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Placidus
23-05-2018, 09:41 PM
A fairly deep M83 in monochrome. (We have a ways to go to match Paul Haese's 23 hour image).

Not going to get colour on this before next new moon, and we're too keen to leave it in the cupboard till then.

Total exposure 13.5 hrs. 6.5 hours in half hour subs this new moon, plus 7 hours in 1 hour subs from 2016.

Big one here (https://photos.smugmug.com/Category/Astrophotography-at-Placidus/i-TH5pRqv/0/4aed96cc/O/M83%20Lum%2013%20hrs%2030%20min.jpg )


In processing we had four goals:

- To preserve the detail close in to the galactic nucleus, without burning it out (only partially successful).
- To show the extensive faint halo (success)
- To show detail, including the intriguing and extremely faint outer ring around the inner of the two tiny galaxies close in at about 1 o'clock.
- To show as many other distant galaxies as possible. Although mostly tiny, their number is beyond counting. Sobering to think that each has say 200,000,000,000 stars.

We've not gone for a super-contrasty look in the mid-zones, which would have either changed the overall look of the galaxy or defeated the other goals.

An added surprise was what we guess will prove to be a quite detailed strand of star formation at the tip of the very faint spiral arm at two o'clock. The strand is oriented in an 11 o'clock 5 o'clock direction and is very thin. This strand seems concave away from the main galaxy. It is visible in Paul's Haese's 2016 image, but has come out very nicely here.

Paul mentioned that there appears to be a dark ring around the galaxy, which did not appear attributable to flats or processing. We see the same thing, and do not believe it is due to flats or processing either.

Also of some comfort was that the 2018 image and the 2016 image looked virtually identical, and the equipment is not degrading with time*.

Aspen CG16M on 20 inch PlaneWave on MI750 fork. As usual, scope, focus, and dome motors controlled using electronics built by us. Observatory firmware and software, and image processing software all written by MBJ.

Very best,
Mike and Trish

* Unlike our ride-on mower's hydraulics and Mike's elbows.

IanP
23-05-2018, 10:02 PM
WOW !!!
WOW !!!
and WOW !!!

batema
23-05-2018, 10:03 PM
Beautiful.

Atmos
23-05-2018, 10:20 PM
All four achieved, it’s an amazing result MnT!
Although you may not have managed the 23 hours of Paul, you’ve got S 20” vs a 12” and that makes a big photon count catch up.

As for the dark ring, I think it may be a psychological thing as the high contrast galaxy meets low contrast outer extension hits black. In that ring is a region of less bright stars which would be coincidence :)

kosborn
23-05-2018, 11:02 PM
Mach bands perhaps?

Kevin

rustigsmed
23-05-2018, 11:38 PM
whoa! nice one!
dark matter holding M83's stars in check confirmed! ;)

RobF
24-05-2018, 12:35 AM
Just stunning - reference image for this one for me at least now.
Looking forward to a future colour rendition!

Placidus
24-05-2018, 07:06 AM
Thanks Ian! :)


Cheers!



Thanks, Colin. You may well be right.



Had to look that one up.



Thanks Russell!

Atmos
24-05-2018, 07:56 AM
Hadn’t ever heard of that but that’s what I had in mind :)

gregbradley
24-05-2018, 08:19 AM
Wonderfully deep. I have wondered what those outer bands would look like.

Very patient of you.

Greg.

Placidus
24-05-2018, 09:19 AM
Thanks Greg.

We noticed a wonderful wide-field shot by Mike Sidonio, which shows that there is a distinct but very faint tidal tail about 4 or 5 galactic radii out from the centre. Sadly, that is way out of field in our shot.

multiweb
24-05-2018, 09:49 AM
That's a great shot Mike. Very well processed. :thumbsup::thumbsup::thumbsup:

Paul Haese
24-05-2018, 10:09 AM
I looks pretty bright to me and very deep already. The ring is clearly visible in your image and have often wondered about that. Perhaps it is Mach banding but I don't see this with other galaxies I have imaged. So it remains a mystery.

strongmanmike
24-05-2018, 11:25 AM
Wow excellent guys, very grand feel to this one and the dynamic range has been nicely handled :thumbsup: You know you are shooting deep on M83 when you can clearly see the curved Vader tie fighter (https://vignette.wikia.nocookie.net/starwars/images/b/ba/DVTX1.png/revision/latest?cb=20150827050808) panels that are at the end of the arms and perpendicular to the plane of the smaller of the two satellite galaxies at the edge of M83. The dark ring around M83 is a well known feature, it is in all shots of M83....as to what it is exactly..dunno?

The decon/wavelettes is just scraping under my radar too...so that's good..give yourselves a pat on the back :2thumbs:

Mike

Andy01
24-05-2018, 12:02 PM
+1^ above - what Mike and the others have said!
:bowdown:

Lognic04
24-05-2018, 12:49 PM
Simply stunning! So much detail!!! :eyepop:

Placidus
24-05-2018, 01:10 PM
Thanks Marc!



Cheers, Paul. Perhaps the dark ring was left by Hydra the water snake.

… at night the water, like a witch's oils, burned blue, and green, and white.



Thanks muchly Mike. Yes, definitely a Tie fighter.



Thanks Andy!



Many thanks Logan. :D

Camelopardalis
24-05-2018, 03:35 PM
Cracking shot M&T :thumbsup: that’s quite some faint extension, look forward to the colour additions.

alpal
24-05-2018, 05:44 PM
Hi Mike & Trish,
Great shot.

You've certainly shown the structure and dust lanes of those 2 tiny galaxies
which I believe are PGC 724525 and PGC 48132 -
about 600 million light years away.
They must be large galaxies to be visible so clearly from that distance.

2nd picture down here:
http://leylandobservatory.squarespace.com/spain-2014/day-191-monday-6th-october-2014-m83-pgc-724525-and-pgc-48132.html



cheers
Allan

Placidus
24-05-2018, 07:58 PM
Thanks Dunk!



Thanks Allan! 600 million light years is a long way.

-----

The seeing here at Placidus is 1.8 seconds of arc tonight - perhaps the best we've ever seen.

The sky was sparkling clear all day, but now thin cloud is washing in. It's almost reached where we were trying to photograph.

Waah! Boo!

SimmoW
24-05-2018, 08:14 PM
Amazing stuff, and that ring is mysterious, superb.

Placidus
25-05-2018, 04:04 PM
Cheers Simon!

gregbradley
26-05-2018, 08:24 AM
I have noticed that dark ring in my own images of M83 in the past. I always assumed I made a processing error like I used the lasso tool or something. Now I think its an actual thing.

Not just on M83 either.

Greg.

cometcatcher
26-05-2018, 09:17 AM
Wonderful image M&T! Really resolving those tiny background galaxies too. I try and process out the dark bands lol. Oops.

When images show so many background galaxies, I always wonder what sort of life might be there. So many opportunities for it!

Placidus
26-05-2018, 10:23 AM
Would love to know more about the dark ring.

If there really is a dark ring, it is because there is a lighter ring further out. Galaxies that have sustained a direct hit by another galaxy can have a faint outer smoke-ring. Others more typically don't have an outer edge, but fade gradually into intergalactic space. This one, as Mike Sidonio pointed out, does have a faint but photographable tidal tail much further out, but it is only partial.

Putting all that together, on balance, I'm inclined to think that this particular time, it's most likely an artifact of our processing.

RickS
26-05-2018, 07:55 PM
Fantastic detail, M&T! Dunno about the ring. Martin Pugh's CDK17 has been collecting data on M83 so I'll see if I end up with one too :)