In The Sky This Month – March 2010

This feature highlights a number of meteor showers, comets and asteroids which are visible during the month of March 2010. Mars is still the dominant planetary object in the evening sky though it it being joined by Venus in the early evening hours and Saturn in the late evening.

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 – The innermost planet spends most of the month too close to the Sun for most observers. During the last week of the month, Mercury quickly climbs out of the evening twilight sky on its way to its best evening apparition of the year in early April. By the end of March it can be found a few degrees to the lower right of Venus.

Venus - Here in Tucson, Venus is relatively easy to see thanks to our clear sky and lack of obscuring trees. For most people, the planet is still a difficult sight requiring a clear western horizon. At the start of the month, it sets a little less than an hour after the Sun. This gap grows to ~1.6 hours by the end of March. Not to worry though, Venus will be much higher and easier to see over the next few months. For northern observers, it will be highest in June. The best time for southern observers will be August.

Mar 17 - Moon passes 6° from Venus

Mars – Mars was at opposition (the point opposite the Sun in the sky) on January 29. Opposition means Mars is closest to Earth and at its brightest. This month the Earth and Mars continue to move further apart. As a result, Mars will quickly fade from magnitude -0.6 to +0.2. Still it will be a brilliant red beacon high in the eastern sky right after sundown outshining all but the brightest few stars. Note that unlike the stars which twinkle, Mars shines with an unwavering red glow.

Mar 25 - Moon passes close (4°) to Mars

Saturn – Saturn is at opposition in Virgo on March 21 when it will shine at magnitude +0.5. Telescope users should note that Saturn’s rings are still within a few degrees of edge-on.

Mar 2 - Moon and Saturn within 8° of each other

JupiterJupiter is too close to the Sun for most observers. It will once again be visible in the early morning hours next month.

Meteors

March marks the month with the lowest level of meteor activity. 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 March, 8-10 or so Sporadic meteors can be observed per hour from a dark moonless sky.

Major Meteor Showers

No major showers 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 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.

The nucleus of comet Wild 2 taken by the Stardust spacecraft. Credit: NASA/JPL/Stardust team.

This year Wild 2 reached perihelion on February 22 at 1.60 AU while 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. At mid-month the comet a morning object located in Virgo at a distance of 1.61 AU from the Sun and 0.71 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/2009 K5 (McNaught) and C/2009 O2 (Catalina)

These two long-period comets should become brighter than magnitude 10 this month. Both were found by components of the Catalina Sky Survey, one in Australia and the other in Arizona.

Comet McNaught was discovered by Rob McNaught on the night of May 27, 2009 deep in the southern sky. The discovery was made with the 0.5-m Uppsala Schmidt telescope from Australia as part of the Siding Spring Survey (one of the three Catalina Sky Survey components) for unknown asteroids and comets. At the time, the comet was a faint 17th magnitude.

With perihelion on April 30 of this year at a distance of 1.42 AU from the Sun, C/2009 K5 is now bright enough to be seen in small backyard telescopes from dark sites. During the month it should be as bright as 9.0 to 10.0 magnitude as it moves north while paralleling the Milky Way in Aquila. The comet will be a morning object all month long. At mid-month it will be located 1.57 AU from the Sun and 1.67 AU from Earth.

Comet Catalina was first spotted as an asteroidal object by observers at the Catalina Sky Survey proper on July 27, 2009. At the time the comet was 19th magnitude and probably just barely visible in images taken with the 0.68-m Catalina Schmidt telescope.

This comet is currently only 11th magnitude. The comet should rapidly brighten as it approaches its March 24th perihelion at a distance of 0.70 AU from the Sun. At that time the comet may be as bright as magnitude 9.0 as it cruises through the Milky Way constellations of Vulpecula, Cygnus, Lacerta and Andromeda in the morning sky.

Asteroids

Binocular and Small Telescope Asteroids (V < 9.0)

(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 next year 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 starts the month at magnitude 6.2 and steadily fades to mag 6.8. Sixth magnitude is close to the brightest Vesta can get and is easy for binocular observers. If you are lucky enough to be located in a very dark rural site you may even be able to see Vesta by naked eye among the stars in the ‘sickle’ of 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.

(532) Herculina

Herculina is a stoney S-type asteroid with a run-of-the-mill albedo of 16%. Though one of the brightest asteroids in the Main Belt, it avoided discovery for a century after the first asteroids were found (being found in 1904). As a result, this is the highest numbered asteroid that is relatively easy to see with a backyard telescope.

In March Herculina is at opposition and is between magnitude 8.8 and 9.0 for the entire month as it travels among the stars of Coma Berenices.

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.

(2) Pallas

Pallas is a dark 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 similar in size to Vesta with dimensions of 350x334x301 miles or 582x556x501 km. The reason it is fainter than Vesta is its darker albedo of 16%. Though no spacecraft are scheduled to visit Pallas, Hubble was able to get some good images that clearly show its nearly spherical shape.

HST Image of asteroid (2) Pallas. Credit: NASA/STScI.

This month it brightens from  magnitude 9.0 to 8.7 over the course of the month as it travels north through the constellation of Serpens.

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 Pallas from Heavens Above.

Meteor Activity Outlook for February 27-March 5, 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.

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 antapex radiant lies highest above the horizon this time of  year during the evening hours.

During this period the moon reaches its full phase on Sunday February 28th.  At this time the bright moon will be in the sky all night long making meteor observing difficult at best. As the week progresses the moon will rise later and later in the evening offering a few hours of dark sky between the end of evening twilight and moonrise.The estimated total hourly rates for evening observers this week is ~1 for those in the northern hemisphere and ~2 for those south of the equator. For morning observers the estimated total hourly rates should be ~5 from the northern hemisphere and ~7 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.

The radiant positions and rates listed below are exact for Saturday night/Sunday morning February 27/28. 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.

Shower Name                RA     DEC   Vel     Rates
                                        km/s   NH    SH
ANT Antihelions          11h 28m  +02    30     1     1
GNO Gamma Normids        15h 44m  -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

Feb 18/19/20/21 Meteors

Meteor activity from last weekend followed the pattern we’ve seen for the past month or so. Rates are decent though not very high and there is little activity from any known showers.

After the storm on the night of Feb 21/22, my camera shifted its position somehow. As a result I need to recalibrate its pointing by talking a series of deep exposures and measuring the position of 50+ stars. Due to the bright evening Moon I haven’t been able to do this yet. When I do I’ll have stats for this week’s observing sessions.

Obs  Date(UT)      Time    TOT SPO ANT DLE
TUS  2010-02-21   00h 00m  Clouds - No Meteors
TUS  2010-02-20   11h 09m   12  11  1   0
TUS  2010-02-19   11h 11m   15  12  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
DLE - Delta Leonids

Meteor Activity Outlook for February 20-26, 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.

February offers the meteor observer in the northern hemisphere a couple of weak showers plus falling sporadic rates. This may not seem too exiting but you never know when surprises are in store. An errant earthgrazer from the Centaurid complex may shoot northward. Better yet, a bright fireball may light up the sky. February is the start of the fireball season, when an abundance of fireballs seem to occur. This lasts well into April and seems to occur mostly during the early evening hours.

Observers in the southern hemisphere are treated to the Alpha Centaurid peak on the 8th plus the entire Centaurid complex of radiants is active all month long. Sporadic rates are slightly less than those seen in January, but still stronger than those witnessed north of the equator.

During this period the moon reaches its first quarter phase on Monday February 22nd. At this time the moon lies 90 degrees east of the sun and sets around midnight local standard time (LST). The estimated total hourly rates for evening observers this week is ~2 for those in the northern hemisphere and ~3 for those south of the equator. For morning observers the estimated total hourly rates should be ~12 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.

The radiant positions and rates listed below are exact for Saturday night/Sunday morning February 21/22. 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 11:00 (165) +05. This area of the sky lies in a remote area of southwestern Leo. The nearest star that is easily visible is 4th magnitude Sigma Leonis, located 5 degrees east of the center of the radiant. This radiant is best placed near 0100 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 western Leo, Sextans, Crater, or western Virgo could be a candidate for this shower. Rates at this time should be ~ 2 per hour no matter your location. With an entry velocity of 30 km/sec., the average Antihelion meteor would be of medium-slow speed.

Alpha Centaurids (ACE)

The last of the Alpha Centaurids (ACE) are visible this weekend. This shower is only visible south of thirty degrees north latitude. The further one is located south (down to 60S) the better the radiant is situated in the sky. Expected rates from the southern hemisphere is now < 1 per hour, even with the radiant located high in the sky. The current radiant position lies at 15:03 (226) -63. This position lies in extreme southeastern Centaurus, five degrees southeast of the brilliant zero magnitude star Rigel Kentaurus (Alpha Centauri). 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 Alpha Centaurids would produce mostly swift meteors.

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 00m  +05    30     2     2
ACE Alpha Centaurids     15h 03m  -63    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

2 Bright Stars and a Planet in the East to Southeast Sky

[Editor's note: I notice that lots of people are still finding this now a few years old post. If you are trying to find out what those bright stars in the eastern evening sky (Sirius and Jupiter) and eastern Morning sky (Venus) are (Jan/Feb 2014), go to the front page of this blog at transientsky.wordpress.com for the latest posts.]

When it is dark enough to see a few stars in the sky during evening twilight, look to the East and Southeast. About a third of the way from the horizon to the zenith (straight up), 3 bright “stars” can be seen spread out from due East to the South-South-East (see the chart below).

View of the East-Southeast sky in the early evening. The star Procyon is located between Mars and Sirius. Chart made with Stellarium.

The 3 “stars” are, in fact, 2 stars and a planet: Sirius, Procyon, and Mars. Let’s start with the Sirius, the southernmost and brightest of the three. Not only is Sirius the brightest of the three (at magnitude -1.5), it is the brightest star in the entire night sky. Only the Moon, Venus, Jupiter, and occasionally Mars are brighter.

Relative to the Sun, Sirius is twice as massive, has a radius 70% larger, and is 25 times more luminous. Still there are many stars in the sky that are even larger and more luminous than Sirius. The reason for its status as the brightest star in the sky is due more to its relatively close distance than its luminosity. At a distance of 8.6 light years, it is the 5th closest stellar system.

Sirius is an A-type star which causes it to shine with a white-blue color. Many times, though, the star will appear to rapidly change color. The reason for this is due to the Earth‘s atmosphere. Turbulence in the atmosphere causes the star’s light to be “bounced” all over the place. The light of the star is made up of many different colors which all “bounce” around differently. As a result, normally blue Sirius can appear to rapidly switch between many different colors when it is close to the horizon (meaning its light is passing through more atmosphere than usual). All stars experience this effect, it is just that Sirius‘ brightness makes it more evident. Watching Sirius when low in the sky with a telescope or just your eyes can be one of the best sights in the night sky.

Next in line is white Procyon, the seventh brightest star in the sky at magnitude 0.3. Procyon appears fainter than Sirius because it is intrinsically fainter (7.7 times brighter than the Sun versus 25 times brighter for Sirius) and farther away (11.4 light years vs. 8.6 light years). It is also less massive (1.5 times solar mass) but a bit larger (2 times solar radius) than Sirius.

The name Procyon comes from Greek and means “before the Dog”. In this case, the “Dog” is Sirius which has long been associated with a dog. Procyon‘s name derives from its slightly more northerly declination which causes it to rise a few minutes before Sirius (at least for northern observers).

The final “star” in the line is the red planet Mars. Last month Mars was at its closest and brightest for the year. At the time its brightness almost matched that of Sirius. Unlike Sirius Mars does not appear to twinkle and is a constant red beacon in the East.

Why does Sirius twinkle and change colors while Mars does not? Check out Phil Plait’s explanation on his Bad Astronomy site.

Feb 13/14 to 17/18 Meteors

We’ve had a nice run of clear nights here lately. Though February is usually a low activity month for meteors, my zenith facing camera is averaging 15-20 meteors per night.

I decided to shut down my north facing camera for the foreseeable future. Instead, its computer is now running a much wider field camera for fireball detection.

Obs  Date(UT)      Time    TOT SPO ANT BHE DLE
TUS  2010-02-18   11h 13m   20  17  2   -   1
TUS  2010-02-17   11h 15m   15  13  2   -   0
TUS  2010-02-16   11h 17m   15  14  0   -   1
TUS  2010-02-15   11h 09m   20  14  4   1   1
TUS  2010-02-14   11h 17m   20  17  2   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
ACE - Alpha Centaurids
PIH - Pi Hydrids
BHE - Beta Herculids

Meteor Activity Outlook for February 13-19, 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.

February offers the meteor observer in the northern hemisphere a couple of weak showers plus falling sporadic rates. This may not seem too exiting but you never know when surprises are in store. An errant earthgrazer from the Centaurid complex may shoot northward. Better yet, a bright fireball may light up the sky. February is the start of the fireball season, when an abundance of fireballs seem to occur. This lasts well into April and seems to occur mostly during the early evening hours.

Observers in the southern hemisphere are treated to the Alpha Centaurid peak on the 8th plus the entire Centaurid complex of radiants is active all month long. Sporadic rates are slightly less than those seen in January, but still stronger than those witnessed north of the equator.

During this period the moon reaches its new phase on Sunday February 14th. At this time the moon lies near the sun and is invisible at night. Next week the waxing crescent moon will enter the evening sky but will set long before the more productive morning hours arrive. The estimated total hourly rates for evening observers this week is ~2 for those in the northern hemisphere and ~3 for those south of the equator. For morning observers the estimated total hourly rates should be ~14 the northern hemisphere and ~20 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.

The radiant positions and rates listed below are exact for Saturday night/Sunday morning February 13/14. 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 10:32 (158) +07. This area of the sky lies in southwestern Leo, seven degrees southeast of the first magnitude star Regulus (Alpha Leonis). This radiant is best placed near 0100 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 western Leo, Cancer, Sextans, or extreme western Hydra could be a candidate for this shower. Rates at this time should be ~ 2 per hour no matter your location. With an entry velocity of 30 km/sec., the average Antihelion meteor would be of medium-slow speed.

Alpha Centaurids (ACE)

The Alpha Centaurids (ACE) reached maximum activity on Monday February 8th. This shower is only visible south of thirty degrees north latitude. The further one is located south (down to 60S) the better the radiant is situated in the sky. Expected rates from the southern hemisphere is now < 5 per hour, even with the radiant located high in the sky. The current radiant position lies at 14:28 (217) -61. This position lies in southeastern Centaurus, directly between the brilliant stars Rigel Kentaurus (Alpha Centauri) and Hadar (Beta Centauri). 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 Alpha Centaurids would produce mostly swift meteors.

Beta Herculids (BHE)

Studies by Sirko Molau and Juergen Rendtel of video radiants has revealed a radiant active in Hercules this time of year. The Beta Herculids (BHE) are only active for five nights and reach maximum activity on Friday February 12th. Hourly rates on that morning should be ~ 1 shower member per hour as seen from the northern hemisphere. Those situated south of the equator should average slightly less than one meteor per hour. The radiant position on the 14th lies at 16:32 (248) +22. This position lies in western Hercules, just north of the third magnitude star Beta Herculis. 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 Beta Herculids would produce mostly swift meteors.

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          10h 32m  +07    30     2     1
ACE Alpha Centaurids     14h 28m  -61    56    <1     3
BHE Beta Herculids       16h 32m  +22    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

Jan 28/29 to Feb 12/13 Meteors

February is usually a slow month for meteor watchers. There are no major showers active and even the background rate of sporadic meteors is near a seasonal low. Combine that with an active weather pattern in the US Southwest and the observed rates of meteors for my 2 meteor cameras have been rather low.

Bob’s notes from Feb 12/13: “Totally clear tonight. The hours prior to 2am (10 UT) were very slow with hardly any activity being recorded.”

… the night of Feb 11/12: “Clouds interfered with tonight’s session, reducing counts by 2/3rds.”

… the night of Feb 10/11: “I only recorded two meteors on February 9th before the skies clouded over. The 10th was a total loss. Tonight was a typical February night with a total number of meteors in the 30’s.”

… the night of Feb 9/10: “I only recorded two meteors on February 9th before the skies clouded over. The 10th was a total loss. Tonight was a typical February night with a total number of meteors in the 30’s.”

… the night of Feb 8/9: “The last four nights were lost due to clouds and rain. Tonight was mostly clear,
with a few drifting clouds, allowing the camera to operate again.”

… the night of Feb 3/4: “Last night was lost to clouds but tonight was perfectly clear. Rates were double tonight compared to recent sessions but only half that seen last month. Rates should improve slightly once the moon becomes less of a factor.”

… the night of Feb 1/2: “The last two nights were mostly cloudy and only a couple of meteors were seen each night. Tonight was a bit better but the bright moon is still a major factor, reducing the number of meteors seen.”

… the night of Jan 29/30: “No clouds tonight but a bright moon still severely hampered observations.”

… and the night of Jan 28/29: “Thick cirrus clouds and a full moon were a bad combination tonight. The highlight of the night was the capture of an Alpha Centaurid meteor.”

Obs  Date(UT)      Time    TOT SPO ANT DLM ACE PIH BHE
TUS  2010-02-13   11h 00m   11  10  0   -   -   -   1
SDG  2010-02-13   10h 38m   32  30  2   -   -   -   0
TUS  2010-02-12   11h 14m   13  9   0   -   -   -   3
SDG  2010-02-12   07h 39m   10  9   0   -   -   -   1
TUS  2010-02-11   00h 35m   1   1   0   -   -   -   0
SDG  2010-02-11   10h 14m   36  29  5   -   -   -   2
TUS  2010-02-10   10h 30m   6   5   1   -   -   -   0
SDG  2010-02-10   00h 00m   Bad Weather - No Meteors
TUS  2010-02-09   11h 28m   25  20  3   -   -   -   -
SDG  2010-02-09   --h --m   2   -   -   -   -   -   -
TUS  2010-02-08   09h 51m   19  15  2   -   -   2   -
SDG  2010-02-08   10h 07m   28  25  2   -   -   1   -
TUS  2010-02-07   00h 00m   Bad Weather - No Meteors
TUS  2010-02-06   11h 33m   18  14  0   -   0   4   -
TUS  2010-02-05   09h 51m   21  19  1   -   0   0   -
TUS  2010-02-04   00h 24m   2   2   0   0   0   -   -
SDG  2010-02-04   06h 45m   25  20  4   1   0   -   -
TUS  2010-02-03   00h 00m   Bad Weather - No Meteors
TUS  2010-02-02   08h 44m   3   3   0   0   0   -   -
SDG  2010-02-02   06h 30m   8   7   0   0   1   -   -
TUS  2010-02-01   09h 34m   3   3   0   0   0   -   -
TUS  2010-01-30   08h 10m   4   3   0   0   0   -   -
SDG  2010-01-30   07h 17m   13  11  1   1   0
TUS  2010-01-29   00h 00m   Bad Weather - No Meteors
SDG  2010-01-29   10h 53m   12  10  0   1   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
ACE - Alpha Centaurids
PIH - Pi Hydrids
BHE - Beta Herculids

U Scorpii erupts (and an update on V496 Scuti)

Nova in Latin means new. This is an apt name for a type of star that appears to brighten from out of nowhere. A small sub-class of these objects, called recurrent novae, have been observed to erupt on multiple occasions. U Scorpii is such an object having been observed in outburst in 1863, 1906, 1917, 1936, 1945, 1969, 1979, 1987, and 1999. Recent studies suggested another outburst was due in 2008-2010 and this study appears correct. On Jan 28, Barbara Harris of New Smyrna Beach, Florida imaged U Sco at a relatively bright magnitude of V = 8.05 (bright enough for binoculars and small telescopes). Only a night earlier Harris had measured its brightness at a dim V = 18.2.

U Scorpii is a “fast” nova meaning it rapidly decreases in brightness. The chart below shows the rapid decrease in brightness of roughly a magnitude per day. Though I didn’t attempt to observe the nova, Salvador Aguirre was able to observe it visually on 4 consecutive nights (the blue crosses on the chart below). The nova is now around magnitude 14 which is too faint for all but CCD-equipped astronomers.

Much more on the history and science of U Sco can be found at the AAVSO.

While U Sco is am example of a fast nova, another nova first seen in November is of the “slow” variety. V496 Scuti was an easy object for evening observers and I was able to observe it over the course of a few weeks. Unfortunately the object got too low to be seen from my backyard and I had to stop my observations. After a month or so too close to the Sun for any observers, the nova is once again visible. Surprisingly the nova is still a reasonably bright 9th magnitude and only ~1.5 to 2.0 magnitude fainter than at maximum. That’s a fading of 1.5 to 2.0 magnitude over a 2+ month period. Compare that with U Sco’s rate of ~1 magnitude per day. More on this object can be found on earlier Transient Sky posts here and here.

Hubble Images “Comet” P/2010 A2 (LINEAR)

Last month an apparent “comet” was discovered in the inner part of the usually asteroidal Main Belt. Early observations quickly uncovered an object that looked less like a comet and more like the result of a traumatic event on an asteroid. Whether that event was due to a collision between 2 small asteroids or the break-up of an asteroid due to rapid rotation has not yet been determined, but these 2 explanations seem to be the most likely. It would be the 1st time we’ve observed either of these processes in real-time. For more on this object, which is still named Comet P/2010 A2 (LINEAR), see the post titled “The Curious Case of Comet LINEAR“.

David Jewitt (UCLA) led a team which used the Hubble Space Telescope (HST) to take the highest resolution images of the “comet” yet. [See the HST press release here.] Ground-based images have not recorded much detail in the dust trail. The superior resolution of HST (it really helps to observe above the Earth’s atmosphere) fines a number of criss-crossing linear features. The remains of the asteroid that released the dust can be seen as the faint star leading (to the lower left) the dust trail. Hopefully data from HST as well as an assortment of other telescopes will allow modelers to determine what caused the event. I’m sure this will not be the last update on this unique object.

HST image of P/2010 A2. Credit: NASA, ESA, David Jewitt (UCLA).

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