Back in 2019 we, as radio amateurs, used an amateur radio payload with a camera on board the Chinese DWLSP-B lunar satellite to take a similar picture of the July 2nd eclipse. Our initial posts on twitter are gone, but a write up is available at destevez.net/2019/07/resu...

The orbital data for this satellite suggests it has been operational until earlier this year, when the altitude was lowered to the new operational altitude of 480km. After that it was lowered to about 320km to let drag have it re-enter. The decay of the last part seems uncontrolled.

A defunct #Starlink satellite just re-entered in the atmosphere over the Netherlands. These images were captured by my allsky camera. This was one of the early Starlink satellites, having been launched in August 2020.

Gezien met mijn allsky camera. Zichtbaar op meerdere 15 sec opnames dus te langzaam voor een meteoor.

Using NASA's General Mission Analysis Tool (GMAT) I simulated non-lifting re-entry trajectories using the default spacecraft properties. A narrow range (~2 km) in initial perigee altitudes yield a skipped re-entry. With lift the spacecraft can control the skip altitude and downrange distance.

An absolutely awesome display of Northern Lights over the Netherlands during the past hour! Red glow in the North and a green curtain passing over whose motion was very obvious with the naked eye. This is 1 hour worth of 15 second exposures with my all sky camera from 21to 22UTC. #auroraBorealis

Picking up the old hobby of catching radio signals from newly launched satellites. These are 5 satellites from the Space X launch that happened less than 3 hours ago. Signals from 4 CONNECTA IOT satellites on 401.5MHz and 2240MHz, as well as CarbSAR at 2243.333MHz.

Yes, here it is. Tracking the motion of the planets is a bit tricky, but the motion of the Sun and Moon is very obvious.

Indeed, the keogram is the observed version of the S&T almanac. In the high resolution zoomable version at astron.nl/~dijkema/keo... you can even see the motion of the stars and planets. This part of the keogram shows Mars (left) and Jupiter (center) moving earlier in the sky.

Well spotted! That is because the Earth's orbit around the Sun is elliptical and the inclination of the Earth with respect to its orbit, resulting in the Sun passing through the Southern meridian early/late depending on the time of year (see the yellow line at 12h). en.wikipedia.org/wiki/Equatio...

This plot shows the exposure time and gain (camera sensitivity) used by the camera for one night, when compared to the keogram for that night. Sunset and sunrise are at the red lines. The camera remains sensitive to colors during evening and morning twilight.

This is the 5th year that the all sky camera has been running 24/7/365, and hence the 5th year-long keogram I've been able to make. These are the keograms from 2021, 2022, 2023 and 2024. The hourglass shape is the same, but the diagonal bands of the Moon shift from year to year.

In the year-long keogram, 365 of these daily keograms are concatenated vertically to make up the full keogram. This image shows the 2021 keogram and daily keograms and separate all sky images for 3 separate days spread throughout the year.

In a keogram, the pixel values along a line running (approximately) from South to North are extracted from each image and concatenated in time. This video shows 24 hours of images, and the resulting keogram. It shows the colors of the night and day and the passage of the Sun, Moon and stars.

Sometimes can camera captures rare events, such as Aurora borealis (Northern lights), an Earth grazing meteor, or even the atmospheric re-entry of a Space X rocket.

Every 15 seconds, the camera takes a picture of the entire sky such as these, showing the Sun, Moon, stars and their constellations, but being in the Netherlands, lots of clouds. The exposure & gain of the camera are automatically adjusted, to 15 seconds at night, and 32 microseconds during daytime.

The all sky camera consists of a 6 mega pixel astronomical color camera from ZWO with a fish-eye lens that is controled by a Raspberry Pi mini computer and housed in a weather proof enclosure with an acrylic dome. The computer also controls a relay to enable a fan and a dew-heater against moisture.

Since posting this 2025 year-long keogram, there have been quite a few questions asking how it was created and what is visible. In this thread I'll try to explain how it all works.

Happy new year! My all sky camera imaged the sky every 15 seconds and this picture shows what happened in the sky in 2025. It shows the length of the night and day with the hourglass shape, the monthly lunar cycle with the diagonal bands, the elevation of the Sun at local noon, and lots of clouds.

Two days too late and perhaps only funny for those speaking Dutch. (H/T Gemma Janssen.)

Original paper is at ui.adsabs.harvard.edu/abs/1967AJ..... and our simulations could reproduce the observed curves for all their observing dates. The backscatter power relation we used is from Evans & Hagfors (Radar Astronomy, p306).

Thanks for the independent analysis! The doppler spread curve is one that we had looked at to estimate the loss in the link budget, which was about 3dB in 1Hz. Using Arecibo radar measurements of Venus from 1964 we could reproduce the delay-doppler curve from Dyce et al. 1967 (red points).

A bit late, but here is some additional analysis of the Earth-Venus-Earth radar experiments with @radiotelescoop.bsky.social from March 22nd, 2025. It takes the 4 recordings at the Dwingeloo and Stockert telescopes and searches in Doppler frequency and Doppler rates for the radar reflections.

This video shows the Moon occulting several stars from the Pleiades star cluster (M45) earlier this evening. The 40 minute observing run is condensed into 40 seconds. The brightest star is Merope (23 Tau) at magnitude 4.2. Now to work through 20GB of timestamped images to extract occultation times.

Some how I completely missed the fact that the Moon was going to occult several of the stars in the Pleiades. I managed to quickly put together a CMOS camera and a 300mm lens to capture the motion of the Moon across these stars at 10fps. Here's the occultation of the 8th magnitude star HD23361.

Zooming in on the final minutes of the descent burn, we can see the braking burn transitioning into a hover around 17:28UTC and then a slower descent. At 17:28:45UTC there's a jump in frequency and then a slower leveling off to the Doppler frequency of the Moon. Congratulations on the landing!

This spectrogram shows the signal from when #IM-2 emerged from behind the Moon around 16:30UTC, and then started its descent burn at 17:16UTC. The signals faded a bit during powered descent, but around 17:28:55UTC the frequency drift stopped, indicated it had successfully landed!

For the second time this week, the @radiotelescoop.bsky.social had a front row seat on a lunar landing attempt. This time by @intuitivemachines.bsky.social #IM-2 lunar lander. We listed to Doppler effect on the S-band signals at 2210.6MHz during its successful descent to the lunar surface.

As we've seen with other spacecraft near the Moon, we also see reflected radio signals from the lunar surface as the fuzzy signals above the carrier signal from 08:26 to 08:33UTC. When the velocity of the spacecraft decreases, these signals merge with the carrier as they have the same Doppler shift.

The zoomed in plot shows the observed line-of-sight Doppler shift during the landing burn, until terminal guidance around 08:32UTC, and the wobble during landing guidance around 08:33UTC. Landing is at 08:34UTC and the Doppler shift then stabilizes as it follows that of the Moon.