NGC1365 - Great Barred Spiral Galaxy

[PRejto (Peter)]

The great barred spiral galaxy located ~ 56 million light years distant in Fornax. It is 2x in length the size of the Milky Way.

This photo is the 3rd experiment using the AstroPhysics Barlow - BARADV this time with a TEC180FL, and first time use of the Player-One Poseidon-M using Deep Sky Astronomic filters.

Effective focal length was f14 or 2,520 mm at a resolution of .31 arc sec. Guiding was at bin 4 using an SX Ultrastar on a Paramount MEII.
13.5 hours of data was collected, but only 10 hours survived culling. All subs were 480 sec:

27 luminance (Astronomik CLS) 3.5 hours
18 Red 2.5
14 Green 2.0
15 Blue 2.0

Total: 10 hours

All processing was in Pixinsight.

I'm probably done for now with these experiments. My conclusion is that a barlow can certainly be considered when one hopes to achieve a greater imaging scale and resolution. Yes, there is certainly some cost in imaging time, but I did not think the cost was unreasonable given the results. Also, considering that seeing is more often than not the limiting factor in resolution, achieving an image scale equal to that of a non-existant TEC-360fl, the cost of the BARADV is miniscule! Certainly a 14" OTA will have the potential to achieve a fantastic resolution, but more likely than not, it would need a home in the Andes! There is also the notion that BlurX works best on over sampled data, of which mine certainly was. I also drizzled in Pixinsight and saw marked improvement in resolution even though drizzling is supposed to only work for under sampled data. Anyway, I'm glad I ran these experiments. The large image scale is a lot of fun!

Thanks for looking!

Peter

https://www.astrobin.com/q8w83n/

[alpal]

Hi Peter,
what a fantastic picture of the galaxy.
It's getting close to the results of giant telescopes.

The background looks a little strange as though something is missing.
Did you use DBE in PixInsight?
https://jonrista.com/the-astrophotog...undextraction/

cheers
Allan

[PRejto (Peter)]

Hi Allan,

Thanks for your comments.

As for the background, yes I did use DBE on both colour and luminance which was primarily a vignetting effect that I guess the flats did not completely take out. Personally I think the background is maybe too dark at around.08. I initially had it brighter and got some complaints. Perhaps it's too smooth and that is what you are reacting too? Anyway, I'm totally over - at this point - any further processing. I think I would go totally bonkers!

P

[alpal]

Originally Posted by PRejto

Hi Allan,

Thanks for your comments.

As for the background, yes I did use DBE on both colour and luminance which was primarily a vignetting effect that I guess the flats did not completely take out. Personally I think the background is maybe too dark at around.08. I initially had it brighter and got some complaints. Perhaps it's too smooth and that is what you are reacting too? Anyway, I'm totally over - at this point - any further processing. I think I would go totally bonkers!

P

Sorry Peter,
I didn't mean to cause you any distress.
It's just that every other picture I look at seems to have far more stars
and a lot more going on in the background - examples:

https://astropixels.com/galaxies/NGC1365-CDK21-C01.html

https://apod.nasa.gov/apod/ap171012.html

https://upload.wikimedia.org/wikiped...red_Spiral.jpg

I just thought that since those stars look brighter than the galaxy halo they should appear in your image.
Then I thought maybe DBE in PixInsight had removed many of them?
I could be wrong and maybe in a few months you could have a 2nd look?
Still - you have a wonderful image that you should be proud of.

cheers
Allan

[PRejto (Peter)]

Okay, no worries! That is quite a fair comment. I think I know what happened there. My initial attempts at processing were not satisfying. One problem was the stars looked a bit blown when I knew they were not. On this last attempt I did an initial mild linear stretch and decided to use that stretch for the stars. I guess I was too conservative! This wouldn't be too hard to fix...but I won't do it soon, that's for sure. When you sit and look at an image for hours and days there is something mad about this hobby.

P

[alpal]

Originally Posted by PRejto

Okay, no worries! That is quite a fair comment. I think I know what happened there. My initial attempts at processing were not satisfying. One problem was the stars looked a bit blown when I knew they were not. On this last attempt I did an initial mild linear stretch and decided to use that stretch for the stars. I guess I was too conservative! This wouldn't be too hard to fix...but I won't do it soon, that's for sure. When you sit and look at an image for hours and days there is something mad about this hobby.

P

Thanks Peter,
I'm not in the same league as you but I'm glad I could still be of assistance.
I only wish that I could get my much more humble equipment to a dark site and take some nice pics.

cheers
Allan

[strongmanmike (Michael)]

Nice image Peter

Cool approach too, with an awesome scope

Mike

[gregbradley]

That's a phenomenal image Peter. Congrats.

Greg.

[Dennis]

The galactic structure, all the tendrils and other regions are stunning in the full res version.

Well done.

Dennis.

[Ryderscope (Rodney)]

Great work Peter. I like your innovative approach turning a hefty refractor into a long focal length instrument. Clever!

[PRejto (Peter)]

Thanks Rodney!

I have to admit that my experiment was just a long standing idea that someday I would test out the barlow this way. It sat in a drawer for many years after reading about it on the AP website. Obviously Roland C knows of what he speaks, so the idea was intriguing. With all my issues with my large heavy KAF16200 camera, while Josh was busy making numeroues adapters and corrections, the opportunity presented itself.

After the fact I was pointed to Russ Crowman's MTF webpage. The numbers are very interesting. Whilst some years back it was common practice, I believe, to recommend an imager like the KAF8300 or KAF6200 for an OTA with a focal length of around the 1 meter mark, advice certainly seems to be shifting in the direction of what would have been considered over-sampling.

Take a look at the two comparisons below. The first shows my TEC180 at f7 with the KAF16200 CCD. It appears to be seriously under sampled. Then just adding a smaller pixel size camera, the IMX571 nearly perfects sampling. The barlow completely wipes away the under-sampling and provides quite a lovely image scale to boot.

Now, I'm back setup with the KAF6200 CCD and wondering if I'll be satisfied with it!

P

[wasyoungonce (Brendan)]

I'm loving the dust details