Cees Bassa

@cgbassa
1.2K Followers
277 Following
167 Posts
Astronomer at ASTRON, working with the LOFAR low frequency radio telescope. Posts mainly about space related topics.
Cees Bassa37m ago
Dwingeloo Radiotelescoop6h ago

Vandaag precies 75 jaar geleden werd in Amerika door Ewen & Purcell de waterstoflijn gemeten. Het bestaan van deze '21-centimeterlijn' werd door Henk van der Hulst in 1944 voorspeld. Dat deze lijn gemeten kon worden, eerst in Amerika en een paar maanden later ook in Kootwijk, was een groot succes voor de radioastronomie.

Tegenwoordig kunnen ook amateurs de waterstoflijn meten. Zij kwamen vorige week in Dwingeloo bijeen voor het seminar 'Waterstof in je achtertuin'. Zie https://www.camras.nl/blog/2026/seminar-waterstof-in-je-achtertuin/

Cees BassaMar 9
Dwingeloo RadiotelescoopMar 9
De vuurbol van 8 maart 18:55, die in Duitsland als meteoriet neerkwam, is ook vastgelegd door een camera op het dak van @astron, met een gastrol voor de radiotelescoop.
De camera heet DAARO! en wordt onderhouden door de Werkgroep Meteoren.
Cees BassaJan 23

RE: https://social.beachcom.org/@nasa/115946511465975281

The Dwingeloo @radiotelescoop will be one of the teams tracking the Artemis II mission. We're in the list as CAMRAS, the Netherlands.

Cees BassaJan 20
Dwingeloo RadiotelescoopJan 20
RTV Drenthe maakte een nieuwsitem over het noorderlicht gisteren, met Michiel Brentjens van @astron, rondom de radiotelescoop. We hebben vanuit de radiotelescoop live explosie op de zon kunnen laten horen!
https://www.youtube.com/watch?v=D8xeFI34YyQ
Geweldige beelden van het noorderlicht boven Nederland | RTV Drenthe

YouTube
Cees BassaJan 19
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 21:00 to 22:00UTC. The storm is still ongoing. #auroraBorealis
Show threadCees BassaJan 6
A high resolution zoomable version of the 2025 keogram was made by @tammojan which also shows the motion of clouds, stars and planets from day to day. https://astron.nl/~dijkema/keogram/
Year-long keogram 2025

Show threadCees BassaJan 6
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.
Show threadCees BassaJan 6
For the 2024 keogram I compared the observed keogram with predictions, where the yellow lines show sunset (dash-dotted), sunrise (dotted) and when the Sun is in the South (solid line), while the red lines show the same for the Moon. They match though the camera is sensitive to color into twilight.
Show threadCees BassaJan 6
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.
Show threadCees BassaJan 6
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.