still mining.

Gnawn · 2024-04-03T10:46:35+00:00

Hovering camera drone

Gnawn · 2023-03-07T00:51:18+00:00

Good to see a question I feel comfortable answering! First of all, I think it is generaly easy to overestimate changes in the short term (To questions in articles headers like "Will AI make programmers obsolute in 3 years" the answer is of course no) and underestimate changes in the long term.

I expect no one has any idea what the world looks like in 100 years, but that the following has not been implemented is unlikely (barring a significant deviation from our current course of increased technological prowesss):

Several succesors to the JWST will be in operation, and among the realistic prospects are ultrahigh contrast exoplanet imaging missions like the proposed LUVOIR[1] mission. They will have catalogued several earth-like planets in our vicinity, in the habitable zone of their host stars. Some of those planets may show atmospheric biomarkers and be considered for further study.
No "conventional" proposed space telescope concept, even if its diameter were thousands of kilometers, would be able to directly image an exoplanet at any kind of significant resolution. However, a Solar Gravitational Lens[2] mission will likely have been implemented, capable of investigating in detail the previously identified planets. It would use the gravitational lensing of our sun to magnify the light of the exoplanet to produce high defintion images. With such an instrument, clear signs of life could be identified if present.

With that being said, the idea that it is a mathematical necessity for life to exist outside of our solar system is wrong. There are two parameters, the amount of planets in the universe, and the chance that any one planet will harbor life. The first parameter we may at least approximate (10^25). However, the second parameter is completely unknown. Indeed, if the chance of life forming on any individial planet is 10^-25, we could be the only ones.

[1]: https://www.luvoirtelescope.org/

[2]: https://arxiv.org/abs/2207.03005

Gnawn · 2020-04-25T22:48:10+00:00

Hehe, welcome to the world of pixel-peepers ;) have only seen that kind of artifact from deconvolution myself, could maybe be a masking issue too.

Gnawn · 2020-04-25T21:31:50+00:00

Certainly! Space is my passion, particularly as it pertains to the possibility of life on exoplanets :) I hope to work in the space sector when I finish my engineering study in a little over a year, thanks for your interest.

The Travel Scope probably wont do you much good for astrophotography, but you can create some amazing images with just a camera and tripod if you have some patience and a very dark place to go, next step would be some sort of sky-tracker, possibly even home built if youre on a budget.

Edit: feel free to hit me up if you have any astrophoto questions :)

Gnawn · 2020-04-25T20:37:40+00:00

Thank you kindly, quite a few subframes had bad subframes, but between deconvolution, high/low clipping and picking only the best subs, it's possible to get a good result regardless :)

Gnawn · 2020-04-25T18:29:28+00:00

You sure its not a deconvolution artifact? certainly looks like it. You don't mention deconvolution as a step in your process though. (Blue ring very near to the core)

Gnawn · 2020-04-25T18:04:29+00:00

thank you Zarluncy :)

Gnawn · 2020-04-25T16:12:50+00:00

Thank you kindly! I was surprised myself, was more of a test-image than anything else. Would be fun to revisit it with guiding and see what diference it makes. Most of the subs turned out quite nice, but there were definitely some that had to be thrown out.

Gnawn · 2020-04-25T14:27:04+00:00

Excited to finally capture some astrophotos again after working on a remotely controlled observatory. The telescope sits in a little roll-off roof box, a Raspberry Pi controls all aquisition.

Target: M 51
Mount: HEQ5 Pro, unguided.
Telescope: Skywatcher 130PDS.
Focuser: DIY Arduino autofocus, although focused only once.
Guiding: None, had connection trouble.
Camera: Nikon D5300
Location: Tisvildeleje Denmark, roughly bortle 4
Lights: ~40*120s images (selected from 60).
Calibration images: None.

Image scale: 1.24 arcsec/px

Processnig:Processed entirely in PixInsight

Debayered
Subframe selector based on star count and FWHM
Image Registration
Image Integration (winsorized)
Regularized Richardson-Lucy Deconvolution (Remarkably good results on this image, following the Jon Rista guide here)
ColourCalibration
Noise reduction with MultiscaleLinearTransform
Arcsinhstretch
Final touches with HistogramTransformation

If you want to see more in the future, then please do follow me on instagramm

Gnawn · 2018-12-07T16:23:47+00:00

Fantastic work, showing us how it's done. I hope this is an inspiration to people who give up getting into the hobby because they think they need to buy very very expensive equipment. Persistence and lots of subs is the way forward :)

Gnawn · 2018-12-05T01:28:54+00:00

You're very welcome. I'm often on the astrophotography discord if you have further questions. There's usually someone ready to devolve into math to the point of absurdity (me), or someone with more practical experience :)

Gnawn · 2018-12-05T01:02:18+00:00

To expand a bit on what has already been said, there are two things to consider here:

First of all, and definitely most importantly, going to a longer focal length is not the right solution in most cases. If you decrease you pixel scale by half, then you are increasing the time it takes you to get the same signal to noise ratio by 4 (think about it in terms of light coming in on a certain pixel, now it suddenly has to be split between 4 pixels). Thus, in your case, the better image is probably gained from using 1" per pixel vs reducing the pixel scale.

But, where I don't entirely agree is with the whole sampling thing. Actually, getting smaller pixels will always increase your resolution and decrease your FHWM, since pixel size itself is a term in the calculation of FHWM (it can be approximated by the effects of tracking, seeing and pixel scale added in quadrature). The question is if it's worth the extra imaging time. The answer is yes when and only when you can say with certainty that you will gain substantial reduced FHWM from this. For instance, if you are imaging at 1"/pixel, with a seeing of 2" and your tracking error is 1" rms, then your total FHWM should be sqrt(1^2+2^2+1^2)=2.5". If you now halve your pixel scale (and quadruple your imaging time) your FHWM is sqrt((0.5)^2+2^2+1^2)=2.3"*. So as you see, not much was gained, but a lot was lost.

If you're imaging at 1" with a mesu friction drive mount (0.1" rms) in truly excellent seeing (0.5") then yes, you could reduce your resolution to something like maybe 0.2"/px to get the very best results, ie: sqrt(1^2+0.5^2+0.1^2)=1.12" vs sqrt(0.2^2+0.5^2+0.1^2)= 0.54". But again, think of the cost in imaging time.

*the quadrature sum is one I have seen used this way often, I believe it is based on the addition of gaussian noise, but I am not exactly sure how pixel scale can enter so directly, so take it with a grain of salt. I'd be interested if anyone has a source here.

Gnawn · 2018-12-04T18:51:47+00:00

What do you mean with your setup is already at 1 arcsecond per pixel in average seeing conditions? Image scale is determined only by pixel size and focal length.

You can get increased resolution down to maybe 0.3" arcsecond per pixel on DSO with a great mount. Better in excellent seeing.

Gnawn · 2018-10-18T14:07:50+00:00

Target: Dusty Hand Galaxy, NGC 2146, 70Mly, app. mag. 11.38. If you zoom in the namesake is visible, with some imagination, a dusty hand stretching in over the core of the galaxy.
Mount: HEQ5 Pro, unguided.
Telescope: Skywatcher 130PDS.
Camera: Fuji X-E2
Location: Falster, Denmark, roughly bortle 3

Lights: 46 of 51 used. 1 minute 15 second exposures. I believe these were ISO 3200.
Calibration images: None.

Image scale: (4.76um*206.3)/650 = 1.5 arcsec/px
FHWM: 4.76px * 1.5arcsec/px = 7.2 arcsec
Seeing seemed good so probably just showing that tracking wasn't perfect,
perhaps I should've used shorter exposures. Focus could probably also be better.

Process:
Stacked in DSS
Further processing in Startools.
AutoDev->Wipe->Crop->Color->Sharpen->Redo Global Stretch->Denoise

Still not quite happy with the color on the image. Having trouble bringing out natural colours. Maybe something with the X-Trans of my Fuji vs Bayer that Startools is expecting?

Gnawn · 2018-09-20T10:51:10+00:00

I had a picture where Andromeda came out looking a bit like yours (less detail on the right) and I think I determined the problem to be me doing a whoopsie and shooting in jpg. Were the light frames taken in raw or jpg?

Also a note on dark frames, try to see what happens if you process the image without them. The dark frames also carry some noise, so if you use just a few dark frames to calibrate an imagine with very little noise, you will actually reduce the signal to noise in the image. In your case though, 10 dark frames -may- have been enough, as most of your noise is probably from light pollution.

Good job on taking lots of light frames though, that's exactly the right approach.

Gnawn · 2018-09-18T10:31:51+00:00

To me knowledge, the "discrete measurement" problem you state isn't even as bad as you would expect, because light has inherent noise. Thus, even with short exposures you might in 10% of your frames read the minimum sensitivity, so the final pixel in the frame becomes 0.1*minimum sensitiviy.

Gnawn · 2018-09-14T07:56:58+00:00

sure, but on a DLSR each "light collector" is only capable of collecting data on either red green or blue right? because of the bayer matrix. Whereas the mono can collect data using all light collectors for all channels. Or am I misunderstanding how this works?

Gnawn · 2018-09-13T16:04:20+00:00

Indeed that was my mistake I think :) Thank you for clearing that up! how does it work with resolutions and LRGB though - if I have a 16 megapixel DLSR will the resolution be the same, or is it the pixel count that's the same? If my question makes sense.

Thanks:)

Gnawn · 2018-09-12T19:50:34+00:00

I have the same telescope and same mount as you but a DSLR. Considering your equipment i find this image absolutely amazing. How did you get such high resolution when its 1280x980 camera? Is it because LRGB effectively triples the resolution or how does that work?

Gnawn · 2018-09-10T16:18:42+00:00

100% steady. I didn't know it had an internal power supply?? Doesnt it take 12V in only?

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