Apr 21/22 to 25/26 Meteors and the peak of the Lyrids

The stretch of 5 nights summarized in this post covers the maximum of the Lyrids shower. The Lyrids are often considered a major shower but with only a max rate of 15-20 meteors per hour they can be considered either the weakest major shower or the strongest minor shower.

This year’s display was produced the usual number of Lyrids with a peak visual ZHR of ~20 per hour. Over 30 observers from 15 countries reported 396 Lyrids to the International Meteor Organization. Maximum occurred around 20 hours UT on April 22.

Visual ZHR for the Lyrids around the time of their peak. Credit: International Meteor Organization.

The night of April 21/22 started off wet and cloudy in Tucson. Since the weather maps showed evidence of clearing later in the night I decided to start my camera even though it was still raining. Luckily the sky did clear around midnight and almost 6 hours of observing produced 19 meteors, 14 of which were Lyrids.  The next 4 nights didn’t detect many more Lyrids as weather conditions again limited the detection efficiency of my camera.

With the Lyrids out of the way, we can now look forward to one of the Earth’s biannual treks through the debris of Comet Halley. Unfortunately this year’s Eta Aquariids will be hurt by bright moonlight.

Obs  Date(UT)      Time    TOT SPO ANT ZCG LYR PPU
TUS  2010-04-26   08h 59m   8   7   1   -   -   0
TUS  2010-04-25   08h 53m   2   2   0   -   0   0
TUS  2010-04-24   02h 22m   6   5   0   -   1   0
TUS  2010-04-23   00h 00m   Clouds all night
TUS  2010-04-22   05h 54m   19  4   1   -   14  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
ZCG - Zeta Cygnids
LYR - Lyrids
PPU - Pi Puppids

Apr 11/12 to 20/21 Meteors

The doldrums of the Spring meteor season continue. The fact that most nights also experienced a good share of cirrus and light cloudiness also haven’t helped meteor observing. The stretch of nights summarized below ends the night before the predicted maximum of the Lyrids. Unfortunately a storm system was also forecast to swing through AZ just in time to wreck the maximum.

Obs  Date(UT)      Time    TOT SPO ANT ZCG LYR PPU
TUS  2010-04-21   02h 26m   5   4   1   -   0   0
TUS  2010-04-20   04h 57m   7   7   0   -   0   0
TUS  2010-04-19   06h 14m   5   3   1   -   1   0
TUS  2010-04-18   03h 05m   1   1   0   -   0   0
TUS  2010-04-17   07h 00m   9   7   1   -   1   0
TUS  2010-04-16   02h 02m   1   0   1   -   0   0
TUS  2010-04-15   06h 13m   5   3   2   -   -   -
TUS  2010-04-14   09h 23m   10  9   1   -   -   -
TUS  2010-04-13   09h 25m   10  8   2   0   -   -
TUS  2010-04-12   09h 27m   8   6   2   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
ZCG - Zeta Cygnids
LYR - Lyrids
PPU - Pi Puppids

Pop Goes the Comet – The Outburst of Comet P/2010 H2 (Vales)

I’ve always been drawn to comets. Maybe it is their unpredictability. Even the most well-behaved comets can unexpectedly split into multiple pieces, brighten by orders of magnitude, or even just fizzle away into nothing. A recent find is a perfect example of a comet seemingly rising from out of nowhere to be one of the year’s most interesting objects (at least so far…).

On the night of April 16 UT, Slovenian astronomer Jan Vales detected a normal looking 12th magnitude asteroid. Normal in that it was moving at a rate that was typical for a run-of-the-mill object in the asteroid Main Belt. The weird thing is it wasn’t known. All the asteroids this bright were found years ago (in fact ~70 years ago). In fact, this object is so bright that I should be able to see it in my 12″ telescope without the use of a digital camera.

As the image below shows (taken by Italian astronomers Ernesto Guido and Giovanni Sostero with a remote telescope in New Mexico), the object sure looks like an asteroid. As further observations came in, more and more observers started to note the object was slightly more diffuse than the background stars… and growing in size.

CCD observations of Comet Vales. Credit: E. Guido and G. Sostero.

The only explanation is a recent outburst from previously unknown comet. Only a night earlier, the Catalina Sky Survey searched the part of the sky containing the comet but found no trace of it. If it had been brighter than magnitude 20.1 it would have been seen. Since the comet is now magnitude 11.5 to 12.0, this means it brightened by a factor of ~200 in under 24 hours.

Though comet outbursts (outburst being the usual term to describe a sudden increase in the activity or dust/gas release of a comet) are common, such dramatic outbursts are fairly rare. At this early stage the outburst is very similar to that of Comet Holmes which experienced outbursts in 1892, 1893, and 2007. Note, that although Holmes became bright enough to be seen with the naked eye, this outburst will probably always require a large backyard telescope to be observed.

The comet now known as P/2010 H2 (Vales), or just Comet Vales, circles the Sun once every 7.6 years. It’s orbit takes it to within 3.09 AU of the Sun (3.09 times further from the Sun than the Earth’s distance). It’s orbit is similar to those of the Hilda asteroids. Hildas orbit the Sun 3 times for every 2 times that Jupiter orbits the Sun. As a result, Hildas are on stable orbits and can stay away from Jupiter for billions of years. The orbit of Comet Vales is similar but slightly different from the Hilda asteroids. This suggests that it is in a pseudo-Hilda orbit. Comets can sometimes be perturbed into Hilda-like orbits that are stable for years, and sometimes centuries, but ultimately will be kicked out of this orbital configuration by a future close approach to Jupiter. As more observations come in, the orbit of Comet Vales will be refined and we should learn more about its past and future.

Orbit and position of Comet Vales, valid for April 19, 2010. Created with C2A. Credit: Carl Hergenrother.

In the meantime, it will be interesting to watch the dust released by Vales’ outburst slowly expand. Perhaps it will even resemble the dust shells of Comet Holmes as seen in these pictures I took back in 2007.

Meteor Activity Outlook for April 17-23, 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.

Meteor activity picks up a bit during April as two major showers are active during the month. The first of these, the Lyrids, are active from the 16th through the 25th, with a pronounced maximum on the 22nd. The Eta Aquariids start appearing near the 28th and reach maximum activity during the first week in May. Sporadic rates are low but steady as seen from the mid-northern hemisphere (45 N). Sporadic rates seen from the mid-southern hemisphere (45 S) rise this month toward a maximum in July.

During this period the moon reaches its first quarter phase on Wednesday April21st . At this time the moon lies ninety degrees east of the sun and sets near 0100 local daylight time (LDT), depending on your location. This weekend the waxing crescent moon will set shortly after the end of evening twilight and will not cause any inteference to meteor observers. 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 ~10 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 April 17/18. 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:

Pi Puppids (PPU)

The elusive Pi Puppids (PPU) are now active from a radiant located at 07:12 (108) -46. This area of the sky lies in western Puppis near the double star Iota Puppi. This radiant is best placed as soon as it becomes dark as it culminates during the afternoon hours when the sun is still above the horizon. These meteors are nearly non-existent away from the night of April 23rd. Even on that night it would be lucky to spot just one, especially from the northern hemisphere, where the radiant lies low in the southwest at dusk. This shower has produced outbursts in the past so it should be monitored whenever possible, especially from the southern hemisphere. With an entry velocity of only 18 km/sec., the average Pi Puppid meteor would crawl through the sky at a snails pace.

Sigma Leonids (SLE)

The team of Sirko Molau and Juergen Rendtel have discovered a weak radiant active at this time in the constellation of Virgo. Video data shows that the Sigma Leonids (SLE) are active from April 18th through the 25th with maximum activity falling on the evening of April 21st (22nd UT). The radiant is currently located at 13:16 (199) +05. This position lies in central Virgo, five degrees northeast of the third magnitude star Delta Virginis. The radiant is best placed near midnight LDT, when it lies highest above the horizon. At 20km/sec. the Sigma Leonids would produce obvious, slow meteors. Expected rates are less than one per hour no matter your location.

h Virginids (HVR)

There is also a second new radiant active in Virgo this time of year. Video data shows that the h Virginids (HVR) are active from April 22-25 with maximum activity occurring on the 22nd. On the evening of the 21st (22nd UT), the radiant is currently located at 14:16 (220) -16. This position lies on the Virgo/Libra border, two degrees southeast of the fourth magnitude star Kappa Virginis. The radiant is best placed near 0200 LDT, when it lies on the meridian and is highest above the horizon. At 24km/sec. the h Virginids would produce more obvious, slow meteors. Expected rates would also be less than one per hour no matter your location.

Antihelions (ANT)

The wide Antihelion (ANT) radiant is now centered at 14:40 (214) -13. This area of the sky lies in western Libra, three degrees west of the second magnitude star Zubenelgenubi (Alpha Librae). This radiant is best placed near 0200 local daylight time (LDT) 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 Hydra, Libra, or eastern 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.

Lyrids (LYR)

The major shower known as the Lyrids (LYR) are active from April 16th through the 25th. Maximum activity occurs on the morning of April 22th. The radiant is currently located at 18:00 (270) +35. This position actually lies in eastern Hercules, eight degrees southwest of the brilliant blue-white zero magnitude magnitude star known as Vega (Alpha Lyrae). The radiant is best placed during the last dark hour before dawn, when it lies highest above the horizon. At 48km/sec. the Lyrids would produce meteors of medium velocity. Expected rates this weekend are near one per hour during the last dark hour before dawn. At maximum, hourly rate between 10-20 can be expected. Due to the northerly declination of the radiant, these meteors are not well seen from high southern latitudes.

Nu Cygnids (NCY)

The team of Sirko Molau and Juergen Rendtel have a third weak radiant active at this time in the constellation of Cygnus. Video data shows that the Nu Cygnids (NCY) are active from April 18th through May 7th. Maximum activity occurs on the morning of April 20th. The radiant is currently located at 20:08 (302) +38. This position lies in central Cygnus, four degrees southwest of the second magnitude star Sadr (Gamma Cygni). The radiant is best placed during the last dark hour before dawn, when it lies highest above the horizon in a dark sky. At 42km/sec. the Nu Cygnids would produce meteors of medium velocity. Expected rates are near one per hour during the last dark hour before dawn. Due to the northerly declination of the
radiant, these meteors are not well seen from south of the equator.

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
PPU Pi Puppids           07h 12m  -46    18    <1    <1
SLE Sigma Leonids        13h 16m  +05    20    <1    <1
HVR h Virginids          14h 16m  -11    24    <1    <1
ANT Antihelions          14h 40m  -16    30     1     2
LYR Lyrids               18h 00m  +35    48     1    <1
NCY Nu Cygnids           20h 08m  +38    42     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

Update on the Wisconsin Fireball (and meteorites)

A brilliant and well observed fireball was observed flying over the American Midwest Wednesday evening. The map below shows that sightings were made from Kansas in the south to Minnesota in the north and from Indiana in the east to South Dakota in the north. The yellow stars denote a sighting while the red stars denote reports of sonic booms (a tell tale sign that meteorites may have survived to hit the ground).

Map of fireball and sonic boom reports for the April 15 Wisconsin fireball. All reports were submitted to the Amercian Meteor Society and this blog. Yellow stars denote sightings and red stars denote sonic boom reports. Credit: Carl Hergenrother

Zooming in on the area where most of the sonic booms were heard brings us to southwestern Wisconsin. We now know that meteorites were found in this area. Not only did the sonic booms  and the large number of videos point meteorite hunters to this area but as many as 3 NWS Doppler radars picked up the meteorites as they were falling through the atmosphere. The blue square pinpoints were the radars place the most likely area of meteorite falls.

Zoomed in map of fireball and sonic boom reports for the April 15 Wisconsin fireball. All reports were submitted to the Amercian Meteor Society and this blog. Yellow stars denote sightings, red stars denote sonic boom reports and the blue square denotes most likely point of meteorite landings. Credit: Carl Hergenrother

All of these observations have allowed researchers to quickly find meteorites from this fireball. Meteorite related stories can be found here and here.

Finally a YouTube video of the fall…

Bright Fireball Over the Great Lakes Area

The net is hopping with reports of a brilliant fireball seen from Wisconsin to Missouri. All reports are consistent with a meteor that rivaled the Full Moon in brilliance. Reports of sonic booms also suggest  that shattered remains of the small asteroid (original size was probably no larger than a basketball, but that’s only a guess) may have survived to hit the ground as small meteorites (maybe fist sized, probably much smaller).

I’ll try to get more info and maybe even post a sighting/sonic boom map.

In the meantime, here are some comments posted to this blog.

From Jennifer in Spring Grove, IL:

I think I saw a meteor west of where I live in Spring Grove Il a bit after 10 pm today April 14th. It was very large and brite. It lit the whole sky as if a full moon just peeked out from a cloud. It looked very near to the ground before it fizzled out. So low I waited to hear an explosion.

From Amy near Wautoma, WS:

My husband and I were driving in Mt. Morris near Wautoma, Wisconsin. We were out away from the lights of the city and we both saw a large glowing green ball falling out of the sky! It was cool to my husband, but freaked me out. I was scared! I can never seen something like that before! There was no noise….it was just there, like a movie. I didn’t not see it all the way to the ground. It happened on Wednesday April 14, 2010 just before 10PM. Anyone else see this?

… and a few news stories (KCRG, KTVO, WBAY, WZZM, Discover Blog, WISN).

UPDATE: The Quad Cities IL/IA National Weather Service Office has a page devoted to the fireball. The site includes links to videos as well as a Doppler Radar image showing possible meteoric debris falling over Grant and Iowa counties.

April 3/4 to 10/11 Meteors

Every night is producing a steady drizzle of meteors. My zenith pointing camera (the northern one is no longer operational, something I’ll need to fix in the future) is detecting roughly 12-14 meteors per night. Only the night of April 5/6 produced subpar numbers which may have been due to lots of dust in the air (it was very windy that day).

The evening of April 7/8 saw a brilliant long-lived fireball. I plan to highlight this fireball in a future post.

Obs  Date(UT)      Time    TOT SPO ANT ZCG
TUS  2010-04-11   09h 29m   17  15  1   1
TUS  2010-04-10   09h 32m   14  10  2   2
TUS  2010-04-09   09h 02m   12  10  2   0
TUS  2010-04-08   09h 35m   13  11  2   0
TUS  2010-04-07   09h 38m   14  13  0   1
TUS  2010-04-06   09h 40m   3   3   0   0
TUS  2010-04-05   08h 57m   13  11  1   1
TUS  2010-04-04   09h 44m   10  7   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
ZCG - Zeta Cygnids

Meteor Activity Outlook for April 10-16, 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.

Meteor activity picks up a bit during April as two major showers are active during the month. The first of these, the Lyrids, are active from the 16th through the 25th, with a pronounced maximum on the 22nd. The Eta Aquariids start appearing near the 28th and reach maximum activity during the first week in May. Sporadic rates are low but steady as seen from the mid-northern hemisphere (45 N). Sporadic rates seen from the mid-southern hemisphere (45 S) rise this month toward a maximum in July.

During this period the moon reaches its new phase on Wednesday April 14th. At this time the moon lies near the sun and cannot be seen at night. This weekend the waning crescent moon will not cause any interference to meteor observers. The estimated total hourly rates for evening observers this week is ~3 for those in the northern hemisphere and ~4 for those south of the equator. For morning observers the estimated total hourly rates should be ~10 from the northern hemisphere and ~16 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 April 10/11. 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 14:16 (214) -13. This area of the sky lies on the Virgo/Libra border, ten degrees west of the second magnitude star Zubenelgenubi (Alpha Librae). This radiant is best placed near 0200 local daylight time (LDT) 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 Hydra, Libra, 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.

Zeta Cygnids (ZCG)

The team of Sirko Molau and Juergen Rendtel have discovered a weak radiant active at this time in the constellation of Cygnus. Video data shows that the Zeta Cygnids (ZCY) are active from March 27th through April 18th. Maximum activity occurs on the morning of April 6th. The radiant is currently located at 20:08 (302) +42. This position lies in central Cygnus, six degrees west of the second  magnitude star Sadr (Gamma Cygni). The radiant is best placed during the last dark hour before dawn, when it lies highest above the horizon in a dark sky. At 44km/sec. the Zeta Cygnids would produce meteors of medium velocity. Expected rates are near one per hour during the last dark hour before dawn. Due to the northerly declination, these meteors are not well seen from south of the equator.

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          14h 16m  -13    30     1     2
ZCY Zeta Cygnids         20h 08m  +42    44     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

Don’t Miss Out On Mercury and Venus

If it’s clear this evening and you have a unobstructed view of the western horizon, go out and look for Venus and Mercury. Venus is, by far, the brightest thing in the sky and should be obvious. Mercury is the fainter star to the lower right of Venus. Though Venus will be visible in the evening sky for the next few months, Mercury will only be easily observable for the next week or so.

The image below was taken with a Canon EOS XSi in the early evening (April 9).

x

Asteroid Fly-By Today

A few hours from now (around 2 hours UT on April 9), a small ~20-meter in diameter asteroid will pass close to the Earth. At that time, asteroid 2010 GA6 will be about 10% closer to Earth than the Moon or 270,000 miles. Even though this is relatively close by asteroid standards, the small object will not be very bright (magnitude 15.5 to 16.0) and will be impossible to see without a camera-equipped telescope.

The asteroid was first picked up by the Tucson-based Catalina Sky Survey early on the evening of April 4. Events of this nature are detected a few times a year and may occur every few weeks. Still there is nothing to worry about. Space is big and these objects are small.

More info and a nice orbit diagram can be found at the JPL NEO Project Office.

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