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Cees Bassa @cbassa.bsky.social · 25/09/2026

Nice! What time were you there? Curious to see if there's any additional RFI in the data.

Cees Bassa @cbassa.bsky.social · 28/08/2026

Yes! And while LOFAR doesn't have to worry about frying the receivers by pointing close to the Sun, the large LOFAR field of view means the Sun will be in it and drastically raises the system temperature.

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Cees Bassa @cbassa.bsky.social · 28/08/2026

Funny that you mention this as I was just going down a rabbit whole why I wasn't seeing PSR J1022+1001 in LOFAR observations this week.

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Daniel Estévez @destevez.net · 27/08/2026

New blog post: X-engine correlator on a Ryzen NPU. A few months ago I posted about the basics of NPUs in Ryzen AI chips. I wanted to tackle a real-world problem to get more experience, so I've implemented an X-engine correlator like the ones used in radio astronomy.

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Cees Bassa @cbassa.bsky.social · 18/08/2026

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...

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Jodrell Bank @jodrellbank.bsky.social · 30/07/2026

As a result of the recent news, we have received an extraordinary number of messages, and it has been incredibly moving to read so many heartfelt expressions of support. www.jodrellbank.net/explore/stor...

jodrellbank.net

A message of Thanks from Jodrell Bank Observatory - Jodrell Bank

As a result of the recent news, we have received an extraordinary number of messages, and it has been incredibly moving to read so many heartfelt expressions of support.

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Cees Bassa @cbassa.bsky.social · 24/07/2026

Clearly any attempt to have this satellite re-enter the atmosphere over oceans instead of highly populated areas has failed.

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Cees Bassa @cbassa.bsky.social · 24/07/2026

Lijkt me een goed plan. Laat ze maar met verwondering slapen gaan.

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Cees Bassa @cbassa.bsky.social · 24/07/2026

Waarschijnlijk wel, maar mogelijk dat er ergens in Duitsland of Polen brokstukken terecht gekomen zijn.

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Cees Bassa @cbassa.bsky.social · 24/07/2026

Vertel je kinderen maar de waarheid dat triljardairs ook op deze manier de sterrenhemel en de atmosfeer vervuilen. Zulke opbrandende satellieten zullen in de toekomst helaas vaker te zien zijn dan vallende sterren.

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Cees Bassa @cbassa.bsky.social · 24/07/2026

Het was een Starlink satelliet. De voorspellingen voor Starlink-1541 komen goed overeen met het waargenomen traject.

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Cees Bassa @cbassa.bsky.social · 24/07/2026

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.

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Cees Bassa @cbassa.bsky.social · 24/07/2026

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.

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Cees Bassa @cbassa.bsky.social · 24/07/2026

Het zou STARLINK-1541 [46052/20055AB] kunnen zijn. Die zou dan iets voor kunnen lopen op de voorspelling. Decay msg voorspelde 2026-07-24T22:51:00.

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Cees Bassa @cbassa.bsky.social · 24/07/2026

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

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Cees Bassa @cbassa.bsky.social · 22/07/2026

Agreed, but that's a much larger endeavor that will take more time. Also here, using alpha5 is a stop gap to be able to continue using TLEs, but that's also why I prefer to use numeric NORAD IDs.

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Cees Bassa @cbassa.bsky.social · 22/07/2026

Scott already submitted a PR with his proposed changes, but it sort of clashes with a design decision from my side to only show numerical NORAD IDs in STRF tools, and use the alpha5 format purely for TLE formatting. But this is purely my opinion on this, so I welcome other insights.

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CosmicRami 🏳️‍🌈🏳️‍⚧️ @rami.spaceaustralia.com · 29/06/2026

Most of the world Wi-Fi usage operates around the 2.4 GHz band (allocated spectrum). That means our telescopes have to cut that portion of the band out when doing #RadioAstronomy Tommy from our team has tested some mitigation methods and found we can use 90% of this band! arxiv.org/abs/2605.30761

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Aang23 @aang23.satdump.org · 26/05/2026

CCSDS 8192-bits CADUs, RSS 223/255 I=4

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Radiotelescoop Dwingeloo @radiotelescoop.bsky.social · 02/04/2026

We're still tracking #Artemis II with the Dwingeloo radio telescope, with four very enthousiastic amateurs staying up all night in the control room. We just witnessed the Orion upper stage separation burn in our doppler tracking.

Graph with time on x axis, frequency on y axis. A distinct change in frequency is seen around 03:25 UTC, indicating a burn.

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s2a systems @s2a-systems.bsky.social · 02/04/2026

A first view on Artemis II from South America on 2026-04-02, 01:57:58 UTC

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Radiotelescoop Dwingeloo @radiotelescoop.bsky.social · 02/04/2026

We are tracking #Artemis II with the historic Dwingeloo radio telescope. In the doppler shift of the carrier signal we see the manual manoevers that the astronauts perform while flying formation with the upper stage.

Chart with horizontal time, vertical doppler shift. Wobbles show when the spacecraft manoevers.

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Radiotelescoop Dwingeloo @radiotelescoop.bsky.social · 09/03/2026

The #fireball of 8 March was captured on camera by DAARO! on the roof of ASTRON.

Fireball, with the Dwingeloo radio telescope on the foreground

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Andrea Botteon @andreabotteon.bsky.social · 04/03/2026

What is the origin of 1LHAASO J0343+5254u? by @hen_edler, @itsMariaArias, myself, @cbassa.bsky.social Our multi-band analysis suggests that the PWN candidate previously proposed to be its origin is actually an obscured galaxy cluster, unrelated to the LHAASO emission arxiv.org/abs/2603.03164

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Cees Bassa @cbassa.bsky.social · 10/02/2026

The C_d = 2.2 value is the GMAT default, probably to represent a spacecraft with solar panels and the like. I assume using lower C_d values will lower the perigee.

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Cees Bassa @cbassa.bsky.social · 09/02/2026

Also, the Apollo 11 Flight Journal has a very good description of the entry procedures using the lift of the Columbia spacecraft that allowed Armstrong, Collins and Aldrin to extend their entry range by about 400 km to avoid thunderstorms. www.apollojournals.org/afj/ap11fj/2...

apollojournals.org

Apollo 11 Flight Journal - Day 9, part 1: Approaching Earth

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Cees Bassa @cbassa.bsky.social · 09/02/2026

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.

Three panels showing the altitude, velocity and acceleration of a spacecraft re-entering the Earth's atmosphere from lunar distances. For a narrow range of initial perigee altitudes does the spacecraft skip out of the atmosphere to lengthen the reentry.

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Simeon Schmauß @stim3on.bsky.social · 09/02/2026

It still seems unreal to me that humans will soon be flying back to the moon! They will be returning to Earth at a speed of 40.000 km/h, the fastest ever reentry of a crewed spacecraft. This remastered video shows a similar reentry from the #Artemis 1 mission back in 2022 at 9x speed. 🔭🧪

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Cees Bassa @cbassa.bsky.social · 09/02/2026

I think that such an approach should also work for a re-entry vehicle that can not provide lift, but I must admit I have not seen any real simulations, only my own experience with Kerbal Space Program 😆

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Cees Bassa @cbassa.bsky.social · 09/02/2026

Great thread and awesome to see the skip trajectory for real! One thing I never fully understood is the "lift" requirement of such a trajectory. Even without lift, I think one can aim for a perigee altitude where drag reduces the apogee altitude to within the atmosphere, ensuring re-entry.

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Radiotelescoop Dwingeloo @radiotelescoop.bsky.social · 20/01/2026

Great aurora visible in Dwingeloo yesterday!

Aurora above the Dwingeloo radio telescope

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Cees Bassa @cbassa.bsky.social · 19/01/2026

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

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Cees Bassa @cbassa.bsky.social · 11/01/2026

Yes, this is caused by the Doppler effect.

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Cees Bassa @cbassa.bsky.social · 11/01/2026

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.

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Radiotelescoop Dwingeloo @radiotelescoop.bsky.social · 10/01/2026

Last Thursday, a group of European radio telescopes (HyperFlash / ÉCLAT) detected a flash from the repeating Fast Radio Burst discovered end of December. We also detected this burst! Our detection came in too late to be included in the telegram, but here it is! www.astronomerstelegram.org?read=17588

Graph titled "Dwingeloo Radio telescope detection of FRB 20251229A". Horizontal time (1 seconds total), vertical observing frequency 1300-1400MHz. A faint vertical line is visible around 210.1 seconds.

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Cees Bassa @cbassa.bsky.social · 08/01/2026

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.

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Cees Bassa @cbassa.bsky.social · 08/01/2026

You are absolutely right, there are many many ways of visualizing this dataset. I've played a bit to try to visualize the motion of the planets, but nothing good enough yet to share. Hopefully in the future.

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Cees Bassa @cbassa.bsky.social · 06/01/2026

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.

A zoom of the 2025 keogram on the end of January, beginning of February, showing the motion of stars and planets.

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Cees Bassa @cbassa.bsky.social · 06/01/2026

Thanks! I hope you were able to capture some cool shots over Christmas! Having an all sky camera is very useful in checking if it is clear enough or not, I can just look at my phone instead of having to go outside and possibly have my eyes dark adapt. If patchy clouds, it tells me where it is clear.

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Cees Bassa @cbassa.bsky.social · 06/01/2026

It basically boils down to that while the Moon moves 13deg East every day, it doesn't rise and set about an hour later every day. When it is moving to higher declinations, the rises bunch in time of day and the moonsets spread, while the opposite occurs when the Moon is moving to lower declinations.

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Cees Bassa @cbassa.bsky.social · 06/01/2026

Excellent question, and your answer is correct. The keogram is mapped to the 24h schedule of the Sun which shows this hourglass shape over a year. For the Moon this hourglass shape happens every 29 days or so, so this hourglass shape is stretched diagonally.

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Cees Bassa @cbassa.bsky.social · 06/01/2026

Ah, I see what you mean now. Yes, that might indeed be possible. I don't know enough about HDR how to make that work though. On the other hand, the camera does support RGGB output as 16 bit integers, so there certainly is room for more dynamic range already in the images.

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Cees Bassa @cbassa.bsky.social · 06/01/2026

Unfortunately, taking these observations in HDR would be impractical given the factor 500000 difference in exposure times between day and night time.

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Cees Bassa @cbassa.bsky.social · 06/01/2026

No, the gain and exposure are determined from the preceding image, where the exposure time is adjusted first, and gain second. This ensures that 15 second exposure times are used for most of the night and twilight shots, increasing the chance of detecting satellites and meteors etc.

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Cees Bassa @cbassa.bsky.social · 06/01/2026

I have tried to explain it in this thread. Let me know if there are questions that aren't answered by it. bsky.app/profile/cbas...

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Cees Bassa @cbassa.bsky.social · 06/01/2026

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...

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Cees Bassa @cbassa.bsky.social · 06/01/2026

A high resolution zoomable version of the 2025 keogram was made by @tammo80.bsky.social, which also shows the motion of clouds, stars and planets from day to day. astron.nl/~dijkema/keo...

astron.nl

Year-long keogram 2025

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