Author Archives: Péter I. Pápics

Chasing Comet NEOWISE (C/2020 F3) around Belgium

I was not yet that much into astronomy when Comet Hale-Bopp passed by in 1997, so I have never seen a bright naked-eye comet until recently. There were a few smaller comets in the past decade(s) which became borderline visible, e.g., Pan-STARRS (C/2011 L4) in 2011, or comets that were big and bright but only observable from the Southern hemisphere, such as C/2006 P1 (McNaught). This finally changed with the arrival of C/2020 F3 (NEOWISE) this month.

In the first days it was only visible before sunrise, so I had to get outside very early to catch it in the twilight, thus it made more sense (to me) to simply stay up all night and go to the nearby abbey to take pictures at half past three… I took the first picture on the 11th of July at 03:53 local time (5 sec, ISO 400, Fujilim X-T3 + Fujilim XF 50mm f/2 @ f2.8). The comet was extremely bright, when I arrived to the shore of the lakes next to the abbey it was unmistakeable, even though the sky was already getting brighter.

On the 12th I got up early again (or more precisely: stayed up late again…) to drive to a nearby village hoping to take some pictures under less light polluted skies, but by the time I arrived clouds rolled in and I only got a few pictures that showed at least part of the comet through gaps in the cloud layer – none of which is worthy enough to be shown here.

On the 13th the visibility on the evening sky finally became better than on the morning sky (as the comet travelled further Northwest), but given there were some high clouds, I choose to stay in Leuven, and we simply walked to the Arenberg castle with Clio to have a look from there. While visually the comet was a nice sight hanging over the castle, the photos turned out to be not so special (mostly because of the dull, grey sky). Still, it was pretty amazing that from a quite bright spot inside the city we could see multiple degrees of the comet’s tail with our naked eyes.

After a few cloudy days, the 17th finally brought some clear skies again, so I drove 15 km to the South (parked along a dirt road just SW of the military airport of Beauvechain) to take a series of pictures. There were still some clouds near the horizon, but the view was definitely much better than from Leuven. I could even see the Milky Way above me! I processed the pictures with Astro Pixel Processor (APP). The image below is a result of processing 55 images (taken around local midnight) of the comet (30 sec, ISO 800, Fujilim X-T3 + Fujilim XF 50mm f/2 @ f2.8), and a set of calibration images (20 dark, 10 flat, and 10 darkflat). The (thin blue) ion tail is visible for over 17 degrees (34 times the apparent size of the full Moon)! This image has the same field of view as the first picture with the abbey tower above. With the naked eye, the tails were visible for around 5 degrees from the coma (the head of the comet).

Finally, when I thought I had enough of the comet, I made a last minute decision on the 21st and drove almost one and a half hour to the highest point of Belgium, and set up my camera there for another set of pictures. The sky was as good as it gets from Belgium, so even though the comet had noticeably lost from its brightness during the previous few days, it still looked very nice even with the unaided eye (sowing at least 5 degrees of tail easily). Unlike on the 17th in Beauvechain, this time there were no clouds near the horizon, only a bot of light pollution from the cities further away. I took multiple sets of images, the one below is created from processing 80 exposures (15 sec, ISO 1600, Fujilim X-T3 + Fujilim XF 50mm f/2 @ f2.8) taken around midnight local time (and also using 20 dark, 20 flat, and 20 darkflat calibration frames). The three bright stars in the top third of the image are the rightmost stars of the Big Dipper, and the ion tail on the image is more than 20 degrees long (at least, as it ends outside of the frame).

It took me hours (or rather days) to process these images to get the most detail out of them without blowing up the noise, but I am more or less happy with the end result now. (In the last picture even the bands of airglow are visible – if you know what to look for –  parallel with the horizon, slightly tilted across the image.)

Lunar occultation of Venus

Last Friday morning the Moon passed in front of Venus. This is not a super rare even (unlike, e.g., a total solar eclipse), but it also does not happen very often; the next Venus occultation (visible from Belgium) will take place on the 9th of November in 2023, but that will be much less spectacular. What makes last week’s event so special, is that it happened only two weeks after the inferior conjunction of Venus (when Venus passes – more or less – between the Earth and the Sun). Around this date Venus shines as a very thin crescent, and the apparent size of the planet is much larger than usual (since it is closest to Earth in space at inferior conjunction). The next time the occultation will happen in a similar configuration will only be in 2028.

Just 45 minutes before Venus was about to disappear I set up my equipment in the shadow of a strategically chosen taller building on the university campus (to block out the Sun), then used my binoculars to find Venus and the Moon. Venus was much brighter, without it finding the dim crescent of the Moon would have been much more difficult on the bright daylight sky. Having established their location relative to the nearby building, I managed to find Venus with the naked eye too. Then I could proceed with aiming the 1000 mm “objective” at the target using a red dot sight that I installed on my camera and aligned with the lens earlier. Manual focus is always a bit of a trial and error, but I got fully ready well in time as the crescent Moon got closer and closer to Venus. From a series of photograph, the nicest one is probably the one where a few clouds also got into the field of view just as the two crescents touched. I did not stay for the exit phase, as more and more clouds began to form…

Thanks to my twitter connections, this picture also made it to the evening news (actually the weather segment) of the VRT (the flemish national radio and television). [Single exposure of 1/340 seconds at ISO 160 with a Fujilim X-T3, using a 1000 mm f/10 Maksutov telescope (from TS-Optics), on a Sky-Watcher Sky Adventurer mount]

Spring in the time of Covid-19

This spring (and summer) turned out to be very different than planned, due to the global coronavirus pandemic. Just a few days after my last flight lesson, Belgium went into lockdown, working from home became the new norm, and social distancing undoubtedly established itself as the word of 2020 in an instant. Luckily (or rather thanks to the hard work of scientists, health care personnel, and the willingness of politicians to listen to these groups) we managed to flatten the curve before the health system got overwhelmed, and we are basically done with the measures as even bars and restaurants reopened two weeks ago, and since last Monday international travel is also allowed again. As the virus is still present, and there is no vaccine yet, it seems like life will have to go on in a quite different way compared to how things were used to be before Covid-19, with face masks and keeping a safe distance whenever possible.

While we had no physiological or financial issues (I can work as well – if not better – from home as from the office, and there is enough work to do), mentally these weeks (especially early on) were really not easy. In the beginning my hypochondria was messing with my head way too much, causing large swings in my mood and productivity, which got better only by limiting my news intake, and when hospitalisation numbers finally started going down. Initially I could not even fully enjoy my occasional bike rides outside because of my bad mental state. Luckily individual cycling (and running) was always allowed (and even encouraged), because I am pretty sure I would have gone really crazy without that… But holiday plans (including the so thoroughly planned and booked Trans Pyrenees ride) had to be cancelled (and everything is was too uncertain to start making new ones), we could not go to restaurants, there were no flight training, Liverpool FC was halted on the way to their first Premier League trophy, and I was not even allowed to drive to the Ardennes for a ride :( Mainly 1st world problems, but still, a big negative change in everyday lifestyle is difficult no matter the baseline.

After the initial shock, we slowly got used to the new situation. The exceptionally dry and warm weather (average temperature of my rides in April was 20.2°C, which is several degrees over the historical average, and this April-May was the driest April-May in Belgium since the beginning of measurements) definitely helped by creating plenty of opportunities for biking (and since I work 4/5th as of February, I have more free time in general in any case).

So while my big sportive goal for 2020 suddenly disappeared, I still continued with the training that I started at the beginning of this year (wanting to get my earlier cycling fitness back, and simply wanting to do something else besides sitting in front of the computer). I tried to keep my rides interesting by always picking a different route (while avoiding the busy paths along the waterways), and by participating in small challenges on a few selected road segments. After my burnout last year, I really enjoyed being on the bike again, and I tried biking without looking at the numbers most of the time (so biking for the good feeling, and not to achieve a given amount of kilometers a week or month). Even though I try to not not concentrate on the plain numbers anymore, having completed all main monthly Strava challenges (bike more than 1250 km, with more than 7500 m elevation gain, and including at least one 100 km ride) in April and May, and even getting a few KOMs (back) is something I am happy about (plus it seems like my cycling fitness level has just reached its all time high too). I have also visited some new places, like the spiral bike path looping through the trees and the bike path crossing a lake (in a way that the road is under the water level while your eyes are in line with it) in Limburg, or the geographical middle point of Belgium, and the West side of Brussels. The open road (or gravel path) was also the only place where I could meet up with a few friends when it was already safe to do so, and some of the best rides were these social evening spins just before sunset. I expect that now that flight training is restarting I will bike a bit less, but as we are allowed to take the car to ride somewhere else since last week, I hope to get back to the Ardennes and bike further away from Leuven more often in the coming months (which already started with a nice outing to Luxembourg on Sunday).

I have been riding with my beautiful steel bike too a lot (already more than over the whole past year), not only because it is a very nice bike, but also because I had to miss my Endurace for two weeks… The reason: the frame broke under me (where the front derailleur hanger is screwed onto the seat tube), just 500 m from home, but luckily without me crashing. Fortunately it cost me only 120 EUR to get a brand new replacement frame (instead of 2600 EUR which is the actual price of a new frame), as the bike was still covered by the 6 year guarantee of Canyon.

Work went also quite well the past months, as while coding gets boring sometimes, we have been in the news a lot (among others in the VRT, in De Tijd, in De Standaard, in the Knack, and for example with an article in the Verkeersspecialist) thanks to the traffic monitor that I set up using Telraam data, comparing the measured cars, heavy vehicles, cyclists, and pedestrians to the pre-Covid-19 baseline on a daily and weekly basis. I think one of my biggest achievements is getting uncertainty intervals into the national media :) [As this is the wet dream of any data scientist, isn’t it?]

I think it is safe to say that our numbers became the standard when referring to traffic beyond the highways network. I could write a full paper about this, but I will spare you of the boring technical details (here). It’s enough to say that we tracked the initial fall and the slow and long return of traffic on the streets, and we have also seen how strongly leisure oriented cycling correlates with temperature and the absence of rain. Nothing fundamentally surprising, but scientifically sound, precise measurements of our everyday lives and habits, on a level (geographical extent, various modes, temporal resolution, and precision) that has not been done before.

My PhD student (whom I co-supervised the past years, even when I was not working at the university anymore) has defended her thesis, and while for the internal examination we could still meet up with the whole jury in person (followed by a nice dinner), her “public” defense was the first virtual defense at the department (and also the first PhD defense at the Institute of Astronomy of the KU Leuven that is now on YouTube). It went really well (of course), and having a sip of champagne and a piece of chocolate together with her (and my former) supervisor was a nice moment afterwards, even though nobody else could be present. As illustration of a perfect supervisor-student relationship, we both got each other a LEGO to build (and – unrelated – Clio also got me a really nice set to cheer me up when I was feeling really down, which we build up together on a less sunny weekend).

While I could not fly in real life, I spent quite some time (and that is a clear understatement) to create a very precise model of the airport of Charleroi for the flight simulator (X-Plane 11). Instead of listing all the features here (but it has a hand-crafted terrain model, extremely precise markings and lights, taxiway signs, and even some custom 3D models – which took me back to SketchUp after quite some years -, including the iconic first floor facade of the passenger terminal), I will just link the download page of the scenery for the curious readers. It has been very popular among fellow simmers, it is currently within the 20 most popular scenery downloads of the last month. It feels pretty much like the real thing, it is a shame that I can not fly with a Sonaca 200 in the simulator (and making a plane is a bit more complex than making an airport, so no thank you), that would really help in practising some flows and procedures. Sometimes I really hate my perfectionism, because I keep finding things to improve upon, which on one hand is something I like to do, but on the other hand it takes time away from actually just using the scenery.

Finally, for the rest of the lockdown news, we have seen the “train” of Starlink satellites on the evening sky (and even recorded the view), and also managed to find a game on PlayStation that we can sometimes play together (Minecraft Dungeons). Two weeks ago on Friday I was finally back in the air (then last Saturday too), so expect some flight training related posts in the near future (since I can barely think of anything else than flying since then).

Road to the PPL: Up into the sky and back down to Earth

During February and March I had four more flight training sessions at EBCI (Charleroi), bringing up my total flight time to 7 hours and 36 minutes (after 6 flights). (This sounds so little like this, it’s basically the amount of time I have to work on a single day, wow. No offence to my work, but I remember these hours slightly more vividly.) It happens that I flew with all the four different Sonaca 200 planes my flight school has, including the brand new OO-NCD (or for my non aviation inclined readers, this is pronounced as Oscar Oscar November Charlie Delta, which had only 22 hours of air time when I sat in it; unfortunately I can not report the presence of a new-plane-smell anymore). I also flew with three different instructors, which definitely helps in getting feedback from people with slightly different approaches (and yes, I have my favourites already, but in general I am very happy with everyone I have flown with so far).

There is way too much stuff in my flight bag already, so I am not carrying my Fujifilm X-T3 with me anymore (even though I would love to take better pictures here and there, but there is simply not enough space or time for it), but I have installed a GoPro camera in the cockpit for these flights. For Flight 3, I had my old GoPro 4 Silver as a test, to see how useful or interesting having a recording of my training is, but then I bought a new GoPro 8, which – thanks to the amazing image stabilisation features – provides a perfectly vibration-free result (in 4K – I don’t even own a 4K screen, but this is 2020, people). By Flight 6 I also had the tech to record the radio communication too, but I messed up the settings so instead of having the recording of me talking to the air traffic controllers of an international airport or listening to the great comments of my flight instructor, I got one and a half hour of video without sound. Anyway, I think I know where I made the mistake, and it should be all good the next time (whenever it will be – thanks Obama Covid-19!).

I have posted the most interesting parts of the flights online (edited in DaVinci Resolve 16) on my YouTube “Channel”, with timestamps and more detailed comments in the descriptions, so I will not go over everything here, just have a summary of what I learned (click to the videos for more). Flight 3 started with my first unassisted take-off, then we did climbing and descending turns.


During Flight 4 we did high-power low-speed climbing turns and low-power descending turns (to feel the different rudder input necessary for a balanced flight in these situations), then we experienced slow flight (flying at and around the speed associated with minimum drag). I had my first transmissions on the radio (talking to Ground and Tower until the take-off point as a start). [You can compare the quality of the first two videos, amazing how stable the new GoPro is, right?]


Flight 5 was mainly power-off stalls in various flap configurations (first clean, then take-off, and landing). At the end I finally got to make a full approach and landing on my own, it was great. Now I did all the radio communication except for the phase between returning to the CTR (the control zone of Charleroi) and landing.


Flight 6 was the best training so far. We headed over to EBNM (Namur) for my first circuits and touch-and-gos (meaning that a landing is immediately followed by a take-off, without stopping). EBNM has a 690 meter long and 25 m wide asphalt runway, which felt very different to the huge runway at EBCI (2405 m x 45 m), but it was a very good exercise. I did 7 landings and 2 (planned) go-arounds, so 9 circuits (or patterns), before heading back to EBCI where I had my 8th landing of the day. Here and there the wind was a bit gusty, and there was a light, but variable crosswind too, so some approaches were more challenging than others.

I did all the radio communication until the start of the touch-and-gos, but from then on I had enough to do with flying and navigating (so my instructor took over the radio there, until we were back on the ground at EBCI). This is completely normal at this point during the training. It was an extremely rewarding training with a very steep learning curve, and I managed some very good landings in the second half of it. By now I am also familiar with all the visual reference points that lie to the South of the runway (since we have never went to the North so far). It was also the most tiring flight of my training so far, not only because it was very long (almost two hours), but also because it was very active, there was barely any straight and level flying, there was always something to do. I loved it. (On a side note, EBNM was the first airport I modelled in detail for X-Plane 11, so it was great to finally visit it in real life too!)


Unfortunately Covid-19 screwed up everything, so no flying in the foreseeable future :( Normally I would have had my security briefing at Charleroi today to get a badge to the airport, and I had training flights booked for every week until the first Sunday of April… Time to proceed with studying the theory and flying in the simulator I guess.