After several weeks of rather exceptional good conditions for the BeNeLux CAMS network, weather deteriorate into a worst case scenario towards the Perseid maximum. Clouds and rain showers circulated over Western Europe in all directions making any reliable forecast difficult. 10-11 and 11-12 August did not reveal any single star with a complete overcast sky. Some gaps occurred late afternoon August 12, good to raise some hope for the night. When the CAMS computer started, the sky was saturated with clouds again and when some intense rain showers followed each other, it looked hopeless as these showers seemed to get formed out of nothing on the rain radar. After 23h UT some gaps appeared and yes here and there a star became visible… Was it going to happen after all? The rain radar showed strokes with rain showers moving quickly towards our German neighbors.
Around 23h20m UT I could see more stars appear on the CAMS-monitor and I noticed some meteors in just few minutes on the monitor. Some cameras got more than 50% clear sky while others got filled up with new clouds. Impossible to predict what it would become, overcast again or would the rest of the night be this mixture of clear gaps with fragments of clouds? CAMS registers meteors in these circumstances but the moving clouds generate huge numbers of false detections which must be eliminated manually on sight. I decided to go to sleep as it looked rather hopeless.
Morning 4h UT my clock alerted me that the CAMS had to be switched off. I still do not thrust timers :-). I saw a crystal clear sky with a nice golden color where the sun was few degrees below the horizon. Yes! We must have had at least a while clear sky! I started the camera calibration routine of CAMS and looked at the stacked images as the CAMS software took a snap every few minutes to find the best astrometric result for each camera for this night. A little bit after 1h UT the last clouds had disappeared from all camera fields. Every now and then I saw a meteor trail on the stacked images during calibration. Wow, this was better than I would have expected. At my location the Sun reaches -8° under the horizon at 3h30m UT this night, when twilight ends the CAMS recording session.
Once the camera fields were all recalibrated for the night, I could start the confirmation. The CAMS detection software had registered over 4000 meteor look-alike moving objects, but how many of these were clouds, planes or birds? Until 1h18m UT most detection proved to be false detections caused by clouds illuminated by the moon, but numerous meteors were spotted in the gaps between the clouds. Deleting so many false detections felt like some fitness training for my right index finger, delete, delete, delete, delete? Oeps, no, back, that was a meteor… I went slower through the frames with clouds than usual as every few frames with clouds there was a meteor to be spotted. I came across one bright meteor which meanwhile I know that Koen Miskotte observed this visually as a -6 with a bright persistent train visible for 15 seconds and Koen has it on his all-sky camera. I also recorded many rather faint trails near the bright Moon.
I spent more than 1 hour on the confirmation, as I did not want to miss any meteor trail between the clouds, while on other nights I tend to browse quickly through cloudy periods. It was worthwhile, 496 meteors in less than a half clear night! Although I got less than half of the night clear sky, it felt more like the glass was half full as I had expected much less 🙂
Here folows a small selection of meteors recorded at Mechelen, Belgium 2017 August 12-12. The identification is on top of the photo with camera number, date time of the start of the bin-file with 255 images with 25 images per second. The exact time of the meteor is between 0 and 10 seconds of this time indidication.