Author Topic: Galactic Center Mosaic  (Read 4907 times)

Offline Ignacio

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Galactic Center Mosaic
« on: 2014 July 01 12:25:44 »
Last Friday, I tried for the first time this combination: a full-frame canon 6D with an old SMC Takumar 75 mm f/4 lens (which had proven to be a great performer with APS-C size sensors). I targeted the galactic center, due to its perfect position in the sky this time of the year from my location.

The lens was stopped down to f/5.6, and 12x5-minute shots were taken on each pane. Although there is some distortion towards the corners of the frame, which in part I attribute to a tilted lens mount as one side is considerably worse than the other, the overall performance is very good.

The 3x1-pane mosaic registration and assembly proved to be quite a challenge, due to optical geometric distortion. I ended up using ImageSolver and MosaicByCoordinates. These are remarkable and powerful tools to deal with wide field mosaics. My appreciation to Andres Pozo for such impressive contributions!

I like the final result very much, and hope you do too.

low-res with data: http://www.pampaskies.com/gallery3/Wide-Field/GalacticCenterMosaic_lowres

hi-res: http://www.pampaskies.com/gallery3/var/fulres/GalacticCenterMosaic_hires.JPG

best,
Ignacio

Offline Enzo De Bernardini

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Re: Galactic Center Mosaic
« Reply #1 on: 2014 July 01 15:47:30 »
Amazing!

Offline marekc

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Re: Galactic Center Mosaic
« Reply #2 on: 2014 July 01 15:50:16 »
That's a very nice image! I liked the south-up orientation; it made for a fun time identifying objects like M8, M24, M16/17, etc, compared to the usual `north-up' view that we have here in the northern hemisphere!

- Marek

Offline Alejandro Tombolini

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Re: Galactic Center Mosaic
« Reply #3 on: 2014 July 01 18:27:37 »
Wow!, very well done Ignacio. Congrats!.

Saludos. Alejandro.

Offline kolec

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Re: Galactic Center Mosaic
« Reply #4 on: 2014 July 01 22:55:16 »
Perfekt

Offline Ignacio

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Re: Galactic Center Mosaic
« Reply #5 on: 2014 July 02 06:34:09 »
Thank you Marek, Ale, Enzo and Kolec. Your feedback is much appreciated.

Marek: As you correctly pointed out, this is how we see it from the southern hemisphere. I though about rotating it, but I like how the Antares complex with the "blue horsehead" is framed in the southern view. Is funny how the brain works in this way, isn't it?

best
Ignacio

Offline Juan Conejero

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Re: Galactic Center Mosaic
« Reply #6 on: 2014 July 02 11:01:16 »
I normally don't comment on Gallery images, but this time I can't help myself. Absolutely wonderful!
Juan Conejero
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Offline Ignacio

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Re: Galactic Center Mosaic
« Reply #7 on: 2014 July 02 13:47:02 »
Thank you, Juan, that means a lot.

Ignacio

Offline Andres.Pozo

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Re: Galactic Center Mosaic
« Reply #8 on: 2014 July 02 15:06:35 »
A really great image Ignacio. I have never seen the galactic center like this.

Offline Ignacio

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Re: Galactic Center Mosaic
« Reply #9 on: 2014 July 02 18:58:21 »
Thank you, Andrés, you made it possible with those impressive tools.

BTW, I cannot plate-solve the mosaic with ImageSolver. Could it be due to the Mercator projection? I tried many combinations: thousands of star, hundreds of stars, no distortion, 3rd order, 5th order, linear stack, fully process image, you name it. Each panel solves nicely, though, that's why I suspect it could be the projection.

Many thanks,
Ignacio

Offline AstroScience

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Re: Galactic Center Mosaic
« Reply #10 on: 2014 July 02 23:07:42 »
Ignacio, trully incredible result. High resolution image is more than impressive. Wallhanger for sure, well done.

Offline Andres.Pozo

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Re: Galactic Center Mosaic
« Reply #11 on: 2014 July 03 00:18:30 »
BTW, I cannot plate-solve the mosaic with ImageSolver. Could it be due to the Mercator projection? I tried many combinations: thousands of star, hundreds of stars, no distortion, 3rd order, 5th order, linear stack, fully process image, you name it. Each panel solves nicely, though, that's why I suspect it could be the projection.
Yes, you are right. ImageSolver can not solve wide field images which are not in gnomonic projection.
However, the result of MosaicByCoordinates is already solved. It has all the FITS keywords necessary for AnnotateImage. If you have cropped or resampled the image you can use CopyCoordinates for translating the coordinates matrix between both images.

Offline Ignacio

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Re: Galactic Center Mosaic
« Reply #12 on: 2014 July 03 06:17:39 »
Great, thank you Andrés, I will try that and come back to you if I have any problems.

Ignacio

Offline Ignacio

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Re: Galactic Center Mosaic
« Reply #13 on: 2014 July 04 18:12:14 »
Andrés: the CopyCoordinates approach worked perfectly! Thanks.

Ignacio

Offline JoLo

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Re: Galactic Center Mosaic
« Reply #14 on: 2014 July 11 11:57:17 »
Ignacio - one word, three letters - WOW.
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