I participated in a wonderful conference this week on the beautiful island of La Palma (Spain). It was IAU Symposium 385 about the protection of the dark and quiet skies from satellite constellation interference and pathways forward. #IAUS385
My latest #AstroPhotography snapshot of the North America Nebula #NGC7000. Well, with just above 6 hours for Halpha and O3 it's not really a snapshot anymore 😉
I love the filamentary structure of the dark nebula!
After a year of #astrophotography I revisited M31. This thing is larger in the sky, than the full moon! I spent about 6 hours on it. I also have 6 hours of Halpha data on my disk, but I struggle to combine it properly. (The issue being that a lot of continuum emission makes it through the narrowband filter.)
It's almost a year now that I started with #AstroPhotography and I've come a long way. One of my first targets after buying a proper mount and telescope was the Veil Nebula/Cygnus Loop. But I did everything wrong at the time. First no guiding, then no dithering (which led to walking noise patterns in the data) and I also got the focus wrong. Now, I finally could continue this project, with the source up in the sky again. (You need patience in this hobby...)
This object is really large in the sky. Even with my wide-field setup (300-mm focal length), I needed to do a 2x1 mosaic. There is a fair amount of H-alpha emission in the surrounding area. You don't see this often in images of the Cygnus Loop, but Piotr Czerski made a really cool very-wide-field image: https://www.astrobin.com/feddin/?q=cygnus%20veil
I'll be talking about Astronomy & #ClimateCrisis as part of the LEAPS seminars at the Leiden university today (11 AM @ HL414 if you happen to be in the area)!
Want a deep sky object named after you? @nebulaphotos got you covered. Great video; also about the studying part: how to make sure, it's something new...
Today, a group of scientists including @cgbassa and Yours truly published a paper on A&A. We report about a fascinating finding: #satellite constellations can leak electromagnetic radiowaves, originating from onboard electronics, which we detected using the #LOFAR radio telescope. 1/
While the data only covers one hour of observation, it took a lot of effort to do the processing and analysis. The figure shows material from the press release, visualising what we found. 2/
Some of us are also heavily involved in spectrum management. That is we go to meetings of the ITU-R and other organisations to fight for an interference-free environment at the radio telescopes.
Our spectrum management work is mostly done under the umbrella of the Committee on Radioastronomy Frequencies (#CRAF, https://www.craf.eu/). CRAF was involved with the compatibility calculations done in ECC Report 271 (https://docdb.cept.org/document/1032).
3/
ECC Report 271 (https://docdb.cept.org/document/1032) was the first attempt world-wide to ensure that the Starlink and OneWeb communication signals would not interfere with radio astronomy in the neighbouring frequency band.
The new finding is an entirely different thing. Unlike wanted (antenna) transmissions, electromagnetic radiation from electronics is not under regulation for spacecraft. 5/
Thus, #CRAF is hoping that regulation authorities will consider improving the situation. As this will take time, we are very happy that #SatCon operators so far are very cooperative. 6/
In case you were wondering how we attempted to find satellite signals in the #LOFAR data, here is a summary of the approach:
The basic idea was to use satellite #TLE (two line elements) to predict when a satellite would be crossing the field of view. For each of the beams (pixels) on the sky, whe then extract some data around these event times (+/- some seconds). These are like the spectrograms included in the paper. 7/
The image below shows Figure 7 of the paper; a masterpiece by @cgbassa
The next step was labor-intensive: look into all these spectrograms and watch out for signals that are (only!) visible at the event times.
To be sure, we produced some videos. I created a nice montage for the most relevant frequencies. In this video, you can see how the pixel light up nicely when the satellites cross the field of view.