what are you doing ?

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shane
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#1306 Re: what are you doing ?

Post by shane »

What mic are you using? Mine packed up a while ago, and seemed to have insufficient gain as well.
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jack
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#1307 Re: what are you doing ?

Post by jack »

shane wrote: Thu Mar 21, 2024 7:42 pm What mic are you using? Mine packed up a while ago, and seemed to have insufficient gain as well.
A Clippy Mono EM272 Omni microphone (FC047) from FEL Communications https://micbooster.com/clippy-and-plugg ... one-em272m, plus a furry windcover https://www.amazon.co.uk/gp/product/B07D9CCP19 ...and a UGreen USB soundcard https://www.amazon.co.uk/dp/B01N905VOY

Transducers using the EM272 seem to be the recommended microphone according to the wiki.

It's just under the eaves of my office building so that it's shielded from the worst of the wind & rain. Host is a Pi4B.

I did find that using a microphone extension lead caused all sorts of noise issues, so I moved the Pi instead!
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shane
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#1308 Re: what are you doing ?

Post by shane »

if you try to play back recordings, are they easily audible? With the mic I used (which has now packed up) they were recorded at such a low level they were virtually inaudible, although it seemed to be able to make identifications ok.

I was using one of these with the same Ugreen sound card:

https://micbooster.com/microphone-capsu ... em272.html
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#1309 Re: what are you doing ?

Post by jack »

shane wrote: Fri Mar 22, 2024 2:46 pm if you try to play back recordings, are they easily audible? With the mic I used (which has now packed up) they were recorded at such a low level they were virtually inaudible, although it seemed to be able to make identifications ok.

I was using one of these with the same Ugreen sound card:

https://micbooster.com/microphone-capsu ... em272.html
Sometimes they can be pretty quiet, but to be honest I only listen to the occasional bonkers one just to check what's going on!

The mic I'm using is just their encapsulated EM272, so it's the same transducer as yours, just packaged by them rather than us.
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Max N
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#1310 Re: what are you doing ?

Post by Max N »

I’ve mentioned narrow-band imaging in the context of astrophotography a few times, and I have finally managed to image something using that technique.
In case anyone is interested, here is a brief explanation of the physics:

According to the Bohr model of the atom, electrons exist in quantised energy levels surrounding the atom's nucleus. Electrons may only exist in these states, and may only transit between these states.
When an electron falls from a higher to a lower state, it emits a photon with a very specific wavelength.

An example which is useful in astronomy is when an electron in a hydrogen atom falls from state 3 to state 2, in which case the photon has a wavelength of 656.46 nm. It is of interest because hydrogen is very abundant in space, and because that wavelength falls in the visible part of the spectrum (it is a deep red). It is referred to as Hydrogen-alpha or Hα

Another example is doubly-ionised oxygen, referred to as O III, which emits photons at 500.7 and 495.9 nm (roughly cyan).

Historically such mechanisms were observed by spreading the light gathered by a telescope into a spectrum using a prism, and looking for emission lines or absorption lines. More recently, optical filters have been produced which only allow the passage of very narrow wavelength bands.

So in this image of the dumbell nebula, for which I used a dual-narrowband filter, pretty much all the red bits are hydrogen and all the cyan-ey bits are oxygen:
dumbell small.jpg
dumbell small.jpg (235.12 KiB) Viewed 1866 times
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jack
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#1311 Re: what are you doing ?

Post by jack »

Alcaraz v Paul, Wimbledon court 1. First time here for a few years. Nice to have a day off midweek...

PXL_20240709_150013617_copy_897x675.jpg
PXL_20240709_150013617_copy_897x675.jpg (199.43 KiB) Viewed 1864 times
Last edited by jack on Tue Jul 09, 2024 7:50 pm, edited 1 time in total.
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brig001
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#1312 Re: what are you doing ?

Post by brig001 »

That is cool, thanks for the explanation Max
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#1313 Re: what are you doing ?

Post by simon »

Yes really cool Max, please keep posting them
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andrew Ivimey
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#1314 Re: what are you doing ?

Post by andrew Ivimey »

Outasight man, really outasight!

Too many mojitos in a smelly outright! ( live music and France us losing, Maybe, not sure.... in Funchal. Time for another...
Philosophers have only interpreted the world - the point, however, is to change it. No it isn't ... maybe we should leave it alone for a while.
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andrew Ivimey
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#1315 Re: what are you doing ?

Post by andrew Ivimey »

Bar - really outasight etc etc
Philosophers have only interpreted the world - the point, however, is to change it. No it isn't ... maybe we should leave it alone for a while.
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#1316 Re: what are you doing ?

Post by Max N »

Thanks for the kind words everyone. I will start planning the next target, if it ever stops raining!
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MistyBlue
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#1317 Re: what are you doing ?

Post by MistyBlue »

This is awesome Max!

To think that still, over astronomical distances, we can still do chemical analysis of distant objects, even down to oxidation states, with nothing more than the photons of light emitted from so long ago, that took so long to reach us.

Just pure wonder!
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#1318 Re: what are you doing ?

Post by jack »

Thanks Max for sending me down that Google rabbit hole!

Those duo-band filters are crazy things to be able to get two distinct bands and each with a pretty narrow bandwidth in a single filter. Very cool.
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Max N
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#1319 Re: what are you doing ?

Post by Max N »

jack wrote: Wed Jul 10, 2024 6:37 am Thanks Max for sending me down that Google rabbit hole!

Those duo-band filters are crazy things to be able to get two distinct bands and each with a pretty narrow bandwidth in a single filter. Very cool.
Yep - the signal-to-noise ratio is very much better than without the filter. I captured the data on pretty much the shortest night of the year when it never got properly dark. The filters also block most light pollution.
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#1320 Re: what are you doing ?

Post by Mike H »

Truly fab! :thumbup:
 
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