Totality!

We are now in totality. Luckily the thick cirrus has moved out and it’s relatively clear here in Tucson.

Total Lunar Eclipse Tonight

The astronomical event of the month is Tuesday morning’s Total Lunar Eclipse. With the Moon riding high in the sky near the border of Taurus and Gemini, the eclipse is perfectly placed for observers in North America.

Check out the Shadows and Substance site for animations and graphics about tonight’s eclipse.

The table below lists times for all 4 American time zones. Though the penumbral part of the eclipse starts at 5:28 UT, most people won’t see a noticeable darkening of the Moon until sometime around 6:00 UT.

                              UT    EST     CST     MST     PST
Start of Penumbral Eclipse   5:28  12:28a  11:28p  10:28p   9:28p 
Start of Partial Eclipse     6:32   1:32a  12:32a  11:32p  10:32p
Start of Total Eclipse       7:40   2:40a   1:40a  12:40a  11:40p
Mid-Eclipse                  8:17   3:17a   2:17a   1:17a  12:17a
End of Total Eclipse         8:54   3:54a   2:54a   1:54a  12:54a
End of Partial Eclipse      10:02   5:02a   4:02a   3:02a   2:02a
End of Penumbral Eclipse    11:06   6:06a   5:06a   4:06a   3:06a

Dec 16/17/18/19 Meteors

Dec 16th did bring some rain as forecast (0.24″ to be exact). Not since Nov 28 have we had any rain at the house and not since Oct 20 have we had any measurable precipitation. Even with the rain and clouds, the sky cleared up after midnight and SALSA3 was able to pick up 3 meteors through the fog. So the streak still stands and is currently at 85 nights. Unfortunately the entire western US is being hammered by a wet winter storm system so the next few nights will be iffy.

Obs  Date(UT)      Time    TOT SPO ANT HYD DLM MON COM URS
SAL3 2010-12-19   05h 46m   17  13  0   3   1   0   0   0
ALLS 2010-12-19   04h 51m   14  10  1   3   0   0   0   0
SAL3 2010-12-18   03h 45m   12  7   0   2   1   0   1   1
ALLS 2010-12-18   03h 51m   7   5   0   1   1   0   0   0
SAL3 2010-12-17   01h 15m   3   3   0   0   0   0   0   0
ALLS 2010-12-17   00h 00m       Left Off Due to Rain 

SAL3 - SALSA3 camera in Tucson (Carl Hergenrother)
ALLS - Near all-sky camera in Tucson (Carl Hergenrother)
VIST - Visual observations from Tucson (Carl Hergenrother)
VISH - Visual observations from Hermosillo (Salvador Aguirre)
HERM - PARENI camera in Hermosillo (Salvador Aguirre)
SDG - Camera in San Diego operated by Bob Lunsford
Time - Total amount of time each camera looked for meteors
TOT - Total number of meteors detected
SPO - Sporadics (meteors not affiliated with any particular meteor shower)
ANT - Antihelions   
HYD - Sigma Hydrids
DLM - December Leonis Minorids
MON - Monocerotids
COM - Coma Berenicids
URS - Ursids

Meteor Activity Outlook for December 18-24, 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.

No matter where you live, the first half of December provides some of the best meteor activity of the year. In the northern hemisphere the sporadic rates are still strong plus you can also count on strong activity from the Geminids, which peak on December 14. There are also several minor radiants that add a few meteors each hour. All of these centers of activity are located high in the sky during the early morning hours this time of year. Much of the activity mentioned above can also be seen from the southern hemisphere. While the sporadic rates are not as strong as those seen from the north, they are stronger than the previous months and heading for a maximum in January. The warm, but short summer nights south of the equator make for some great viewing as long as the moon does not interfere.

During this period the moon reaches its full phase on Tuesday December 21st. At this time the moon lies opposite the sun and is above the horizon all night long from most locations. This is the worst time to attempt to view meteor activity as the bright moonlight will obscure all but the brightest meteors. The estimated total hourly rates for evening observers this week is ~3 from the northern hemisphere and ~2 for observers south of the equator. For morning observers the estimated total hourly rates should be ~10 from the northern hemisphere and ~9 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 this period due to moonlight.

The radiant (the area of the sky where meteors appear to shoot from) positions and rates listed below are exact for Saturday night/Sunday morning December 18/19. 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. The detailed descriptions will be continued next week when the moonlight is not as intense.

Shower Name                 RA     DEC   Vel     Rates
                                         km/s   NH    SH
ANT Antihelions           06h 40m  +23    30     2     2
MON Monocerotids          07h 08m  +07    41    <1    <1
GEM Geminids              07h 56m  +31    35     1     1
HYD Sigma Hydrids         08h 56m  +00    61    <1    <1
DLM Dec Leonis Minorids   10h 44m  +31    71     1    <1
COM Coma Berenicids       11h 48m  +18    65     2    <1
URS Ursids                14h 12m  +75    33    <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

(596) Scheila – the asteroid that became a comet

A week ago, Steve Larson of the Catalina Sky Survey came across a bright but peculiar looking comet. At 13th magnitude it was strange to find a new comet that bright in a part of the sky that had been picked over numerous times in the past month or two. Even weirder was the appearance of the comet, a bright stellar core with 2 tails, one straight and one curving almost 180°. But the oddest thing about this new find is that the object isn’t new at all. In fact, it had been discovered over 100 years ago back in 1906. Only from the time of discovery till two night ago it was known as asteroid (596) Scheila.

Up until ~15 years ago, the line between comets and asteroids was sharp and easy to see. Asteroids were rocks baked dry by billions of years of orbiting relatively close to the Sun. Comets were dirty snowballs born in the outer reaches of the Solar System. Sure there were a few objects that straddled the line such as Comets Encke and Wilson-Harrington but those objects could be hand-waved into one camp or the other.

But in 1996 the discovery of Comet Elst-Pizzaro changed all that. This comet was on a boring Main Belt asteroid orbit and probably had been for most of the history of the Solar System. Here was an example of an asteroid that was not bone dry but had, somehow, retained some volatiles over the past 4.5 billion years. It wasn’t long before more ‘Main Belt Comets’ were found: 176P/LINEAR, 238P/Read, P/2008 R1 (Garradd), P/2010 R2 (La Sagra). And now we get to add the large, 100+ km asteroid (596) Scheila to the list. [Note, that though Comet P/2010 A2 (LINEAR) is also on a Main Belt orbit, recent studies suggest its cometary appearance was the result of an asteroid-to-asteroid collision rather than cometary outgassing.]

I was finally able to get an image of this object a few nights ago. The ghostly ‘wings’ extending out from Scheila is dust ejected during its outburst. Based on images from the Catalina Sky Survey, the outburst occurred a day or two before December 3. So the image below was taken 11-12 days after the outburst.

Dec 15/16 Meteors

Two nights ago my cameras detected a total of 206 Geminids (some were probably duplicates). One night ago the total number dropped to 32 Geminids. Last night the number of Geminids was a whopping 2. It’s amazing how quickly the Geminids can fall off after their peak. It is safe to say that the 2010 Geminids are pretty much over for visual observers.

Last night marked SALSA3’s 82nd straight night with a meteor detection. With it currently raining and more forecast for tonight the streak may very well end at 82.

Obs  Date(UT)      Time    TOT SPO ANT GEM HYD DAD DLM MON COM
SAL3 2010-12-16   05h 54m   19  10  1   0   2   1   3   1   1
ALLS 2010-12-16   04h 58m   19  12  1   2   1   1   2   0   0
HERM 2010-12-16   11h 31m   9   7   0   1   1   -   -   0   0

SAL3 - SALSA3 camera in Tucson (Carl Hergenrother)
ALLS - Near all-sky camera in Tucson (Carl Hergenrother)
VIST - Visual observations from Tucson (Carl Hergenrother)
VISH - Visual observations from Hermosillo (Salvador Aguirre)
HERM - PARENI camera in Hermosillo (Salvador Aguirre)
SDG - Camera in San Diego operated by Bob Lunsford
Time - Total amount of time each camera looked for meteors
TOT - Total number of meteors detected
SPO - Sporadics (meteors not affiliated with any particular meteor shower)
ANT - Antihelions   
GEM - Geminids
HYD - Sigma Hydrids
DAD - December Alpha Draconids
DLM - December Leonis Minorids
MON - Monocerotids

Dec 14/15 Meteors (night after the Geminids peak)

What a difference 24 hours makes! Only a day removed from the Geminids peak and rates have crashed to a fraction of their peak. During the past 5 nights SALSA3 detected 12, 22, 69, 124 and now 20 Geminids. This is a characteristic of the Geminids in that the post-peak rates fall off much more rapidly than the pre-peak increase.

The night of Dec 14/15 marked the 81st consecutive nights that SALSA3 detected a meteor. As of right now, there is a good chance that it is clear enough for night 82 to produce a few meteors. Tomorrow night will be iffy as a storm, our first in 2 months, is forecast to bring rain and clouds to the area. Will the streak survive? We’ll have to wait and see.

Obs  Date(UT)      Time    TOT SPO ANT GEM HYD PUP DAD DLM MON COM
SAL3 2010-12-15   12h 10m   53  20  5   20  1   1   1   1   2   2
ALLS 2010-12-15   12h 38m   40  15  4   11  3   0   1   3   1   2
HERM 2010-12-15   11h 50m   28  15  2   10  0   1   -   -   -   0
VISM 2010-12-15   02h 00m   37  0   1   28  3   1   -   -   1   3 (LM = +5.7 to +6.0)

SAL3 - SALSA3 camera in Tucson (Carl Hergenrother)
ALLS - Near all-sky camera in Tucson (Carl Hergenrother)
VIST - Visual observations from Tucson (Carl Hergenrother)
VISH - Visual observations from Hermosillo (Salvador Aguirre)
HERM - PARENI camera in Hermosillo (Salvador Aguirre)
SDG - Camera in San Diego operated by Bob Lunsford
Time - Total amount of time each camera looked for meteors
TOT - Total number of meteors detected
SPO - Sporadics (meteors not affiliated with any particular meteor shower)
ANT - Antihelions   
GEM - Geminids
HYD - Sigma Hydrids
PUP - Puppids-Vellids
DAD - December Alpha Draconids
DLM - December Leonis Minorids
MON - Monocerotids

Dec 13/14 Meteors and the Geminids Peak

The Geminids did not dissapoint! Though the IMO ZHR Live page doesn’t seem to be updating observations made by myself and Salvador show ZHRs that equaled or even exceeded the expected value of 120. Over the course of about 3.33 hours I averaged about 1 meteor per minute under skies that range from a limiting magnitude of +5.0 (when the Moon was still up) to +5.7 (before the break of dawn).

For my SALSA3 and Sentinel cameras it was a record-setting night. The previous single night record for SALSA3 (and its 2 predecessors) was 124 meteors during this year’s Perseids peak. Last night SALSA3 detected 124 Geminids! Add in another 35 non-Geminids and the total for he night was 159 meteors. The near-allsky Sentinel also broke its previous record set during this year’s Perseids by catching 123 meteors of which 84 were Geminids.

The video below contains all 159 meteors detected by SALSA3. It starts in the evening where you can catch a short glimpse of the Moon as it quickly moves out of the frame. Note the top of one of my trees illuminated by Christmas lights for the first few meteors. Though not all of the meteors are Geminids most are and it is fun to watch them radiate from the twin stars of Castor and Pollux.

The next plot is a radiant plot. For every meteor detected my SALSA3, the MetRec software runs the path of the meteor back. Where the back tracks of related meteors cross is the radiant. It is obvious from the plot that most of last night’s meteors are related and radiated from an area near the bright star Castor.

Down in Hermosillo, Salvador spent almost 5 hours watching the Geminids and racked up a total of 308 meteors of which 272 were Geminids. This is in addition to his PARENI camera which also caught 75 meteors.

Obs  Date(UT)      Time    TOT SPO ANT GEM HYD PUP DAD DLM MON COM
SAL3 2010-12-14   12h 10m  159  22  7  124  2   0   2   1   0   1
ALLS 2010-12-14   12h 38m  123  24  9   84  1   1   0   1   2   1
HERM 2010-12-14   11h 42m   75  17  6   49  1   -   -   -   1   1
VIST 2010-12-13   03h 20m  199  31  -  168  -   -   -   -   -   - (LM=+5.0 to +5.7)
VISH 2010-12-13   04h 40m  308  12  3  272  8   4   -   -   5   4 (LM=+5.5 to +6.2)

SAL3 - SALSA3 camera in Tucson (Carl Hergenrother)
ALLS - Near all-sky camera in Tucson (Carl Hergenrother)
VIST - Visual observations from Tucson (Carl Hergenrother)
VISH - Visual observations from Hermosillo (Salvador Aguirre)
HERM - PARENI camera in Hermosillo (Salvador Aguirre)
SDG - Camera in San Diego operated by Bob Lunsford
Time - Total amount of time each camera looked for meteors
TOT - Total number of meteors detected
SPO - Sporadics (meteors not affiliated with any particular meteor shower)
ANT - Antihelions   
GEM - Geminids
HYD - Sigma Hydrids
PUP - Puppids-Vellids
DAD - December Alpha Draconids
DLM - December Leonis Minorids
MON - Monocerotids

Geminids Peak – First Observing Session

The moon is still up, most of the neighbors still have their Christmas lights on full blast and the Geminid radiant is still on the low side and yet the Geminids are already putting on a great show.

During the hour between 10:48 pm (5:48 UT) and 11:48 pm (6:48 UT), I counted 43 meteors of which 35 were Geminids. All this under a rather bright +5.0 magnitude sky. The Geminids came in bunches with 6 seen over 2 minutes at one point (including 2 simultaneously) while earlier in the session nearly 6 minutes went by without a meteor. The best meteor of the night so far was not a Geminid but a -3 Sporadic.

I’ll try to get out there again after the Moon sets and the sky is a little darker.

Dec 12/13 Meteors (a night before the Geminids peak)

Make no mistake about it, the Geminids are back! Though much of the US is griped in either snow or bitter cold, the Mexican state of Sonora and the American states of Arizona and California are seeing warm temps and clear skies.

My SALSA3 camera picked up a total of 94 meteors with 69 of those id’d as Geminids. The near all-sky Sentinel camera saw 55 meteors with 32 being Geminids. Over in San Diego, Bob’s intensified camera caught many more with 171 Geminids seen out of a grand total of 241 meteors.

On the visual side, I was able to observe for ~1.5 hours last night under a +5.4 and +5.7 sky (+5.4 for my first session and +5.7 for my 2nd session). The +5.7 limiting magnitude was the darkest I’ve ever recorded from my home. Between the 2 sessions I spied 53 meteors with 35 being Geminids.

Down in Hermosillo, Salvador is blessed with even darker skies with a limiting magnitude of +6.2. Over 3.5 hours he caught 143 meteors with 104 being Geminids.

According to the IMO’s Live ZHR plot, the Geminids were producing a ZHR between 40 and 60 last night. Of course, if you live anywhere near civilization, your sky is bright and actual rates will  be much lower. For relatively dark Tucson actual hourly rates were closer to 20-30 per hour.

Tonight marks the peak of the Geminids and if history is any guide, rates should twice as high as last night. Remember the Moon will spoil the view early on so its better to wait till after midnight to observe.

Last night also marked SALSA3’s 79th consecutive night with a meteor detection.

Obs  Date(UT)      Time    TOT SPO ANT GEM HYD PSU PUP DAD DLM MON COM
SAL3 2010-12-13   12h 09m   94  15  2   69  3   0   0   0   1   2   2
ALLS 2010-12-13   12h 39m   55  9   2   32  5   1   0   0   4   0   2
SDG  2010-12-13   10h 23m  241  72  7  171  3   3   2   3   4   4   2
VIST 2010-12-13   01h 31m   53  18  -   35  -   -   -   -   -   -   - (LM=+5.4,5.7)
VISH 2010-12-13   03h 30m  143  14  4  104  7   -   4   -   -   7   3 (LM=+6.2)

SAL3 - SALSA3 camera in Tucson (Carl Hergenrother)
ALLS - Near all-sky camera in Tucson (Carl Hergenrother)
VIST - Visual observations from Tucson (Carl Hergenrother)
VISH - Visual observations from Hermosillo (Salvador Aguirre)
HERM - PARENI camera in Hermosillo (Salvador Aguirre)
SDG - Camera in San Diego operated by Bob Lunsford
Time - Total amount of time each camera looked for meteors
TOT - Total number of meteors detected
SPO - Sporadics (meteors not affiliated with any particular meteor shower)
ANT - Antihelions   
GEM - Geminids
HYD - Sigma Hydrids
PSU - Psi Ursa Majorids
PUP - Puppids-Vellids
DAD - December Alpha Draconids
DLM - December Leonis Minorids
MON - Monocerotids
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