First Week of March Meteors

The first week of March continues February’s trend of low meteor rates and no major shower activity. Unfortunately this will be the case thorough most of April.

Bob’s notes …

Feb 28/Mar 1: “Another perfectly clear night with good activity. Two more Gamma Normids were recorded tonight. Leo and Ophiuchus continue to see a lot of meteor activity.”

Mar 1/2: “Another perfectly clear night with slightly less activity than last night. Occasional thin cirrus clouds could have reduced the counts tonight. Two more Gamma Normids were recorded tonight. The Antihelion radiant was more active than usual with 5 members. There were three areas in Ophiuchus that presented possible radiants. None had more than four meteors and they were not particularly sharp so these are most likely sporadic alignments.”

Mar 4/5: “The last two nights were lost to clouds. Tonight was perfectly clear night but rates were down significantly from the first two sessions this month. Two more Gamma Normids were recorded tonight. The first of these was very bright with an estimated magnitude near -3. It shot northward and ended near the handle of the Big Dipper. Plots revealed nothing of note tonight.”

Mar 5/6: “It was mostly clear tonight but with occasional cirrus and mid-level clouds. Overall activity was somewhat quiet but the Gamma Normids and Antihelion were active compared to the sporadic counts. There was a tight radiant in eastern Ophiuchus that produced four of the fifteen spordic meteors recorded tonight. It was not close to any bright star but located directly between Beta and Eta Ophiuchi.”

Obs  Date(UT)      Time    TOT SPO ANT DLE GNO
SAL3 2011-03-06   10h 44m   10  6   3   1   0
ALLS 2011-03-06   11h 05m   4   4   0   0   0
SDG  2011-03-06   10h 31m   20  15  2   -   3

SAL3 2011-03-05   03h 07m   10  8   2   0   0
ALLS 2011-03-05   11h 05m   4   4   0   0   0
SDG  2011-03-05   10h 10m   23  19  2   -   2
HERM 2011-03-05   10h 41m   8   7   0   1   0

SAL3 2011-03-04   10h 23m   10  10  0   0   0
ALLS 2011-03-04   10h 37m   8   8   0   0   0

SAL3 2011-03-03   02h 08m   5   5   0   0   0
ALLS 2011-03-03   11h 18m   3   3   0   0   0
HERM 2011-03-03   10h 41m   6   4   2   0   0

SAL3 2011-03-02   10h 52m   19  17  1   0   1
ALLS 2011-03-02   11h 20m   10  9   1   0   0
SDG  2011-03-02   10h 36m   34  27  5   -   2

SAL3 2011-03-01   10h 54m   10  9   1   0   0
ALLS 2011-03-01   11h 22m   5   3   2   0   0
SDG  2011-03-01   10h 06m   41  37  2   -   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
DLE - Delta Leonids
GNO - Gamma Normids

End of February Meteors

The end of the month brought some more clouds, a little more rain, and even a touch of snow and soft hail to Tucson. Unlike the last storm, I didn’t miss a single night due to the weather.

Still meteor rates remain low which is normal for this time of the year. Bob had better luck with his image intensified camera which can see much fainter than the Tucson based system.

Bob’s notes …

Feb 27/28: “Another storm passed through the area preventing observations since the 23rd. Tonight was perfectly clear and transparent. Activity was very good with 44 meteors recorded over the course of the night. A surprising two Gamma Normids were recorded early in its activity period. While plots revealed no tight radiants tonight, Leo and Ophiuchus appeared to be areas of noticable activity.”

Obs  Date(UT)      Time    TOT SPO ANT DLE GNO
SAL3 2011-02-28   10h 55m   9   6   2   1   0
ALLS 2011-02-28   11h 24m   5   4   1   0   0
SDG  2011-02-28   10h 02m   44  38  4   -   2

SAL3 2011-02-27   01h 10m   4   3   1   0   0
ALLS 2011-02-27   00h 00m   0   0   0   0   0

SAL3 2011-02-26   04h 35m   9   8   0   1   0
ALLS 2011-02-26   11h 27m   4   4   0   0   0

SAL3 2011-02-25   10h 46m   7   6   1   0   0
ALLS 2011-02-25   11h 00m   4   4   0   0   0

SAL3 2011-02-24   11h 00m   5   4   1   0   -
ALLS 2011-02-24   11h 29m   5   4   1   0   -
HERM 2011-02-24   10h 12m   15  13  2   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)
ANT - Antihelions
DLE - Delta Leonids
GNO - Gamma Normids

Meteor Activity Outlook for March 5-11, 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.

March is the slowest month for meteor activity. No major annual showers are active and only two very weak minor showers produce activity this month. The sporadic rates continue a slow decline as seen from the mid-northern latitudes and mid-southern rates reach a first half minimum. There is not much to look forward to this month expect for the evening fireballs that seem to peak this time of year from the northern hemisphere. This could be due to the fact the antiapex radiant lies highest above the horizon this time of year during the evening hours.

During this period the moon waxes from a thin crescent to nearly one-half illuminated. During this entire period the moon will only be in the evening sky and will not interfere with the more active morning hours. The estimated total hourly rates for evening observers this week is near three as seen from the northern hemisphere and four as seen from the southern hemisphere. For morning observers the estimated total hourly rates should be near ten from the northern hemisphere and fourteen as seen from south of the equator. The actual rates will also depend on factors such as personal light and motion perception, local weather conditions, alertness and experience in watching meteor activity. Rates are slightly reduced for the evening hours due to moonlight.

The radiant (the area of the sky where meteors appear to shoot from) positions and rates listed below are exact for Saturday night/Sunday morning March 5/6. 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)

The wide Antihelion (ANT) radiant is now centered at 11:52 (178) +00. This area of the sky lies in western Virgo, only one degree south of the fourth magnitude star Zavijava (Beta Virginis). This radiant is best placed near 0100 local standard time (LST) when it lies on the meridian and is located highest in the sky. Due to the large size of this radiant, any meteor radiating from eastern Leo, southern Coma Berenices, Sextans, Crater, Corvus, or Virgo could be a candidate for this shower. Rates at this time should be near two per hour no matter your location. With an entry velocity of 30 km/sec., the average Antihelion meteor would be of medium-slow speed.

Gamma Normids (GNO)

The Gamma Normids (GNO) is a weak shower best seen from the southern hemisphere. This shower is only visible south of forty degrees north latitude. The further one is located south (down to 50S) the better the radiant is situated in the sky. Expected rates from the southern hemisphere is currently near one per hour, even with the radiant located high in the sky. The current radiant position lies at 16:04 (241) -52. This position lies in central Norma, three degrees southwest of the fourth magnitude star Gamma Normae. The radiant is best placed during the last dark hour before dawn, when it lies highest above the horizon in a dark sky. At 56km/sec. the Gamma Normids would produce mostly swift meteors.

As seen from the mid-northern hemisphere (45N) one would expect to see approximately eight 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 eleven per hour as seen from rural observing sites and three 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
ANT Antihelions           11h 52m  +00    30     2     2
GNO Gamma Normids         16h 04m  -52    56    <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 – March 2011

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

March 2011 Highlights
* Mercury and Jupiter dazzle after evening twilight
* Saturn is up all night
* Venus slowly loses altitude before dawn

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

Moon - The table below lists important lunar dates for the month, including the phases of the Moon and nights of lunar-planetary and lunar-stellar conjunctions.

Mar 1 - Moon 1.6° from Venus
Mar 4 - New Moon
Mar 6 - Moon 6° from Jupiter
Mar 11 - Moon 2° from Pleiades
Mar 12 - First Quarter Moon
Mar 12 - Moon 7° from bright star Aldebaran
Mar 15 - Moon 9° from bright star Pollux
Mar 16 - Moon 5° from Beehive Cluster
Mar 17 - Moon 5° from bright star Regulus
Mar 19 - Full Moon
Mar 20 - Moon 7.5° from Saturn
Mar 21 - Moon 2.5° from bright star Spica
Mar 24 - Moon 3° from bright star Antares
Mar 26 - Third Quarter Moon
Mar 28 - Moon 1.5° from asteroid Vesta
Mar 31 - Moon 5.5° from Venus

Mercury and Jupiter – The innermost planet has its best evening apparition of the year this month (for observers in the northern hemisphere). From mid-month till the end of the month, Mercury will be observable low in the western sky a half-hour or so after sunset. As an added bonus, Jupiter will be located nearby. The two will be closest on Mar 15 when they will only be 2° from each other. By the end of the month both planets will be located too close to the Sun to be easily seen.

Mar 6 - Moon 6° from Jupiter
Mar 15 - Mercury and Jupiter within 2° of each other
Mar 23 - Mercury at Greatest Elongation East

Saturn – Saturn starts the month rising a few hours after sunset. By the end of the month it is only a few days from opposition (on April 3) and rises just moments after sunset. Located in Virgo, the ringed planet is a close match in brightness (mag +0.4) to Spica, the brightest star in Virgo (mag +1.0). Saturn spends the entire month within 10° of Spica.

Mar 20 - Moon 7.5° from Saturn

Venus -  On Mar 1, Venus rises almost 2 hours before the Sun in the eastern sky though this drops to just a little over an hour by the end of the month.

Mar 1 - Moon 1.6° from Venus
Mar 31 - Moon 5.5° from Venus

Mars – Too close to the Sun for observation.

Meteors

Meteor activity is near a seasonal minimum in March. 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 March mornings, 10-12 or so Sporadic meteors can be observed per hour from a dark moonless sky.

Major Meteor Showers

None this month…

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 2011 Meteor Shower Calendar.

Comets

Naked Eye Comets (V < 6.0)

None this month…

Binocular Comets (V = 6.0 – 8.0)

None this month…

Small Telescope Comets (V = 8.0 – 10.0)

None this month…

Asteroids

Binocular and Small Telescope Asteroids (V < 8.0)

(4) Vesta

Vesta is the brightest asteroid in the Main Belt. This is due to its high albedo (or reflectivity) which causes it to reflect ~42% of the light that strikes it. Vesta is also 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 has dimensions of 347x336x275 miles or 578×560×458 km.

The maps below were created from images taken with the Hubble Space Telescope. The geography is dominated by a large impact crater located near the south pole (the blue ‘donut’ in the elevation map). Perhaps this crater is the result of the impact that blasted off the smaller V-type asteroids. We’ll know more this summer when NASA’s Dawn spacecraft enters orbit around Vesta for a full year. Currently the encounter is scheduled for July 2011 to July 2012.

Images and models of the shape of asteroid (4) Vesta. In the upper left is a real HST image, to the upper right is a model of Vesta’s shape, and on the bottom is an elevation map . Credit: NASA/STScI.

Vesta spends the month around magnitude 7.7 as it moves eastwards through eastern Sagittarius.

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.

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