In the book Meteorshowers and Their Parent Comets [1] p. 617 Peter Jenniskens described that there would be a chance for activity of the alpha Monocerotids in 2019. However, new calculations of Jenniskens and Lyytinen in [2] indicated that there might be a better chance for activity than previously assumed. A few weeks before November 22nd, this was announced via Meteornews [2]. There was also a lot of attention in the press for this possible outburst, unfortunately this was often written “over the top” with high expectations for the numbers of meteors visible. One article even promised thousands of meteors! Meteor observers of course know that the short period in which it would all take place would ensure that at most a few dozens of alpha Monocerotids would be visible.
Unfortunately the weather spoiled the opportunity in the BeNeLux. Only the southern part of the BeNeLux experienced some clear skies around the maximum activity. This resulted in one simultaneous Alpha Monocerotid for the CAMS BeNeLux network [3].

First of all, the well-known IMO website ( was consulted to check how much data was available. Unfortunately, there was only few data available, mainly due to the bad weather. 25 observers reported 273 alpha Monocerotids. If we look at the “on-the-fly” graph with the so-called peak period, a maximum ZHR of 102 is found exactly at the expected time of the outburst (November 22, 04:54 UT, see Figure 1.). This graph is based on 238 AMOs. For this graph, observations with a minimum limiting magnitude of 5.0 were used with an assumed population index r of 2.5.

Figure 1. ZHR curve AMOs from the IMO website

It was remarkable that in first instance, observers reported that the visually counted numbers were disappointing, while the video systems that were active under good sky conditions nevertheless noticed good activity [3]. This is probably largely due to the fact that in Europe the twilight started around the time of the expected maximum activity. The radiant heights were also unfavorable in Europe. Fortunately, three observers were also active on the Canary Islands and they were able to add a lot of data after 5:15 UT.
Unfortunately, the author missed this alpha Monocerotid outburst and that is a pity. The author together with Peter Jenniskens, Marco Langbroek, Jos Nijland, Casper ter Kuile and Robert Haas were able to experience the beautiful outburst of 1995.
All data was carefully checked for the radiant heights (minimum 25 degrees elevation) and for the limiting magnitude. Also, the availability of a CP determination was checked for the relevant observers. Minimum limiting magnitude was set at 5.6, which is 0.3 magnitude less than what the author normally set as lower limit. This was necessary because otherwise too many observations could not be used because of the increasing twilight.
It is unfortunate that most observers reported/counted in periods of three, five or more minutes. It is better to do 1-minute counts with this kind of very short intense meteor outburst. In this way, the analyst can determine the counting periods afterwards and calculate ZHR values in overlapping periods.
Another problem was that relatively few observers with a known CP were active. The data of two observers without a known CP were also used because they observed a respectable number of AMOs under good conditions. For one observer, the Cp was set to 1.0, his observations were pretty similar to those of other observers who were active at the same time. The same applied to a second observer whose cp was set to 2.0, so that the ZHR values found also fit in line with observations from other observers around the same time.

Population index r
Unfortunately, because of the rather few visual observations, no r value profile can be achieved. Therefore, all observations between 03:00 and 06:00 UT with a minimum limiting magnitude of 5.6 rounded-off were used. The population index r could be determined on the basis of 154 AMOs. See table 1 for the results.
Since r [0; 5] contains the largest number of AMOs, it has been decided to set r at 3.00 ± 0.18 in the ZHR calculations.

Table 1. Population index r alpha Monocerotids 2019.

For these calculations, all observations were selected with a minimal radiant height of at least 25 degrees and the minimum limiting magnitude was set at 5.6. A total of 179 AMOs were used in this analysis.
As mentioned earlier, the observations were reported with 3, 5 or more minute counts. The problem of three or more minute counts with this kind of short, sharp outbursts is that in the last minute of a period the activity can be doubled or even more than at the time of the first minute. In addition, the mean time of the observations used is also a problem. Observations that are a few minutes apart can already make a significant difference in ZHR.
To tackle these problems somewhat, the period 04:00 to 05:30 UT was split into time bins of 6 minutes and the period 4:36 to 5:15 UT even into time bins of 3 minutes. All ZHR determinations that felt within one particular time bin were then averaged (weighted average. Ultimately, this work method resulted in table 2 and figures 2 and 3.

Table 2. ZHR Alpha Monocerotids 21/22 November 2019.

Figure 2. ZHR graph Alpha Monocerotids 21/22 November 2019.

Figure 3. ZHR graph Alpha Monocerotids 21/22 November 2019.

As can be seen in figures 2 and 3, the real activity started around 4:15 UT and increased slowly from ZHR 6 to ZHR 12 around 4:40 UT, then started a rapid increase with a maximum just before 5:00 UT with a ZHR of 160 ±40. After that the ZHR dropped to 50 around 5:05 UT and then remained stable for a few minutes at 60+. Finally, a small peak appeared around 5:20 UT with a ZHR of 70 and then rapidly faded to ZHR 10-20 around 5: 30 UT. At 5:40 UT the activity seemed to be over, but the twilight set in.

The night before and after the alpha Monocerotid outburst, some visual observers from Israel and Germany also reported activity from the AMOs. This is also confirmed by CAMS observations.

Despite the fact that not so much data was available for this analysis, this seems to be an acceptable result. Maximum activity just before 5:00 UT on November 22, 2019 with a ZHR of 160. A rapid increase, followed by a slightly less rapid decrease.

A huge thank you to all observers who observed the alpha Monocerotids. They are: Alexandre Amorim, Orlando Benitez Sanchez, Riziele Correa da Silva, Michel Deconinck, Paul Gray, Ian Grech, Jan Hattenbach, Gabriel Hickel, Kamil Hornog, Javor Kac, Pete Kozich, Anna Levin, Alexandr Maidik, Pierre Martin, Koen Miskotte, Sirko Molau, Pedro Pérez Corujo, Ina Rendtel,Terrence Ross, Kai Schutze, Tamara Tchenak, Daniel Verde Van Ouytsel, Thomas Weiland, Roland Winkler and Oliver Wusk.
Also, a word of thanks to Carl Johannink, Michel Vandeputte and Paul Roggemans for reading this article and giving suggestions for this analysis. Thanks to Paul Roggemans for checking my English.

[1] Jenniskens P., Meteor Showers and their Parent Comets, Cambridge University Press
[2] Lyytinen E., Jenniskens P., Likely alpha Monocerotids (AMO # 246) outburst on the morning of November 22, 2019.
[3] Roggemans P., Howell A., Gulon T., alpha Monocerotids activity but no spectacular outburst
[4] Steyeart C., Populatie indexbepaling : methode en nauwkeurigheid, Technische Nota nr. 5 VVS Werkgroep Meteoren, September 1981.