Shower Analysis

The Lyrids (LYR) are the first major annual shower of the season. Their maximum occured near 22-23 April 2007, as reported by visual observers through the IMO electronic report form. Once again, an "on the fly" ZHR graph has been made available with early results.

If you haven't submitted your reports yet, this might be the right time!

The Geminids (GEM) peak on the night of December 13/14. Rates will rise steadily this week as we approach the maximum and the moon wanes. The current radiant is located in northern Gemini, five degrees west of the second magnitude star Castor (Alpha Geminorum). These meteors are best seen near 0200 local standard time when the radiant lies highest above the horizon. This shower is best suited for the Northern Hemisphere but some activity can be seen south of the equator when the radiant culminates low in the northern sky. At 35 km/sec. the Geminids produce meteors of average velocity.

The highest peak is expected in the morning of Thursday the 14th. Expect rates up to 120 meteors per hour in real dark areas, down to a maybe a dozen in more urban regions.

An "on the fly" ZHR graph is available, containing the data reported through the IMO electronic report form (+- 2 minutes delay). Note that by using the electronic form, you allow for more effective data processing and quality control.

We hope this feature motivates your observing efforts! Suggestions and changes are very welcome (source code is open). Note that these are automated results without population index or perception corrections applied, so keep an eye on WGN for scientific results.

We encourage all observers to use the electronic visual observation form. This will increase the efficiency of data processing significantly. The information gathered through this form is used to compute a live ZHR graph.

First-time observers are adviced to read through the visual observing sections of this website before observing.

Bob Lunsford explains in this week's Meteor Activity Outlook:

The Leonids (LEO) will be best seen from November 17 through the 19th. The Earth passes closest to the node of comet Temple-Tuttle late on the 17th (Universal Time). The best chance for enhanced activity will most likely be near 0445 UT on the 19th. This timing favors Western Europe and northwestern Africa. From the western hemisphere, northeastern South America and eastern North America may see enhanced activity as the radiant rises in the east on Saturday evening/Sunday morning November 18/19. No one knows exactly the strength of this peak.

Optimistic forecasters are predicting rates of 2-3 Leonids per minute for a short time centered on the peak. Unfortunately these Leonids will most likely be faint so those viewing from urban sites will not be able to see much at all. Other locations than those mentioned above should watch for activity late in the morning while the radiant is high on the dates mentioned above. The radiant is located at 10:12 (153) +22. This position lies in northwestern Leo, just one degree southwest of the third magnitude star Aldhafera (Zeta Leonis). The radiant rises near 2300 (11:00pm) LST and is best placed in a dark sky just before the onset of morning twilight. At 71km/sec., the average Leonid is swift.

The Orionids surprised with heightened activity in 2006. A considerable set of 146 observing priods was collected by 2006 October 25, 14h UT which leads to the below ZHR profile. The maximum was not sharp; high rates were observed throughout the European and most of the American night of Oct 21/22 with ZHR > 50. Large fractions of bright Orionids were reported by the observers. A population index of r=2.0 was assumed for that reason. Such a value is typical for strong showers like the Perseids or the Geminids. Sporadic meteors, for comparson, have a population index of roughly 3 implying a larger fraction of faint meteors. The Orionids used to have intermediate population indices in previous years.

The Lyrid meteor shower exhibited normal activity in 2006. The profile below is compatible with a peak time of solar longitude 32.32 degrees as it is listed in IMO's Shower Calendar. At present, the temporal resolution of the graph is not fine enough to fix the time of maximum to a tenth of a degree (2.4h). The maximum ZHR of 17 is also close to the one found in the long-term analysis by Dubietis & Arlt (WGN 29 (2001), p. 119, WGN).

A possible enhancement due to the 1-revolution dust trail of Comet Thatcher was not observed. Lyytinen gave a time of closest encounter of 2006 April 22, 9h25m UT (meteorobs mailing list). At that time, only a single observer was out, and a weak enhancement may be buried in the small number of Lyrids available.

[CSV] Apr 2006 , Sollong ,nIND , nLYR , ZHR ,+- , lm 21 09h45m , 31.0688 , 8 , 23 , 5.1 , 1.0 ,6.26 21 22h40m , 31.5907 , 10 , 36 , 8.3 , 1.4 ,6.24 21 23h50m , 31.6428 , 8 , 37 , 12.4 , 2.0 ,5.83 22 03h45m , 31.8006 , 10 , 33 , 11.3 , 1.9 ,5.69 22 15h40m , 32.2845 , 7 , 39 , 17.2 , 2.7 ,5.89 22 21h30m , 32.5238 , 12 , 41 , 14.5 , 2.2 ,6.02 23 00h00m , 32.6226 , 9 , 40 , 11.3 , 1.8 ,5.87 23 02h35m , 32.7286 , 9 , 41 , 12.0 , 1.9 ,5.95 23 21h40m , 33.5047 , 24 , 43 , 4.6 , 0.7 ,5.92 24 00h35m , 33.6227 , 3 , 4 , 3.7 , 1.6 ,5.95 [/CSV]

The profile was computed with a constant population index of r=2.2, no additional perception corrections and a radiant height correction of sin(hR). Solar longitudes refer to equinox J2000.0. nIND is the number of observing periods, nLYR is the number of Lyrids in each average. lm is the average limiting magnitude of the observing periods involved.

We are very grateful to the following observers who contributed to this first analysis: Pierre Bader (Germany), Ricardas Balciunas (Lithuania), Ivana Belic (Serbia), Tibor Csorgei (Slovakia), Milan Darijevic (Serbia), Dariusz Dorosz (Poland), Audrius Dubietis (Lithuania), William Godley (USA), Visnja Jankov (Serbia), Ivan Jokic (Yugoslavia), Natalija Jovanovic (Serbia), Mirna Kramar (Croatia), Paul Martsching (USA), Mikhail Maslov (Russia), Koen Miskotte (Netherlands), Markku Nissinen (Finland), Jurgen Rendtel (Germany), Branislav Savic (Serbia), Teodora Savic Popovic (Serbia), Nikola Stankov (Serbia), Wesley Stone (USA), Tomislava Turcin (Croatia), Shigeo Uchiyama (Japan), Iva Valenic (Croatia), Michel Vandeputte (Belgium), Jovan Vasiljevic (Serbia), Thomas Weiland (Austria), Kim S. Youmans (USA), Ilkka Yrjola (Finland), Przemyslaw Zoladek (Poland).

Visual observations of the 2006 Quadrantids received by the IMO before January 8 were used to provide a rough estimate of the 2006 activity of the meteor shower. A total of 303 Quadrantids seen during 34 hours of effective observing time were reported by 21 observers.

The maximum of the shower was lower than usual, with a ZHR of about 85 near January 3, 23h-24h or a solar longitude of 283.39 degrees (J2000.0). The expected maximum would have occurred at 18h20 UT on January 3. Only a single observer from Japan was able to report his data for that time (first line in below table) with a ZHR clearly below 100, too.