NAMN Notes is a monthly newsletter produced by the North American Meteor Network and is available both via email and on the NAMN website at: http://www.namnmeteors.org
Headlines:
* Last Major Shower of Winter; Look Quick by the Dawn’s Early Dark
* Plenty of Minor Showers for the Brave (and Well Prepared)
* Wrapping up 2008
1. QUA - Quadrantid (Bootid) Shower...
2. Swift Meteors from Coma Berenices...
3. ANT - Antihelion Activity...
4. Targets for the Experienced Observer...
5. Please submit 2008 observations...
6. Index to 2008 NAMN Notes...
The last major shower of the winter season occurs just as the earth reaches perihelion on January 3rd. The Quadrantid shower has a ZHR as high as that of the Perseids and Geminids, but observing conditions are rarely as favorable. The true peak only lasts a few hours. In 2008, the eastern US was the favored location, but this year it will be best seen somewhere between the US west coast and Japan. That is an area with few points of terra firma!
The IMO gives the annual peak time as Solar Longitude 283.16, or 12:50 UT on January 3rd. Last year was pretty well covered by eastern and central US NAMN members (10 total), indicating a peak from Solar Longitude 283.244 to 283.329, about 2 hours later. In fact this is probably one of the top few Quadrantid peaks with substantial coverage. At the NJAA, there were two experienced observers and we showed a peak rate toward the end of the period mentioned above. The IMO peak ZHR was shown at SL 283.285 (ZHR 82 +/-8) or 0936 UT, while NJAA observations by Wayne Hally and Pierre Martin showed a peak ZHR of 91 +/-10 at SL 283.329 (1039 UT). Pierre drove from Ottawa to New Jersey for the clear skies and the warmth; after all it was a balmy 12 degrees F! To view the IMO visual data (preliminary only) see:
http://www.imo.net/live/quadrantids2008/Based on the “normal” peak and last year’s timing, the east coast will see only the rising rates before the peak. The further west you are in the US and Canada and westward across the International Date Line, the better your opportunity to capture the peak will be. It would be expected between 1300 and 1700 UT on January 3rd. That is 8 AM to Noon EST, and 5 AM to 9 AM PST. You can therefore see why the further west the better your location will be. The sun rises between 7 and 7:30 AM in North America and the moon sets around midnight, so there are a few dark hours to collect some good counts. I should point out that data on this shower is rather sparse, so a peak a few hours either side of these times is certainly possible.
IMO Video data has indicated a longer period of activity than in the official working list. Before January 1st and after the 5th, extreme care should be used in assigning meteors to this shower even though I list the positions below. These are moderately fast meteors with a velocity of 41 km/sec.
It was suspected that the parent object of this shower was comet 96P/Machholz 1, but recent investigations by Jenniskens, Vaubaillon, Marsden and others has pointed the fickle finger of origin on another object, asteroid 2003 EH1. Since the particular orbit of the asteroid, the comet, and the meteoroids quickly evolve (nutate) it is quite possible all of them are related. The current inclination of the meteor stream, for example, of 72 degrees was 13 degrees only 1500 years ago. We are fortunate to be in the path of this stream at this time.
The radiant is named for a constellation that no longer exists; on today’s map of the sky it is in northern Bootes between magnitude +3.5 Nekkar (the top of the “kite” of Bootes) and Draco’s sinuous body.
If the weather cooperates, bundle up and enjoy the show!
QUA (Quadrantids) - velocity 41 km/sec (medium) UT Date, RA degrees (Hr:mm), Declination Jan 01 229 (15:14), +50 Jan 03 230 (15:19), +49 (Peak) Jan 05 231 (15:24), +49 (End of working list activity) Jan 09 233 (15:34), +48 (Last morning with some moon free time)
As discussed last month, we have multiple radiants to look at for the Comae Berenicid shower. The COM radiant listed below is the historical location, while the CBE radiant is that verified by video observations over the last decade. Both can (and should) be reported to the NAMN and IMO, assigning each related meteor to one shower or the other. The radiants are over 15 degrees apart, so with judicious choice of your field of view, it should be pretty easy to do so. Both peaked in late December and continue until at least January 23rd, with the video data showing activity extending until early February. These are very fast meteors, with a velocity of 65 km/sec, so should really stand out. The radiants are both above and “behind” Leo in the morning sky. The IAU’s JCO (January Comae Berenicids) shower, while only 4 days long, is coincident with the CBE position from the 19th to the 23rd, so they should be reported as CBE meteors.
COM and CBE - Comae Berenicids, velocity 64-65 km/sec UT Date COM RA deg, (Hr:mm), Dec; CBE RA deg, (HR:mm), Dec Jan 01 COM 187 (12:27), +20; CBE 172 (11:27), +26 Jan 06 COM 191 (12:43), +18; CBE 176 (11:45), +24 Jan 11 COM 195 (12:59), +17; CBE 182 (12:07), +21 (Full Moon) Jan 17 COM 200 (13:16), +14; CBE 187 (12:26), +18 Jan 23 COM 204 (13:38), +12; CBE 191 (12:46), +16 (Official end) Jan 30 CBE 199 (13:15), +14
The Antihelion radiant continues its eastward march during the month. This shower consists of multiple, low activity showers over a rather wide area about 20 degrees east and west along the ecliptic, and 5 degrees above and below. Video data shows “peaks” of activity on the 5th and 14th, before and after the Full Moon. The radiant moves from eastern Gemini, through Cancer, and into western Leo during the month.
ANT - Antihelion Radiant, velocity ~ 30 km/sec UT Date, RA deg (Hr:mm), Dec Jan 01 113 (7:32), +21 Jan 06 118 (7:52), +20 Jan 11 123 (8:12), +19 Jan 16 128 (8:32), +17 Jan 21 133 (8:53), +16 Jan 26 139 (9:16), +15 Jan 31 144 (9:36), +13
For those who brave the elements during midwinter, we need to supply some other targets to keep the mind sharp (and warm). The following showers are derived from video data, as well as photographic and radar surveys, and includes one on the IMO working list that is only accessible for our most southern observers.
We’ll start with a working list shower, the alpha-Centaurids (ACE). This is a far southern shower; in fact the radiant just peeks over the horizon before dawn for southern Florida, southern Mexico and Hawaii. There is a paucity of good data, and realistically little scientific use can be made from any sightings in North America, but it’s an interesting target for those with alpha Centauri in view. The radiant is about 20 degrees due south of the jewel like Omega Centauri cluster. Activity begins on January 28th, so I will just give the position for the 31st. It is located at RA 201 (13:25), Dec -57, and the meteors are fast at 56 km/sec.
Next is a shower detected in video data that has also recently been added to the IAU working list based on radar data. It is the alpha-Hydrids (AHY). Low visual meteor rates have been seen from this shower; NAMN observers reported 5 last January. In Sirko Molau’s 2006 list it was shower #89, the refined 2008 list labels it shower #148, it is IAU shower #331. These are medium fast meteors with a velocity between 40 and 44 km/sec, and the radiant is between Monoceros and the 2nd magnitude star alpha Hydrae, the brightest star below Hydra’s head.
AHY - alpha Hydrids, velocity ~42 km/sec UT Date, RA deg (Hr:mm), Dec Jan 01 126 (8:22), -09 Jan 06 129 (8:34), -09 (Peak) Jan 09 130 (8:42), -09 (Last morning with moon free time)
Another shower of interest is the January Leonids. The radiant is within the “Sickle” of Leo at its peak. It was Sirko Molau’s shower 86 in 2006, and matches well with IAU shower #319. These are swift meteors, with a velocity of ~ 54 km/sec. It shows some visual activity from about December 31 to January 7th, with a peak on the 3rd or 4th.
JLE - January Leonids, velocity 54 km/sec. UT Date, RA deg (Hr:mm), Dec Jan 01 148 (09:53), +24 Jan 07 152 (10:07), +22
Next up is Sirko Molau’s 2006 shower #88, the iota-Cancrids (ICA). These are medium fast meteors with a velocity of 39 km/sec. They are also active and peak at the same times as the JLEs above.
ICA - iota-Cancrids, velocity 39 km/sec. UT Date, RA deg (Hr:mm), Dec Jan 01 131 (8:43), +32 Jan 07 131 (8:43), +22
Finally I will mention another shower; this is the southern apex radiant (SPX) which exists all year long in the direction the earth is moving. A few times during the year there is some enhancement in rates. This one was seen in 2006 video data from the 1st to 6th. These are fast meteors (since we hit them head on) at about 62 km/sec. This radiant is in the constellation Crater, just to the west (right) of the squashed square of Corvus.
SPX - Southern Apex UT Date, RA deg (Hr:mm), Dec Jan 01 178 (11:52), -24 Jan 06 171 (11:24), -18
Now that 2008 has ended, if you have any observing sessions from the year lying around that you haven’t submitted, please try and find some time to finish them up before the end of January. During the slow months from now until the Lyrids, I’d like to compile the 2008 annual summary of NAMN observations. Of course, you can send in your data any time and it will be included in our database, but I’d like the 2008 (and 2004-2008) summary that will be included in the NAMN Notes, and posted on the website, to be as complete as possible. Your cooperation is greatly appreciated, as are all the efforts that we all make to document the quickly moving objects of the sky!
Here is the index for subjects in the 2008 NAMN Notes. It has been my pleasure (and challenge) to serve the meteor community during this year. 2009 is the International Year of Astronomy (the 400th Anniversary of Galileo turning his telescope to the sky) and the moon will be far friendlier this year. Hopefully we can together spend more time and record more meteors than ever before.
January 2008 Quadrantids: Best Shower of the Year So Far... Other January Activity... For the Advanced Observer... 2008 Outlook... February 2008 No February 2008 issue published... March 2008 NAMN Notes Missing for February... March’s Sparse Showers... Quick Review of 2007... Quick Review 2008 Quadrantids... The Meteor Month... April 2008 Challenging Lyrids for 2008... A Southern Shower peeking above the Horizon (PPU)... The eta-Aquarids (ETA) Compete with Dawn and the Moon... Ecliptic (ANT) meteors for April... Targets for Plotting... The Meteor Moonth... Index to 2006 Articles... May 2008 (ETA) The eta-Aquarids Greet the Dawn... (ELY) This Newer Shower is Worth Looking for... (ANT) Antihelion Showers in May... The Nights Get Shorter... Lyrids Squashed by the Moon... June 2008 June: The Last Slow Month... June Bootids (JBO) the Shower of the Month... (ANT) Antihelion Activity... Other Showers of Interest... Magnitude References... July 2008 July’s Southern Showers... The Perseids Perk Up... A Multitude of Minor Showers... Magnitude References... August 2008 The Perseids - The Public’s Shower... July’s Southern Showers Wind Down... KCG, the “Other” August Shower... Other Showers of Interest... New Showers from Video Data... Magnitude References... September 2008 (AUR) alpha-Aurigids, No Outburst Expected This Year... (SPE-DAU) Two Minor Showers on a Common Path... (NTA-STA) The Taurids Spice Up the Antihelion Radiant... (ERI-EER) Potential Activity from Eridanus... Active Period for the Southern Apex Sources... Showers Detected in Video Records... Early Perseid Results... October 2008 ORI - Halley’s Comet Dust Returns Again... Will the Draconids (GIA) Roar?... STA & NTA - New Taurid Data... Minor Showers EGE and LMI... DAU - Leftover Aurigids... Sky References... November 2008 Have the Leonids Returned to Being a Minor Shower?... Autumn’s Showers Wind Up and Down... Don’t Blink or You Might Miss an AMO Outburst... The Andromedids Live... Winter’s Showers Start Earlier Than Expected... Sky References... December 2008 Geminids Too Friendly with the Moon... Moon Free Ursids... Dark Skies to Investigate the Comae Berenicids... Antihelion Radiant Returns... Minor Showers of December... 2009 Quadrantids...
For radiant positions and more detailed descriptions of showers, see the IMO 2008 Meteor Shower Calendar at:
http://www.imo.net/calendar/2008For assistance in understanding how to estimate limiting magnitude (the faintest stars you can see) the NAMN has a tool available here:
http://www.namnmeteors.org/lm_calc.htmlIt’s especially helpful for those new to the process.
For those who wish to look for other minor showers not listed here, or want daily radiant positions for all the showers, drop me an e-mail at my meteoreye address below, and I’ll send you my current Excel spreadsheet.
Feel free to contact us for questions and comments!!
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NAMN email: namn@namnmeteors.org
NAMN website: http://www.namnmeteors.org
Mark Davis, meteors@comcast.net
Goose Creek, South Carolina, USA
Coordinator, North American Meteor Network
Wayne T Hally, meteoreye@comcast.net
High Bridge, NJ
Writer, NAMN Notes
Lew Gramer, dedalus@alum.mit.edu
Homestead, Florida, USA
Coordinator, Public Outreach
Owner/Moderator, 'MeteorObs'
Kevin Kilkenny,
namnfireball@earthlink.net
Staten Island, New York, USA
Coordinator, Fireballs and Meteorites
Back issues of NAMN Notes can be found on-line at the NAMN website
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http://www.meteorobs.org
by selecting 'Browse Archive by Month'
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to find out information on our weekly chat sessions:
Contact Lew Gramer at:
dedalus@alum.mit.edu