alpha Monocerotids activity but no spectacular outburst

Abstract: The predicted alpha Monocerotids outburst did materialize. Although early visual and radio reports indicated only ‘some’ weak activity, several video cameras under good sky conditions recorded a significant number of alpha Monocerotids in a short time interval, exactly as predicted by Peter Jenniskens and Esko Lyytinen. Although the level of activity cannot be compared to the 1995 return and definitely no meteor storm took place like announced in some sensation media,  CAMS leading scientist Peter Jenniskens concludes that this was not just ‘some activity’ but a real shower outburst. The outburst is also clearly shown by the results of the Global Meteor Network coordinated by Denis Vida. The lack of bright meteors explains why visual observers saw very few AMO-meteors, especially where a low elevation of the radiant, moonlight and twilight hampered observations.

Introduction

Predictions suggested a fair chance to observe a short-lived outburst of the alpha Monocerotids in the morning of the night 2019 November 21–22. Any activity was expected to be centered around 4h50m UT and the duration of the event would be limited to 15 up to 40 minutes maximum. Read also https://www.emeteornews.net/2019/11/06/likely-alpha-monocerotids-amo246-outburst-on-the-morning-of-november-22-2019/.

The predictions got wide attention in the media worldwide. Some journalists did not pay attention to the details in the original publication and announced a spectacular meteor storm with 1000+ of shooting stars to be seen while no scientist ever predicted such spectacular event. Even if a strong outburst would have occurred, the actual numbers of meteors seen would not be so impressive because of the very short duration of the Earth transit through the dust trail. For a majority of casual watchers with poor sky conditions, light pollution, moonlight and twilight, the number of meteors visible would be only a fraction of the actual number and certainly disappoint observers with too high expectations. The low radiant elevation at some location reduced the visible number of meteors to a fraction of what could be seen in perfect circumstances with the radiant at the zenith.

The reduction of the observational data is going on and will take several days or weeks to get done.

Preliminary results

The first reports from visual and radio observers this morning confirm that some alpha Monocerotids were observed, although only small numbers were seen. The activity was much less than in 1995 when many more meteors were seen. So far it seems that the alpha Monocerotids were rather faint, no particular bright meteors were reported.

The most substantial report so far comes from Denis Vida:  “The Global Meteor Network stations in Croatia and Russia (perhaps elsewhere as well) saw many AMOs, but it definitely was not a meteor storm. The width of the shower was indeed very small. A short analysis results in the following graph (Figure 1), based on single-station data from La Palma (ES0002). From the time lapse it looks like Musk’s Starlink is becoming a serious problem.  AMO’s start around 4:30, and starlink sats start around 6:00 in this time lapse video.”

RMS ES0002 TimeLapse, courtesy Denis Vida.

Figure 1 – Global Meteor Network station ES0002 (La Palma) shower count (courtesy Denis Vida).

Figure 2 – The solar centered ecliptic coordinates in the s.l. range 238.0 to 240.0 with color gradiant in function of the geocentric velocity vg.

Figure 3 – The solar centered ecliptic coordinates in the s.l. range 238.0 to 240.0 with color gradiant in function of the density.

Figure 4 – The solar centered ecliptic coordinates in the s.l. range 238.0 to 240.0. Note the very compact nature of the radiant.

Peter Jenniskens (http://cams.seti.org/) reports that the alpha Monocerotids outbursts has been confirmed by the Brazilian CAMS-EXOSS network (Figure 5). Meanwhile, Chile recorded 20 and Florida 49 triangulated alpha Monocerotid orbits during the outburst, as well as some that were not so precisely measured and that are not captured by the lookup table (Jenniskens, 2019). Chile reported clouds in La Serena. Detected meteors were in +4 to +1 magnitude range, most +3 and +2. The shower clearly peaked in a short period. There was not just “activity”, it was clearly an outburst.

Figure 5 – A composite image, made by Peter Jenniskens, of alpha Monocerotids captured at one of the CAMS-EXOSS cameras (nr. 9999) in Brazil between 04:49 and 05:14 UTC, November 22, (Courtesy of Marcelo De Cicco).

The CAMS networks picked up some orbits that were identified as AMO#246 members in the night of November 21, the night before the expected enhanced activity. Figure 6 shows the position of the AMO#246 radiants, with some other active sources marked as well. This means that some dust of this shower got already well dispersed. Figure 7 displays the map of November 22 which includes the orbits captured during the outburst.

Figure 6 – The radiants of the orbits collected by the CAMS networks during the night before the predicted outburst, November 20-21. The alpha Monocerotids radiants are marked with a yellow circle.

Figure 7 – The 46 radiants of the AMO#246 orbits collected by the CAMS networks during the predicted outburst, November 22. The alpha Monocerotids radiants are marked with a yellow circle.

Figure 8 – Video composite from CAMS 5001 which is located in Gainesville, Florida (courtesy J. Andreas (Andy) Howell ).

Figure 9 – The time distribution of coincidences (courtesy J. Andreas (Andy) Howell ).

Figure 10 – A stack of the 23 AMO meteors captured by the RMS FR000A at Cerilly, France (courtesy: Tioga Gulon).

Figure 11 – Time distribution of the appearance of the AMO meteors.

Enrico Stomeo reports the observations he made during the night of 21-22 November with three cameras at his observatory near Venice. Unfortunately the sky was
almost always largely covered with clouds. It was totally cloudy when the peak of the alpha Monocerotids was supposed to happen. The observations were as follows:

• (1) NOA38 cam
  UT 203000-045000 Teff 3.93h TOT 17 = 3 AMO, 2 LEO, 12 SPO.
  Two aMONs appeared within four minutes at 044134 and 044550 UT.
• (2) MIN38 cam
  UT 204600-044400 Teff 3.38h TOT 21 = 2 NTA, 1 LEO, 1 STA, 17 SPO.
• (3) SCO38 cam
  UT 204400-043900 Teff 3.30h TOT 15 = 1 AMO, 2 STA, 1 LEO, 1 NTA, 10 SPO.

John W. Briggs reports to the Global Meteor Network: “My family and I observed at FOAH Observatory (IAU code V23) near Magdalena, New Mexico, USA, for about 25 minutes through the maximum predicted for the alpha Monocerotids (i.e., centered on about 10:55 Mountain Time here in USA), and we saw two unusual meteors that I believe were associated with the shower.  Both were about 3rd magnitude and travelled on very long arcs rising up from low in our eastern sky — one of them travelling nearly to zenith.  Although we saw no meteor “storm” here, seeing these rather unusual meteors was well worth the effort!  We were lucky to have a clear sky briefly through this period after a very rainy day.”

Ivan Sergei from Belarus reports: “I watched the log files from my RMS (Radio Meteor System, 88.6 MHz). On the interval 04.40-05.00 UT some increase has been registered in the level of meteor echoes. From 03.42 UT to 05.00 UT 22.11.2019 I heard 91 meteors. Brief summary: some enhancement in meteor activity in the radio range has occurred.

Alfredo Dal´Ava Júnior of the Global Meteor Network in Brazil reported a live view from Poços de Caldas/MG/Brazil:

References

Jenniskens P. (2019). “Alpha Monocerotid meteors 2019”. CBAT 4699.