Results of the IMO Video Meteor Network -
December 2008 reported by Sirko Molau reported http://www.imonet.org/reports/200812.html
December 2008 reported by Sirko Molau reported http://www.imonet.org/reports/200812.html
Italian Fireball on Dec 20, 2008, at 21:06:20 UT.
Video of Italian meteor on Dec 20, 2008, at 21:06:20 UT. =========================================================
A very successful year 2008 petered out with a meager December. In the first half of the month, there was reasonable weather at hardly any site, such that the Geminids did not only became a victim of the Moon, but also of the clouds. Only western Germany enjoyed clear skies in the maximum nights. In the second half of December, the weather slowly improved. So there were already a few more observers who caught the Ursid maximum. From Christmas on, the weather became close to perfect at many sites, so that the statistics improved a bit towards the end. Finally there were at least three cameras who managed to get more than 20 observing nights. The monthly total for December was nearly 2,300 hours effective observing time and more than 10,000 meteors.
Last month, we could once more welcome a new observer in the camera network, whom I was especially happy about. With Klaas Jobse, a real "veteran" of video meteor observation found his way to us. Five years before I constructed my first meteor camera, Klaas was already recording meteors by video in the Netherlands with BETSY1. His current system BETSY2 utilizes the same powerful image intensifier as AVIS2 and OND1. So it comes as no surprise, that Klaas managed to get nearly a thousand video meteors from scratch using the perfect weather at the end of 2008.
Let's now have a look at the biggest showers of December. As mentioned before,the Geminids could hardly be observed in 2008. In the IMO Video MeteorDatabase, however, they are the third strongest shower with more than 12,000 members. According to the latest edition of the IMO handbook for meteor observers, they are active between December 7 and 17, reaching their maximum at December 13. In the current video data analysis, the shower was clearly detected between December 5 and 18. The position of the Geminid radiant agrees well with the value from literature (http://www.imonet.org/reports/20081201.gif), only the drift direction differs slightly. The calculated velocity of 35 km/s is identical to the value given in the handbook. The long-term activity profile of the Geminids (http://www.imonet.org/reports/20081202.gif) has an asymmetric shape witha moderate ascent until the maximum on December 13/14, followed by a steep descent. Three days after the maximum the shower is hardly detectable anymore.
A few days before Christmas is the time of the Ursids. This year, we had at least in Italy and Portugal clear skies, such that the maximum on December 21/22 could be covered by seven cameras. The activity profile resulting from 164 Ursids and 200 sporadics is given in figure: http://www.imonet.org/reports/20081203.gif. The Ursid counts were determined in one hour intervals, corrected by the radiant altitude, and averaged overall cameras. For comparison, the hourly sporadic rate is given. The activity of the Ursids was rising up to the maximum between 2 and 3 UT on December 22,thereafter it was declining again. As expected, the sporadic activityincreased steadily towards the morning. Figure http://www.imonet.org/reports/20081204.gif gives a comparison of the Ursids in 2008 and the previous two years, whereby the activity was plotted against the solar longitude. It is obvious that the activity level in 2008 was lower than in the two years before.What do we learn from the video meteor database about the Ursids? Accordingto the IMO handbook, they are active between December 17 to 26. This agrees well with the activity interval December 16 to 25 derived from 750 video Ursids. Due to the lower meteor number, the radiant drift(http://www.imonet.org/reports/20081205.gif) is not as well determined as for major showers. Still, the radiant is on average close to the expected position, and also the determined velocity of 32 km/s agrees well with thevalue from the IMO handbook (33 km/s).The long-term activity profile (http://www.imonet.org/reports/20081206.gif) reveals, that the Ursids are reasonably active in only a very short interval,which confirms the observation from the last two years. The two degrees insolar longitude is an upper limit, because the maximum is smeared out when sliding intervals of two degrees length are used.Let finally have a look at the Coma-Berenicids, which are active in December,too. The current edition of the IMO handbook points to a significant discrepancy between the radiant position published earlier and the results from a first video data analysis in 2006. Could that result be confirmed by the current analysis based on 2,300 shower meteors? On the first glimpse, the observed radiant position seems to match well to the values from the old handbook (http://www.imonet.org/reports/20081207.gif). A closer inspection, however, reveals an offset of about 17 days. On January 6, for example, the radiant is observed at a position given for December 20 according to the old ephemeris. In other words, the radiant is off by 15 degrees (or one hour) in the north western direction. The activity interval, on the other hand, agrees well with the value from literature.The handbook lists an interval of December 12 till January 23 (with amaximum near December 20), whereas the radiant was well observed between December 9 and January 27 in the video data. Also the calculated velocity(64 km/s) is in good agreement with the handbook (65 km/s). Figure http://www.imonet.org/reports/20081208.gif shows the activity profilederived from the video data. The maximum on December 20 is confirmed,whereby the profile is less pronounced than that of other showers. The peak ZHR of five given in the IMO handbook does not seem to be reached. For comparison, the profile derived from visual data (based on the old radiant position) is given with blue dots. Up to a solar longitude of 275 degrees,both profiles agree well. Thereafter there are larger discrepancies. Let's now have an overview of the record year 2008, in which 24 observers (2007: 22) from 10 countries (2007: 9) contributed to the camera network withoverall 37 camera systems (2007: 30). Most of the stations of the IMO network are still located along a north south axis in Central Europe (Germany, Slovenia, Italy), but the situation improves also in other regions. Due to the extention of the camera network, we could collect more data than ever. Thanks to the leap year, we got an unbeaten 366 (2007: 364) observing nights, in which almost 23,000 observing hours (2007: 17,000) could be collected. The average number of meteors per hour (4.0) decreased once more(2007: 4.4). One reason is, that most cameras joining the network are unintensified. In addition, most major showers of 2008 became a victim ofthe weather or the Moon. Still, we could record more than 92,000 meteors (2007: 75,000). For the first time, we managed to get more than a thousand observing hour seach month. In February and August till December, it was even more than two-thousand hours. The best result of all was achieved in October 2008 with 2,750 hours of effective observing time and more than 17,000 meteors. Eight observers (2007: 6) managed to get more than 200 observing nights in 2008. With 336 nights, Sirko Molau was again on top of the list, improving his own record from 2007 by 12 nights. Javor Kac, Joerg Strunk, Carl Hergenrother and Bernd Brinkmann all got about 250 nights. Note that Carl joined the network only in March. Furthermore, all peak performers besides Carl and Bernd operated more than one camera. The results for each observerare given in the next table, whereby the number of cameras and stations refers to the main time of year. ==============================================================
Let's have a look at the ten most successful video systems. REMO1 in Ketzuerand MINCAM1 in Seysdorf were again on top. They are followed by SALSA in Tucson, which will probably take over the lead in 2009. The camera with the highest output (AVIS2: 9790 meteors) and "only" 153 nights did not make it to the TOP 10 Cameras. ============================================================== All observations of 2008 are check for consistency and stored in the video meteor database. In a few days time, the data will be made available is PosDat format at http://www.imonet.org/ for free download. At this point, I would like to thank all participants in the IMO networkfor the fine cooperation in 2008. I wish all of us much success in the new year 2009. Written by Sirko Molau www : http://www.molau.de/
Last month, we could once more welcome a new observer in the camera network, whom I was especially happy about. With Klaas Jobse, a real "veteran" of video meteor observation found his way to us. Five years before I constructed my first meteor camera, Klaas was already recording meteors by video in the Netherlands with BETSY1. His current system BETSY2 utilizes the same powerful image intensifier as AVIS2 and OND1. So it comes as no surprise, that Klaas managed to get nearly a thousand video meteors from scratch using the perfect weather at the end of 2008.
Let's now have a look at the biggest showers of December. As mentioned before,the Geminids could hardly be observed in 2008. In the IMO Video MeteorDatabase, however, they are the third strongest shower with more than 12,000 members. According to the latest edition of the IMO handbook for meteor observers, they are active between December 7 and 17, reaching their maximum at December 13. In the current video data analysis, the shower was clearly detected between December 5 and 18. The position of the Geminid radiant agrees well with the value from literature (http://www.imonet.org/reports/20081201.gif), only the drift direction differs slightly. The calculated velocity of 35 km/s is identical to the value given in the handbook. The long-term activity profile of the Geminids (http://www.imonet.org/reports/20081202.gif) has an asymmetric shape witha moderate ascent until the maximum on December 13/14, followed by a steep descent. Three days after the maximum the shower is hardly detectable anymore.
A few days before Christmas is the time of the Ursids. This year, we had at least in Italy and Portugal clear skies, such that the maximum on December 21/22 could be covered by seven cameras. The activity profile resulting from 164 Ursids and 200 sporadics is given in figure: http://www.imonet.org/reports/20081203.gif. The Ursid counts were determined in one hour intervals, corrected by the radiant altitude, and averaged overall cameras. For comparison, the hourly sporadic rate is given. The activity of the Ursids was rising up to the maximum between 2 and 3 UT on December 22,thereafter it was declining again. As expected, the sporadic activityincreased steadily towards the morning. Figure http://www.imonet.org/reports/20081204.gif gives a comparison of the Ursids in 2008 and the previous two years, whereby the activity was plotted against the solar longitude. It is obvious that the activity level in 2008 was lower than in the two years before.What do we learn from the video meteor database about the Ursids? Accordingto the IMO handbook, they are active between December 17 to 26. This agrees well with the activity interval December 16 to 25 derived from 750 video Ursids. Due to the lower meteor number, the radiant drift(http://www.imonet.org/reports/20081205.gif) is not as well determined as for major showers. Still, the radiant is on average close to the expected position, and also the determined velocity of 32 km/s agrees well with thevalue from the IMO handbook (33 km/s).The long-term activity profile (http://www.imonet.org/reports/20081206.gif) reveals, that the Ursids are reasonably active in only a very short interval,which confirms the observation from the last two years. The two degrees insolar longitude is an upper limit, because the maximum is smeared out when sliding intervals of two degrees length are used.Let finally have a look at the Coma-Berenicids, which are active in December,too. The current edition of the IMO handbook points to a significant discrepancy between the radiant position published earlier and the results from a first video data analysis in 2006. Could that result be confirmed by the current analysis based on 2,300 shower meteors? On the first glimpse, the observed radiant position seems to match well to the values from the old handbook (http://www.imonet.org/reports/20081207.gif). A closer inspection, however, reveals an offset of about 17 days. On January 6, for example, the radiant is observed at a position given for December 20 according to the old ephemeris. In other words, the radiant is off by 15 degrees (or one hour) in the north western direction. The activity interval, on the other hand, agrees well with the value from literature.The handbook lists an interval of December 12 till January 23 (with amaximum near December 20), whereas the radiant was well observed between December 9 and January 27 in the video data. Also the calculated velocity(64 km/s) is in good agreement with the handbook (65 km/s). Figure http://www.imonet.org/reports/20081208.gif shows the activity profilederived from the video data. The maximum on December 20 is confirmed,whereby the profile is less pronounced than that of other showers. The peak ZHR of five given in the IMO handbook does not seem to be reached. For comparison, the profile derived from visual data (based on the old radiant position) is given with blue dots. Up to a solar longitude of 275 degrees,both profiles agree well. Thereafter there are larger discrepancies. Let's now have an overview of the record year 2008, in which 24 observers (2007: 22) from 10 countries (2007: 9) contributed to the camera network withoverall 37 camera systems (2007: 30). Most of the stations of the IMO network are still located along a north south axis in Central Europe (Germany, Slovenia, Italy), but the situation improves also in other regions. Due to the extention of the camera network, we could collect more data than ever. Thanks to the leap year, we got an unbeaten 366 (2007: 364) observing nights, in which almost 23,000 observing hours (2007: 17,000) could be collected. The average number of meteors per hour (4.0) decreased once more(2007: 4.4). One reason is, that most cameras joining the network are unintensified. In addition, most major showers of 2008 became a victim ofthe weather or the Moon. Still, we could record more than 92,000 meteors (2007: 75,000). For the first time, we managed to get more than a thousand observing hour seach month. In February and August till December, it was even more than two-thousand hours. The best result of all was achieved in October 2008 with 2,750 hours of effective observing time and more than 17,000 meteors. Eight observers (2007: 6) managed to get more than 200 observing nights in 2008. With 336 nights, Sirko Molau was again on top of the list, improving his own record from 2007 by 12 nights. Javor Kac, Joerg Strunk, Carl Hergenrother and Bernd Brinkmann all got about 250 nights. Note that Carl joined the network only in March. Furthermore, all peak performers besides Carl and Bernd operated more than one camera. The results for each observerare given in the next table, whereby the number of cameras and stations refers to the main time of year. ==============================================================
Let's have a look at the ten most successful video systems. REMO1 in Ketzuerand MINCAM1 in Seysdorf were again on top. They are followed by SALSA in Tucson, which will probably take over the lead in 2009. The camera with the highest output (AVIS2: 9790 meteors) and "only" 153 nights did not make it to the TOP 10 Cameras. ============================================================== All observations of 2008 are check for consistency and stored in the video meteor database. In a few days time, the data will be made available is PosDat format at http://www.imonet.org/ for free download. At this point, I would like to thank all participants in the IMO networkfor the fine cooperation in 2008. I wish all of us much success in the new year 2009. Written by Sirko Molau www : http://www.molau.de/
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