By Carl Johannink and Paul Roggemans
Abstract: A summary of the activity of the CAMS BeNeLux network during the month of December 2021 is presented. 19579 meteor detections were recorded of which 9080 multiple station meteors. The weather was very unfavorable; all rich Geminid nights were completely missed. 25 nights allowed to collect some orbits with 8 nights with more than 100 orbits. In total 3072 orbits were added to the CAMS BeNeLux database.
Introduction
December is one of the top months for meteor astronomy. The nights are long, meteor activity is high, not only because of the rich sporadic activity, but also thanks to very active meteor showers. The Geminids being the most impressive meteor shower of the year, but also some minor showers deserve attention during this month. What would this year bring, could we be lucky with the weather in 2021?
December 2021 statistics
CAMS BeNeLux collected 19579 meteor detections of which 9080 paired meteors in December 2021 (against 8150 in 2020 and 12329 in December 2019). Indeed, this number suggests the weather circumstances were not favorable at all this year. All the rich Geminid nights 12–13, 13–14 and 14–15 December remained totally cloudy. The final number of orbits reached a total of 3072 orbits (against 2693 in 2020), still an impressive number when taking the poor weather circumstances into account. But this result is far less than the 4908 orbits of December 2018 when CAMS BeNeLux had its best December month ever.
This month counted only 8 nights with more than 100 orbits (8 in 2020 and 13 in 2019) and 6 nights remained without any orbits (7 in 2020 and 3 in 2019). Best night of December 2021 was 21–22 with 559 orbits, during the Ursid maximum. Until 2020 this night remained one the nights with the lowest number of orbits since 2012, with only 24 orbits collected during all previous years before 2021. It is mostly thanks to the result of the night 21–22 as well as 8–9 and 20-21 December that the month got at more than 3000 orbits. These three nights were good for about half of the monthly total. Especially the Netherlands got to deal with partial or completely cloudy nights. During many nights only a part of the operational cameras could register meteors.
The statistics of December 2021 are compared in Figure 1 and Table 1 with the same month in previous years since the start of CAMS BeNeLux in 2012. In 10 years, 231 December nights allowed to obtain orbits with a grand total of 25392 orbits collected during December during all these years together.
December 2021 had 84 cameras at best and 76.0 on average capturing meteors. The network was expanded with one new camera, on December 16 Tim Polfliet got RMS 3820 operational in Gent.
Figure 1 – Comparing December 2021 to previous months of December in the CAMS BeNeLux history. The blue bars represent the number of orbits, the red bars the maximum number of cameras running in a single night and the green bars the average number of cameras running per night.
Table 1 – December 2021 compared to previous months of December.
| Year | Nights | Orbits | Stations | Max. Cams | Min. Cams | Avg. Cams |
| 2012 | 12 | 117 | 6 | 7 | – | 2.4 |
| 2013 | 23 | 1053 | 10 | 25 | – | 15.7 |
| 2014 | 19 | 1540 | 14 | 37 | – | 25.8 |
| 2015 | 27 | 1589 | 15 | 49 | 8 | 33.8 |
| 2016 | 25 | 3492 | 21 | 58 | 25 | 48.3 |
| 2017 | 25 | 2804 | 22 | 86 | 49 | 68.9 |
| 2018 | 23 | 4908 | 21 | 78 | 52 | 69.8 |
| 2019 | 28 | 4124 | 21 | 82 | 64 | 72.8 |
| 2020 | 24 | 2693 | 24 | 86 | 56 | 72.4 |
| 2021 | 25 | 3072 | 25 | 84 | 67 | 76.0 |
| Total | 231 | 25392 |
Table 2 – Data for the observed alpha Hydrids in December 2021 with the geocentric radiant position (source: data CAMS BeNeLux).
| Date | Time UT | Sites | R.A. | Decl. |
| Dec. 22 | 01h18m46s | Ermelo-Gronau | 117.7° | –4.4° |
| Dec. 22 | 03h03m05s | Oostkapelle-Alphen a/d Rijn-Mechelen-Gent-Grapfontaine | 120.3° | –5.4° |
| Dec. 22 | 03h21m26s | Ermelo-Gronau | 119.1° | –8.4° |
| Dec. 25 | 01h59m08s | Flatzby- Holdorf | 120.0° | –5.7° |
| Dec. 26 | 02h18m31s | Ermelo-Woold | 122.2° | –7.5° |
Some peculiar data
A significant dataset has been obtained for the Ursids which will be covered in another article. Of course, several other showers were recognized as well. During the last decade of the year five alpha Hydrids (AHY, #00331) were recorded. The radiant of this minor shower is located about 10 degrees south of the radiant of the sigma Hydrids (HYD, #0016), which could be observed visually at the middle of the month. The alpha Hydrids with vg = 43 km/s, are slower than the sigma Hydrids with vg = 59 km/s and the orbits of both meteoroid streams differ mainly in inclination i. Table 2 lists some details of the observed alpha Hydrids.
On December 9, at 02h48m18s UT, Jean-Marie Biets, Luc Gobin and Paul Roggemans recorded an alpha Canis Majorid (ACA, #00394). It is remarkable we could record a member of this southern hemisphere meteor shower from our northern latitudes (50° to 53° north). The geocentric radiant of this meteor was at R.A. = 106.0° and decl. = –12.4°.
As early as December 17 at 00h37m54s UT, Paul Roggemans and Klaas Jobse recorded the first Quadrantid of the season. Data for this major shower will be discussed in the January report.
Conclusion
December 2021 brought barely better weather than previous year. With more cameras operational 7 on 7 than previous years, mainly newly installed RMS cameras, the best could be derived from partial clear nights. December 2021 wasn’t as bad as December 2020, but will remain one of the poorest months of December in the CAMS BeNeLux history.
Acknowledgment
This report is based on the online data taken from the CAMS website and the CAMS BeNeLux own data. Many thanks to all participants in the CAMS BeNeLux network for their dedicated efforts. The CAMS BeNeLux team was operated by the following volunteers during the month of December 2021:
Hans Betlem (Woold, CAMS 3071, 3072 and 3073), Jean-Marie Biets (Wilderen, Belgium, CAMS 379, 380, 381 and 382), Ludger Boergerding (Holdorf, Germany, RMS 3801), Martin Breukers (Hengelo, Netherlands, CAMS 320, 321, 322, 323, 324, 325, 326 and 327, RMS 319, 328 and 329), Giuseppe Canonaco (Genk, RMS 3818, RMS 3819), Pierre de Ponthiere (Lesve, Belgium, RMS 3816), Bart Dessoy (Zoersel, Belgium, CAMS 397, 398, 804, 805 and 806), Tammo Jan Dijkema (Dwingeloo, Netherlands, RMS 3199), Isabelle Ansseau, Jean-Paul Dumoulin, Dominique Guiot and Christian Walin (Grapfontaine, Belgium, CAMS 814 and 815, RMS 3814, RMS 3817), Uwe Glässner (Langenfeld, Germany, RMS 3800), Luc Gobin (Mechelen, Belgium, CAMS 3890, 3891, 3892 and 3893), Tioga Gulon (Nancy, France, CAMS 3900 and 3901), Robert Haas (Alphen aan de Rijn, Netherlands, CAMS 3160, 3161, 3162, 3163, 3164, 3165, 3166 and 3167), Robert Haas (Texel, Netherlands, CAMS 811, 812 and 813), Kees Habraken (Kattendijke, Netherlands, RMS 378), Klaas Jobse (Oostkapelle, Netherlands, CAMS 3030, 3031, 3032, 3033, 3034, 3035, 3036 and 3037), Carl Johannink (Gronau, Germany, CAMS 3100, 3101 and 3102), Reinhard Kühn (Flatzby, Germany, RMS 3802), Hervé Lamy (Dourbes, Belgium, CAMS 394 and 395), Hervé Lamy (Humain Belgium, CAMS 816), Hervé Lamy (Ukkel, Belgium, CAMS 393), Koen Miskotte (Ermelo, Netherlands, CAMS 3051, 3052, 3053 and 3054), Tim Polfliet (Gent, Belgium, CAMS 396, RMS 3820), Steve Rau (Zillebeke, Belgium, CAMS 3850, 3852, RMS 3851, RMS 3853), Paul and Adriana Roggemans (Mechelen, Belgium, RMS 3830 and 3831, CAMS 3832, 3833, 3834, 3835, 3836 and 3837), Hans Schremmer (Niederkruechten, Germany, CAMS 803).
