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Forum » SpaceEngine » Science and Astronomy Discussions » Astrophotography (Post your astrophotos here)
Astrophotography
FastFourierTransformDate: Monday, 08.12.2014, 20:33 | Message # 406
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I think this is wonderfull project that you are improving inmensly. Great job!!! smile

With that network of cameras you could triangulate de hight of the object and the speed vector, permiting you to find this cosmic gifts all around your region smile

Awesome. Truly awesome!
 
midtskogenDate: Tuesday, 09.12.2014, 21:39 | Message # 407
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Another nice meteor last night (visible for 3.2 seconds).

Added (09.12.2014, 20:39)
---------------------------------------------

Quote Watsisname ()
Did any other cameras capture these events as well


I got this solution:




No meteorites dropped from that one.

I also made a video of the meteors of the last two nights. It's in 5 frames per second. The cameras support 10 frames per second, but I'm not yet able to process that realtime currently, so it's set to 5 for the time being.





NIL DIFFICILE VOLENTI


Edited by midtskogen - Tuesday, 09.12.2014, 14:52
 
WatsisnameDate: Tuesday, 09.12.2014, 22:47 | Message # 408
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Great stuff! The video of last night's meteor is spectacular. And if I'm interpreting your plot right, then its speed was about 20km/s?

I imagine it would be a stupendous amount of work, but it'd be awesome to be able to back-trace these trajectories to find the initial orbital path of these, like NASA's automated plots seen on Spaceweather. Probably only worthwhile for the dropped stones, in case a find can be tied to a parent asteroid.

edit: 15, not 20.







Edited by Watsisname - Tuesday, 09.12.2014, 22:50
 
midtskogenDate: Saturday, 20.12.2014, 08:19 | Message # 409
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That was the 2014-12-08 meteor, which lasted 2.6 seconds. So about 20 km/s. For the brighter 2014-12-09 (posted last) I have this solution:

which is slightly faster 22-23 km/s.

Orbital calculations can be automated and is on the todo list. It could be valuable if a meteorite is recovered, as only a handful (twenty something) meteorites worldwide have a known orbital origin. And much cheaper than sending a probe to the asteroid to return samples.

Added (15.12.2014, 10:18)
---------------------------------------------
Here's a collection of the brightest meteors that I got during the Geminids. 2560x1920 video or YouTube

Added (20.12.2014, 07:19)
---------------------------------------------
Fairly faint, but twice exploding meteor passing near zenith and through the Big Dipper last night:





NIL DIFFICILE VOLENTI
 
WatsisnameDate: Tuesday, 30.12.2014, 22:08 | Message # 410
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Made an attempt at M42 last night. Used the zoom lens at 250mm f/5.6, 6400 ISO, 6s exposure. RAW output with adjusted levels and noise removal. Encountering a bit of a camera shake problem here, as even with a fairly rigid tripod and 2s shutter delay, the opening of the shutter causes some vibration and blurs the stars. May have to try the beanbag approach next time so I can get some cleaner shots for stacking.



Added: Another retouch of the old Milky Way in Cygnus image. Better white balance and gradient flattening, and richer color information pulled out of the galaxy now.



And a redo of M31:





 
WatsisnameDate: Monday, 12.01.2015, 15:08 | Message # 411
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Starting to hit on a pretty robust method for removing light pollution and enhancing faint details in these shots. I never would have guessed how much I could draw out of these given that I live under a suburban (Bortle 5) sky and this was taken near the light polluted horizon:








 
FireintheholeDate: Monday, 12.01.2015, 16:08 | Message # 412
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Watsisname, impressive results! Would you share you method? smile




Love SpaceEngine!
 
midtskogenDate: Monday, 12.01.2015, 16:55 | Message # 413
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Looks pollution free to me!

I don't know what Wats did, but a simple method working reasonably well is to blur (e.g. gaussian) the image and subtract that from the original. It has the effect of removing everything low frequency, that is, the background. In this case with the Milky Way some experimenting is probably required in order not to remove the Milky Way glow.

The method also works to remove moonlight or twilight, and will enhance faint stars.





NIL DIFFICILE VOLENTI
 
WatsisnameDate: Monday, 12.01.2015, 19:21 | Message # 414
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I really can't take too much credit since a lot of the tricks I do I have learned from watching tutorials. One of my favorites is by Ian Norman (of LonelySpeck), who does amazing work. I don't have photoshop though, so I had to modify a lot of the process to work with what I do have (freeware programs: GIMP and its UFRaw plugin), and throw in my own little tweaks and things.

The basic idea with removing light pollution is somewhat similar to doing dark frame subtraction in professional CCD astronomy. I.e. you try to characterize the light pollution and use image blending modes to cancel it out. This only goes so far though, since light pollution directly reduces the contrast of whatever you're photographing. You can't pull out detail if it doesn't exist, so if you're deep in urban sky glow then there's not much it will do. (For that kind of work, you'd need actual filters for canceling whatever wavelengths most contribute to the pollution. City light pollution usually covers a lot of wavelengths though, so this is nearly impossible. It's much easier with emission nebulae, since then you can use narrow band pass filters that permit the nebula and block everything else.)

Anyway, we're using a simple approach that just deals roughly with the color and brightness of light pollution to remove it. Once you've got your image ready (I take sets of up to 8 or so and align and blend them together first to reduce noise), open it up in GIMP or whatever and make a new transparent layer above it. Then, on your base layer, use the color picker tool with "Sample average" over a fairly large radius to select the light pollution color, and set that as your foreground color.

On the transparent layer, use the gradient tool with FG color to transparency to try to recreate the appearance of the sky pollution in the image. Play around with the opacity and gradient shape (e.g. radial, linear), and just try to get as close as you can. Then set the layer mode to "subtract", and play with opacity again until it subtracts out the sky glow without diminishing the Milky Way detail too much. (You can always switch to subtract while in the process to check the effect your modification is having as you go). When satisfied, merge the layers. Now you've got your light-pollution reduced image.

Next I try to enhance the brightness and colors of the galaxy, and this is where midtskogen's trick comes really handy. Duplicate the layer *three times*. On the top, apply gaussian blur, set layer mode to subtract, and merge with the copy below it. Now you have a layer which is just stars. Then, set this layer mode to subtract. When merged with the next copy below, you'll have just the galaxy (mostly, anyway, some star fluff may remain). Despeckling may help remove it further.

Now that we have a layer with just the galaxy, we can use it to enhance the galaxy in the final image. Set the layer mode to "dodge". Then do curves adjustment to boost its brightness and contrast. Adjust the main channel, and then each color channel as well to improve the coloration. You can be pretty creative here, including split-toning the image, to produce some nice aesthetic effects.

Final touches: At this point I usually like to do a denoising pass, since all the editing may introduce some coloration noise. Depending on the overall coloration and nature of noise in the image, you may want to experiment with the different color modes. In the above image I did not have much green, and most of the noise was red/blue, so I used LAB (Luminance-red-blue), denoising only the a* and b* channels by equal amounts.





 
WatsisnameDate: Wednesday, 14.01.2015, 15:31 | Message # 415
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First Milky Way shot with the Rok! Facing almost directly opposite the galactic center here in January, but there is still lots of cool stuff to see in this part of the sky. Conditions weren't ideal, as although I managed to get above the marine layer where the air is less hazy, there were still thin wisps of cirrus which dimmed the stars and glowed dim red with the distant city light. Couldn't even tell they were there with the eye, but the camera sure picked them up, and made my editing job more "fun".








 
FireintheholeDate: Wednesday, 14.01.2015, 15:50 | Message # 416
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Watsisname, wow truly an amazing shot! What's a Rok?




Love SpaceEngine!
 
WatsisnameDate: Wednesday, 14.01.2015, 17:42 | Message # 417
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Sorry, just what I've been calling the lens. It's a Rokinon 16mm f/2.0.




 
FireintheholeDate: Wednesday, 14.01.2015, 18:40 | Message # 418
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Quote Watsisname ()
Sorry, just what I've been calling the lens. It's a Rokinon 16mm f/2.0.

It follows the rotation of Earth I assume?





Love SpaceEngine!
 
WatsisnameDate: Wednesday, 14.01.2015, 19:44 | Message # 419
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I wish. biggrin Just a dumb lens on a dumb tripod. smile Someday I'd love to build a simple tracker to do that with, but for now I just take sets of exposures. This was seven shots, each 13 seconds long. I do of course have to account for the rotation's effect building up with each successive shot, but this is fairly easy to correct with any image editor.

Added: What is it with me and accidentally finding weird little blue/green things when I'm about to delete my extra photos from a session? First it's the planet Uranus, now it's comet Lovejoy. Maybe I should pay more attention to sky charts before heading out. wacko






 
HarbingerDawnDate: Thursday, 15.01.2015, 01:25 | Message # 420
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Very impressive work Watsisname smile Even the tail on Lovejoy is clearly visible!

I got this shot of C/2014 Q2 Lovejoy about one week ago



I'll probably try to get another one as soon as the weather allows since it's much higher in the sky now, and thus less impacted by light pollution.





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Edited by HarbingerDawn - Thursday, 15.01.2015, 01:25
 
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