Nov 19/20 Meteors
The Leonids are becoming much fewer in number. Still the relatively high number of Sporadic meteors is keeping the nightly totals elevated.
My 2 cameras produced an interesting result last night. The zenith (straight-up) camera found a half-dozen or more meteors that appeared to radiate from a broad area on the Ursa Major/Lynx border. But, the north camera, which also happened to directly image the supposed “radiant” saw nothing from that area. The lack of agreement between the two cameras suggests that either a) this was just a fluke alignment, or b) bad astrometry and these were actually Leonids, or c) there was an unknown shower active last night. Personally I believe explanation ‘a’.
Bob’ notes for the night of Nov 19/20 : “It was clear and transparent all night long. Rates were back up to what was expected. The Northern Taurids were the most active shower surpassing the Leonids.”
Obs Date(UT) Time TOT SPO NTA STA LEO AMO NOO AND OER TUS Nov-20 11h52m 52 28 4 3 11 2 2 1 1 SDG Nov-20 11h55m 66 44 9 - 6 2 4 0 1
TUS – Camera in Tucson operated by Carl Hergenrother
SDG – Camera in San Diego operated by Bob Lunsford
TotTime – Total amount of time each camera looked for meteors
TOT – Total number of meteors detected
SPO – Sporadics (meteors not affiliated with any particular meteor shower)
NTA/STA – Northern and Southern Taurids (includes Antihelions)
LEO – Leonids
AMO – Alpha Monocerotids
NOO – November Orionids
AND – Andromedids
OER – Omicron Eridanids
Update on Nova V496 Scuti
Nova V496 Scuti is still near maximum brightness at magnitude ~7.4. For the back story on this object check out my post from Nov 15: “Nova Scuti 2009 = V496 Scuti“.
The plot below was created by the American Association of Variable Star Observers (AAVSO) from their archives. It includes 97 observations made by 33 observers from 13 countries. The blue crosses represent my own observations which were made visually with 30×125 binoculars. You can also check out Salvador Aguirre’s blog (in Spanish) for his observations of V496 Scuti.
The nova has been rather steady in its brightness for the past 5 days or so. Based on the data below, it’s possible it is still slowly brightening. Regardless, at some point in the next week or so, the nova should start to rapidly fade. I say should because some nova have been known to stay bright for weeks to months and even experience multiple outbursts.
AAVSO archival data of nova V496 Scuti. Credit: AAVSO (www.aavso.org)
Meteor Activity Outlook for November 21-27, 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.
As seen from the northern hemisphere, meteor rates continue to be strong in November. While no major showers are active this month, the two Taurid radiants plus the Leonids keep the skies active. The addition of strong sporadic rates make November one of the better months to view meteor activity from north of the equator. Skies are fairly quiet as seen from the southern hemisphere this month. Activity from the three showers mentioned above may be seen from south of the equator, but the sporadic rates are much lower than those seen in the northern hemisphere.
During this period the moon reaches its first quarter phase on Tuesday November 24th. On that date the moon lies ninety degrees east of the sun and will set near midnight local standard time (LST). This weekend the waxing crescent moon will set long before the more active morning hours arrive, allowing dark skies for those who venture out during the morning hours. As the week progresses the moon sets later each night narrowing the window of opportunity to view under dark conditions. The estimated total hourly rates for evening observers this week is near four as seen from the northern hemisphere and three from the southern hemisphere. For morning observers the estimated total hourly rates should be near twenty from the northern hemisphere and ten 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 due to moonlight.
The radiant positions and rates listed below are exact for Saturday night/Sunday morning November 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.
Andromedids (AND)
Sirko Molau’s studies of video radiants has revealed that activity from the famous Andromedid shower, noted for intense storms during the 19th century, may still be seen throughout November. This position lies in eastern Andromeda, two degrees south of the fourth magnitude star Nu Andromedae. The nearest bright star is second magnitude Almach (Gamma Andromedae), which lies four degrees to the northeast. Visual activity is expected to be low, but detectable. The Andromedid radiant is best placed near 2200 (10pm) local standard time (LST) when it lies on the meridian. At 19km/sec., the average Andromedid will appear as a very slow moving meteor. Sirko mentions that these meteors are “conspicuously slow and of almost constant activity” during this period.
Northern Taurids (NTA)
The Northern Taurids (NTA) are active from a large radiant centered at 04:29 (067) +24, which lies in northern Taurus, eight degrees north of the orange first magnitude star Aldebaran (Alpha Tauri). The radiant is best placed near 0100 LST, when it lies highest above the horizon, but activity may be seen all night long. Meteors from the Northern Taurids strike the atmosphere at 29km/sec., which would produce meteors of slow velocity. Expected rates would be ~3 per hour as seen from the northern hemisphere and ~2 per hour as seen south of the equator.
November Orionids (NOO)
The November Orionids (NOO) were recently discovered by analyzing video data. This shower is active from November 18 through December 9. Maximum activity occurs on November 30. The radiant is currently (11/18) located at 05:44 (086) +15. This position lies on the Orion/Taurus border, six degrees north of the third magnitude star Lambda Orionis. These meteors are also best seen near 0300 LST when the radiant lies on the meridian and highest above the horizon. At 44 km/sec. the November Orionids produce mostly medium velocity meteors.
Alpha Monocerotids (AMO)
The Alpha Monocerotids (AMO) are active from November 15-25, with maximum occurring on the 21st. This shower has produced outbursts in the past but none are expected for many years to come. Rates are expected to be < 1 shower member per hour, even on the night of maximum activity. The radiant is currently located at 07:52 (118) +01. This position lies in southeastern Canis Minor, five degrees southeast of the zero magnitude star Procyon (Alpha Canis Minoris). These meteors are also best seen near 0500 LST when the radiant lies highest above the horizon in a dark sky. At 65 km/sec. the Alpha Monocerotids produce mostly swift meteors.
Leonids (LEO)
The Leonids (LEO) reached maximum activity on the morning of November 17th with ZHR’s exceeding 100 as seen over Asia. Current rates would be near one per hour no matter your location. The radiant is currently located at 10:27 (157) +20. This position lies in western Leo, just one degree northeast of the famous second magnitude double star Algeiba (Gamma Leonis). At 70km/sec., the average Leonid is swift with a high percentage of trains. The radiant does not rise until the late evening hours so it is advised to wait until after midnight before beginning serious observations. The radiant is most favorably located during the last dark hour before the onset of morning twilight when it lies highest in a dark sky.
As seen from the mid-northern hemisphere (45N) one would expect to see ~16 Sporadic meteors per hour during the last hour before dawn as seen from rural observing sites. Evening rates would be ~3 per hour. As seen from the mid-southern hemisphere (45S), morning rates would be ~6 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.
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
AND Andromedids 01h 38m +39 19 <1 <1
NTA Northern Taurids 04h 29m +24 29 3 2
AMO Alpha Monocerotids 07h 52m +01 65 <1 <1
LEO Leonids 10h 27m +20 70 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
Nov 18/19 Meteors
Leonid activity is rapidly decreasing in intensity with rates less than half of what they were just a night ago. Still the nights are producing lots of meteors. Last night saw a large number of “long” meteors that traveled over 20 degrees of sky. The best example can be seen in the video below. This sporadic meteor was seen at 9:22 pm MST (4:22 UT). It actually starts in the FOV of my zenith camera before moving far enough north to enter the FOV of my northern camera (the video below is from the north camera). If you look closely at the beginning of the video you will notice material falling off the meteor. Unfortunately my system dropped a few frames which is why the meteor appears to jump ahead a few times.
Bob’ notes for the night of Nov 18/19 : “Clouds plagued observations most of the night so meteor numbers are far below what they should be.”
Obs Date(UT) Time TOT SPO NTA STA LEO AMO NOO AND OER TUS Nov-19 11h51m 69 35 4 4 17 2 5 1 1 SDG Nov-19 07h42m 37 25 2 2 8 0 2 0 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)
NTA/STA – Northern and Southern Taurids (includes Antihelions)
LEO – Leonids
AMO – Alpha Monocerotids
NOO – November Orionids
AND – Andromedids
OER – Omicron Eridanids
Nov 17/18 Meteors and the Leonids over Asia
As predicted, the Earth’s passage through the 1466 and 1533 dust trails of Comet Tempel-Tuttle resulted in enhanced Leonid activity. Due to the time when the activity occurred, it was only visible to observers in Asia. Visual reports to the International Meteor Organization (IMO) suggest a peak around 20-21 hours UT with rates 80-140 per hour. This matches the lower values predicted by computer models. Though early predictions called for 500-1000 meteors per hour, recent revisions brought the predicted rates down to 100-200 per hour. The plot below from the IMO shows rate of activity for the past few days (you should be able to click on the plot to expand it).
Visual ZHR for the Leonids. Credit: International Meteor Organization.
Even though rates of 100+ meteors per hour are great and real fun to watch, they are not high enough to be considered a meteor storm. In fact they are comparable to the peak activity ofthe annual Perseid and Geminid showers. So if you missed the Leonids at their best, don’t worry, the Geminids will be just as good in a few weeks (Dec 13/14).
Last night’s video data shows activity levels that were a bit lower than the night before. As the IMO plot above shows, the times when the Leonids were observable from my site (~8 to 13 hours UT) bracket the peak activity. For the last 2 nights, Leonid activity over the US has been moderate with ZHRs of 20-30 per hour. Rates should gradually decrease as we move away from the Leonid dust trails.
Bob’ notes for the night of Nov 17/18 : “Last night saw fog rushing in at dusk only to retreat shortly thereafter. This went on all night long therefore rates are slightly down compared to yesterday. The Leonids were down significantly from the previous night. I would expect a slight improvement in Leonid rates on the 19th. After a good showing last night. the Andromedids failed to appear tonight.”
Obs Date(UT)Time TOT SPO NTA STA LEO AMO NOO AND OER TUS Nov-18 11h12m 81 22 3 1 40 5 2 1 1 SDG Nov-18 11h40m 62 28 6 2 20 3 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)
NTA/STA – Northern and Southern Taurids (includes Antihelions)
LEO – Leonids
AMO – Alpha Monocerotids
NOO – November Orionids
AND – Andromedids
OER – Omicron Eridanids
Utah Fireball – November 18
A brilliant fireball was seen over Utah a few minutes past midnight last night. Video images give the time of the fireball as ~12:07 am MST (7:07 UT). At least 2 comments to this blog describe the event.
Miah wrote:
Did you guys see the one in Bountiful Utah a half an hour ago Nov. 18th 2009 12:12 A.M. It had to be at least 30 feet wide with a fire blazing tail that lasted for a couple of seconds stringing out at least a mile long and it lit up the dark night like it was a really bright sunny day. The kind of day you really need to wear sunglasses from horizon to horizon for at least 6 seconds it threw my heart up into my throat and I received an immediate and outrageous adrenalin rush. This experience was by far the coolest thing I have ever seen in the night sky. If anybody else saw this please post and I really hope someone or somebodys business buildings camera got this on tape and they post it soon. I really want to relive that moment again… All I can say is WOW…
and Melissa wrote:
i was at walmart shopping and when i came out to put my items away the whole sky lit up like it was morning for about 3 seconds and then i turned around and then things got dark again and i saw an orange tail in the sky looked like fire and then it was gone it was so weird and scary
KSL TV has a whole bunch of videos listed on their website. Especially check out Patrick Wiggins video where he gives a great and thorough explanation of what the fireball was. Some of the videos show the actual fireball in the sky while others show the ground being lit up as bright as day. Further news stories can be found at The Salt Lake Tribune and Spaceweather.com.
Six or so hours later, as the sun was rising, a ghostly blue trail was observed over Utah. This trail appears similar to those seen after other bright fireballs. What is amazing is that trail had not dissipated after such a long time. Note, the crazy meandering pattern of the trail does not mean the fireball was moving erratically. The erratic pattern of the trail is due to varying wind speeds and directions in the upper atmosphere.
So far I have not seen any images or videos of the fireball. All the videos and images just show the ground or sky lighting up. As Miah wrote above, the fireball lit up the ground as bright as day.
Though it was probably below the horizon as seen from Tucson, the sky did brighten towards the north. My north facing meteor camera did detect a brightening of the northern sky. Though I recognized it as something unusual when I looked over the data this morning, I deleted the data since there was no obvious meteor in the field. Only later did I read about the Utah fireball. Luckily the MMT all-sky cam picked up the flash from Mount Hopkins, just south of Tucson. The flash was observed to the north at the exact time of the fireball so there is no doubt they are related. If the flash was seen as far south as Tucson, it is likely that it was also seen from a wide area including the states of UT, AZ, NM, CO, WY, ID, CA,NV, and OR.
Though the fireball occurred at a time when the Leonids were at their best, it is doubtful it is related to the Leonids. The Leonids are extremely fast meteors, in fact they are almost as fast as meteors can get (~70 km/s). As a result, Leonids rarely last more than a second and usually burn out in one very quick burst. The fact that this fireball lasted for some time (~5 seconds) means it was a much slower meteor that probably descended to a low altitude (~20-50 km). It is more likely it was caused by a small (0.5 to 2 meter) asteroid.
Nov 16/17 Meteors and a good Leonid display
Last night the Leonids put on a respectable show. My 2 cameras detected 45 Leonids which was about 40% of the number of Orionids observed during that shower’s peak last month. Though this comparison is an apples-to-oranges comparison it does suggest that Leonid visual rates were on the order of a ZHR of ~20. (Remember this rate, called the Zenithal Hourly Rate, is valid for a dark rural sky and when the radiant is overhead, most observers will be observing under worse conditions and will see fewer meteors.)
Last night visual observers detected a rate of up to ~36 Leonids per hour from a dark site. This value will change as more data rolls in. Check out the IMO’s Live ZHR Leonids page to see the latest activity rates.
I was one of those visual observers out watching the meteors. From 9:41 to 12:51 UT (little over 3 hours) I counted 51 meteors, of which 38 were Leonids. These observations were made under a sky with a limiting magnitude of +5.5. It really was a tale of 2 showers. For the 1st hour, not much was going on with only 7 Leonids sighted. The 2nd hour saw active pick up big time. Between 10:52 UT and 12:18 UT 24 Leonids were seen. On 2 separate occasions 2 meteors were observed at the same time. By the end of the night activity seemed to be settling down. The plot below shows the distribution of Leonids in 10 minute intervals.
Compare the above plot with the distribution of video meteors. The video plot starts earlier so the range on the x-axis does not match in the 2 plots.Though the video data also shows low activity early on, this is most likely due to the low altitude of the radiant. Whereas the visual data doesn’t show an uptick in activity until ~10:50 UT, the video data shows a steady increase in activity from about ~9:30 UT onwards. The falloff in activity at the end of the night in both the visual and video data may be due to the brightening sky rather than a true reduction in rates.
The best meteor of the night was a brilliant fireball that occurred around 11:54 UT. I usually observe towards the north because that is the only part of the sky that is not obscured by trees in my yard. For a split second, the house was lit up by an obvious bright meteor to the south of me. Even though I didn’t directly see the fireball and it was out of the FOV of my cameras, 2 other cameras did pick up the fireball. Jim Scotti set-up his DSLR to take near all-sky images of the sky. One of his images captured the fireball streaking through Orion. Even half and hour later, the dust train produced by the fireball was still visible. Go here for Jim’s picture of the fireball and the resulting train.
The fireball was also picked up by the MMT all-sky camera. In the image below the fireball is seen moving behind the MMT’s dome.
According to the published predictions, enhanced activity should have been seen over Asia. For us, tomorrow should provide lower rates than last night.
Bob’ notes for the night: “The Leonids doubled their totals from last night with 30 shower members being recorded. Several bright sporadics are also suspected of being Leonids. A surprising 5 Andromedids were recorded. The normal is only 1-2 per night. No Omicron Eridanids (OER) were recorded last night.”
Obs Date(UT)Time TOT SPO NTA STA LEO AMO NOO AND OER TUS Nov-17 11h41m 111 38 11 3 45 3 0 1 0 SDG Nov-17 11h11m 79 32 5 2 30 2 3 5 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)
NTA/STA – Northern and Southern Taurids (includes Antihelions)
LEO – Leonids
AMO – Alpha Monocerotids
NOO – November Orionids
AND – Andromedids
OER – Omicron Eridanids
Leonids in 2009
Note: Most of this article was first posted a year ago. It has been updated to include predictions for this year’s Leonid display.
The Leonids are the meteor storm-producing shower against which all other showers are measured. In most years the Leonids are a rather minor shower producing up to 15 meteors per hour, but on occasion they can produce some of the most spectacular meteor displays ever seen.
Comet 55P/Tempel-Tuttle, The Leonid Parent Comet
The Leonids are the result of dust released by Comet Tempel-Tuttle. Similar to the stories of the discoveries of Comets Encke (parent of the Taurids) and Biela (parent of the Andromedids), Comet Tempel-Tuttle was observed a few times before its periodic nature was noted. The first sighting happened way back in 1366 when the comet was observed by Chinese astronomers. Though the Chinese reported very accurate positions of the comet, especially impressive in an age without telescopes, the science of computing comet orbits had not yet been invented. Hence, there was no way to for them to know if this comet could return.
Fast forwarding a little over 3 centuries, Gottfried Kirch of Guben, Germany, finds a new comet on the night of 1699 October 26. Unfortunately, the comet is no where to be found on later nights. We now know that this was Comet Tempel-Tuttle and it was moving to the south so rapidly that the comet was not observable from Germany on the nights after Kirch’s discovery.
The comet would have to wait another ~167 years before it was found again. This time two of the 19th centuries premiere comet hunters, Ernest W. L. Tempel (Marseille, France) and Horace P. Tuttle (Cambridge, MA), found the comet almost 3 weeks apart. Tempel found the comet first on the night of 1865 December 19. Since news traveled slow in those days, the comet was independently discovered by Tuttle on 1866 January 9 before the news of Tempel’s discovery reached America. Not only was the periodic nature of the comet recognized at that time but so was its association with the Leonid meteors.
The comet resides on an orbit that spans from just inside the orbit of the Earth (0.98 AU) to slightly beyond the orbit of Uranus (19.7 AU). It takes the comet ~33 years to orbit the Sun. The the comet last passed perihelion (closest distance to the Sun) in 1998 and was well observed at that time.
- Orbit of Comet Tempel-Tuttle and the Leonid meteors. Orbit diagram produced with the C2A planetarium program (http://www.astrosurf.com/c2a/english/index.htm)
The Leonids Roar
- The most famous depiction of the 1833 meteor storm. It was actually produced in 1889 for the Adventist book ‘Bible Readings for the Home Circle’ based on a first-person account of the 1833 storm by minister Joseph Harvey Waggoner on his way from Florida to New Orleans.
The first recorded appearance of the Leonids was in 902 AD when the shower was seen from Italy and Egypt. For the next few centuries, impressive Leonid displays were observed every 33 to 200 years or so.
Two Leonid storms stand out from all the others. On 1833 November 13, the entire eastern United States was awaken to a sight very few had every seen. The sky appeared to be filled with meteors. Modern researchers now know the cause of this outburst. It is estimated that a rate of up to ~70,000 meteors per hour was observed. That works out to ~20 meteor per second.
The 1833 storm marks the dawning of the modern age of meteor science. It was due to observations of this storm that astronomers first recognized that meteors originate in space. About 30 years later, after the discovery of Comets Swift-Tuttle (parent of the Perseids) and Tempel-Tuttle (the parent of the Leonids), the connection between comets and meteor showers was made.
The 1833 storm ranks as one of the 2 best meteor displays in recorded history. 133 years after the 1833 storm, the Leonids once again set the skies ablaze. On the night of 1966 November 17, the western United States experienced a storm just as strong as the 1833 storm.
When the comet returned in 1998, there were many predictions for spectacular Leonid activity. Though meteor rates never got close to that seen in 1833 or 1966, rates as high as a few thousand meteors per hour were observed in multiple years. The best meteor shower I have ever seen was the 1998 Leonid fireball display. Though I would observe Leonid displays with much higher rates of meteors, the sheer number of extremely bright meteors in 1998 was breathtaking.
Predictions for the 2009 Leonids
Now that it is over 11 years since the perihelion of Comet Tempel-Tuttle, what can we expect. In most years when the comet is not in the vicinity of Earth (which is true this year), the Leonids are a nice but relatively light shower with rates up to 15 meteors per hour.
This year the peak is predicted for the morning of November 17. But there are predictions by a number of different research teams for enhanced activity this year. The International Meteor Organization summarizes this year’s prediction with the following taken from their 2008 Meteor Calendar:
This year may produce another enhanced return of the Leonid meteor shower, with ZHR hourly rates expected to exceed 150+ according to independent studies by Jérémie Vaubaillon, Mikhail Maslov, Esko Lyytinen (WGN), David Asher, Mikiya Sato and their respective collaborators. The main peak(s) are expected to occur in the night of November 17 to 18 around 22h00 UT (= 17h00 US Eastern, 23h00 Central Europe, 3h30 India, 6h00 Beijing), although variable activity may happen at almost any stage between November 16 and 18. Continuous monitoring is necessary. Leonids are generally only visible after local midnight from any longitude, with the exception of some long Earth-grazing Leonids before midnight when the radiant is still very low.
What does this mean? Most of us, especially in the United States, will only see the “normal” maximum on the mornings of November 17 and 18 with rates on the order of 20-50 per hour. Observers in the Far East and central Asia may see rates as high as 100-200 per hour on the morning of November 17. The following times may see enhanced activity as the Earth encounters dense dust trails created by Comet Tempel-Tuttle during some of its past perihelion passages. Note, the times are for the predicted peak in activity. The dust trails are wide so expect enhanced activity for a few hours before and after the predicted peak times.
YYYY-MM-DD HH:MM Trail Rev Rates
(UT) Year
2009-11-17 07:27 1567 13 25
2009-11-17 21:43 1466 16 115
2009-11-17 21:50 1533 14 80
2009-11-18 03:29 1102 27 10-50
YYYY-MM-DD - Year, Month and Day of trail encounter in UT
HH:MM - Hour and minute of trail encounter in UT
Trail Year - Year the trail was created by Comet Tempel-Tuttle
Rev - Number of orbits trail has completed
Rates - Possible meteor rates per hour (this is on top of the background rate 10-30 per hour)
The International Meteor Organization has a “live” graph of reported Leonid activity at their website.
The best way to see the Leonids is to find the darkest site possible. Even if you are in brightly lit area, some Leonids will be observable. The Leonids, like many meteor showers, are only observable after midnight. You will not see any Leonids in the evening. The best time is from 2am till the start of dawn. The meteors will appear to radiate from the east from a spot in the constellation of Leo. Leonids are very fast and each individual meteor will only last for less than a second. Some of the Leonids may be bright and they often leave behind faint glowing trails that can last from a second to many minutes after the meteor occurred.
As for the future, we may have seen the end of the great Leonid storms. The orbits of the Leonids and Comet Tempel-Tuttle are slowly moving away from Earth due to the gravity of the planets. Though there may be Leonid displays with meteor rates as high as hundreds to a few thousand per hour around the time of Comet Tempel-Tuttle’s next perihelion in 2031, there will be no great storms. There is a possibility of one last hurrah for the Leonids around the time of its perihelion in 2131.
Nov 15/16 Meteors
The Leonids are here! Actually observers have been able to catch the occasional Leonid every night for the past week or so, but now the action is picking up. Last night visual observers detected a rate of ~19 Leonids per hour from a dark site. (Remember this rate, called the Zenithal Hourly Rate, is valid for a dark rural sky and when the radiant is overhead, most observers will be observing under worse conditions and will see fewer meteors). Check out the IMO’s Live ZHR Leonids page to see the latest activity rates.
The real action begins tonight as the Earth encounters multiple Leonid dust trails. Observers in the Far East and central Asia may experience rates as high as ~100-200 meteors per hour. Those of us in Europe and the Western hemisphere will see more normal activity wit rates between 20 and 50 per hour. Of course, surprises may happen. I’ll post more specific info on the Leonids later today.
Bob’ notes for the night of Nov 14/15 : “It was another crystal clear night in the San Diego area. The Leonids were quite active this morning, gearing up for their best showing tomorrow.”
Obs Date(UT)Time TOT SPO NTA STA LEO AMO NOO AND OER TUS Nov-16 11h38m 71 32 5 5 23 3 3 0 0 SDG Nov-16 11h23m 73 46 3 5 16 1 - 0 2
TUS – Camera in Tucson operated by Carl Hergenrother
SDG – Camera in San Diego operated by Bob Lunsford
TotTime – Total amount of time each camera looked for meteors
TOT – Total number of meteors detected
SPO – Sporadics (meteors not affiliated with any particular meteor shower)
NTA/STA – Northern and Southern Taurids (includes Antihelions)
LEO – Leonids
AMO – Alpha Monocerotids
NOO – November Orionids
AND – Andromedids
OER – Omicron Eridanids
Nova Scuti 2009 = V496 Scuti
This blog usually focuses on comets, asteroids and meteors. This post focuses on a type of object that hasn’t mentioned on the blog so far.
Nova Scuti 2009 is a newly discovered nova first seen on 2009 Nov. 8.37 UT. The object was found by Japanese amateur H. Nishimura of Miyawaki, Kakegawa with a commercial off-the-shelf Canon Eos 5D and Minolta 120mm lens. Since the nova is a variable star, it now has the permanent variable star designation V496 Scuti.
At discovery the nova was around magnitude ~8.5. Since then it has brightened to around magnitude 7.5. Friend of the blog Salvador Aguirre estimated a brightness of 8.4 on Nov 10.06 and Nov 11.11 UT. I was able to make brightness estimates of magnitude 8.5 on Nov. 11.08, 7.6 on Nov 14.10, and 7.6 on Nov. 15.08 UT. The nova is probably near its brightest though these objects can surprise. Most likely, it will start fade in the next few days. The nova will require binoculars or a small telescope to see. It is located at
R.A. = 18h43m45s.65, Decl. = -7o36'41".5 (equinox 2000.0).
The image below was taken last night with an old Pentax Takumar 200mm f/4 lens. The nova is the star between the two tick marks.
For more on what novae are see the following articles at the American Association of Variable Star Observers (AAVSO) (2nd AAVSO article) and Wikipedia. In short, novae are explosions on the surface of white dwarfs. White dwarfs are the highly dense and compressed remnants of dead small to medium sized stars. If a less massive star is orbiting a white dwarf, the dwarf’s gravity may strip material from the smaller companion. Over time this material builds up on the surface of the white dwarf. Finally the gaseous material becomes massive enough that pressure and temperature is large enough for a thermonuclear explosion to occur. The explosion “blows” off the accumulated material though is not strong enough to do much damage to the white dwarf. During this explosion, the star will appear to brighten by 8-15 magnitudes (1500 to 100000 times brighter). After the nova eruption, the process starts all over again resulting in a series of nova events every tens to thousands of years.
How do we know it is a nova? The simple answer is spectroscopy. The spectrum of the star shows the tell-tale sign of an explosion ejecting material at velocities of ~700 km/s. Another friend of the blog, David Balam, was able to spectroscopically observe the object with the 1.82-m Plaskett telescope on Vancouver Island. The spectrum (seen below) showed V496 Scuti to be a nova of the FeII class.
