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Astrophotography...
http://forum.celestialmatters.org/viewtopic.php?f=9&t=927
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Author:  schreiberste [ Sun, 03-03-19, 15:14 GMT ]
Post subject:  Re: Astrophotography...

A new image: the Coma Cluster.
Taken with the usual setup, stack of 301 images of 100s each (8:21 hours total exposure time).

This is perhaps not the most beautiful astro photo ever taken, but it totally amazes me, how many galaxies are visible in an image taken by an amateur with quite simple equipment!

Fridger, as always I would love to see the celestia.Sci rendering :)
I have no idea, how many of those tiny galaxies are included in the catalogs coming with Celestia?

Grüße,
Steffen

Attachments:
File comment: Coma Cluster
Coma-Cluster_2019-02_(301x100s_cal_driz_newbgx_phcc)_4k.jpg
Coma-Cluster_2019-02_(301x100s_cal_driz_newbgx_phcc)_4k.jpg [ 1.11 MiB | Viewed 2457 times ]

Author:  schreiberste [ Sun, 03-03-19, 15:18 GMT ]
Post subject:  Re: Astrophotography...

And another one: M95, M96, M105, NGC 3371 and NGC 3389

318 x 100s (8:50 total exposure time)

Attachments:
File comment: M95, M96, M105, NGC 3371 and NGC 3389
M95,M96,M105_2019-02_(318x100s_cal_driz_bgx_phcc_asinh_hist)_4k.jpg
M95,M96,M105_2019-02_(318x100s_cal_driz_bgx_phcc_asinh_hist)_4k.jpg [ 888.98 KiB | Viewed 2457 times ]

Author:  t00fri [ Sun, 03-03-19, 17:53 GMT ]
Post subject:  Re: Astrophotography...

Hello Steffen,

nice to enjoy more of your deep-sky astro photos after a while. I am VERY impressed how many DSOs you can see! Celestia.Sci is also doing pretty well. Have a look:

Coma cluster:

[Click on images by all means for a bigger size]
Attachment:
Screenshot_20190303_184007.png
Screenshot_20190303_184007.png [ 116.83 KiB | Viewed 2451 times ]


M 95, M 105 etc
Attachment:
Screenshot_20190303_183301.png
Screenshot_20190303_183301.png [ 100.16 KiB | Viewed 2451 times ]


Zoomed into the M 105 region:
Attachment:
Screenshot_20190303_183608.png
Screenshot_20190303_183608.png [ 247.29 KiB | Viewed 2451 times ]


The orientations of the galaxies are also pretty good...

Cheers,
Fridger

Author:  schreiberste [ Sun, 03-03-19, 19:01 GMT ]
Post subject:  Re: Astrophotography...

Indeed, the celestia.Sci renderings are very good, as good as they can be just from the limited data the catalogs provide! Even the almost ring-like shape of the outer arms of M96 show pretty good.

The colors also match quite well. I was not so sure about the very strong blue tint of NGC 3389, but your screen shots convince me that it is for real and my color calibration was not too far off.

Grüße,
Steffen

Author:  t00fri [ Mon, 04-03-19, 7:56 GMT ]
Post subject:  Re: Astrophotography...

schreiberste wrote:
...
The colors also match quite well. I was not so sure about the very strong blue tint of NGC 3389, but your screen shots convince me that it is for real and my color calibration was not too far off.

Grüße,
Steffen


Indeed, Steffen, below is your excellent photo-realistic :lol: version of the M 105 environment! The matching with celestia.Sci is really close, given that the colors of my galaxies are a purely theoretical prediction, depending on the B-V color index from the catalogs and the color (filter) profile used during the shot. Since celestia.Sci always refers to the SDSS profile, the remaining rotation in color space can possibly still make some differences...Qualitatively, low values of B-V < 0.5 give blue galaxies and high B-V (near 1) give orange colors. Most elliptics have high B-V > 0.7 and thus are orange.

[Click on image by all means for an appropriate bigger size]
Attachment:
m105_schreiberste.png
m105_schreiberste.png [ 883.19 KiB | Viewed 2438 times ]


Cheers,
Fridger

Author:  t00fri [ Wed, 06-03-19, 19:53 GMT ]
Post subject:  Re: Astrophotography...

Steffen,

are there some chances that you can photographically reach these two interacting fellows (NGC 3786 and NGC 3788)?
[Click on the image for an appropriate size]
Attachment:
Screenshot_20190306_172636.png
Screenshot_20190306_172636.png [ 323.2 KiB | Viewed 2372 times ]


Here is a nice SDSS photo:
https://de.wikipedia.org/wiki/Datei:NGC ... S_DR14.png

Cheers,
Fridger

Author:  schreiberste [ Thu, 07-03-19, 7:48 GMT ]
Post subject:  Re: Astrophotography...

t00fri wrote:
are there some chances that you can photographically reach these two interacting fellows (NGC 3786 and NGC 3788)?

Each of these is slightly smaller than blue NGC 3389 above, so it should certainly be possible, but not a lot of detail can be expected.
Could be a good photo anyway, if the field is interesting...?

On the other hand - there are still so many objects on my TODO list, and the weather doesn't play nice with me...

Author:  t00fri [ Thu, 07-03-19, 13:47 GMT ]
Post subject:  Re: Astrophotography...

Steffen,

Quote:
and the weather doesn't play nice with me...


Despite the partially horrible weather, this Astrophotography forum enjoys quite a lively interest
(> 11400 reads and 118 writes!)
not least thanks to your and fenerit's active and interesting contributions.. :clap:

Cheers,
Fridger

Author:  Guckytos [ Sat, 09-03-19, 17:56 GMT ]
Post subject:  Re: Astrophotography...

Well Fridger,

that's no big wonder as this thread is one of the few places where we can actually see good real life star photos and then coming from you the Celestia.Sci renderings.

We normal ones, can't do the renderings as Celestia.Sci is still not released and noone has an idea if it ever will be. You are starting to put "It's done, when it's done" into a new league. Duke Nukem is starting to look worried :twisted:

Apart from that rant: Real nice photos Steffen, keep going!

Regrads,
Christian

Author:  LukeCEL [ Sun, 10-03-19, 2:26 GMT ]
Post subject:  Re: Astrophotography...

Not sure if this is off-topic, but is there any chance we can see lenticular galaxies in Celestia.sci? The original renderings in Celestia look a bit like lumpy purple discs :lol:

Author:  t00fri [ Sun, 10-03-19, 9:02 GMT ]
Post subject:  Re: Astrophotography...

LukeCEL wrote:
... is there any chance we can see lenticular galaxies in Celestia.sci?...


Sure... :D
since Celestia times, I have put a lot of theoretical research into the rendering of galaxies in general, as well as of elliptical (E-type) and lenticular (S0-type) galaxies in particular. I have re-coded the rendering from scratch using modern (VBO) shader techniques. For elliptical and lenticular galaxies this led to photo-realistic displays. Note that for all galaxies the coloration (SDSS color profile) is computer-based (automatic).

Here are two examples:

Head-on view: NGC 524:

On the left, SDSS (Sloan Digital Sky Survey, DR14) photo
on the right, celestia.Sci rendering

[Click on image for a bigger size by all means]
Attachment:
lenticular_ngc524.png
lenticular_ngc524.png [ 186.74 KiB | Viewed 2279 times ]


Side-view: NGC 5308:

On the left, Hubble photo
Image credit: NASA / ESA / Hubble / Judy Schmidt, http://www.geckzilla.com.
on the right, celestia.Sci rendering

[Click on image for a bigger size by all means]
Attachment:
lenticular_ngc5308.png
lenticular_ngc5308.png [ 187.64 KiB | Viewed 2279 times ]


Cheers,
Fridger

Author:  LukeCEL [ Sun, 10-03-19, 18:08 GMT ]
Post subject:  Re: Astrophotography...

Looks very nice, although they do look a bit more orange-colored than the Hubble photos. I wonder why that is?

Author:  t00fri [ Sun, 10-03-19, 19:39 GMT ]
Post subject:  Re: Astrophotography...

LukeCEL wrote:
Looks very nice, although they do look a bit more orange-colored than the Hubble photos. I wonder why that is?


Note: As emphasized above, celestia.Sci refers to the SDSS color profile NOT to the Hubble one! The Hubble color profile differs substantially from that in SDSS which I use as a starting reference in celestia.Sci. To map one profile to the other, one needs to perform certain rotations in color space! These in turn may be determined from the filter hardware used in the respective photographic exposures. Meaning: Color is not an absolute concept in astro-photography! It's all very analogous to the so-called "color management" in computing (*.icc files applied to monitor, printer etc.).

In my first example (head-on view of NGC 524) I have therefore used an SDSS photo for comparison, which matches pretty well the celestia.Sci color. That's how it should be!

Cheers
Fridger

Author:  LukeCEL [ Mon, 11-03-19, 1:45 GMT ]
Post subject:  Re: Astrophotography...

Ah, I see. The renderings do look very close to the SDSS pictures :)

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