velocity. To read more on viewing the Ursid shower visit the AMS website at: http://www.amsmeteors.org/showers.html#ursids

As seen from the mid-northern hemisphere (45N) one would expect to see ~15 Sporadic meteors per hour during the last hour before dawn as seen from rural observing sites. Evening rates would be ~2 per hour. As seen from the mid-southern hemisphere (45S), morning rates would be ~12 per hour as seen from rural observing sites and ~2 per hour during the evening hours. Locations between these two extremes would see activity between the listed figures. Evening rates are reduced this week 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 but may be used all week long.

Shower Name                RA     DEC   Vel     Rates
                                        km/s   NH    SH
ANT Antihelions          06h 44m  +23    30     3     2
DLE Dec Leonis Minorids  10h 46m  +31    64     2    <1
COM Coma Berenicids      11h 48m  +18    65    <1    <1
URS Ursids               14h 32m  +75    33    <1     0

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

Dec 15/16/17/18 Meteors

Meteor rates continue to be elevated. Though the Geminids are now history for 2009, a number of minor showers are displaying an impressive amount of activity. In particular, the December Leonis Minorids are producing between 10 and 25% of the nightly total. It will be interesting to see if this shower remains active over the next few days.

From Bob’s note for the night of Dec 15/16 : “There was scattered cirrus at dusk last night. Conditions were still good enough for video observations. Unfortunately conditions quickly deteriorated and thicker cirrus prevented the recording of any activity between 0400 and 0900 UT (8pm-1am PST). Conditions improved during the remainder of the morning allowing the recording of some activity before dawn arrived.”

… for the night of Dec 16/17 : “The cirrus was less widespread than yesterday. It was more prevalent during the evening hours and then cleared during the morning hours. It’s puzzling to see the dip in rates between 11-12 UT when it was mostly clear. It’s also surprising not to see any Antihelions prior to midnight, as the radiant is high in the sky.”

… and for the night of Dec 17/18 : “The cirrus clouds were back tonight with vengeance. It was mostly cloudy until 11UT (3am PST). The next hour seemed to be totally clear and then clouds interfered again the next hour. The last 46 minutes had mostly clear skies again. The new “COM’s” have been a disappointment. They are supposed to be slightly weaker than the “DLM’s” but the difference to me is striking with the “DLM’s” being the far stronger shower. Note that my first Ursid was detected tonight.”

Obs  Date(UT)      Time    TOT SPO ANT GEM HYD MON DLM DAD COM URS
TUS  2009-12-18   12h 12m   36  13  2   -   5   4   9   -   2   1
SDG  2009-12-18   11h 55m   33  23  4   -   2   1   2   -   0   1
TUS  2009-12-17   12h 12m   48  29  2   0   1   1   9   -   3   2
SDG  2009-12-17   12h 00m   64  47  4   -   4   1   7   -   1   0
TUS  2009-12-16   12h 06m   13  4   2   3   2   0   0   -   2   -
SDG  2009-12-16   11h 58m   32  23  2   2   1   1   2   1   0   -

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)
ANT - Antihelions
GEM - Geminids
HYD - Sigma Hydrids
MON - Monocerotids
DLM - December Leonis Minorids
DAD - December Alpha Draconids
COM - Coma Berenicids
URS - Ursid