Aug 24-30 Meteors

The usual Arizona monsoon weather kept the number of detected meteors down this past week. We did get one very clear night (Aug 28/29) which saw 38 meteors imaged. That’s a bit higher than expected and for awhile I wondered if a small outburst from an unknown shower had occurred. Instead it seems that all of the background active minor showers were a little more active that night.

Now that the Perseids are done for 2015, we can look forward to this year’s Orionids. These pieces of Comet Halley peak in mid-October. Though we have some time till the Orionids are worth staying up late for, the never tired SALSA3 camera can watch as this shower slowly ramps up in activity.

Obs Date(UT)     Time    TOT SPO ANT ORI SDA KCG AUR Oth
SAL 2015-08-30  08h 25m   17  15  2   0   0   0   0   0
SAL 2015-08-29  09h 49m   38  26  2   3   2   3   2   0
SAL 2015-08-28  03h 14m   8   6   1   1   0   0   0   0
SAL 2015-08-27  04h 05m   18  14  1   2   1   0   0   0
SAL 2015-08-26  04h 43m   11  6   2   -   3   0   0   0
SAL 2015-08-25  00h 00m         --- CLOUDS/RAIN ---
SAL 2015-08-24  00h 20m   1   1   0   0   0   0   -   0

SAL - SALSA3 camera in Tucson (Carl Hergenrother)
VIS - Visual observations from Tucson (Carl Hergenrother)
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
ORI - Orionids
SDA - Southern Delta Aquariids
KCG - Kappa Cygnids
Oth - other minor showers

Aug 14-23 Meteors

It’s been over a week since the peak of the Perseids and overall meteor activity has settled down. This is quite the norm after major showers since their period of high activity only lasts for a few days. It also doesn’t help that the Perseids ramp down more rapidly than they build up. Still background activity during the Summer and Fall is rather high. Much higher than it is during period from January to June when activity is at a low.

Here in Tucson, the monsoon took a break and we had a nice stretch of clear (or mostly clear) nights. About 2/3rds of the meteors these nights are Sporadics meaning they don’t belong to any known shower. A number of minor showers have been steady, yet weak, producers of meteors.

Obs Date(UT)     Time    TOT SPO ANT PER ORI SDA ERI KCG ATR UCE Oth
SAL 2015-08-23  05h 18m   15  7   1   4   1   1   -   1   -   0   0
SAL 2015-08-22  08h 25m   27  20  1   4   1   0   -   1   -   0   0
SAL 2015-08-21  09h 17m   21  9   2   3   3   0   -   1   1   2   0
SAL 2015-08-20  09h 35m   33  20  2   1   2   2   -   2   1   3   0
SAL 2015-08-19  08h 56m   34  19  4   5   1   1   -   1   3   0   0
SAL 2015-08-18  09h 31m   26  17  0   4   0   2   0   0   2   0   0
SAL 2015-08-17  05h 49m   12  5   1   3   0   0   0   1   2   0   0
SAL 2015-08-16  03h 36m   7   3   1   2   -   0   0   1   0   0   0
SAL 2015-08-15  07h 54m   45  19  3   18  -   0   1   2   2   0   0
SAL 2015-08-14  00h 00m            ---- Clouds/Rain ----

SAL - SALSA3 camera in Tucson (Carl Hergenrother)
VIS - Visual observations from Tucson (Carl Hergenrother)
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
PER - Perseids
ORI - Orionids
SDA - Southern Delta Aquariids
COM - Southern Iota Aquariids
ERI - Eridanids
KCG - Kappa Cygnids
ATR - Alpha Triangulids
UCE - Upsilon Cetids
Oth - other minor showers

Aug 12/13 Meteors + Perseids Peak

 

Well… what can I say. This year’s Perseids were very good.

The sky was nice and clear for the night of the peak (Aug 12/13 UT). I went outside just before 2 am and watched for 2.25 hours. During that time I saw exactly 1 meteor per minute under a 6.3 magnitude sky. Not all of those meteors were Perseids but 85% were or 116 of the 135 meteors. As can often be the case, the best meteor of the night was neither the brightest or a Perseid. It was a sporadic meteor of ~0th magnitude that lasted for over 4 seconds as it slowly broke into multiple pieces before fading out.

The SALSA3 camera was also running and picked up 125 meteors throughout the night. At least 97 of these meteors were Perseids. I suspect that a few meteors listed below as Other were actually Perseids mistakenly identified as another shower by the MetRec program.

Observations from around the world are still coming into the IMO. Their 2015 Perseids Live ZHR page shows a max ZHR of 83. This is still very preliminary and will be updated. Then we’ll know the real strength of this year shower. Just using my visual data I get an average ZHR of ~83. The 15 minute period with the most Perseids (10:21 – 10:36 UT) gives a ZHR of 110. All in all a very enjoyable shower.

This year’s Perseids also produced a large number of fireballs. The NASA All-Sky Fireball Network picked up 250 Perseid fireballs from its network of cameras across the US. Down in Hermosillo, Sonora, Mexico, my friend Salvador Aguirre picked up 10 fireballs which can be seen here.

Obs Date(UT)     Time    TOT SPO ANT PER SDA ERI KCG Oth
SAL 2015-08-13  08h 32m  125  16  1   97  1   0   0   11
VIS 2015-08-13  02h 15m  135  19  -  116  -   -   -   -

SAL - SALSA3 camera in Tucson (Carl Hergenrother)
VIS - Visual observations from Tucson (Carl Hergenrother)
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
PER - Perseids
SDA - Southern Delta Aquariids
COM - Southern Iota Aquariids
ERI - Eridanids
KCG - Kappa Cygnids
Oth - other minor showers

Aug 10/11/12 Meteors

If everything goes according to schedule, tonight will mark the peak of the Perseids meteor shower. Over at the IMO, observers from around the world have reported over 4000 Perseids with rates reaching as high as ~46 per hour (assuming dark skies and perfect conditions). Hopefully those rates will double tonight.

Two nights ago (Aug 10/11) were clear here in Tucson. The SALSA3 video system detected 43 meteors of which 18 were Perseids. This number may seem low for a camera system that was running all night. It is when comparing against the number of meteors that a visual observer would see. For starters the camera can only detect brighter meteors (down to 2nd/3rd magnitude) and it only covers a small part of the sky (~50×60 degs).

That night I also spent an hour watching the shower with my own eyes. During that hour I saw 14 meteors of which 9 were Perseids. That isn’t bad for 2 days before the peak and with thick cirrus affecting half of my view.

Yesterday was a wet one in Tucson with major thunderstorms hitting the house around 7 am and 7 pm. Though I woke up a few times during the night to see if it was clear to observe, I ultimately didn’t go out since the sky was always covered in patchy clouds. To my surprise, the video camera picked up 41 meteors between the clouds. It probably would have seen many more if it were clearer.

Obs Date(UT)     Time    TOT SPO ANT PER SDA ERI KCG Oth
SAL 2015-08-12  04h 21m   41  10  1   22  3   2   0   3
SAL 2015-08-11  08h 42m   43  12  4   18  1   1   0   7
VIS 2015-08-11  01h 00m   14  5   -   9   -   -   -   -
SAL 2015-08-10  00h 43m   3   2   0   1   0   0   0   0

SAL - SALSA3 camera in Tucson (Carl Hergenrother)
VIS - Visual observations from Tucson (Carl Hergenrother)
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
PER - Perseids
SDA - Southern Delta Aquariids
COM - Southern Iota Aquariids
ERI - Eridanids
KCG - Kappa Cygnids
Oth - other minor showers

August 9/10 Meteors

The plan was to get myself outside last night and start my 2015 Perseids visual observing campaign. Unfortunately, there were other showers going on in Tucson with rain occurring off and on all night long. My SALSA3 camera system was running and did manage to pick up 3 meteors between the clouds. In short, I can’t personally add much to what the Perseids were up to last night.

Luckily it can’t be cloudy everywhere and others were able to observe the Perseids. Observers from around the world reported observations to the International Meteor Organization. These reports show a shower that is already producing ~25 Perseids per hour. This number comes with the caveat that it is valid for those observing from very dark skies, with no obstructions to their vision and the Perseids radiant overhead. Most observers will be observing under lesser conditions and will see fewer meteors.

In addition to visual observers, automated electronic surveys have also been watching the sky. Up in Canada, the Canadian Meteor Orbit Radar (CMOR) detects small meteors. In many cases, these meteors are smaller and fainter than those visible to the average backyard meteor watcher. A map of the sky from ~17 UT on 2015 August 10 shows a number of active showers. At least for very small particles, the Perseids are not the most active shower. The Southern Delta Aquariids (SDA) appear more active than the Perseids (PER) and the Northern Delta Aquariids (NDA) are a little less active than the Perseids. This will change over the next 2 nights.

 

equatorial_cmos_radar_20150810

Map of meteor radiant locations for 2015 August 10 at ~17 UT from Western Ontario, Canada. Meteors were detected by the Canadian Meteor Orbit Radar (CMOS). Credit: The University of Western Ontario Meteor Physics Group.

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While radar was good at picking up very small meteors, all-sky fireball cameras are excellent at seeing the very largest meteors. What we call fireballs. NASA has a number of cameras set up to “triangulate” the observation of fireballs and determine their original orbits around the Sun. There are 4 groups of cameras in NASA’s All Sky Fireball Network including 3 in the Tucson area that I was somewhat involved in setting up. Even thought the Tucson cameras were hampered by the same rain and clouds that I was at home, the other camera groups detected a number of fireballs. Of the 21 fireballs, 14 of them were Perseids. At least at the large end of the meteor ‘spectrum’ the Perseids are dominating the night sky.

orbital_fireball_20150810

Orbits of fireballs detected on the night of 2015 August 10 UT by NASA’s All Sky Fireball Network. Most of the orbits are similar because most of the fireballs are Perseids. Credit: NASA All Sky Fireball Network/NASA Marshall.

Here come the 2015 Perseids!

The Perseids are one of the 2 annual showers worth getting up early for. This year the peak will occur on the morning of August 13. The Moon will not be a problem this year allowing for a wonderful meteor watching opportunity.

From the International Meteor Organization’s 2015 Meteor Calendar:

The Perseids produced strong activity from an unexpected primary maximum throughout the 1990s, associated with the perihelion passage of their parent comet, 109P/Swift-Tuttle, in 1992. The comet’s orbital period is about 130 years. Further enhanced activity ahead of the usual maximum was last seen in 2004. Recent IMO observations (see HMO p. 145) found the timing of the mean or ‘traditional’ broad maximum varied between λ⊙ ∼ 139.◦8 to 140.◦3, equivalent to 2015 August 13, 01h30m to 14h00m UT. Jeremie Vaubaillon anticipates from theoretical modelling that the dust trail from the comet’s 1862 return should pass closest to the Earth (the separation is about 0.00053 astronomical units, only 80 000 km or so) at 18h39m UT on August 12, although the activity levels are uncertain. Enhanced rates, if they happen at all, may persist for several hours around this potential peak. Plus of course, neither this prediction, nor the nodal crossing time given in the box above, are guarantees of what will occur! New Moon on August 14 means whatever happens, dark skies will prevail for checking on it. Sites at mid-northern latitudes are more favourable for Perseid observing, as from here, the shower’s radiant can be usefully observed from 22h –23h local time onwards, gaining altitude throughout the night. The August 12 peak time especially favours Asian longitudes, while the August 13 near-nodal part of the ‘traditional’ maximum interval would be best-viewed from North American sites, assuming either takes place when expected. All forms of observing can be carried out on the shower, though regrettably, it cannot be properly viewed from most of the southern hemisphere.

Additional information can be found on the American Meteor Society’s webpage at Perseids 2015: the Amateur Guide.

The best time to look will be after about 1-2 am on the night of August 12/13. Meteors will appear to radiate from the constellation of Perseus in the northeast sky.

Over the past few years, the Perseids have peaked with zenithal hourly rates (ZHR) of 68 (in 2014), 109 (in 2013), 122 (in 2012), 58 (in 2011), 91 (in 2010), 173 (in 2009), 116 (in 2008) and 93 (in 2007). These are the rates that would be seen under perfectly dark skies, with no Moon and with the radiant overhead. In reality these conditions are never really met especially if you live anywhere near a city. Still observed rates of 20-40 meteors per hour are possible even under suburban skies.

The Perseids were produced by Comet 109P/Swift-Tuttle which orbits the Sun once ever ~135 years. This comet was discovered by American astronomers Lewis Swift (Marathon, New York) and Horace Tuttle (Cambridge, Massachusetts) in July of 1861. During that return the comet reached a bright 2nd magnitude and developed a tail up to 30° long. The comet returned late in 1992 and brightened up to 4th-5th magnitude. Based on our updated knowledge of Swift-Tuttle’s orbit it is now known that the comet was also seen in 1737 and likely seen in 188 AD and 69 BC.

Back in 1992, Tim Spahr and I used the Catalina schmidt to take a photographic image of Comet Swift-Tuttle (seen below).

Comet Swift-Tuttle observed with the University of Arizona Catalina Schmidt in 1992. This is a scan of a photographic image taken by Tim Spahr and Carl Hergenrother. Credit: Carl Hergenrother/Tim Spahr.

The SALSA3 meteor shower camera has been monitoring the sky every night this summer. Though the weather in Tucson can be hit or miss during the Summer Monsoon season, last night was completely clear allowing SALSA3 to detect 43 meteors with 12 of them being Perseids. These numbers also highlight that there are many other, albeit more minor, showers active as well (such as the Southern Delta Aquariids). The SALSA3 camera system is only sensitive to meteors about 3rd magnitude or brighter (about what you would expect from inside a city like Tucson). Observers under darker skies would have witnessed many more meteors during the course of the night. The Perseids will be getting more active with every night. Right now the shower is producing about 10-20 meteors per hour during the second half of the night. That number will go up to 60-120 per hour by Thursday morning.

Obs Date(UT)     Time    TOT SPO ANT PER SDA SIA ERI KCG Oth
SAL 2015-08-09  09h 14m   43  14  0   12  6   2   4   1   4

SAL - SALSA3 camera in Tucson (Carl Hergenrother)
VIS - Visual observations from Tucson (Carl Hergenrother)
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
PER - Perseids
SDA - Southern Delta Aquariids
COM - Southern Iota Aquariids
ERI - Eridanids
KCG - Kappa Cygnids
Oth - other minor showers

xxxx

Dec 15-21 Meteors

Last weekend the Geminids reached there 2014 peak. As it usual for this annual shower, they did not disappoint. Observers from around the world reported their Geminid counts to the International Meteor Organization (IMO). As of today (12/21/2014), 105 observers from 28 countries reported 10,360 Geminids to the IMO. A graph of the Geminid ZHR can be seen below.

Geminids2014_ZHR

Rather than a smooth rise, peak and fall, the 2014 Geminids produced at least 3 maxima between mid-December 13 and late December 14. The two highest datapoints correspond to ZHRs of ~160. These rates are a bit suspect since they are based on very few Geminids (hence the large error bars). A more reasonable ZHR peak for this year’s shower appears to be ~130 per hour. This fits in well with the high end of Geminid ZHR rates over the past few years (134 per hour in 2013, 109 in 2012, 198 in 2011, 127 in 2010, 120 in 2009, 139 in 2008, 122 in 2007 and 115 in 2006).

Video meteor watching here in Tucson has been hampered by bad weather over the past week. In addition to a few almost completely clouded out nights (12/17 and 12/18), many nights saw heavy dew and some ground fog form. Still the rapid decrease in the Geminids is apparent as video detected rates fell from 139 on the night of the peak (12/14) to 18 on the 15th and then only a single possible Geminid over the next 5 nights.

Sometimes refered to a major shower, the Ursids are a rather fickle shower prone to outbursts but usually very weak. This year’s Ursids were on the weak side with only ~1 per night being reported by my camera system.

Obs Date(UT)     Time    TOT SPO ANT GEM HYD COM URS Others
SAL 2014-12-21  09h 29m   27  21  2   1   -   1   1    1
SAL 2014-12-20  12h 01m   29  25  1   0   -   1   1    1
SAL 2014-12-19  09h 30m   12  8   1   0   -   0   0    3
SAL 2014-12-18  01h 51m   1   1   0   0   -   0   0    0
SAL 2014-12-17  02h 26m   1   1   0   0   0   0   1    0
SAL 2014-12-16  06h 26m   8   3   0   0   2   0   1    2
SAL 2014-12-15  11h 54m   51  18  4   18  3   1   1    7

SAL - SALSA3 camera in Tucson (Carl Hergenrother)
VIS - Visual observations from Tucson (Carl Hergenrother)
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
GEM - Geminids
HYD - Sigma Hydrids
COM - Comae Berenicids
URS - Ursids
Others - other minor showers
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