Cees Bassa
@cbassa.bsky.social
Astronomer at ASTRON in the Netherlands, working with the LOFAR low frequency radio telescope.
Pinned
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.
I've tried to explain this in this thread bsky.app/profile/cbas... For each image pixels along a vertical line from (approximately) South to North are taken and concatenated. The 15 seconds cadence is then averaged to once a minute. In the yearlong keogram each daily keogram is averaged to 4 pixels.
Reposted by Cees Bassa
Great aurora visible in Dwingeloo yesterday!
January 20, 2026 at 10:08 AM
Great aurora visible in Dwingeloo yesterday!
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
January 19, 2026 at 10:27 PM
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.
January 11, 2026 at 4:53 PM
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.
Reposted by Cees Bassa
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
Our detection came in too late to be included in the telegram, but here it is!
www.astronomerstelegram.org?read=17588
January 10, 2026 at 12:23 PM
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
Our detection came in too late to be included in the telegram, but here it is!
www.astronomerstelegram.org?read=17588
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.
January 6, 2026 at 1:19 PM
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.
Reposted by Cees Bassa
I put together a mosaic of 2025 from the timelapse camera on my roof jwheare.com/year-mosaic/... (not a keogram, but inspired by @cbassa.bsky.social)
January 4, 2026 at 11:01 AM
I put together a mosaic of 2025 from the timelapse camera on my roof jwheare.com/year-mosaic/... (not a keogram, but inspired by @cbassa.bsky.social)
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.
January 1, 2026 at 8:54 PM
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.
Reposted by Cees Bassa
It's cleared up in Sydney and I can see the shadow creeping across the Moon! 🥳🌚🔭
Lunar eclipse fans, there's a total lunar eclipse this weekend! All of Australia (and a bunch of other countries) will be able to see all the best bits. The eclipse will be in the evening of Sunday the 7th or the morning of Monday the 8th of September 🧪🔭🌝
www.abc.net.au/news/science...
www.abc.net.au/news/science...
When and where can I see Monday's total lunar eclipse from Australia?
A total lunar eclipse, also known as a "blood moon", will be visible across all of Australia next week. Here's what you need to know to get the best view and snap the best photo.
www.abc.net.au
September 7, 2025 at 4:38 PM
It's cleared up in Sydney and I can see the shadow creeping across the Moon! 🥳🌚🔭
Reposted by Cees Bassa
💥Greater (partial) success for #amateurradio and #amsat satellite operators in dispute with AST Spacemobile over commercial use of the 430-440 MHz amateur radio band for TT&C! 💥 In its reference Attachment to the recent grant, dated August 29, 2025, the FCC imposes clear limits ⬇️
September 6, 2025 at 12:41 PM
💥Greater (partial) success for #amateurradio and #amsat satellite operators in dispute with AST Spacemobile over commercial use of the 430-440 MHz amateur radio band for TT&C! 💥 In its reference Attachment to the recent grant, dated August 29, 2025, the FCC imposes clear limits ⬇️
Reposted by Cees Bassa
NOAA-15 was decommissioned today at 15:26 UTC, with its AVHRR/3 Instrument still in better state than the last 2 remaining on MetOp-B & C.
It wouldn't be so disappointing if this wasn't done for the wrong reasons... Makes you wonder what happened to NOAA.
It wouldn't be so disappointing if this wasn't done for the wrong reasons... Makes you wonder what happened to NOAA.
August 19, 2025 at 4:39 PM
NOAA-15 was decommissioned today at 15:26 UTC, with its AVHRR/3 Instrument still in better state than the last 2 remaining on MetOp-B & C.
It wouldn't be so disappointing if this wasn't done for the wrong reasons... Makes you wonder what happened to NOAA.
It wouldn't be so disappointing if this wasn't done for the wrong reasons... Makes you wonder what happened to NOAA.
Reposted by Cees Bassa
#skao2025 Federico Di Vruno on impact of satellites on #RadioAstronomy from intended emissions (strong enough to saturate receivers) & unintended electromagnetic radiation (originating from on satellite electronics). In future 🛰️ constellations could impact 25% of our observing time! 🔭📡🧪
June 16, 2025 at 9:53 AM
#skao2025 Federico Di Vruno on impact of satellites on #RadioAstronomy from intended emissions (strong enough to saturate receivers) & unintended electromagnetic radiation (originating from on satellite electronics). In future 🛰️ constellations could impact 25% of our observing time! 🔭📡🧪
Reposted by Cees Bassa
New paper day! In 'Near-future rocket launches could slow ozone recovery', we show that scaling up use of launch vehicles 🚀 has a point where the healing of the ozone layer is affected 🧪🛰️
Open access, free to read & share
Open access, free to read & share
Near-future rocket launches could slow ozone recovery
npj Climate and Atmospheric Science - Near-future rocket launches could slow ozone recovery
rdcu.be
June 10, 2025 at 1:31 AM
New paper day! In 'Near-future rocket launches could slow ozone recovery', we show that scaling up use of launch vehicles 🚀 has a point where the healing of the ozone layer is affected 🧪🛰️
Open access, free to read & share
Open access, free to read & share
Reposted by Cees Bassa
Here, strf was used by the UVSQSat-NG team :
- at the beginning of the mission to optimize the preliminary TLEs so that the university could establish the most reliable communication possible,
- for monitoring purposes since refined TLEs have become available...
Thank you for the great work!
- at the beginning of the mission to optimize the preliminary TLEs so that the university could establish the most reliable communication possible,
- for monitoring purposes since refined TLEs have become available...
Thank you for the great work!
June 7, 2025 at 5:01 PM
Here, strf was used by the UVSQSat-NG team :
- at the beginning of the mission to optimize the preliminary TLEs so that the university could establish the most reliable communication possible,
- for monitoring purposes since refined TLEs have become available...
Thank you for the great work!
- at the beginning of the mission to optimize the preliminary TLEs so that the university could establish the most reliable communication possible,
- for monitoring purposes since refined TLEs have become available...
Thank you for the great work!
Reposted by Cees Bassa
Unfortunately the surface of the Moon is also quite hard.
June 5, 2025 at 7:35 PM
Unfortunately the surface of the Moon is also quite hard.
Reposted by Cees Bassa
We lost HAKUTO-R M2 signal suddenly
June 5, 2025 at 7:18 PM
We lost HAKUTO-R M2 signal suddenly
Reposted by Cees Bassa
We have lost signal of Hakuto-R M2 Resilience! We saw the signal and its Lunar reflection close to each other before LOS, indicating that it was very close to the surface when the signal disappeared. Space is hard!
June 5, 2025 at 7:19 PM
We have lost signal of Hakuto-R M2 Resilience! We saw the signal and its Lunar reflection close to each other before LOS, indicating that it was very close to the surface when the signal disappeared. Space is hard!
Reposted by Cees Bassa
We are now tracking the landing attempt of #Hakuto-R Mission 2 #Resilience. Check our livestream at www.youtube.com/live/C7-MQ2U...
Livestream CAMRAS Radiotelescoop
YouTube video by CAMRAS Radiotelescoop
www.youtube.com
June 5, 2025 at 6:36 PM
We are now tracking the landing attempt of #Hakuto-R Mission 2 #Resilience. Check our livestream at www.youtube.com/live/C7-MQ2U...
Reposted by Cees Bassa
On the occasion of the @unesco.org International Day of Light, we created a 'light painting' using the Dwingeloo Telescope by mounting a light bulb at the focus for half an hour. #lightday2025 @idlofficial.bsky.social
May 16, 2025 at 6:55 AM
On the occasion of the @unesco.org International Day of Light, we created a 'light painting' using the Dwingeloo Telescope by mounting a light bulb at the focus for half an hour. #lightday2025 @idlofficial.bsky.social
Reposted by Cees Bassa
And Magritte fans 😀
May 9, 2025 at 7:29 PM
And Magritte fans 😀
Two days too late and perhaps only funny for those speaking Dutch. (H/T Gemma Janssen.)
May 9, 2025 at 7:14 PM
Two days too late and perhaps only funny for those speaking Dutch. (H/T Gemma Janssen.)
Reposted by Cees Bassa
Maybe the upper stage failure ended up tumbling the spacecraft fast enough to break it up?
April 30, 2025 at 9:35 PM
Maybe the upper stage failure ended up tumbling the spacecraft fast enough to break it up?
Reposted by Cees Bassa
Following up on @marcolangbroek.bsky.social 's post on the upcoming Venera capsule reentry, I've done a writeup describing my own analysis of this object, which I first got interested in a quarter century ago!
planet4589.org/space/debris...
planet4589.org/space/debris...
Probe No. 670 was boosted to solar orbit and named Venera-8 ("Venus-8"). It was launched on 1972 Mar 27 and successfully landed on Venus on 1972 Jul 22, surviving for 50 minutes on the surface.
planet4589.org
April 30, 2025 at 7:30 PM
Following up on @marcolangbroek.bsky.social 's post on the upcoming Venera capsule reentry, I've done a writeup describing my own analysis of this object, which I first got interested in a quarter century ago!
planet4589.org/space/debris...
planet4589.org/space/debris...