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Author:  t00fri [ Sat, 20-10-18, 16:17 GMT ]
Post subject:  Re: Astrophotography...

By the way - I hope that I can try imaging the Draco Triplet you mentioned earlier, but it will have to wait for next year, maybe around April. Before that, our house is in the way - no unobstructed view in northern direction.

Well, Mother Nature can never be pushed aside ;-)
So I have some further time for fine-tuning the Draco Triplet display until April ...

Since my two collaborators are currently again in "pause" mode for professional reasons, I returned to galaxy rendering and texture aspects in the meantime.

E.g. I experimented with inserting another galactic "dust layer"(with a gradient) into the galaxy templates for the various Hubble types. This renders things a little more "washed out" like in the real Universe ...

Example of a Sb-type galaxy (NGC 6978):

[click on image for a bigger image]
ngc6978_Sb.jpg [ 40.12 KiB | Viewed 5161 times ]

Let's wait and see...


Author:  fenerit [ Tue, 13-11-18, 11:33 GMT ]
Post subject:  Re: Astrophotography...

Amazing shot of NGC 7331 group and Stephan's Quintet. You go deep, indeed! ;) 8)

Author:  schreiberste [ Fri, 16-11-18, 8:26 GMT ]
Post subject:  Re: Astrophotography...

Apropos deep... :D

This is my newest image: the perfectly edge-on galaxy NGC 891 next to the Abell 347 galaxy cluster.
The result could surely be improved by even more exposure time, but even now with 5 1/2 hours (199 x 100 seconds) there are a lot of faint galaxies visible.
The colors are more or less "artistic", as I really had a hard time to get naturally looking star colors across the whole image. Somehow there was a bad color gradient from the center towards the edges.
But I think for an image taken with a DSLR on a small 6" under always much too bright city sky it turned out quite ok ;)


File comment: NGC 891 and Abell 347
ngc891_2018-11_(199x100s_driz_hist_bgx_cc_dt_gimp_fw).jpg [ 2.2 MiB | Viewed 5024 times ]

Author:  t00fri [ Fri, 16-11-18, 11:17 GMT ]
Post subject:  Re: Astrophotography...


And as usual -for comparison- NGC 891 from celestia.Sci

A) Wide view with bright star HIP 11185 / HD 14771/ SAO 38002
n891.jpg [ 28.49 KiB | Viewed 5017 times ]

B) NGC 891 zoomed
n891_big.jpg [ 28.45 KiB | Viewed 5017 times ]


Author:  fenerit [ Fri, 16-11-18, 23:59 GMT ]
Post subject:  Re: Astrophotography...

Great Andromeda shot and screendumps!

Author:  fenerit [ Sun, 30-12-18, 12:51 GMT ]
Post subject:  Re: Astrophotography...

A target for color camera ^^. NGC 2237 (Rosette Nebula, Monoceros) 130mm f/6 refractor 1x180sec luminance binning 1x1. No flat/dark/bias. Bad cropped at 1024px.

Ngc2237_20181228232180sec1x1_L2_1024px.jpg [ 496.07 KiB | Viewed 4819 times ]

Author:  schreiberste [ Tue, 01-01-19, 15:18 GMT ]
Post subject:  Re: Astrophotography...

Excellent result for just a single exposure. With my unmodified DSLR I would probably have to capture hours of light to get anywhere near this.
But well, at the moment weather does not permit a single minute of photography...

Author:  schreiberste [ Sat, 05-01-19, 16:52 GMT ]
Post subject:  Re: Astrophotography...

Finally, one clear night again. And guess, what object I chose...?
The polar alignment was less than perfect, so the stars are far from round and needle-sharp.
This is a stack of 80 images, 100 seconds each.

File comment: Rosette Nebula
Rosetta_Nebula_2019-01_(80x100s_driz).jpg [ 712.26 KiB | Viewed 4758 times ]

Author:  fenerit [ Mon, 07-01-19, 20:39 GMT ]
Post subject:  Re: Astrophotography...

Well... you got it! Being not an imager I believed this nebula were somewhat easy; don't seem so.

Author:  schreiberste [ Mon, 07-01-19, 21:58 GMT ]
Post subject:  Re: Astrophotography...

Yes, it certainly is somewhat easy, the nebula is bright and large. Except that it is mostly emitting light in the lower red spectrum (H-II lines), which are filtered out by non-modified DSLRs for the largest part. Therefore, my image doesn’t look as deeply red as most photos taken with dedicated astro cameras or modified DSLRs. Anyway, I happen to like this look more, as some blue light (from oxygen?? Or maybe star light reflected by the gas?) is visible that way, which is otherwise swamped in the bright red.

Author:  fenerit [ Mon, 07-01-19, 22:36 GMT ]
Post subject:  Re: Astrophotography...

Blue are other hydrogen emission lines captured by the camera, mainly the H-beta which is made "darker" by the others along with the exposure. OIII lines should be a bit greenish; there is not much OIII in this nebula. OIII is abundant in planetary nebulae.

Author:  schreiberste [ Tue, 08-01-19, 7:45 GMT ]
Post subject:  Re: Astrophotography...

Ah, ok, thanks.
By the way, this is what a single unprocessed source image looks like out of my camera. It's the thumbnail preview image extracted from one of the RAW images.
Not much to see there after 100 seconds, especially in comparison with the image you posted!

Rosette_src_preview.jpg [ 94.85 KiB | Viewed 4694 times ]

Author:  fenerit [ Tue, 08-01-19, 12:56 GMT ]
Post subject:  Re: Astrophotography...

Ykes! :shock: There is nothing there aside the cluster. One of the advantages of CCD cameras and/or modified DSLRs is the sensibility in the far red. Moreover they are cooled to avoid IR heat/noise (your RAW frame is an example); we operate with sensor's temperature around -40°C. Imagine what can do those cooled by liquid nitrogen...

Author:  schreiberste [ Tue, 08-01-19, 13:44 GMT ]
Post subject:  Re: Astrophotography...

fenerit wrote:
Moreover they are cooled to avoid IR heat/noise (your RAW frame is an example);

Are you sure that you are seeing IR heat/noise in this image? Are you referring to that brown background with heavy gradients? I think that this is rather caused by a combination of the heavy light pollution in my area and some vignetting.

Author:  fenerit [ Wed, 09-01-19, 0:12 GMT ]
Post subject:  Re: Astrophotography...

Is that light pollution? Too bad. I wonder how do you got the Abell cluster or the Stephan's Quintet...

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